Gallery, Projects and General > How do I??
Lathe belts
Darren:
After discussing my belt problems with John and Stew last weekend whilst visiting Johns place, it became clear that something was very wrong with my S&B lathe.
When doing anything a little tough, like cutting a 10mm thread with a die, my lathe belt would slip making the job impossible to do. John previously indicated that my lathe should manage a 10mm thread with ease. But it couldn't.
The situation was such that I would tighten the belt to such a point that it would destroy itself. If I didn't it just wouldn't grip. I have tried 3 belts now. One leather, one nylon backed leather and one synthetic type called Belta.
This is the Belta, as you can see it's tearing apart and it's not been on very long.
So I decided to try a car "Serpentine" belt. The reasoning was that such a belt on a car had a far harder life than my lathe would ever subject it to. The other bonus is that it would not need jointing.
So, now having purchased a suitable belt from Unipart I set to stripping the headstock in order to fit it. Worth noting is that Unipart can select a suitable belt by the length you specify in mm. This makes life far easier than trying to find which car you need a belt from, such as in Halfords. The belt cost £12 which is a bargain.
Here I have started to strip the headstock, look at the diameter of that front bearing, 4 inches :bugeye:
It became clear that the spindle had to come out the front, so off comes this lot.
Now out comes the front bearing, turns out to be a double race.
Spindle out, look at the size of it for such a small lathe....
The rear bearing
Alas, it now became apparent that a continuous belt could not be fitted to this lathe. Here is why.
The headstock
Well, a jointed belt it has to be then. The headstock parts were cleaned, re-lubed and put back together. Thankfully everything was in excellent contdition with no signs of any detectable wear to be found.
One bonus, I found a spindle lock. Long overdue/missed and will come in real handy when removing the chuck.... :thumbup:
Darren:
Well I needed a new belt, so what to do....
I now had the serpentine belt and I didn't really want to go down the leather route again so I took the plunge and cut the belt, drilled some some holes in it.
Then I threaded it together with some fishing line
Interesting point to note, against the pulleys the line slips inside the belt grooves. This will protect the line from abrasive wear. I have tried this type of lacing before with leather belts. But it never lasts long due to rubbing on the pulleys.
Time to do some test cuts. I kept the belt slack. In fact it was slack enough to change pulley speeds without slackening the motor leaver thingy that you would normally used.
Here I am taking a 100 thou cut, yes that's right 1/10th of an inch !! No problem, the belt was slack and it didn't slip.
And the real test, a 10mm thread, yep, no sweat, it cut this with ease, again no belt slip...
What a revelation, a slack belt and plenty of grip.
The fishing line by now didn't look too good, it was starting to give. So I re-laced it with Stainless welding wire.
This type of belting is a revelation over leather types. It's far smoother, quieter and has bags of grip. I don't need to tension the belt much at all now and hopefully it will last as a result. And so will the headstock bearings...
Not to mention that they are cheap and readily available in many sizes too... can't be bad.
Only one thing to do now, I would like to find a better way of jointing the belt. Maybe an over band and rivets....
Suggestions please.. :thumbup:..
dsquire:
--- Quote from: Darren on March 06, 2009, 05:25:37 PM ---HI John,
I have just this min taken the belt off the lathe and popped it in the car, was going to visit Halfords on the way to yours to see what they might have. It's a 50 mile round trip for me just to go there (yes I'm that far out in the sticks, hills, mountains chaps..... lovely, mostly :lol:)
Not wishing to push you, do I hang fire or pop in there anyway?
I have tried gluing and crock clips but it just don't hold. The glue holds ok but the belt breaks next to it. The crock clips just fall apart after a while and rip out. Trie leather belts, leather/nylon, and some funny stuff I'll show you tomorrow.
It's the join that gives the problems, hence thinking car belts. Surely they must be strong enough. I think the real prob it that this is a high speed lathe, up to 3000rpm
--- End quote ---
Darren
I have had a thought on this and wonder if you have ever used a belt dressing on this lathe or belt. THis would reduce the slipperyness of the belt and make it somewhat sticky. This would mean the belt would not have to be as tight to get a grip to turn the spindle. This in turn would place less stress on the joint.
The belt dressing that I used to use looked like a stick of tar about 1 /2" Dia. x 8" long. You just held the end of it against the belt and the friction caused heat and melted a bit off onto the belt causing it to be a bit sticky.
Cheers :)
Don
Darren:
Hi Don,
John and Stew mentioned this stuff to me at the weekend, I'd never heard of it. Amber they called it. I suppose I should have given it a try. The Belta belt is sort of rubbery, you'd think it would offer tons of grip but it didn't. Rather took me by surprise as that's why I bought it.
I have the serpentine belt now, so I'll see how that goes. I've been doing a bit of googling on these belts today. Seems that yet again I've come up with nothing new :doh:
Over on Practical machinist many over there swear by these belts over leather, seems to be a leather revolt going on :dremel:
dsquire:
--- Quote from: Darren on March 09, 2009, 08:36:39 PM ---Hi Don,
John and Stew mentioned this stuff to me at the weekend, I'd never heard of it. Amber they called it. I suppose I should have given it a try. The Belta belt is sort of rubbery, you'd think it would offer tons of grip but it didn't. Rather took me by surprise as that's why I bought it.
I have the serpentine belt now, so I'll see how that goes. I've been doing a bit of googling on these belts today. Seems that yet again I've come up with nothing new :doh:
Over on Practical machinist many over there swear by these belts over leather, seems to be a leather revolt going on :dremel:
--- End quote ---
Darren
I remember this stuff from when I was a kid with my grandfather back in the late 40's. Grandpa would always put it on the belts running from the tractor to the different equipment on the farm. I have even used it on ocasion on a v belt that wanted to slip to keep from having to put to much pressure on the spindle or shaft to keep from slipping. This would also decrease the load on the bearings.
While typing this I have just thought of another belt. It is a link type belt that can be made in any length. I have seen it advertised for table saws to promote smooth running as the belt does not take a set like a v-belt does which in turn can sometimes take up a vibration. If I can find anytthing on this I will get a link to you.
cheers :beer:
Don
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