Mutual Power Hercules 610 Review

[jbs24]

I've been gleaning information of this board for a while and I just wanted to give my two cents cause Mutual Power seems like a newly offered brand and not much is known about them.

I just got a Hercules 610 after using a Klippermate for years. Wanted fixed clamps and 6-point mounting. Drop weight is fine for me since I only string a few racquets a month. I string mostly squash racquets and a few tennis. Supposedly it can do badminton racquets as well.

Pros:
Nice design, easy 6-point mounting
Don't need allen wrenches for adjustments, can do it all by hand
Linear, ratcheting string gripper is nice
Drop-weight arm has stops so it won't hit floor or stringer.
Comes with two drop-weights for badminton/tennis stringing tension ranges
Fixed clamps are very handy compared to flying clamps that i'm used to (worth it just for this)
Price is great. Comparable units cost a few hundred dollars more.
Came with 12 sets of different string, some are nice multifilaments and hybrids.

Cons:
Tension scale "factory calibration" was off a bit. Using a tension scale calibrated to free weights, the stringer tension was about 10% too high. Had to peel and restick the tension scale.
Have to make minor modifications to the stringer to have 2 of the 6 points reach my squash racquet heads---ones with narrower, tear-drop shaped bases.
Fixed-clamp posts have a little play in the bases. I would have hoped for slightly better tolerances

I would expect that more expensive, professional units be slightly higher quality all-around, but for the price, this is a great unit that will pay for itself in no time.

 

[palikero]

Cons:
Tension scale "factory calibration" was off a bit. Using a tension scale calibrated to free weights, the stringer tension was about 10% too high. Had to peel and restick the tension scale.


I would expect that more expensive, professional units be slightly higher quality all-around, but for the price, this is a great unit that will pay for itself in no time.

JBS24 :
I just received my Herc 610 and would like to calibrate it to correct tension. Can you please go into detail as to how to recalibrate it? And what tension scale are you referring to that you had to peel and restick?

Thanks for the help.

 

[dancraig]

Hopefully, your machine is correctly "calibrated". I think he was referring to the strip with the pound/kg numbers printed on it. I'm thinking that he peeled it off the bar and placed it in a little different location to make the tension pulled match the number indicated. You could check that with a tension calibrator.

 

[dancraig]

I communicated with him in the past. He is a good guy and I think he would email you back if you sent him a question. Just click on his user name to email him. Good luck.

 

[jbs24]

JBS24 :
I just received my Herc 610 and would like to calibrate it to correct tension. Can you please go into detail as to how to recalibrate it? And what tension scale are you referring to that you had to peel and restick?

Thanks for the help.

Yes, Dancraig is right, I had to test the dropweight at different positions to get and idea of what tension was produced at each position.
I don't think any machine's stickers are totally correct throughout the whole range, so just pick a range where you think you'll be using it most and go with that.

 

[danotje]

Hi, all. This is my first post on this board, although I've been checking it regularly for some time now. I've finally decided on a machine and should be receiving a Herc 610 sometime in the next week or so. Since there isn't a lot of info out there on it (and yet I still decided on getting it above some other notable machines), I thought I'd add my own review on to this one to help some other people with their decision. Give, not take, right? Although I've been playing for awhile, I've never strung my own racquet. Like most everyone else, I don't like forking-out money for something I believe I can do, and sometimes, like my current situation, it is difficult to find someone who can string.

My first impression with MP is good. Mr. Young answers my emails within a day (I'm in the UK atm) and always provides good info. He also worked out how to ship it over here to an APO address, which is what killed my first choice--although I've always considered the 610 due to its features, price and perceived rep. More on that in the review. Like I said, I should be receiving it soon and will post my thoughts in case anyone else is looking at this machine/company.

Regards,

Dan

 

[dlo]

I have had my Hercules 610 for a couple of weeks now. I have strung 5 rackets and now it sits in the corner on end with a pillow case cover. I would love to string more, but it was bought as an occasional toy. I second what jbs24 had to say about it. For me it fit the bill and still does. I expect to get my money back in time. The fixed clamps are a nice feature.

 

[meh]

Mr. Young is very helpful and prompt in his responses. While Mutual Power doesn't make the highest quality machines (the finish is a bit suspect), they're a great value, without having to turn to Eagnas, and are great for occasional at-home stringers. I also own the Herc 610, and will probably look at a MP crank machine in a few years, when I have the money.

 

[TonyB]

Any further information on the 610 machine? How do those fixed clamps perform? Has anyone else who has used this machine noticed that the clamps have excessive play when clamped?

I guess if you had some small amount of "drawback" on the clamps when the tension is released, it would basically be similar to a flying clamp anyways. But it would still have the benefit of the convenience of a fixed clamp, so it should be better, right?

I don't mind doing a little bit of deburring or minor modifications to the unit to get it straightened out, I guess. The price is right and if the machine is durable and the clamping system is acceptable, then it seems like a good machine.

Have you guys discovered any problems or issues with your machines now that you have had a little bit of time to use them?

