Will a floating clamp work?

T

Tao69

Semi-Pro
Hi All,

I have an Eagnas drop weight table top stringing machine (similar to the Hyper 260) that is probably getting to the end of its life. It's a drop weight machine with fixed base clamps on it, and a six point mounting system.

Unfortunately the thread on one of the bolt/screws that adjusts two of the clamps/mounting points at one end is a little worn, so it slips under pressure allowing the frame to move as much as 1/2". Its also damage the paint on some of my frames.

There's no replacement part available from Eagnas, and I may not be able to get one economically replicated on a metal lathe.

My question is, if I use floating clamps, is the frame movement still an issue?
 
W

Wes

Hall of Fame
Tao69 said:
Hi All,

I have an Eagnas drop weight table top stringing machine (similar to the Hyper 260) that is probably getting to the end of its life. It's a drop weight machine with fixed base clamps on it, and a six point mounting system.

Unfortunately the thread on one of the bolt/screws that adjusts two of the clamps/mounting points at one end is a little worn, so it slips under pressure allowing the frame to move as much as 1/2". Its also damage the paint on some of my frames.

There's no replacement part available from Eagnas, and I may not be able to get one economically replicated on a metal lathe.

My question is, if I use floating clamps, is the frame movement still an issue?
Click to expand...

Hi @Tao69,

Based on what you've written, it sounds like you've described that the mounting tower itself is what is slipping/moving (therefore the frame's hoop is not being supported in the manner that it should).

If that is indeed the case, then which type of string clamps you choose to use (fixed clamps vs. floating clamps) is not going to be any better/worse than the other - because the issue is that the mounting tower is not holding sufficiently/properly.
Switching to floating clamps is not going to fix/improve anything. You just need to rectify whatever is allowing the mounting tower to slip/move.

If you're able to show some photos (or video) of exactly which bolt/screws you're talking about, it might help clarify things (and make it easier for us to provide suggestions).

BTW, I looked up a photo of an Eagnas Hyper 260, but the photo I found is of a table-top crank machine, rather than a DW machine.

hy260.jpg


Is this actually what the turntable and mounting towers look like on your drop-weight machine?
 
T

Tao69

Semi-Pro
Hi Wes,

Appreciate the response.

That is exactly what the turntable looks like, the red mounting towers themselves do not move, so they're fine. On the outside of the mounting towers you can see the black adjustment knob which moves the two mounting points in and out to hold the racquet in place. The thread on that adjustment screw is worn, so while it can move the mounting points in and out still, once you tension the string and apply pressure to them they move so the string is straight. Essentially the middle part of the thread on the adjustment knob has worn down and it slips to where the thread is still okay.

So what happens after you apply the clamp to the string and remove tension, the frame moves, and the string clamp is no longer inline between the holes. This goes on until the frame is no longer mounted straight at all.

If I can't get an adjustment knob replacement, I'm just wondering if floating clamps are a work around as they clamp to two strings in the racquet and maybe it doesn't matter if the frame moves a little between tension pulls?
 
W

Wes

Hall of Fame
Tao69 said:
Hi Wes,

Appreciate the response.

That is exactly what the turntable looks like, the red mounting towers themselves do not move, so they're fine. On the outside of the mounting towers you can see the black adjustment knob which moves the two mounting points in and out to hold the racquet in place. The thread on that adjustment screw is worn, so while it can move the mounting points in and out still, once you tension the string and apply pressure to them they move so the string is straight. Essentially the middle part of the thread on the adjustment knob has worn down and it slips to where the thread is still okay.

So what happens after you apply the clamp to the string and remove tension, the frame moves, and the string clamp is no longer inline between the holes. This goes on until the frame is no longer mounted straight at all.

If I can't get an adjustment knob replacement, I'm just wondering if floating clamps are a work around as they clamp to two strings in the racquet and maybe it doesn't matter if the frame moves a little between tension pulls?
Click to expand...

Ah... so it now sounds like you're referring to the knob that moves the shoulder/side supports in (and out).

I still don't think that floating clamps are the solution.
One way or another, try to obtain the requisite part(s).

