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blowlamp06/12/2010 16:56:04
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1885 forum posts
111 photos
Looks like it could be a good candidate for a Poly-V belt conversion, if you can get the right length.
 
Martin.
Gordon A06/12/2010 22:08:23
157 forum posts
4 photos
Prior to parting company with my Hobby 818 lathe, I was planning to install a countershaft driven by a poly-V belt in order to reduce its bottom speed from 250 rev/min to something more acceptable.
I obtained a suitable belt from a local independent electrical shop specialising in domestic appliance spares.
The use of this type of belt in washing machines, dryers, vacuum cleaners etc is not uncommon.
 
Just food for thought.
 
Gordon.
 

 
 

Terryd06/12/2010 22:26:48
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1946 forum posts
179 photos
Hi JasonB,
 
If that is the case and the toothed belt is simply a drive from the motor to the countershaft.  Is it possible that this part of the drive is where the highest torque could cause problems and perhaps excessive slip at slow speeds?  The manufacturers must have had a reason to put this type of belt drive here.  If a vee or round belt would suffice surely they would have taken this cheaper solution?  And if they are just mimicking the European machines then the European manufacturers would likewise have a sound reason for this type of drive?
 
Sorry to seem nitpicking but it seems to me that someone, probably a design engineer, has seen the need, probably an empirical decision following experience, to put this type of drive here and if it were me I would research all possibilities before making such a drastic modification without knowing all the details.  That modification would be my last resort. Still, each to his own,  Let us know how you get on Gordon.
 
Terry
 
 
John Olsen07/12/2010 00:09:44
1294 forum posts
108 photos
1 articles
Hi All
 
I have been wondering about the torque requirement too, although since it is the first reduction when in the low ratio, it should not be handling as much torque as the second belt does.
 
Having seen the pictures of the setup, my own inclination would be to modify the pulleys to take a standard readily available toothed belt. Actually I would probably go the whole hog and use toothed belts for all of the reductions, although that might be a problem if there is not enough room. I did that with my Unimat and fitted it all within the standard cover, a great leap forward for the little machine. One advantage of the toothed belts in my view is that they do not require to be under any great tension, so other than the drive forces they do not put any loads on the headstock bearings.
 
It should be possible to turn the existing teeth off the existing pulley, and either allow the new set to be a little undersize, or else fit on a  ring turned from a suitable piece of tube to bring it back up to the nominal size. With the big area available, loctite should be fine to hold such a ring in place.
 
regards
John
Terryd07/12/2010 02:44:11
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1946 forum posts
179 photos
Hi John,
 
When I was discussing the torque at the primary drive I was thinking of the starting torque.  The lathe does not have motor speed control so it is trying to start at full speed.  I don't really know enough about the theory involved,  that's for others to discuss.  I just feel that the toothed belts are there for a reason, it's not an accident or an offhand decision to use this type of drive it is a deliberate design decision.  It would have been so much easier just to add another vee pulley to the cones if it didn't matter. 
 
If Grizzly do the equivalent of the 10" version of this lathe someone will surely supply the 8" model being discussed here.  personally I think the way to go would be to research suppliers of the lathe rather than belts.  Saves a lot of work and possible expensive components if they could be located..
 
Regarding your idea of skimming the pulleys, excuse me if I seem thick, but did you mean that teeth for a new pulley could be cut when the new ring is in place to match a standard Belt?
 
Terry
John Olsen07/12/2010 04:28:30
1294 forum posts
108 photos
1 articles
Hi Terry,
 
Yes, I would agree with you that  it is not an accident that they have used this type of belt. The price of the belt itself is probably not much different between toothed and V, but the pulleys do tend to be dearer for the toothed one.
 
I was thinking it would be possible to fit a ring neatly in place and then cut the teeth to suit something standard. A bit like a ring gear on a car. Of course the motor end would have to be done too, which might be harder. If a supplier of the belts could be found that would actually be the way to go.
 
regards
John
JasonB07/12/2010 07:26:18
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25215 forum posts
3105 photos
1 articles
Some of the larger Emco machines use a toothed primary belt and its well know that these form the basis for a number of the far eastern machines.
 