 

[dlo]

Hello: my name is dlo, and I am addicted to stringing.
I have had mine for over a month now. I have done 9 rackets. I was exited about buying a machine and did a bit research and decided that the 610 was close enough for what I wanted. It is not for making money, but rather for me to take my time and enjoy stringing my family’s rackets. All that a side, you must bite the bullet and pick one. If you are planning on stringing a lot and for others, I would not get the drop weight. In that case it looks like all of MP’s clamps are the same except glide rails. You might feel safer with a big name. If you keep coming back to the 610, then get it with the understanding that you can sell it or throw it away and start over. I know where you are coming from and it looks like a good deal. I personally have had no problems with mine or the purchasing process. It is what it is, but 2 months ago I could not string my own rackets and now I can. Do something.

 

[TonyB]

Another perspective

Ok, I promised everyone that I would do a complete review on the Hercules 610 stringer when I received it. Well, I received it today and had the chance to take it out of the box. I just wanted to get my first impressions written down so that I could move on to setting up the machine and stringing a racquet.

Before I start, I just wanted to mention that I am a mechanical design engineer and have worked in industry for over 15 years. I don't give praise lightly and I am fairly critical of almost every piece of equipment that I've ever come across. I make it a habit to look for flaws in design and how they can be corrected. Ok, now on to the review.


First off, I had no trouble with the ordering and shipping process. The machine arrived in a week's time, no problem. I didn't expect any problems, but it's always nice when things go smoothly.

The unit is made in Taiwan, it says so right on the box. But I didn't want to form any preconceptions about it, so I just opened the box and took a peek.

The user's manual is not the greatest. It has a pretty rough picture of the machine and a list that shows you what's what. But honestly, if you're going to buy a machine like this (bargain price, entry-level, lack of public information on the net, etc.), you really should do some preliminary research and know what to expect before you buy. I knew what to expect and did not count on the user's manual to guide me through the stringing process. That being said, it would be a nice touch if they could renovate the manual a bit so that their product looks a little less "cheap."

The unit's fit and finish is actually surprisingly clean. The paint job is almost a "powder coating" style of paint, and looks to be pretty durable. I could find no instances of any burrs or sharp edges anywhere on the machine. In fact, the linear tracks for the cone-lock fixed clamps have clearly been chamfered and deburred, then oiled. Once the lever arm has been sufficiently loosened, the clamp slides very easily along the track using only one-handed operation.

The turntable is very solid -- 1/4" thick aluminum (again, powder coated), reinforced with 1/4" steel tracks for the fixed clamps. The table is very, very solid.

The 6-point mounting system looks to also be top-notch and each "point" is infinitely adjustable -- they're spring-loaded arms that are extended or retracted via a knob/screw combination. Very clean, very easy to use, and as I said, allows infinite adjustment.

The clamps that hold the racquet onto the 6-point mounting system are all covered with 1/8" thick textured hard rubber pads. It appears that they will allow a very sturdy mounting for the racquet without risking any damage to the frame itself.

The cone-lock clamp bases are very nice, quite frankly. The play in the vertical clamps is minimal -- probably around 0.005" radial clearance in the tubes. Obviously, the higher they are raised, the more sideplay they have because of the increase in clearance angle between the plunger and the tube. But that's not really a big deal. If the clamp itself moves any more than 1/16", I'd be very surprised. It's more like 1/32" nominally. The sliding base clamps down very securely with less than one-half turn of the lever. Closer to 1/4 of a turn, I'd say. It locks very securely.

The linear gripper seems to be functional. I haven't strung a racquet, but the ball bearings inside the linear gripper seem to be very simple in design, which doesn't allow for too many things to go wrong. I'll make sure I check to see how well it actually grips the string and update this review at a later date. The clutch is a non-ratcheting clutch -- it's continuously variable, allowing infinite adjustment of the weight arm. It is very smooth in operation and appears to be well lubricated. The ball bearings inside the clutch housing seem to be sturdy and should perform well for a long while.

Ok, the machine isn't perfect. I found a small issue with some excessive friction (only a pound or two, mind you) in the clutch bearing hub. But after disassembling it and retightening the hub, I was able to eliminate it so that the entire assembly moves a complete 360 degrees without any noticeable friction at all.

Another imperfection is with the fixed clamps. They claim to be "diamond-dusted" but I cannot verify that feature. It almost appears that the clamps are simply "textured" aluminum, but I haven't put them under the microscope to verify anything. If there could be an improvement to this machine, it would definitely be in the clamp jaws. But as I said, if they hold the string tightly without slippage, then I guess I can live with them. If nothing else, I'll be able to take a file to them and make some small grooves in the metal which will help the gripping surfaces perform better. I have no problem modifying the clamps if they are insufficient, but it would be nice if they were a little better manufactured. Also, they don't seem to grip 100% evenly across the length of the clamp jaws -- one side is noticeably tighter on the string than the other. Again, not a really big deal, as long as the string isn't damaged and the clamp jaws hold securely enough to prevent slippage.

And the final issue that I've noted is with the braking system. Basically, it's a knob-screw system that locks the turntable directly at the hub. However, it does not do a very good job and tends to hang up, adding a significant amount of friction to the turntable when you attempt to rotate it. I've played with it a bit and finally got it freed up, but I believe that I may have to disassemble the turntable from the base and see what's wrong with it if it continues to act up. Again, this is a somewhat minor issue, since most entry-level machines don't even have a braking system to begin with.

