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Drummond round bed lathe - belt removal

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Peter Lord27/10/2018 14:59:41
8 forum posts
5 photos

Hi,

I wonder if anyone can give me any advice on how to remove the belt?

It's a one inch flat belt and runs on a 3 step plane pulley.

I have unbolted the chuck but there doesn't seem to be anyway of removing the face plate that the chuck bolts on to.

Any help would be much appreciated.

Peter

Keith Long27/10/2018 17:53:04
781 forum posts
10 photos

Peter if your round bed is standard the the chuck back plate unscrews from the spindle - it's a 3/4 inch, 10 tpi (BSW) thread - unless in the passage of time someone has changed it. The 3 step pulley is secured to the spindle by a grub screw in the smallest diameter pulley. Undo that and the pulley should then turn on the spindle. Slacken off the pinch bolts on the bearings , remove any collars, gears or spacers from the left hand end of the spindle, and the spindle should come out, either towards the tail stock or in the opposite direction. It's not fussy, the spindle is a constant diameter so can go either way. Look out for the thrust washer that fits between the pulley and the left hand bearing. That can be a bit of a fiddle to put back in but a bit of 1 inch bar popped into the left hand bearing while you slide the spindle back in from over the bed makes things a lot easier.

On my round bed the belt is joined with a "crocodile" or "alligator" clip (different trade names for the same thing) and I can just remove the coupling pin and take the belt off. You have to put up with the "click - click" noise as the lathe runs - I find it quite soothing actually!

HTH

Keith

Peter Lord27/10/2018 18:55:06
8 forum posts
5 photos

Hi Keith,

Thank you for the reply.

Is the spindle a Right hand thread?

If it is, If I hold the 3 step pulley and turn the chuck anti-clockwise it should come off? It's really tight and I don't want to break it.

The belt on my lathe is not standard. It's a variable speed belt with teeth. My intention is to drive it from a DC treadmill motor with variable speed and use a flat poly-v belt.

I attached a couple of pictures. (hopefully)

Thanks

Keith Long27/10/2018 19:16:45
781 forum posts
10 photos

Hi Peter, assuming the lathe hasn't been altered in the past, then yes it's a standard right hand 3/4 inch BSW thread. It's probably stuck due to oxidised oil varnish or in the worst case a bit of rust. You won't do any harm by using a hot air blower (paint removing type) on the flange, warming it may soften the hardened oil. If your changing the belt anyway then use that as a strap wrench to get extra purchase on the pulley, you could also bolt a bar of some sort across the backplate to give you extra leverage. I see your lathe has the later type of integral cast iron bearing, the pinch screws are the big slot headed ones, back those off to give a bit more clearance for withdrawing the spindle. If you cant shift the back plate in situ, the spindle will come out along the bed towards the tail stock and you could then work on freeing the back plate in the vice.

Keith

Peter Lord27/10/2018 19:29:39
8 forum posts
5 photos

Hi Keith,

Thank you so much for your expert knowledge. I will try this out tomorrow.

Regards,

Peter

Peter Lord29/10/2018 09:13:34
8 forum posts
5 photos

Hi Keith,

I managed to get the chuck backplate off but still can't get the shaft to pull out. I have removed the long grub screw (C)from the pulley, removed 2 grub screws (A)from the collar.
I have slackened off both pinch screws(D).
Do I need to remove the 2 allen grub screws (B) and (E)?
So far, the shaft moves a little but something is preventing it sliding out completely.

Please see attached pictures.


Can you offer any further tips please?

Peter

Keith Long29/10/2018 11:16:03
781 forum posts
10 photos

Hi Peter,

I guess what's stopping the shaft coming out is the collar that you've removed the screws "A" from - it's threaded onto the shaft! It's the collar used for removing end play in the spindle and acts to pull the spindle towards the rear bearing to adjust the end float. It's a normal right hand thread - quite fine pitch about 20 tpi I think - but if the grub screws are out it should unscrew quite easily. If it hasn't been adjusted for some time you might need to use a bit of rod as a tommy bar into one of the grub screw holes to get it started. The other thing to check is that the pulley can rotate on the shaft now that the long grub screw is out. There is no key there so the pulley should turn fairly easily. If it doesn't have a look down the hole in the pulley, there might be a second grub screw down there, 2 screws down the same hole is a common method of locking the first screw in place so that it doesn't work loose. You won't be the first to be caught by that and you certainly won't be the last - guess how I know!

The other possibility is that there is a burr on the main spindle caused by the grub screw in the pulley. The nose of the grub screw should enter into a dimple on the spindle to prevent that. If in the past it's been tightened onto a plain part of the shaft then it could have raised a burr. If you look down the grub screw hole you should be able to see the shaft and check that. If there is a burr then removing it before resorting to force to get the shaft out would be preferable, but access down the hole would be difficult. If you need to do that them a small circle of wet and dry stuck to the end of a rod or dowel might work for polishing the shaft locally - it isn't hardened so is quite "workable". I don't think there should be any problems due to wear ridges on the shaft, the spindles that I've seen show some scoring in the bearing areas but nothing significant otherwise. If wear was an issue you'd feel it with the bearing being slack.

Do you need to remove grub screws B and E - YES - and leave them out!! Those holes are for oiling the bearings and you definitely don't want a permanent screw in there to stop the oil getting through. On my round bed lathes those holes are generally plain NOT threaded. If I was screwing anything into either of those holes it would be an oil cup to help with lubrication or a knurled thumb screw to keep debris out. A plain shanked cap would be just as good. The bearings run on a total loss system so you need to be able to add a few drops of oil a regular intervals as you work - it doesn't need a lot - but having to remove grub screws to top up would be a significant disincentive for me!

Good to hear that you got the back plate off - you're getting there.

It would be worth you having a look at - and joining - the Yahoo Drummond lathe Owners and Users group. There is a stack of useful information there and a sizeable body of Drummond owning enthusiasts who can help with queries etc.

Good luck

Keith

Ian S C29/10/2018 11:35:57
avatar
7348 forum posts
229 photos

With grub screws in pulleys etc., always check that after you have removed the screw, that there isn't another one down the hole, there often is.

Ian S C

Peter Lord29/10/2018 12:03:19
8 forum posts
5 photos

Hi Keith,

You've gone to a lot of trouble to help me and I really appreciate this. I acquired this lathe from my dad. It's been sitting idle for years in the garage and I'm keen to start using it. I will follow the steps you have given and your advice.

Thank you so much.

Peter

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