"If Grizzly do the equivalent of the 10" version of this lathe someone will surely supply the 8" model being discussed here"
 
Back on the first page I linked to Quantum who do the belt drive DB8 clone, would be better contacting them to see if they can provide a spare.
Terryd07/12/2010 15:39:10
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1946 forum posts
179 photos
Hi Jason,
 
You're probably right about the Quantum lathe, In fact they now supply them through Excel in Coventry who may be able to source the belt due to their connection with the company.
 
By the way I finally decided on the Warco WM280 VF but my garage rebuild has been held up by the weather (and inefficient builders appointed by the insurance company ). So I probably won't be able to have it delivered until after Christmas, very Frustrating . 
 
I'll console myself with the old adage that good things are worth waiting for.  I just wish that I could persuade myself of that. 
 
Regards
 
Terry
Dinosaur Engineer07/12/2010 16:00:42
147 forum posts
4 photos
Maybe the toothed belt is used due to a small pulley being used  ( high torque at small radius) and the pulley wheel centres are close so that it's difficult to provide enough "wrap around" for a 'V' belt. A friction belt would be better than a "geared" belt as it's more likely to slip rather than cause mechanical damage. The equivalent ' v ' belt drive would probably need more space and/or a tensioning roller to increase the small pulley "wrap around" 
blowlamp07/12/2010 16:30:15
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1885 forum posts
111 photos
Posted by Dinosaur Engineer on 07/12/2010 16:00:42:
Maybe the toothed belt is used due to a small pulley being used  ( high torque at small radius) and the pulley wheel centres are close so that it's difficult to provide enough "wrap around" for a 'V' belt. A friction belt would be better than a "geared" belt as it's more likely to slip rather than cause mechanical damage. The equivalent ' v ' belt drive would probably need more space and/or a tensioning roller to increase the small pulley "wrap around" 
 
 
 I agree with all of that and would say that if a small 'toothed belt' drive pulley is used, then that is probably a bad thing in this instance, as the belt will be prone to shedding its teeth.
Poly-V belts are much better under these circumstances, due to their slim construction and will wrap around smaller pulleys than other V-belts, but do need to be properly tensioned.
If the lathe in question has inadequate tensioning arrangements then that might be why the maker went with a toothed belt design, as it is more forgiving if left loose.
Almost all other manufacturers use V-belts of one style or another.
 
Martin.
Terryd07/12/2010 17:06:08
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1946 forum posts
179 photos
Hi Dinosaur and Blowlamp,
 
Those are very likely to be a couple of the reasons for hte decision to use these belts.  Dinosaur surely the slip factor is built in to the other (vee) belts from the countershaftand if Poly bets were used with their better grip it would tend to decrease the safety factor element.?
 
Regards

Terry
Gordon W12/01/2011 09:50:52
2011 forum posts
Just for interest:_ Have now got a new toothed belt for my Chester DB8 lathe. Well bought 2, following up suggestions on this forum, from Lathemaster in Baton Rouge US. Very helpful man, only prob. was Royal Mail charging £11.90 "handling fee". Pity I couldn't have got one from Chester.
ncd08/09/2011 10:20:57
1 forum posts
Hi,

Just as an update to this - I also tried to get the belt for my DB8 from Chester who were very helpful but it seems there may be two designs of DB8 out there. they very kindly offered to source one for me but I chose to try locally first.
 
Mine uses the older style wide belt which I bought from http://www.brammer.co.uk in case anyone else faces this in the future.
 
Cheers,
N
Ron Shaw23/09/2015 12:15:04
2 forum posts

This was interesting as i have the db10g and same issue, want spare belt, mine listed in manual as an M1.5xZ124

Can you give me the part no for the ones you bought?

Also i love the lathe so would like to mod pulleys if these belts cant be readily found as it would seem

Hoping we can keep this alive

Ron

mahgnia23/09/2015 15:28:55
45 forum posts
23 photos

C6 spare part:

**LINK**

C6-944 Timing belt from Arc-Eurotrade 1.5 x 124 x 15

 

Andrew

Edited By mahgnia on 23/09/2015 15:30:25

Ron Shaw23/09/2015 22:41:43
2 forum posts
Thanks a bunch there Andrew!!

Great link mate
cheers Not same lathe as mine but parts like belts same though

Edited By Ron Shaw on 23/09/2015 22:46:55

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