Overall, this is a pretty well-engineered piece of equipment. I have no issues with the fit and finish of the machine whatsoever. All facets of the design appear to be functional and sturdy enough for long-term use. Aside from the few very minor issues that I've noted above, everything about the machine design indicates to me that I made a good purchase. While this machine won't win any prices for Best Stringing Machine Ever Made, it most certainly must be very far from the worst.

Oh, one more thing I just noticed. There is a small white dot on both the clutch hub and the support housing for the weight arm. I checked the arm with a bubble level and found that the two dots were perfectly aligned when the arm was sitting at 0.0 degrees (horizontal). I did a quick calculation on what distance a +/-10-degree variation would have on the travel of the hub and it turns out to be around 0.4" total. So, I made some indications with a Sharpie marker on the support housing at +/- 0.2" from the center of the dot. These marks now indicate the rotational limits of the hub to hold the string tension within a +/- 1 lb. range. The amount of travel allowed for the arm to swing within those limits is actually surprisingly large. So, if you have one of these machines, put a mark at a distance of 0.2" on either side of the white dot on the support housing and you'll ensure that your stringing tension is within +/-1 lb.

Unless some major problem rears its ugly head while I'm stringing a racquet tomorrow, I think I'll be quite satisfied with this purchase for a long time to come and would recommend this machine to anyone who has a small budget and wants a fixed-clamp, 6-point-mounting-capable machine.


More to follow after I get some time to string a racquet. I promise.

 

[TonyB]

Ok, I've gotten more into setting up and calibrating the machine. I set up the weight to the "40 lb." position on the arm. I wanted to see what the actual pulling force was at the hub.

Using a calibrated scale (8 lb. max), I was able to measure the load at a distance of 14.125" from the center of the hub to be 4.3 lb. This gave a torque of 60.73 in-lb. Now, the hub where the string is tensioned is exactly at a radius of 1.25" from center. So, taking 60.73 in-lb. divided by 1.25" gives 48.6 lb. of "tensioning" force. This is approximately 20% off on the high side from the 40 lb. set point.

I set the weight on the arm to the "60 lb." position as indicated by the scale and repeated the measurements/calculations. This time, I got exactly 70 lb. of "tensioning" force. This is less than 20% off, but still quite high.

It appears that not only is the scale inaccurately delineated , but it is also inaccurately positioned. I would suggest that anyone who has this machine double- and triple-check the tension calibration to make sure you know what tension is REALLY applied, as the "calibrated scale" is surprisingly very far off.


EDIT: I just tried lifting a 50-lb. free weight (calibrated) using the machine oriented vertically and was just barely able to lift the 50 lbs. with the arm indicating "50 lb.". At the 45 lb. setting, I was unable to lift the free weight. At the 55 lb. setting, the weight lifted very easily.

So, for whatever reason (friction in the bearings under load, maybe?), the arm appears to be able to apply the correct load to the string when acting against a known resistance. I'm not sure exactly how this will translate into the racquet strings, but at least it appears to be a little closer than I originally calculated.

Or maybe I just need a REAL spring tension calibrator?

 

[TonyB]

Not off to a good start here.

On my first attempt, using el-cheapo Ashaway Liberty 16g strings for practice, the string broke at hole 4H, right at the grommet. From what I can tell, the string was not damaged in any way at that point. It was a clean break.

Sigh. There goes one string set into the garbage before I even got started.

I still have another set. Wish me luck.

 

[TonyB]

Ok, switched to some Klip Kicker 17g synthetic gut and finished the racquet. No problems this time around. Took probably around an hour to get everything finished up.

I must admit that the machine seems pretty easy to use. The linear gripper takes a bit of getting used to... you really need to have it in the right starting position BEFORE inserting the string, because as the string stretches and the drum goes around and around... the back side of the linear gripper can make contact with the string as the drum turns around 180 degrees or so from the starting point. So, in order to get it reset, you need to release the tension, then FORCE the gripper jaws open with your fingers to release the string. Not fun, but at least you can prepare for this in terms of positioning the linear gripper correctly to start with. I had no problems once I found the correct starting position.

The stringbed does seem pretty damn tight. I'll bet that it's at least 5 pounds or more higher than the set point. I knew I should have trusted my original calculations!

I am going to string up my backup racquet with the same string, only starting 8 pounds lower this time. I know it seems like a lot, but this is a pretty stiff racquet to begin with and I want to make sure I can FEEL the difference in tension when I play. At least the two racquets should tell me if I'm close at either tension.

One other thing: after I finished stringing up this frame, I laid a new frame over the top of the freshly-strung racquet. The strung racquet is noticeably shorter (1/16") and the top of the hoop is compressed (wider at the head than at the throat). Is this normal? I don't think I've ever compared a new frame with one that's strung.

 

[dlo]

Didn't you get 12 different sets of string with the purchase?

 

[TonyB]

No. No strings. Free shipping, but no strings.