Even if they aren't available from typical sources, you can always keep your eyes peeled for used machines being sold (especially if they are partial/incomplete machines for whatever reason).
If you come across the requisite type of machine (that used the same parts), you could buy it (likely at a heavy discount) just to rob the spare parts off of it.

Whereabouts are you located? That may have a big influence on how easy/difficult it might be for you to find another machine with the same workings/parts.
 
T

Tao69

Semi-Pro
Wes said:
Ah... so it now sounds like you're referring to the knob that moves the shoulder/side supports in (and out).

I still don't think that floating clamps are the solution.
One way or another, try to obtain the requisite part(s).

Even if they aren't available from typical sources, you can always keep your eyes peeled for used machines being sold (especially if they are partial/incomplete machines for whatever reason).
If you come across the requisite type of machine (that used the same parts), you could buy it (likely at a heavy discount) just to rob the spare parts off of it.

Whereabouts are you located? That may have a big influence on how easy/difficult it might be for you to find another machine with the same workings/parts.
Click to expand...
Yeah, I'm in Australia, Eagnas don't have a presence here so there's very few around, if any; I picked it up secondhand. I looked into getting the part machined up at a metal work shop, but they have a minimum order that is half the price of a new drop weight machine. All the plastic parts need replacing, which Eagnas have, just not the Adjustment knobs.

Appreciate your response, good to know before I bought floating clamps.
 
J

jim e

Legend
Is the thread that is worn just s large bolt with that plastic knob on the end? If so some hardware stores sell threaded rods, possibly if you get proper size most likely metric, you could fabricate one?
I'm not sure how that adjustment bolt is designed to get an idea exactly what is needed.
 
T

Tao69

Semi-Pro
Yeah, can’t use a regular bolt as adjustment bolt take a screw on the other end to hold it in place. Will see if lilylee come back to me, if not will true to get one fabricated.
 
10shoe

10shoe

Professional
Since the threads on the old part are shot you really don't have anything to lose by purchasing a die and reducing the threads to the next size down. You can probably source a replacement for the knob at any industrial supply house but it will have to match the size of the new threads.
 
diredesire

diredesire

Moderator
Tao69 said:
Yeah, I'm in Australia, Eagnas don't have a presence here so there's very few around, if any; I picked it up secondhand. I looked into getting the part machined up at a metal work shop, but they have a minimum order that is half the price of a new drop weight machine. All the plastic parts need replacing, which Eagnas have, just not the Adjustment knobs.

Appreciate your response, good to know before I bought floating clamps.
Click to expand...
You should just go to the shop anyways, they'll probably help you with one off requests like this if they have some spare cycles for a very reasonable fee. Some people just like solving problems.

Also - at this point, I'd highly recommend just posting some pictures. You've got several folks here that are more than happy to help you find a very simple/cheap solution, but you gotta give us a little more to work with.

Snooping around, looks like you actually have an Eagnas Hyper 60, it's not super clear from the crappy pictures on their site, but it looks like it might be a retained bolt with a bushing on the other end (on the inside of the frame)? It's probably going to be an "e-clip, or a circlip" holding the bolt in so it can free spin, and the threads are doing all the work of moving the arms. It looks like popping the gray top cover off would give you access to see the mechanism inside. If the cap head thing on the inside of the mounting stock (covered up by the 6/12 mounts) is a simple bushing, that's probably reusable.

Photo below points to maybe-bushing.

jKTUIJW.jpg
 
T

Tao69

Semi-Pro
I pulled it apart to work out the issue, can take some pics and put them up.

Good tip on hitting the workshops, perhaps someone will do it as a little cash job, probably only take 15 mins.
 
M

mauricem

Semi-Pro
Have you tried Tennis Warehouse in Melbourne? They're pretty good with spare parts for different machines? You could probably just overwrap it with several (lots!) of turns of plumber's teflon tape if it's not too worn. Not a permanent solution by any means but if you're only stringing occasionally?
 
T

Tao69

Semi-Pro
TW doesn’t have a machine with the same design unfortunately, but I have used them for the spring in drop weight mechanism.

Tried the teflon tape, but maybe I need use a lot more to make it really tight, suspect it could work for one to two string jobs at a time. Will give it a go.
 
T

Tao69

Semi-Pro
When I thread the adjustment slider onto the adjust screw, when you get to the middle section of the screw, it loses grip and you can force it to slid about 1/4" each way. Thinking a replacement might have to be CNC machined.
 
