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Link belt on Myford

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John Haine08/07/2012 18:19:34
2577 forum posts
133 photos

Last MEX I bought a link belt for my Myford S7 having read that they gave smoother running and less vibration, from a well-known ME supplier. So with slight trepidation I cut through the original Vee belt and fitted the new one, and I have to say that I'm extremely disappointed! Normal running is OK though not noticeably better, but now I CANNOT part off - the belt just keeps slipping even though I have it as tight as I can get it.

Yes, I have cleaned the pulleys, but it makes no difference. Actually even when I tighten the belt it doesn't make much difference. Parting used to be trouble-free but now effectively I can't do it at all.

Does anyone else have any experience of these please? I bought the one I did because it was a third of the price of the "Powertwist" belt sold by Tony at Lathes.co.uk, maybe I can see now why it's only a third the price! Can anyone give a positive (or negative) recommendation for the Powertwist belts please? I'm reluctant to fork out 30 quid + for another link belt unless I know it'll work, but I really really don't want to have to dismantle the headstock to fit a normal belt!

John.

MichaelR08/07/2012 19:32:35
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336 forum posts
58 photos

Before you do anything drastic why not try Belt Dressing, in my days as joiner we used spray can Belt Dressing for slipping belts on some woodworking machines.

Link see here.

KWIL08/07/2012 19:40:28
3106 forum posts
56 photos

I really cannot understand why some owners of Myford S7 are so diffident about changing the drive belt. You do not have to do it very often and it really does not take all that amount of time.

Clive Hartland08/07/2012 20:58:14
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2456 forum posts
40 photos

Just one point, is the belt laid on the right way round? There is a specific direction of the links so that the drive gives the most impetus.

On Fenner belts there is an arrow to show the drive direction.

Clive

Chris Trice08/07/2012 21:15:17
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1362 forum posts
9 photos

Is it a genuine Fenner belt or a cheap equivalent? It makes a difference.

Cornish Jack08/07/2012 22:22:27
914 forum posts
120 photos

John

Is it the black 'plastic-cy' type belt? If so, I have one similar, fitted recently on an ML7 together with a 3 phase motor and it (so far, fingers crossed!!) worked OK. I don't know about correct orientation - if there is a right or wrong way, I have no idea. The only other change which I made was a new drive pulley (31/2 versus original 21/2) because the motor shaft was larger. Don't know if that has any effect. Have only done a couple of small diameter parting off jobs and they seemed to go OK.

Rgds

Bill

steamdave08/07/2012 23:44:29
413 forum posts
34 photos

 

This is the direction link belts should be fitted

 

Dave

The Emerald Isle

Edited By Katy Purvis on 01/06/2015 12:37:03

Ady109/07/2012 00:36:20
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3463 forum posts
513 photos

This is the direction link belts should be fitted

ah...

You learn something new every day

 

Mine was manky when I got it, so no arrows

So does this mean you cant use a linked belt on a lathe which does any work in reverse?

 

Edited By Ady1 on 09/07/2012 00:42:03

John Haine09/07/2012 08:21:39
2577 forum posts
133 photos

Thanks for the comments.

Kwil, it's not that I'm diffident (if I was I wouldn't have taken a cutter to the original V belt!) just that I'm hacked off that what I bought in good faith hasn't delivered.

This isn't a Fenner belt but the cheap equivalent and yes, it is plastic-y. I have tried it both ways round but it makes little difference.

Bill, I guess you have fitted the belt on the motor-countershaft? Mine is on the C/S - H/S mandrel. On the S7 the M-C belt isa poly-vee anyway. The problem I get is that even if I put the lathe in back gear, the work doesn't go fast enough for the tool to cut properly so it digs in and jams the mandrel. With the belt on the motor to countershaft I guess you get an extra stage of reduction...

Oh well, I guess I'll need to buy the expensive Gates product..thanks for your replies. Is there anyone who can confirm that the Gates product really does the business please?

blowlamp09/07/2012 09:33:53
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1196 forum posts
82 photos

To be honest John, I wouldn't use link belt of any make to drive the spindle. I've tried in the past with similar results to you and went back to using a decent conventional vee belt.

Martin.

KMP09/07/2012 10:15:01
73 forum posts
2 photos

John Hi,

Sorry to say that my experience is similar to Martin, I used both expensive and cheap link belts on my S7 to try and remove a clicking from the backgear gear assembly caused by wear in the locking pin. it did remove the noise but gave other issues which caused me to revert to the original belt in the end.

I found with the cheap type belt that they had to be extremely tight to provide a reliable drive. They also tended to stretch and needed links removing regularly in the first few weeks of running. In the end I was getting the belt as tight as I could with the countershaft in the drive position and then removing 1 or 2 links. This meant that the countershaft was under a good deal of load when running and I could see the bearings objecting if left like that for long.