I still would like to know if the frame distortion is normal. The stringbed does seem awfully tight!

 

[dlo]

Must have been a promotion. I am an industrial designer and did my research as well that lead me to the 610. I agree with your assessment and still think I am happy after 11 string jobs. I think that the scale is 10 lbs to heavy. I haven’t noticed any racket distortion at 50 lbs (for 60 lbs) and even if I am wrong, the job seems tight and plays great. Write Mr. Young back and see if you were supposed to get some string. It really made the first jobs easy knowing the string was for free.

 

[Richie Rich]

No. No strings. Free shipping, but no strings.

I still would like to know if the frame distortion is normal. The stringbed does seem awfully tight!

what racquet is it? did you have the racquet properly mounted and secured? sometimes if it is lose the racquet can deform a little. most racquets, if properly secured should not deform, even when going outside the tension range by a few lbs

 

[TonyB]

Nope, it was completely secured. It's a Head i.X3. What apparently happened was that the throat section actually pulled inwards a bit, leaving the outer clamps for the 6-point mounting system slightly loose.

The head of the racquet subsequently applied additional force to the outer clamps, which were tight before I removed the racquet. Once the racquet was removed, the head must have bowed outwards slightly.

I strung my backup racquet (identical frame) at 48 lb. using the identical string. It seems much, much better overall in terms of "feel" in the stringbed. I believe it's still 10 lb. over tension (which would put it around 58lb., or at the center of the recommended range). I will try to play with them tomorrow to see which is best.

I'm not overly concerned about the free string. I quite probably would never have used it anyways, maybe with the exception for stringing a few friends' racquets for free. Aside from the breakage that I experienced with the Ashaway Liberty 16g, the next 2 jobs went very smoothly. I actually like the Klip strings much better anyways, and they don't stretch as much, even though the Klip strings were 17g.

I had no issues with mobility of the turntable nor with the cone-lock clamps either with slippage or adjustability. The machine seems to be pretty decent and unless something breaks (which I just can't see happening, as all the machined parts and bearings are of good quality), this machine should last quite a long time.

If I were to grade the machine, it would probably be as follows (out of 10):

Design: 8
Construction: 9
Ease of use: 7.5
Durability (estimate): 8.5
Stringing quality: 9
Overall: 8.4


That seems about right.

 

[Court_Jester]

One other thing: after I finished stringing up this frame, I laid a new frame over the top of the freshly-strung racquet. The strung racquet is noticeably shorter (1/16") and the top of the hoop is compressed (wider at the head than at the throat). Is this normal? I don't think I've ever compared a new frame with one that's strung.

Not really but 1/16" is pretty much the limit of the amount of distortion allowed for any racquet.

Make sure that the mounting posts are tightened very well and the mounting arms and the shoulder supports are snug against the racquet.

 

[TonyB]

I'm getting the feeling that I've overstressed the frame and that my original estimate of the "calibrated scale" being 10 lb. on the high side. That is, I think my "58 lb." racquet is probably really strung at 68 lb., which would put it more than 6 lb. outside the upper recommended range for that racquet.

I sure hate to cut out the strings right away, but I definitely don't want to damage the frame, either. Should I just go ahead and try to play with it as is, or should I avoid the risk and just cut them out and start at a lower tension?

Like I said, the "48 lb." setting on the calibrated scale actually FEELS more like 58 lb. That particular racquet also shows a bit of distortion, but not as much as the first one.

 

[Court_Jester]

The stringbed will always feel very stiff right after stringing. Give it a day or two to slacken and relax. And even then, it will still feel stiff if you are simply pressing down on it with your fingers. You can tell the difference once you try hitting with it.

I sure hate to cut out the strings right away, but I definitely don't want to damage the frame, either. Should I just go ahead and try to play with it as is, or should I avoid the risk and just cut them out and start at a lower tension?

I wish I bookmarked that article but it says that a 1/16"-distortion is still acceptable so it's safe to play with it. But if you're still uncomfortable with it, just cut it out. No point saving a $10-string set if it ruins the racquet in the process.

 

[TonyB]

Thanks for the response. I'll give it a shot and see how it plays. It definitely doesn't seem to be so tight that it's like a rock, but it is much, much tighter than any racquet I've ever played with.

I have no qualms about cutting out the strings. They're only $3.50 a set, after all. I just have no idea how this will feel when I play, so I'm inclined to try to go and hit with it just out of curiosity more than anything else.

 

[Richie Rich]

I have no qualms about cutting out the strings. They're only $3.50 a set, after all. I just have no idea how this will feel when I play, so I'm inclined to try to go and hit with it just out of curiosity more than anything else.

you probably won't damage the frame. if you do cut out the strings after hitting for a few minutes just look at it as a learning experience (and be thankful you didn't string with gut). i know my machine doesn't give me the tension i want either because of the floating clamps so i pull 5 lbs higher to get the tension that is right for me.

 

[gotwheels]

TonyB, I also suffer from an anal retentive engineering disease. Are you accustomed to the feel of a frame stung on a lock-out style stringer? If so, a constant pull style stringer provides a firmer stringbed (10% range). If so, adjust your target tension 10% below the lock-out tension. Also, during your calibration, did you observe the added lever arm torque effect of the linear string gripper? Something to be aware of.