S

struggle

Legend
Search for Pro's Pro parts. Essentially the same as Eagnas in many respects, likely with better tolerances.

another option might be to put a washer and nut on the backside of the knob where the threads are still good to hold it in place once you've adjusted it where it needs to be for the particular racquet. OR, adjust the towers so that you are using a different part of the threads that are still good on the "billiards" (Mounting posts that slide in and out with the threads).

edit: i didn't look at the p[ics first, these solutions may not be viable...
 
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10shoe

10shoe

Professional
Judging by the metal filings in between the threads on the screw in the last picture (the screw removed from the machine) I would say the screw is fine but the piece it goes through is shot. You might be able to repair it with a helicoil insert, but if you have to enlist the help of a machinist the expense could exceed the value of the machine.

Speaking of machinists, in lieu of trying to find a local machine shop and talking them into doing something like this, you might post to a machine shop forum online and see if anyone contacts you via direct message with an offer.
 
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diredesire

diredesire

Moderator
10shoe said:
Judging by the metal filings in between the threads on the screw in the last picture (the screw removed from the machine) I would say the screw is fine but the piece it goes through is shot. You might be able to repair it with a helicoil insert, but if you have to enlist the help of a machinist the expense could exceed the value of the machine.

Speaking of machinists, in lieu of trying to find a local machine shop and talking them into doing something like this, you might post to a machine shop forum online and see if anyone contacts you via direct message with an offer.
Click to expand...
I agree... If you happen to have a metal bristled brush (or just any firm bristled brush), try to clean up the threads on the bolt. If they are intact, then the hole is shot. However, if it really is only happening in a limited range of travel, that doesn't make sense... Unless this is at the far end of travel and only half of the hole is damaged.

2qgXBBH.png


Either way, though - this actually isn't as bad to recreate as it looks. You don't really need an identical part if the threaded hole on the yoke isn't trashed.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com
www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com

A little luck needs to be involved, but this looks like a partially threaded thumb screw with a pilot point tip. My guess is that the unthreaded area near the knob is going to be standard sized for the thread that was cut, and the other end of the bolt actually doesn't really matter if you can fit a bushing on the other end. I'm linking mcmaster carr here for inspiration (and figuring out what stuff is named), but you really only need to match the length of the bolt. The screw and washers do all the work of holding the threaded rod in place in your machine, and as that screw moves, the carriage is pulled/pushed along by the threads. If the holes are snug on both ends, I'd take a look to see if there's any inserts in the machine. It appears that the left (red circled) surface is narrower diameter than the rest of the bolt. If worse comes to worse, I'd drill out the hole on the other end and drop in a (sacrificial) bushing and call it a day. The bushing is just there to keep the bolt shaft in the correct alignment and provide a surface to ride on. Note that you don't need to retain the bolt in the same way (with a screw from the other end). As mentioned, the screw is just there to keep the bolt from floating in and out. You can just cut the thumbscrew down to length, and then use a nylock nut with the same results. It's more ideal if you can remove the threads, but you're not likely to get that done precisely without some machine work... You could buy a way longer bolt than you need, chuck it up in a drill, and then grind it with a carbide cutter, or something, but at that point, custom machining is fine.

www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com

Edit: Next steps if you still can't find help on this is to take that bolt to a hardware store and ID what the machine thread is. I'm guessing it's metric, maybe M6 from the looks of it... Then do your best to measure the lengths of the threaded area, the unthreaded areas, and if you can (calipers), the diameters of the unthreaded areas.
 
T

tjanev

Rookie
If you had the proper sized tap tool, you can run the screw through it to clean it up and really know if the screw is damaged. One thing you could do that will mostly likely NOT work for too long ( lol ) is.....once you clean up the screw, and the piece that it screws into, what you can do is cover the threaded area with JB weld ( just a thin amount ) then run the screw in and out many times till it starts hardening thus filling in the screw thread and possibly the thread inside the mechanism and fixing the broken threads. Make sure you don't leave the bolt in the threaded portion so they weld together. Work it for a few minutes, then pull the screw portion out and let both sides dry before re assembling. If it can somehow hold up, you will have fixed the issue temporarily ( but not holding my breath ). I know it sounds like a red neck fix, but you never know if it will work or how long it will last.
 
