Myford drive belt

[Peter Simpson 1Participant @petersimpson1]

Hi all, My Myford super 7 drive belt is just about knackered can anybody suggest a suitable replacement, I would rather not split the headstock down to fit an original style belt.

Peter

[Peter Simpson 1Participant @petersimpson1]

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[John HaineParticipant @johnhaine32865]

Fenner Powertwist

Similar to Brammer. I use it on my S7 lathe and VMB mill.  There are probably cheaper sources.

Some ME suppliers also stock a similar product moulded from a black plastic – I found it distinctly inferior. 

Edited By John Haine on 30/01/2021 10:55:34

[brickyParticipant @bricky]

Brammer belt, but the one with the metal rivet head if they are still availible ,they are a composite material and give a good grip.I have an old S7 which was fitted with a Brammer belt to stop vibration 32 years ago and is still going.I tried the new twist type of belt on my other S7 but got nothing but slippage,so I removed the spindle and fitted the correct v belt which cured the problem.

Frank

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by John Haine on 30/01/2021 10:54:17:

Fenner Powertwist

Similar to Brammer. I use it on my S7 lathe and VMB mill. There are probably cheaper sources.

Some ME suppliers also stock a similar product moulded from a black plastic – I found it distinctly inferior.

Edited By John Haine on 30/01/2021 10:55:34

+1 for everything John says. Happy with the powertwist on my S7.

Rod

[Ex contributorParticipant @mgnbuk]

As a counter view, I have not been satisfied with the performance of any modern variety of link belt & would just "bite the bullet" and fit the originally specified vee belt. After all, how long has your original belt lasted ? Chances are a correct OE spec.replacement fitted at this point would out last your usage !

The only variety of link belt I have used that performed adequately was the pre-plastic version of the metal studded belts that used a canvas based fabric for the links. My mid-60s Boxford CUD came with one of those which, even in a well-worn, tatty and oily condition performed better than the new plastic variety that was the current version of the same belt when I replaced it.

I did once come across this type of split vee belt that appeared to work as well as a normal version, but have been unable to find a UK supplier. IIRC the machine that had one fitted had come to us fro the USA. Basically a long length of vee section belt, perforated along it's length & joined with plates top and bottom screwed through the holes.

Nigel B.

[noel shelleyParticipant @noelshelley55608]

As some have said I would NOT use link belt other than in an emergency. The job of removing the spimdle is not difficult. There are plenty of places to find the instructions, all you will need is a cast ER32 C spanner from ARC (code 050 110 32540) which will need minor adjustment( GRINDER) to fit fine on the bearing adjusters, cost £4.54. And a new good quality A 29.5" or A780 V belt. The belt on mine needs changing and was fitted in 1969, it's probably a job you do once in a life time, so just do it ! It's also a good opertunity to clean all the headstock bits. Good luck Noel.

[Tim StevensParticipant @timstevens64731]

The link offered by mgnbuk is very like the belts used on early motor bicycles (and light cars) – except that the owner was expected to make his* own holes, and be prepared to make another at the roadside.

* no sexism here – a female owner would surely have had the belt fitted, and checked weekly, by a fully qualified and competent work-person.

Snowing in mid-Wales, and just had a power cut, ie – business as usual.

Tim

[bernard towersParticipant @bernardtowers37738]

Can’t understand your reasoning Noel, some Machine manufacturers use them from new,and they don’t get a set in them when not used for a while. My Fenner one has been on my S7 for close to 20 years!!

[Harry WilkesParticipant @harrywilkes58467]

Purchased a linked belt for my S7 from Lathe Spares link

more than pleased with it

H

[Howard LewisParticipant @howardlewis46836]

Roger Warren ad vised me that when the time came to change the B section belts on a Warco BH600 to used link belting such Poweretwist, or Brammer, rather than disturb the bearings and oil seals.

During recommissioning a ML4, I fitted an A section plastic link belt and that was an improvement over the well past it lifetime Vee belt. And the motor was a 2 pole, 3,000 rpm one!

So, another vote for link type belting.

Howard

[SteviegtrParticipant @steviegtr]

Nastly horrible link belts are for emergency use or where a shaft cannot be removed. The myford 7 is not hard to strip & replace with a silent running standard belt. The longest job is the counter shaft removal. Gives a chance to check everything over too.

If anyone says the link belt is great then go fit one on you car.

Steve.

[duncan webster 1Participant @duncanwebster1]

Not all that relevant but generator drive on Tornado and compressor drives on Bure Valley locos are all link belt

Edited By duncan webster on 30/01/2021 23:46:51

[SteviegtrParticipant @steviegtr]

Unfortunately there will always be folk who rave about a link belt. Not aiming at anyone. I have been involved most of my working life on machinery. I do accept that in certain circumstances a link belt is the way to go for reasons of being able to fit an alternative to an awkward situation.