I recently replaced an Alpha Pioneer III with an Alpha Pioneer DC Plus and have been pleased with the build quality and performance. Calibration to a certified weight range was spot on, the spring assist clamps are very smooth, and Alpha's service is top notch($399 pricing!)

Enjoy stringing.

 

[TonyB]

As I said, it's not 10% off, it's actually 10 pounds off. I've "calibrated it" from 40 to 70 lb. and it's just about the same amount off at each test point.

The only reason this is a problem for me is that the weight scale STARTS at 40 lb. for the "tennis" weight. So, to get a tension range in the 40's (I like my racquets strung loose), I need to actually go to the badminton weight and scale in the 30-lb. range. Sort of a hassle.

The lever arm of the linear gripper does not come into play at all, since the string actually wraps around the drum of the arm. It doesn't get tensioned by the gripper arm itself.

I'm curious why you would mention that, since you just said you own the Alpha machine which has a linear gripper. You should know that it doesn't matter where the gripper arm sits, as long as the string is wrapped at least partially around the drum.

 

[gotwheels]

TonyB, I find you comment, "You should know...." somewhat condescending, but that's probably just your style. Your calibration technique must be different than the one I used. The linear gripper on my stringer does cause a tension variation of up to 1.5 pounds dependent on the position of the linear gripper.

 

[TonyB]

As you've guessed, I'm a technically-oriented person, not a diplomat. I didn't mean to sound condescending, if that's how you interpreted it. Just trying to state the facts.

As long as the string is wrapped partially around the drum, the tension will not be changed by the linear gripper in any way, as long as the gripper itself does not interfere with the string as it travels around the hub (which would only happen if it went more than 180 degrees around).

That is, if the gripper is ~10 degrees below vertical or more, the string should be wrapped around the drum. At any position between that point and where the backside of the linear gripper comes in contact with the string (~180 degree rotation), the tension on the string will be the same if the arm is horizontal. The actual rotational position of the gripper itself will have no effect on the tension.

 

[TonyB]

Just thought I'd post an update now that I have several racquets under my belt.

I've strung about 6 racquets so far with the machine and everything seems to be going pretty smoothly. I'm not sure what to make of the weight calibration issue, but it doesn't seem to be a major problem at the moment. The initial racquet that I strung at 58 lb. was way too tight and I strung it again with a tension of 48 lb. It definitely seemed much better and I would guess that it's probably right around the center of the recommended range for the racquet -- 58 lb.

Another racquet that I strung at 37 lb. seems quite low. Since the recommended range for that racquet is 50-60, my guess is that it was actually 47 lb., which ended up even lower after the initial tension loss. I'm guessing that it's playing somewhere around 42 lb. right now, which is well outside of the recommended range.

All in all, I'd say that the machine is solid and well-built, but could have had more effort put into the weight system calibration and scale. I don't know what went wrong with the design, but I estimate that the scale is around 10 lb. off throughout the entire usable range of 35-70 lb. It's possible that the weight itself is incorrect, but since I have no point of reference, I cannot say for sure.

I find the machine easy to use and my personal opinion is that the fixed clamps and 6-point mounting system make this a definite value at the purchase price of $319. Once you get past the erroneous tension reading, it's smooth sailing from there.



EDIT:

Ok, I just couldn't live with the weight discrepancy, so I went about trying to determine exactly what the weight SHOULD be in order for the scale to read properly. I measured and weighed everything: the weight, the arm itself, the drum, and took several load measurements at various points along the weight arm.

After double- and triple-checking the calculations, and comparing them against each other, I believe I've discovered why there is a discrepancy in the weight scale/tension. The amount of weight necessary to generate the proper tension at the drum corresponding to the number on the calibrated arm scale is 5.58 lb. (taking the average of the weight required at 40 lb. through 65 lb., in increments of 5 lb.).

The actual value of the weight itself? Exactly 6.58 lb. (for both weights, including weight-attachment screw and hand-screw).

My guess is that when they produced the weights, they made an error and produced the pair exactly 1 lb. heavier than it should be. Or, another explanation is that when they designed the machine, they did not account for the weight of the lever arm itself in their calculations. The result of that error would be to require a weight of 6.49 lb., which is pretty close to the 6.58 lb. weight that is currently on the machine.

Anyways, I thought I'd share this with everyone. What I plan to do is to drill some holes in my "tennis" weight to bring the total weight of the assembly down to 5.58 lb. in order to have the actual tension match the scale reading. I estimate that I should be able to get within 1 lb. accuracy by correcting this problem.

 

[flash9]

Stop

Or maybe I just need a REAL spring tension calibrator?

Before drilling any holes in your weight , you really need to purchase some kind of scale. Either a spring tension calibrator or digital fish scale that is accurate between 40-70lbs.

 

[dlo]

Are you going to drill holes in the smaller weight as well? I have not taken the weights apart, but since they do come apart, if you put a spacer (long bolt) between the two, that should change the weight differential.