The more expensive belt I have to say was very much better but still not perfect. It settled down fairly quickly and I only had to remove 1 link in the initial few days of use. I used it for several months without problem but when I eventually decided to adjust the spindle bearings I changed back to the vee belt which is still on the machine today. I just didn't feel confident with it and worried about the long term effects on the countershaft bearings and the pully profile, both reflectons of me rather than the belt I expect.

Another thing strikes me as you say your S7 has a poly vee primary drive, it must be a later model and I see that Myford list a different belt for later machines. It might be just the length difference on the big bore headstock but you might want to check that the pully profile is the same as the older type S7.

I guess my experience must be slightly different that the norm as many people seem happy with the link belts and expound the advantages with gusto. So perhaps my expensive belt wasn't the right type of expensive belt, i'm sorry to say that I cannot remember the actual maker but five years ago it was well over £25.

Best regards

Keith

Tony Jeffree09/07/2012 10:31:30
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361 forum posts
6 photos

I bought T-link belts for my ML-7 a while back from **LINK** - they have worked very well for me, no worse than a standard belt slip-wise and much less vibration.

Regards,

Tony

John Haine09/07/2012 11:57:34
2577 forum posts
133 photos
Thanks Tony. Do you have the standard or power twist type?
Tony Jeffree09/07/2012 12:02:33
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361 forum posts
6 photos
Posted by John Haine on 09/07/2012 11:57:34:
Thanks Tony. Do you have the standard or power twist type?

The standard type (with the metal fastners). I have replaced both belts.

Regards,

Tony

Ady109/07/2012 12:25:00
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3463 forum posts
513 photos

Mine is powerlink

So this means the belt moves across from left to right if I understand correctly

 

I just thought you slapped it on. duh

Edited By Ady1 on 09/07/2012 12:26:12

Ken Fox09/07/2012 19:44:40
13 forum posts

I put one of these belts (Fenner) on my Atlas 618 a while ago and I was only moderately satisfied with it--it was very noisy. As a result of these postings I took a closer look to-day. First I tried reversing the direction with not much difference then I went over the drive train tightening set screws etc. and this was the magic solution. It quietened right down to little more noise than a normal V belt with little significant vibration and also it makes no difference which way it runs. I can only suspect that what vibration there is excites any loose parts to rattle and shake.

One possible problem I see is that if the v-grooves are a shade large (or the belt a shade small) the belt could ride low enough in the groove that the little nubs on the bottom could be riding on the bottom of the groove. This would certainly cause slipping at any reasonable tension and the higher the tension the higher the vibration.

Ken

bricky10/07/2012 19:23:07
373 forum posts
47 photos

I had vibration problems 20 years ago on my s7,I asked advice from Myford and was advised to fit a Brammer link belt. This cured the problem and I never had slippage with this make .When I bought my large bore Myford it had some vibration problems amongst other things and so I fitted a Power Twist link belt .I experienced slippage and no amount of tightening would solve it.The cone pully is smaller than my old lathe which is A size this new lathe hardly takes a Z size and dose not fill the pulley.I have had Darren and Pete who service Myfords and they removed the link belt and fitted a new belt along with other problems that were causing the vibration.Make sure the clutch pulley and the motor pulley are in perfect alignment,mine wasn,t and this had some bearing on my vibration problems.The service I received from guys was excellent and worth the money.

Francis

John Haine11/07/2012 08:59:46
2577 forum posts
133 photos

Thanks Francis, but now I'm really confused! I also have the big bore machine, I assume that you are talking about the belt from C/shaft to mandrel? I've noticed that the belt that I have looks rather wide for the pulley groove - it is about 12.9 mm. So is that right, the groove width on the big bore machine is narrower than on the older ones? I see that Z size is 10 mm and A size 13 mm. I could get Z size in either PowerTwist or T-Link from RS, did you try the Powertwist Z size please?

John.

Nicholas Farr11/07/2012 10:06:01
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1911 forum posts
920 photos

Hi John, below is a photo of standard belt sizes.

beltsize.jpg

Do make sure that non of your pulley grooves are badly worn and that any belt you use is not running on the bottom of the pulley groove. Vee belts should never be drum tight.

Hope this helps.

Regards Nick.

John Haine11/07/2012 10:18:08
2577 forum posts
133 photos

Thanks Nick. Well, that seems clear then, measuring the width of the top of the vee groove on the pulley it is very slightly under 10 mm so it is unlikely that the 13mm belt that RDG sell as suitable for Myford is actually suitable for the newer big bore S7. Actually looking closely you can see the belt virtually riding on top of the pulley rims, so there is very little actual surface area to give friction and therefore drive. Lathes.co.uk also quote A-section for the h/s drive belt but on the newer lathe it should be Z-section it would seem. Bricky seems to have had problems with z-section Powertwist so I'm inclined to try the more expensive T-link, still cheaper than getting the service engineers out and worth a try as an alternative to dismantling the headstock for an endless belt. As they say, when you're up to your a***e in alligators it can be hard to remember you set out to drain the swamp!

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