Belt mistery

[JasonBModerator @jasonb]

I would expect it to be longer as Sonic’s lathe has riser plates effectively making it an 8″ swing not 7″ swing

[JasonBModerator @jasonb]

Looking at a copy of the spare parts list there was a change in motor and the belt length also changed. The vellow page number 3 towards the beginning gives the 6.** numbers and down on page 16 & 17 you can see the two different belt lengths . Though still likely to be different a sit is 8″ swing

https://groups.io/g/emcoV10lathe/files/Emcomat%207-7L%20Spareparts%20SCAN.pdf

If you can’t open th elink the earlier belt is a 190 XL 062

[Phil PParticipant @philp]

Assuming the riser plate is 1/2″ thick then his belt would need “very approximately” another 5 x 0.2 pitches of teeth making it 20″ long rather than 19″.
So maybe it is fitted with a 200 XL 075 ??, if it is much longer than that, it would be too slack.

I am really curious now to see what the eventual outcome of this mystery is. I know Sonic is adamant that he only has the one belt, but we are running out of options and that might be all that is left to consider somehow.

Phil P

[JasonBModerator @jasonb]

I don’t think it will affect things as the motor end castings “look” symmetrical but we are running out of ideas. Looking at the two videos before and after the motor bearings were replaced the output end has either lost a lot of paint or it has been put back together with the end castings swapped over. Could this be something to do with the problem?

[Grindstone CowboyParticipant @grindstonecowboy]

A clear photo taken straight on to the end of the motor should show if the mountings are offset from the centreline. As Sherlock Holmes used to say (or something very close to) “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the solution”.

Non-symmetrical end castings? Maybe.

Rob

[Phil PParticipant @philp]

I think the photo we have already seen rules out any ofset in the motor mountings.

[Grindstone CowboyParticipant @grindstonecowboy]

Ah, hadn’t seen that!

Rob

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, well looking at the original photo, and cropping and enlarging the area around the adjusting pulley on the before one, the adjuster is push up higher then on the after photo, so maybe something has got in the way of it going up higher. It shouldn’t need to go much higher to take out the slack that you have.

Regards Nick.

[Howard LewisParticipant @howardlewis46836]

The idler appears to be high up, near the drive pulley for the spindle.

In view of the small diameter motor pulley, is it possible to reposition the idler so that it increases angle of wrap of the belt around the motor pulley?

On the face of it, it sounds like misassembly, since none of the components have changed.

My inclination would be over check the assembly without any soft spacers, as much to the original set up.

You haven the original components, which worked, so ensuring that they are assembled in the right place and order ought to solve the problem.

Howard.

[Phil P]

I want to summarize some conclusions:

– there could be some spacers for the motor. I’m not the first owner of the lathe. But moving the motor horizontally doesn’t tension the belt. Unless it is not moved by a considerable distance.

– I agree that I did something wrong in reassembling it. But I want to make some progress with the lathe. There are many months since I’m waiting for the moment to turn it on and now I’m very close. That is why I want to order a new belt. I don’t see nothing wrong in the way it is assembled now. With a shorter belt it should run fine.

– the adjuster idler can’t tension the belt. No mater if I reverse it, rise it to the maximum or anything else. The belt is way too large for it to be able to compensate. Bellow are two pictures with the tensioner mounted in both positions. Also look at the motor screws, I tilted it as much as possible.

On Phil P Said:

Sonic
Can you tell us what the numbers are marked on the belt ?

According to the parts list it should be a 190 XL 075
With details on this link, does it actually have 95 teeth ?

https://www.tyma.eu/products/190-xl-075-conti-synchrobelt-neoprene/?srsltid=AfmBOoqo5EAvD95hTaxqt_kbJLVbKXUW0VH4lwzqnBOKFbUNNpmiOOP2

My belt has 105 teeth. Here is the type. But maybe the extra length comparing to the one from the part list is justified by the headstock riser block. I even tried to count the teeth of the belt in the first pictures. Just in case the seller gave me another belt and I forgot (very unlikely). But the number of teeth was also ~105.

 

[noel shelleyParticipant @noelshelley55608]

Do I take it the lathe was not used before dismantling ? 2 thoughts, first bring the rear belt run forward and put the adjuster on the rear run. Or take out the top mounting pin allow the motor to hang out and back, refit the pin and allow the motor to be held against the pin by belt tension. This uses all the parts but in a different way. Good luck. Noel.

[Ian PParticipant @ianp]

 

 

Possibly a wild idea and its hard to judge looking at the picture, but could you move the idler mount plate ‘pivot point’ temporarily at least, to the long hex nut at the top right on the motor? The adjuster bolt and washer would keep the plate aligned so you could at least try the lathe.

TBH as its assembled in this picture there does not appear to be a massive amount of excess belt length and I wonder whether removing the packing where the motor feet sit against the bed casting would be ‘just enough’ to tension the belt

Ian P

[mark costello 1Participant @markcostello1]

Could the idler plate be flipped around with the front that is facing Us become the back that is against the head stock? Then mount the idler pulley on the new front side putting the idler closer to the motor pulley? Maybe swap the pivot point around. If more adjustment needed a bigger pulley might help.

[SillyOldDufferModerator @sillyoldduffer]

I tried comparing the relative distances between reference points on the before and after photos, hoping a displaced part would show up.

Looks to me as if all the relative references under the circles are proportionally similar. I can’t see anything in the comparison suggesting an assembly error.  For example, the red circles show the motor and headstock pulleys are the same distance apart relative to half-way up the lathe bed and the reversing lever in both photos.