 

[TonyB]

Good point

You bring up a good point. No, I am not going to start drilling holes just yet. I do plan to verify my findings with an appropriate scale before I make any modifications.

Besides, I did some more calculations and it might just be easier for me to fabricate a new scale to tape to the lever arm. That way, I can use the existing weight, but just have new positions for the appropriate tension indications.


dlo: I was thinking about the holes and the only way that the calculations would be accurate is if I drilled holes through the ENTIRE length of the combined weights, as I need to keep the center of mass constant. I cannot simply go drilling holes whereever I want. Nor can I shave off any material from the ends of the weight. The only other option would be to turn down the diameter of the weight on a lathe, which is a reasonable option, but not quite as easy as just making a new scale.

So, my plan is to make a new scale with new tension indications, then verify that all is well by using a fish scale to measure actual tension applied to a piece of string.


BTW, if anyone has one of these machines and would like to do something similar, you can send me an email with the ACTUAL weight of your weight assembly (should be around 6.58 lb.) and I will send you a new scale to tape to your lever arm.

 

[dlo]

If you change the scale you will loose your lower end which is probably used more than the higher end (65+). You might remove the small weight and add a new weight instead. This only really matters if you plan to string for others. I am comfortable stringing for myself with how it is set up. I emailed Mr. Young and told him about the weight issue and he ssid he would send it to the manufacturer, so that should take care of it. (written in sarcasm). Good luck.

 

[spun_out]

my results of calibrating the Hercules 610

Hi,

I've been following this thread with great interest because I recently purchased the Hercules 610. And after feeling that my racquet strung at 55lbs was tighter than expected and reading the possibility of machine's miscalculations, I decided to check the calibration of the machine.

First, I purchased the Berkeley fishing scale (up to 50lbs) and weighed a known weight to make sure the scale was accurate. It was basically accurate (about half pound over at 45lbs).

Second, I hooked a string (poly) between the hook on the scale and the linear gripper, and measured the read out at 40lbs and 48lbs (didn't want to go over 50lbs).

To my surprise, the scale read little over 40lbs and 48lbs respectively, showing accurate calibration of the machine.

Of course, there are factors that might have caused the scale to give me an inaccurate reading. For example, I fixed the scale (the handle end) by putting a metal rod through it and supporting the rod against a table and the machine to make sure that neither the scale nor the machine moved (didn't want to hook the handle directly to center support for the fear of breaking it).

It's hard to explain, but certainly there could have been some loss of tension when pulling on the scale (although I waited until the scale settled down). Even then, however, I don't think the loss of tension could have been in the ballpark of 10lbs.

I am certainly not saying that TonyB made a mistake in his calculations. Rather, I am simply confused, especially because when I weighed the dropweights (tennis, badminton, and the two screws), it came out to 6.55lbs, which was the same as TonyB's findings.

One possibility for the discrepancy, as I mentioned above, is that my testing method yielded 10lbs of tension loss.

Another possibility, although not likely (but the best I got), is that the location of the calibration sticker (or the calibration sticker itself) is different on various machines. My calibration sticker begins as soon as the lever arm flattens to allow for the sticker to be placed (about 0.7cm from where the lever arm meets the drum). My 40lb marker is 11.1cm from where the lever arm meets the drum.

I would appreciate it very much if others can also check the location of the sticker.

Sorry for the long post, but I would like to get to the bottom of this.

 

[TonyB]

spun_out: Thanks for posting that information. Looks like our machines are just about equal to each other in terms of physical construction. Yes, my scale sticker is placed at the same location (actually, 4.40" from the drum).

Same weight, too (mine at 6.58 lb.). I will definitely get a fish scale to check the tension on the machine, both before and after applying the new scale.

But your post just confirms what initially gave me reason to pause (stop the drilling modification) and take a new approach with a new scale. By doing that, it will allow me to just pull off the new scale and bring the machine back to its original configuration. I think that's important, just in case there's something else going on with the machine that accounts for the extra 1 lb. on the current weight.

I'll let you know the outcome of my fish scale measurements.

 

[dlo]

My 40 lb marker is 10.5 cm from the drum. I think I will do some investigating as well.
I just got it out and did some test with the spring callibrator and reattached the strip. Should work, but I lost the lower weights below 45lbs. (due to the gripper hitting when rotated)

 

[pmata814]

I don't understand. Why go through so much hassle! Why not just send it back and exchange it for another one? It SHOULD be under warranty.

 

[TonyB]

Because I don't think this is an issue that they can/will resolve. This is either a measurement issue on my part or a design problem with the machine. Besides, it does a nice job with the stringing, it's easy to use, the parts appear to be of good quality, and it's inexpensive. I sort of expected some "issues" with just about any machine I would have purchased. I don't regret it one bit. In fact, if I were just about anyone else, I would never have known about the discrepancy; I would have just set up the machine and started stringing. And to that end, the machine works great.

I don't mind doing any of this investigative work. I'm an engineer, after all. This is actually FUN for me. And it's a hobby. What more can you ask for?

 

[dancraig]

http://tt.tennis-warehouse.com/showthread.php?t=64067&highlight=hercules+610

At the very start of this thread, you will see that someone solved the problem by moving the tension scale strip.