What would be the comments if someone said , have you seen the new Audi . Awesome car & it has link belts. If you cannot fit a proper belt because of incapability or a position of logistics , then by all means a link belt is an alternative to doing the job right. After all they were invented for exactly that reason.

What i do not understand is that many forum members build the most wonderful steam engines, clocks & many other things. But seem incapable of changing a blooming belt.

Steve.

[Peter Simpson 1Participant @petersimpson1]

What I find strange is a very simple thing as changing a belt opens up two distinct camps, I have a S7 with probably it's original belt which is on it's last legs. I also have a Boxford ME10 which came with a linked belt both lathes operate fine with no issues. My view is both belts work fine, so why bother to strip the spindle down just to fit a belt.

[Ex contributorParticipant @mgnbuk]

I also have a Boxford ME10 which came with a linked belt both lathes operate fine with no issues.

Yet I sold my CUD because of it's dismal performance with a modern plastic link belt ? No option but to use a link belt on an underdrive Boxford & I guess that Boxford used the link belt on the ME10 as they bought the stuff by the reel. ME10s were not made in anything like the quantities of underdrive machines. In the year I spent there finishing my apprenticeship I can only recall seeing one batch of 50 ME10s – painted RAL 6011 Reseda Green for an American contract rather than the two tone brown/beige that was standard. at the time, they rather stood out all sat on pallets on the floor of the fitting shop.

An other consideration is cost. A quick look at on-line bearing / power transmission sellers shows a traditional wrapped A29.5 vee belt to be available from £1.80 + Vat, though my preference would be a cogged raw edge AX29.5 from £2.85 + Vat. Various sellers have Powertwist or Nu T Link A section link belts from £28.50 + Vat per metre. 10 times pricier for a link belt over an AX to save a bit of straight forward dismantling to fit & get an inferior drive performance ? Not for me, though I do admit to suffering from "Advanced Yorkshireman Syndrome " when it comes to letting my credit card see the light of day !

Nigel B.

[Howard LewisParticipant @howardlewis46836]

Interestingly, for some time we used link belts while testing engines in volume production, before changing to stretchable polythene belts, which being round, did not grip the pulleys as well, so needed more tension..

One of the engines in our Heritage collection now does demonstration runs, with link belt to drive the water pump!

If link belts were not used so often, no one would bother to manufacture and sell them.

They may not be suited to protracted running at the high surface speeds to which automotive belts are subjected, but they do have their uses.

They offer the ability to provide a drive where replacing a Vee belt would entail a lit of stripping. Sometimes in an industrial environment the time is just not available to have a line shut down for the time for a complicated strip and rebuild involved in belt replacement.. Some processes and material would be ruined by a long shut down.

Howard

[noel shelleyParticipant @noelshelley55608]

Peter has the benefit of our collective opinions ! I will be fitting a new A29.5 to my S7 I don't think link belt is right in this application. I have used link belt at work and found that as it bedded in it streched quite a bit, it was good quality with steel pins, it wore quite well. It has its uses ! Noel.

[John BaguleyParticipant @johnbaguley78655]

I've replaced both belts on my ML7 with 'cogged' Vee belts as sold by SimplyBearings etc. with a big improvement in smoothness and quietness of running. They are more flexible than a normal Vee belt and run with less vibration. I discovered them after having bad vibration problems with my mill after replacing the dual belt drive system with one long belt and a VFD drive. The normal Vee belt I tried flexed a lot at certain speeds and vibrated badly. The cogged belt that I tried as a last resort virtually cured the problem. I had thought of trying a link belt until I saw the price!

John

[peak4Participant @peak4]

I've noticed that people often link to secondary retailers of linked belts, rather than pointing directly to a manufacturers site.
We should remember that conventional rubber/cord V belts are mass produced and therefore the cheapest option, not necessarily the best for every application.

The cheaper black or white linked belts from RDG, amongst others, don't seem quite as good as a high quality rubber V belt, and seem more susceptible to oil contamination leading to slippage; I found the white to be marginally better than the black.

I've not tried a genuine Fenner Powertwist, but the manufacturer's site lists several advantages over conventional V belts; not all are just about ease of installation.
Less drive vibration, and better oil resistance amongst them.

I do use Brammer, and Fenner Nutlink, and another unknown similar design, as I bought a bag full at a steam rally some years ago.
One thing I should note, is that I'm currently using son T-Nut belt on my Warco720 (Myford S7 clone)
It works well, but does cause a problem, in that it makes selecting the lowest of the 4 belt speeds on the headstock difficult. The belt is deeper than either Powertwist or conventional V belt; the outer diameter fouls on the casting as there is not enough clearance.
It doesn't bother me too much though as the lathe is fitted with a Newton-Tesla VFD drive; one of the reasons I bought the lathe, along with the gearbox (and the price of course).

Note that the Powertwist belts are reinforced, unlike the cheaper black/white plastic ones from other sources.

Bill

Edited By peak4 on 31/01/2021 13:20:47

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