The only thing that’s obviously wrong is the belt.  Except Sonic said in the opening post that there’s only one, so it can’t be that!  However, to quote Sherlock “Whatever remains, however improbable, must be the truth.”  As we’ve all failed to identify anything wrong apart from the belt not fitting, try a shorter belt!

Is this the most puzzling question ever asked on the forum?

Dave

[Nigel Graham 2Participant @nigelgraham2]

Dave –

It’s certainly has us all scratching our heads!

Aha – carefully studying the photos as you’ve edited with all those circles…

Would bringing the motor back against the casting take up much of that slack, by increasing the wrap round the tensioner roller? Endless belts don’t need much lateral movement to tighten them appreciably.

 

Sonic –

Try that first- move the motor fully back to the bed so the roller has more effect.

If that does not do the trick, was the belt too slack even before you took it all to bits?

If so, I agree the fault must be an incorrect belt, fitted by the previous owner. Replace the motor and tensioner as they should be; and obtain a belt as specified in the service-manual.

As I said above that resilient pad may cause more trouble than it’s trying to solve, but a thin washer or two on the studs may be necessary if the motor’s accurately-made feet do not all sit fair and square on the casting, with the shafts nicely parallel.

++++

As for the most puzzling question…

I reckon this one is runner-up; the most puzzling being that strange “circular slide rule” someone posted about 3 or 4 years ago!

[noel shelleyParticipant @noelshelley55608]

The circular slide rule was ME ! and that was never answered either. Noel.

[Nigel Graham 2Participant @nigelgraham2]

Sonic –

Look carefully at IanP’s reply a few messages up from this.

I think he’d twigged it before I did, because your photo he cites is full-on to that area and shows that although the belt is too slack there, it does not look ever so “too long”.

With the tensioner that way round (the quadrant between the belt sides and pointing upwards, roller on the outside) the amount of slack in the belt looks small enough for what he suggests, and as I did later, bolting the motor back to the bed.

 

Noel – 

I did enjoy that puzzle!

I tried various lines of enquiry:

Blundell-Harling, who make special-to-trade circular slide-rules, had never seen one like that.

On a hunch I wondered pipe-organ design, due to the curious fractions. Harrison & Harrison were intrigued by the photo and enquiry but said they did not recognise it as anything to do with musical instruments.

(Incidentally, I found that company’s web-site really fascinating, and the considerable use of manual craft skills it shows, very inspiring.)

I tried searching the Science Museum catalogue. Its vast web-site is difficult to navigate unless you really know what to ask, and at one point I blundered into 19C surgical instruments, one rather distressing when I twigged its likely use. So a blank there. If I recall rightly, I tried pharmaceuticals too, which used to have odd units of weight. Another blank.

I did see a photo of, I think, a duplicate elsewhere on-line but still without anyone having the foggiest what it was for.

Whatever it was, it makes trying to fit a toothed belt to a lathe, seem easy!

 

[Phil PParticipant @philp]

Wrap a piece of string around where the belt needs to run and measure its length, I recon it will be 20″ so a 200 XL 75

[noel shelley]

On noel shelley Said:

Do I take it the lathe was not used before dismantling ? 2 thoughts, first bring the rear belt run forward and put the adjuster on the rear run. …Noel.

We have a winner. That would put the idler pulley in the more normal position on the return side of the belt  not the drive side.

[cedric 1]

On cedric 1 Said:

On noel shelley Said:

Do I take it the lathe was not used before dismantling ? 2 thoughts, first bring the rear belt run forward and put the adjuster on the rear run. …Noel.

We have a winner. That would put the idler pulley in the more normal position on the return side of the belt  not the drive side.

Good idea, and I hope it’s right.  Don’t bet the farm on it though:

Maybe with the tensioner reversed? I think it makes the collision worse.  Over to Sonic! Does that belt arrangement fit in the real world? With luck my drawing on an angled photo looks tighter than it really is.   Fingers crossed!

Dave

[JasonBModerator @jasonb]

As it is not far off being tight in some photos you could use your other lathe to make a sleeve to fit around the tensioner wheel which would allow it to take up more slack.

Easy to see if this will work by putting a finger between belt and tensioner then pivoting the tensioner to see if the effective larger radius due to your finger tightens the belt.

[Colin HeseltineParticipant @colinheseltine48622]

In all the pictures of the tensioner (including Jason’s in previous post) there still looks to me to be around 1/2″ of slot left to go.  If the tensioner was pulled right up to the end it would increase wrap round the top pulley.

Colin

[noel shelleyParticipant @noelshelley55608]

Is there a sleeve missing off the idler ? If not then fitting one will solve the problem. Noel.

[SillyOldDuffer]

On SillyOldDuffer Said:

On cedric 1 Said:

On noel shelley Said:

Do I take it the lathe was not used before dismantling ? 2 thoughts, first bring the rear belt run forward and put the adjuster on the rear run. …Noel.

We have a winner. That would put the idler pulley in the more normal position on the return side of the belt  not the drive side.

Good idea, and I hope it’s right.  Don’t bet the farm on it though:

Maybe with the tensioner reversed? I think it makes the collision worse.  Over to Sonic! Does that belt arrangement fit in the real world? With luck my drawing on an angled photo looks tighter than it really is.   Fingers crossed!

Dave

Indeed. Close but no ceegar according to the sketch. Worth a try though.

Looking at this latest pic though, it appears there is a gap between the motor base lugs and the lathe bed. Is it possible to tighten the 4 bolts that go through the two rods and pull the motor in snug against the lathe bed, thus increasing the wrap around the tensioner pulley and tightening the belt?

[JasonBModerator @jasonb]

Cedric. Look at the early photos where the motor was pulled up tight to the bed. I the photo you are looking at Sonic  slackened it off so it would pivot away from the bed and reduce the slack but it does not take up enough.

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