 

[TonyB]

Ok, this should be my last update.

Went out and bought a Berkeley 50-lb. fishing scale tonight. It's 100% accurate all the way from 3 lb. 10 oz. (smallest known weight I had) up to 48 lb. 5 oz. (largest known weight I had). The fishing scale is spot-on.

Installed it into the machine with a short length of leftover string and clamped it into the linear gripper. I hung the handle of the fish scale onto the adjustable metal head/throat support lug. I figured if this lug was strong enough to restrain a racquet during stringing, it should be strong enough to support the scale.

I tested the weight scale arm from the 40 lb. setting all the way up to the 55 lb. setting. Lo and behold, the tension was dead-nuts right on target! Well, sort of...

If I released the arm very, very gently, I was able to get it to stabilize at a horizontal position roughly 5 lb. BELOW what was indicated on the weight arm. And if I let it drop fairly quickly (not a free-fall, but pretty quick), I was able to force it to stabilize at a horizontal position at 6 lb. ABOVE the set point of the weight arm. But I must admit, if I just let it come to rest "normally", I was able to get the fishing scale's reading within 1 or 2 lb. of the set point of the weight arm.

I believe the issue is one of friction in the drum's bearing. You can see that even though the arm is perfectly horizontal every time, the tension is not necessarily accurate with respect to the setting on the weight arm. That's because if the arm overtravels (if you let it drop quickly), it won't come back to it's "normal" tension set point. The friction will keep it steady at the higher tension. Likewise, if you let the arm come to rest very, very slowly, the excess friction in the drum takes away from the REAL tension that should result from the dropweight.

I haven't used any other machines, but I would suspect that this is fairly consistent from one dropweight machine to another. I think as several people already mentioned, it's a matter of learning how to be consistent with these machines.

But I guess the final word is that (as much as I hate to admit it), the calculations do not apply to the actual performance of the machine. The machine's lever arm scale is verified pretty much exactly spot-on relative to ACTUAL tension when measured by the fishing scale. The key is to get the "feel" for the weight arm and learn how to let it come to rest repeatably to get a consistent tension time after time.

The bad news is that I was wrong in thinking there was an error with the machine. The good news is that I have a machine that's performing with near-100% correlation with the tension scale. And that's really what matters most.

 

[dancraig]

Crank machines can also give different tensions depending on how slow or aggressive the handle is turned.

 

[spun_out]

TonyB,

Great, I think you did get to the bottom of this. Thanks for all your hard work. Now, I'll just have to practice my skills on the Hercules 610.

 

[TonyB]

I just wonder if I should go back and delete all of my erroneous information in this thread. Anyone reading through it for the first time might get the false impression that the machine is unreliable or inaccurate, when in fact it was MY error from the beginning.

Hmmm...

 

[flash9]

Great News

Tony,

Great to learn you got to the bottom of this in the end.

Somewhere earlier in the post you said you felt the tension was considerably higher then you were familiar with from previous string jobs you had received. In all likelihood all of your earlier string jobs were 10% to 20% below what you thought you were getting. This really does not surprise me. The reason I got back in to stringing was because at my club it seemed every time I had my racquets strung the tension was never consistent. So I asked how often they checked the calibration on their Neos 1000. His answer was every time. He then said they do it by adjusting this here little knob. Which was actually the knob you turn to set the tension on the crank! I came to learn they did not even have anyway to test the tension!

Basically, a well working drop weigh machine will produce the most accurate tension.

Flash9

On a side note, I do not own a drop weigh machine, but I have used a few. I do not think you should be seeing the friction that you describe in the drop weight mechanism.

 

[TonyB]

On a side note, I do not own a drop weigh machine, but I have used a few. I do not think you should be seeing the friction that you describe in the drop weigh mechanism.

This brings up an interesting point.


Can anyone who has another type of dropweight machine (Klippermate, Gamma, ATS, Alpha, etc.) do a test to see if the tension changes due to friction in the drum as I've described?

Basically, just set up your fishing scale / tension calibrator to 45 lb. and let the weight drop very gently, take a reading, then raise the weight again and let it drop very quickly, and take another reading.

If you can do this, please let me know the type of machine you are using and the range of weights that you recorded. I'm curious to see if other machines have a wide range of tension resulting from variations in the rate at which the dropweight is lowered.

Thanks!

 

[danotje]

Hello, again.

I'm the guy who went and resurrected this thread a while back after ordering a 610 because of a lack of info on the net. Well, I finally received it. It wasn't the company's fault, but the slow process of USPS sending it overseas to a military PO. I haven't had a chance to string with it, yet, but I can give my initial impressions, much like other users in this thread.

I'm no engineer, but I do know a quality product when I see one, so here goes:

1. My overall impression is that it appears to be a good machine. It certainly is bigger and heavier than I thought it would be, too.

2. The "main" parts of the machine--turntable, base, mount supports, tension arm support--all are THICK metal and are painted very well. There is no doubt in my mind that these parts will outlast my tennis playing and possibly stringing ability.