10shoe

10shoe

Professional
OP is in Australia. There's got to be an industrial supply house closer than McMaster.

BTW, I was just looking at the threads on an M6 screw and comparing them to the threads in the OP's pic and there's seems to be far more tilt in the threads of his thumbscrew. Given that it is designed to behave like a worm gear it's possible that the threads are not typical fastener pitch.
 
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S

struggle

Legend
10shoe said:
OP is in Australia. There's got to be an industrial supply house closer than McMaster.

BTW, I was just looking at the threads on an M6 screw and comparing them to the threads in the OP's pic and there's seems to be far more tilt in the threads of his thumbscrew. Given that it is designed to behave like a worm gear it's possible that the threads are not typical fastener pitch.
Click to expand...
they do look steeper than your average bolt, no matter the standard.
 
10shoe

10shoe

Professional
OP will probably be waking up in a few hours so given that I have changed my mind half a dozen times since the beginning of this thread I just want to take a final position that the small block of metal the thumbscrew goes through will likely need to be replaced and his best bet is to post his pics on a forum for machinists and see whether he gets some offers.
 
S

struggle

Legend
Symptoms and photo indicate that the screw is shot. LIkely the "nut" is also toast, but still holds at the unstressed parts of the "screw".
 
10shoe

10shoe

Professional
I don't think it would be a bad idea to replace both screw and nut but the screw is probably steel and the nut is probably aluminum and the damage is probably to the softer of the two, the aluminum. One of the things he should discuss with the machinist is the choice of material for the replacement. I know nothing about metal grades but I am guessing Eagnas is choosing cheap vs quality.
 
diredesire

diredesire

Moderator
10shoe said:
OP is in Australia. There's got to be an industrial supply house closer than McMaster.

BTW, I was just looking at the threads on an M6 screw and comparing them to the threads in the OP's pic and there's seems to be far more tilt in the threads of his thumbscrew. Given that it is designed to behave like a worm gear it's possible that the threads are not typical fastener pitch.
Click to expand...
As I mentioned, the MCM links are for inspiration/reference. I'm not suggesting they purchase from there.

struggle said:
they do look steeper than your average bolt, no matter the standard.
Click to expand...
Yeah, I agree with both of you. I just grabbed an M6 bolt and confirmed. I'd be a very surprised if they were using lead screws, so I'm at a loss - I'm not a mechanical engineer, so i'm at the end of my solution space :)
 
T

Tao69

Semi-Pro
So a few things to respond to...

The thread on the screw looks filthy because I tried the teflon tape to tighten it up and haven't cleaned it all out. I'm fairly confident its the screw because when you run your fingers over it you can feel the middle part get narrow ever so slightly.

I think the sliding nut is okay because it seems to hold when I position it at either end of the screw where the thread is still okay.

I have tried using either end of the screw, but it doesn't work. If I position it so the mounting points are wide, the mounting tower then sits under the frame so I you can't get the clamp close to the frame at one end. If I position it so the mounting points are narrow, when you pull the crosses the K mounts start to turn and the frame rotates ( I managed to save the string job). So the middle of the screw is optimal. This makes me think I may be able to find some spacers from the hardware store that will fit over the screw and I could fix the sliding nut in the middle part of the screw, where it is closer to optimal in terms of the width of the mounting points.

I did look at JB Weld just wasn't keen to mess that up.

I will have a look at the Pros Pro parts and if I get replacements fabricated will definitely get two sets done, will try the forums for that and see if I have any luck.

I've just realised that if I use the spacers on one screw, if the other screw goes then I'm going to have to fix that end as well and will have to clamp the frame by moving the mounting towers...

Appreciate all the input, if all else fails I'm just up for a new stringing machine.
 
T

Tao69

Semi-Pro


So found a piece of plastic tube (its the middle roll from my dog's poop bags, had a whole pile of them), and it fit the screw perfectly, I cut a few different length to experiment and get the mounting points in a good position for most racquets, should work till I either get replacement parts fabricated or I buy a new stringing machine.
Thanks for all your responses, helped me think about the problem differently.
 
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