Linear Gripper Test

[flash9]

I would like to ask for anyone who is willing to perform this little test to help me figure out if I have a potential problem or not with my linear grippers?

When I string with thinner gauge (17ga) string at high tensions (70lbs) I will occasionally get slippage through my linear gripper. This of course scratches the fibers of a multifilament based string. There is a set screw at the back of the gripper that I have screwed in as far as it can go, and this allows the gripper plates to travel further forward and thus move closer together.

The “test” I am asking you to try if you have a stringer that uses a linear gripper to grab the sting during a tension pull is as follows: Please place a piece of scrap sting (preferably 17ga) in the linear grippers and manually pull forward, once the grippers are holding the string try to lift up. See the link to the picture below:
http://tinypic.com/fjfbdk.jpg
Does your gripper hold uniformly front to back? In my case the front 1/3 is not gripping tightly, and I can easily lift the string up out of the grippers.

I have a new WISE 2086 with a roller bearing linear gripper. I believe this liner gripper is relatively new design for the WISE 2086 and older units have a ball bearing design. What I have noticed is that with the thinner strings the gripping plate moves further forward of the outer two holders and it appears the pressure on the string is not uniform.

Anyone willing to do this test please report back your findings.

Thank you

 

[Mike Cottrill]

No, It should not do that. I thought the cleaning fixed the bearing issue? Did Herb send you a new gripper? What has Herb said?
Mike

 

[jj300]

yup that would be a problem. I have a revo 4000 and there is noway I can do that. Call Herb and see what he says. I think there was another problem of this sort that I remember reading somewhere.

 

[Gamma Tech]

I'm not sure if the wise gripper is the same as the gamma (wouldn't be surprised if it is), but if have the screw at the base all the way in then you have it adjusted the wrong way. the plates get tighter as they move in, the current position of the screw isn't allowing the plates to move as far in as possible. adjust the screw all the way out and it should correct the problem

bret

 

[flash9]

Linear Gripper

Mike – Yes cleaning helped. I just did my racquets with a thin 17ga and three or four pulls scratched the strings when I had some slippage. Herb had offered to send a new gripper parts before I had done the cleaning, but once I had cleaned the roller bearings and I screwed the set screw all the way in the problem appeared to go away until this weekend. NOTE: I did not redue this test after cleaning the roller bearings, but did after having the slippage this weekend, and it is no different then before the cleaning the roller bearings. The grippers just now move much more freely then when I recieved the unit with the grease in the roller bearing slots.

I really would like to have some of you try this with your linear grippers before I go back to Herb. Anyone with a linear gripper doing this test it would be greatly appreciated. Especially anyone who has just recently purchased a WISE 2086 that had the roller bearings rather then the ball bearings (Barry?)

Gamma Tech – I know what you are talking about with every other linear gripper I have ever used there is a set screw that you pull back to make the gripper plates come closer together but the WISE unit it is reversed. Not the best pictures but maybe this might help.
http://tinypic.com/fjmbe8.jpg
http://tinypic.com/fjnwna.jpg
In the first picture there is a little pin coming off of the top (for reference in the picture) moving plate. As the plates move left eventually this pin will bottom out on the set screw that I am referring to. The second picture (badly out of focus) shows kind of what I am talking about.

 

[Gamma Tech]

I thought you might have over-looked something small but I see from the picture that the wise gripper is different. the set screw is a good idea because it would be less of a string catcher.

bret

 

[flash9]

Test

Gamma Tech - Bret
I know your linear grippers are different then mine, but since you would appear to have tension heads right there, would you mind doing my little test and report back if the tension is uniform from front to back in the gripper plates?

I also think the overall design of the WISE gripper is nice in that the set screw is out of the way and does not catch the string. I also know that some time recently (how recent I do not know and have not asked) WISE went from Ball Bearing Linear Gripper design to Roller Bearing Linear Gripper design. I just think the gripper plate’s travel too far forward and thus are not grabbing at the very front of the gripper plates. If the gripper plates were just a little thicker then they would not travel quite so far forward and then they might grab more uniformly?

 

[barry]

Gamma Tech - Bret
I know your linear grippers are different then mine, but since you would appear to have tension heads right there, would you mind doing my little test and report back if the tension is uniform from front to back in the gripper plates?

I also think the overall design of the WISE gripper is nice in that the set screw is out of the way and does not catch the string. I also know that some time recently (how recent I do not know and have not asked) WISE went from Ball Bearing Linear Gripper design to Roller Bearing Linear Gripper design. I just think the gripper plate’s travel too far forward and thus are not grabbing at the very front of the gripper plates. If the gripper plates were just a little thicker then they would not travel quite so far forward and then they might grab more uniformly?

I did your experiment using 17 gauge Polylon SP on my Wise 2086 and was unable to remove the string from the back of the gripper. It almost sounds like your gripper is wrapped. I did not have to do any adjustments when I received my Wise unit as it worked with both 17 and 16 gauge string right out of the box.
I received my Wise couple of weeks ago, and it does have the roller bearings.

Hope this is helpful.

 

[fwtennis]

Flash, Are the roller bearings set in nlyon strips? Usually they are. It is usually less expensive to manufacture a sliding part by setting roller bearing strips rather than individual ball bearings. The roller bearings can be a little more fragile than ball bearings and they gunk up much faster because dirty grease fills in the slots that they spin in. It might be best to remove the strips and check the rollers carefully for nicks or dings. Also check if there are tiny metal scrapings, like a fine powder from the rollers scoring the metal on the jaws. That's not a good sign. If clear, soak the roller IN their nylon strips in a cleaner ok'd by the company. Then re-pack the same type of grease used by the company. That should do it for you. Roller bearings should work fine but they will need more maintainance more frequently. Not likely that anything is warpped.

 

[flash9]

Thanks

Barry - Thanks for doing the test. I just want to make sure, when I pull with the string it does not grab tightly in what I consider the "front", or in my picture the left side, of the gripper plates. The "back", or in my picture the right side, is where the grippers are holding the string tight. You can see this in the first picture I posted in my original posting.

fwtennis - Thanks but the seven roller bearing ride in slots that were machined out of the medal plates. There are no nylon strips holding the roller bearings. I think either the gripper plate is too thin or the slots the roller bearings ride in are too deep. The fact that the grippers grab the string tighter on one end then the other also make me believe that the slot might have been machined a little deeper on one end relative to the other end of the slot.

All - I talked with Herb and his is sending me all of the parts to a new gripper assembly, hopefully this will fix my problem. I would still like to hear from others if anyone else has done this test.