3. The turntable is very solid, like I said, and turns 360 degrees very smoothly and solid. The clamp guide rails that are fixed to it are ok, but seemed to be roughly machined--they have tiny grooves left from whatever machine cut them out. While this does not affect operation of the clamp bases, I'll probably remove them and smooth them out with some fine sandpaper/emory cloth. I'm just picky about things like that.

4. The mounting system kind of surprised me, as it is likely the "cheapest" feeling part on the machine. I can't explain it exactly, but I like smooth, polished, "heavy-feeling" metal (like Snap-On tools), but the support arms feel like they are made out of a less than top-shelf material--kind of like a Wal-Mart wrench. I did mount a racquet, though, and everything performed as advertised. I had absolutely zero movement when all was tightened and I grabbed the racquet handle to try to get it to wiggle. I think the arms will, again, outlast my abilities, but it was something I noticed.

5. The clamps...being my first ever machine, I cannot comment on how good or bad the clamps are by comparision, but I can say that they are again, not top-shelf, but seem like they will do the job--which is really all I want in the first place. They open and close smoothly and easily, slide along the guide rails well, and when everything is locked down, are very solid. They, just like the arms, seem like they are made of an inferior material. Will this affect performance? Not likely, but like I mentioned, I like the feel of Snap-On tools.

To sum it up, I am very pleased with my purchase. For $320, I got some great features--6 pt mounting, fixed clamps, turntable brake, clutch, linear gripper--and a machine that feels up to the task, perhaps even overbuilt in most areas. I can't see ever needing to buy another machine, but I may possibly upgrade the clamps in the future, depending on how these perform. All in all, it is an excellent bargain, and if you're on the fence about a few machines like I was (SP, Klipper, Alpha and Gamma (both $100 more)), and leaning towards this machine, I think you, too, will be pleased with it. Once I string a racquet or two, I'll post some performance reviews.

On a side note, Mr. Young does not include strings when he ships for free. I got free shipping, so no strings (part of the reason I haven't used it, yet). I just saw that discussion somewhere up in this thread. Let me know if you have any questions.

Dan

 

[Gugafan_Redux]

TonyB, a belated thanks for the Hercules review. I've been scrolling and trolling all week, trying to pick my first stringer. I can afford something better than the Gamma X2 or Klippermate or String Pal. Really want 6 pt mount and fixed clamps. Without your review, I would know nothing about the Hercules. Now I do. (yes, I read the whole thread!) And as someone else said, you just have to pick something. So I think the Hercules is the way to go.

BTW, I've emailed the folks in houston (James Young), asking when the 680 will be available. This is appears to be the updated model number for the 610. It's unclear from the website if they still have the 610 for sale.

Thanks again!

 

[tennis-skater]

If I were you I would spend (like I wish I would have) a little bit more and get an alpha. I have the 610 MP and their customer service sucks. If you look on "E" many times you can find an alpha dropweight w/everything you want for about 300

 

[TonyB]

Glad the information was useful. I had some difficulty getting used to the machine, evidently, but once everything was sorted out, it actually performs quite well. I've strung maybe a few dozen frames on it so far and I haven't had any further issues.

That said, if I had the extra $100 or so to spend on a machine at the time, I might have considered the Alpha Pioneer DC. It looks to be a great machine and has all the same features of the Hercules 610, plus a string package and some good (from what I understand) customer service.

But it all comes down to what you want out of the machine. For me, I wanted to spend the least amount possible but still have the features that I wanted (6-point mounting and fixed clamps). I took a chance on the quality and customer service, but fortunately I am pleased with the quality so far and haven't had to use the customer service.

Good luck.

 

[Gugafan_Redux]

Well, I really went crazy with the research this week, having nothing to do at work right now. Went back and forth, back and forth. a friend recommended the estringer electric. Egnas was an easy "no-go." Read many great reviews of the alpha pioneer. But also a lot of endorsements from first-timers like myself for the basic Gamma X-2, saying it gets the job done.

Then a couple sticks turned up in the for sale forum. League starts next week, and I figure after 7 years playing, it's time I kept two frames in the bag. Then I got a reply from James saying they'd get the shipment of 680's next week. That's all, just one sentence, no other info or greeting, hello, thank you, anything. This read like the penultimate generic sales answer. "Oh, sure, we'll get a shipment next week!"

So I called and spoke with the woman at mutual power. Asked for James about two minutes after receiving his email. She hemmed and hawed, and seemed to be making something up -- said he wasn't around. That seemed odd after receiving his email. So I explained I'd just heard from him about the 680, said they'd arrive next week. "Oh, yeah, next week, next week." Um, really?

So I asked if I could place and order now, should I call back, should I watch the website? She gave a strange convoluted answer, and frankly didn't seem to understand my question. She asked if I wanted to order now. I said, Can I? Then she said to call back next wednesday.

That kind of cinched it for me. If something goes wrong, I don't need to deal with that kind of communication. I started working in retail at 16, and I come from a customer is king point of view. If something goes wrong or I'm not happy, I expect to be able to be understood and get treated well.

So, short story long -- I ordered the Gamma X-2 from ATS this morning.

Nevertheless, the info on the Hercules was excellent!

:grin: