What width flat belt should I use?

Look under power transmission in your Yellow Pages and see if there's a place near you that makes up flat belts still. Then go talk to them. In Seattle the place is Peat Belting.

My 9" SB has 1" wide pulley flats and the book calls out a 7/8" belt. I didn't know that at the time and am using a 1" belt, which works fine. I don't think it's critical, but based on this if I were you I'd buy a 1" belt.

If you can remove the spindle (often a good idea, lets you clean out the headstock and renew the oil wicks, etc.) then you might want to consider measuring the length you need and buying a timing belt that length at the auto parts store, then turning it inside out. Those belts are just great.

GWE

For what it's worth, I used to have an old Bradford lathe (1910's vintage or so I think) that used a 2" wide belt. The guy I got it from put a final drive belt from a Harley-Davidson on it (smooth side in), and it _never_ stretched. Might be worht considering, but I have no idea how you could make it narrower if you needed to. I can't imagine it'd be easy to slit.

I was very happy with the synthetic belt in this application. Far as I know, the guy I sold it to is still using it, and it's been years.

Dave Hinz

As long as your pulleys are properly crowned, and the spindles are aligned, a 1" belt should stay centered without rubbing on the next larger step. Grant's timing belt idea sounds great if they are flexible enough to hug the whole width of the pulley, and not just ride on the peak of the crown.

Ken Grunke

Thanks for the info. I went to the auto parts store and the only belt I could find that was 48" long was a 3/4" flat belts that has the grooves running the parallel to the edges. Is that the wrong kind of belt?

I removed one of the spindle caps and there was some kind of paper gasket material. Do I need to replace the gasket now that I've opened it?

Also, not sure what wicking is, but this lathe has nifty little oil caps that lift up and reveal a port in which to squirt oil. The oil then fills a sump which has a revolving loop that seems to distribute the oil around. Once I have the bearings open, is there any other maintenance that I need to do.

Once again, thanks for all the help.

-Aaron

No, that one will work fine.

I can't answer a single one of your other questions, though.

GWE

That material may be serving as a shim for the bearing cap, if I understand you correctly. The bolts for the bearing caps should be fairly tight--but if the spindle drags or stops turning, you need to add shims between the bearing cap and headstock until you can tighten the cap bolts without placing any drag on the spindle. Normally metal is used, but I guess paper is OK. I've used aluminum can pieces, about .003".

I would just say to clean everything well, make sure no grit gets in there to scratch the shaft journals.

Another thing to check is the spindle axial play, or movement in line with the spindle. I'm not familiar with this particular lathe, but there may (and should be) an adjustment collar or nut bearing against a thrust washer, probably at the inside of the outboard bearing. If this is too loose, you'll run into problems getting a good cut on anything chucked or otherwise held in the headstock without tailstock support.

Ken Grunke

Aaron,

I also have a 10" Seneca Falls Star lathe. My pulley sheaves are

1-1/4" wide, and I use a 1-1/4" belt, which has worked fine. The smallest pulley sheave, where the belt might otherwise get pinched, is actually about 1-5/16".

Another poster mentioned checking spindle end play. This is a very good idea, especially if your lathe has fiber end-play washers, as mine does. When I first started using the lathe, I couldn't figure out what was going on. For a while, the end play kept increasing, so I thought that the end play washers were wearing rapidly - then the end play started decreasing! It turns out that the washers were swelling as the humidity increased, and shrinking as the weather became drier.

On this lathe (assuming it's the same as mine), the end-play is adjusted at the far left end of the spindle. Just loosen a setscrew that pinches the adjusting washer.

By the way, feel free to contact me with questions about this lathe, as I've used mine quite a bit, and have extensively refurbished it.

Dave

Thanks everyone for all the good information about the belts and adjusting the spindle. Hopefully I'll get the lathe working this weekend.

-Aaron

That is not a timing belt, I think its what is called a Microgroove belt here in Aus. I might work though. The timing belts are very strong as they have either steel wire or Kevlar in the flat part of the belt. I think a company called Gates makes them in the US.

No! I suspect that that material is used to set the clearance between the bearing halves and the shaft. It is important that the clearance is correct as if it is too loose the shaft will wobble in the bearings and you will get a poor accuracy and finish on your work. If its too tight, It will sieze onto the shaft and melt the bearing material. For general purpose shafts on industrial machinery, we gererally used a "rule of thumb "of one thou clearance per inch of shaft diameter. It may be a bit tighter for a machine tool.You can check it by using "Plastigage" which should be available from an automotive supply. Put a piece of the material on the shaft and assemble the bearing and torque it up to specs. Remove the bearing cap (without turning the shaft) and use the width gauge on the packaging to determine the bearing clearance

The common US term is "serpentine belt". --Glenn Lyford