Another 10" Logan Project + A Question

FIRST CHIPS, BUT...

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Gave the lathe it's first sea trials today by turning some scrap pieces of aluminum and steel. Lathe is very smooth and quiet, and the surface
finish on the parts was good. But, when the flat belt is on the center pulley, it slips off under power. The pulleys seem aligned pretty well, but I'm thinking
it's an alignment problem anyway. Anyone experience this before? I'm also unsure of how tight the flat belt should be.

Also, when I switch the v-belt from one pulley to the other, the tension changes enough
that I'll need to adjust it each time. I assumed that this wouldn't be needed. Is this
normal?
 
While I can't speak to this particular make and model of lathe, in general, machine manufacturers carefully calculate the PD of the various steps of both pulleys so that each step needs the same belt length. If that isn't the case here, then my guess would be that one of the two pulleys (usually the motor one) isn't OEM. On the flat belt problem, I've no suggestions.
 
On my Logan 820 I don't need to change the tension when moving the motor belt from one pulley to the other.

As you probably already know the upper belt cover also acts as the mechanism to tension the flat belts. Opening the lid loosens the belt. Adjustment of "LA-366" is important. I have mine adjusted so that the lid sits is about 1/8" above the rubber lid stops. If I adjust it so that the lid is actually resting on the rubber lid stops the flat belt will slip. The rubber lid stops that I have are generic ones from the hardware store, they may be a bit thinner than the originals (which were missing from my lathe). I have a composite flat belt with metal clips. If I do push the lathe real hard I can make the flat belts slip, which is probably a good thing at least for me.

When I got my 820 it did not come with the rear support leg, mine is the older pipe style. The length of this leg is also critical to getting everything right.

Drive820.PNG
 
For the flat belt, I would try and bring the right side of rear pulley shaft in a smidge. I think doing that will make the flat belt want to ride to the right (it shouldn't take much). When I had my 200, I had the newer style rear shaft without the adjusters ... never really had an issue with the flat belt (other than slipping).

I did have a similar issue with the motor belt, after I replaced the motor (original pulleys). I really think that is more a trial and error of motor positioning to find a sweet spot that works for both pulleys. I remember beating myself over the head on that issue. With the old motor the belt was easy to flip from one pulley to another, I never did get the same result with the new motor.
 
While I can't speak to this particular make and model of lathe, in general, machine manufacturers carefully calculate the PD of the various steps of both pulleys so that each step needs the same belt length. If that isn't the case here, then my guess would be that one of the two pulleys (usually the motor one) isn't OEM. On the flat belt problem, I've no suggestions.

It's a bit of a mystery, since I bought the motor pulley from Logan, and the countershaft pulley has the correct Logan part number on it. I might give Logan a call on this one.
 
On my Logan 820 I don't need to change the tension when moving the motor belt from one pulley to the other.

As you probably already know the upper belt cover also acts as the mechanism to tension the flat belts. Opening the lid loosens the belt. Adjustment of "LA-366" is important. I have mine adjusted so that the lid sits is about 1/8" above the rubber lid stops. If I adjust it so that the lid is actually resting on the rubber lid stops the flat belt will slip. The rubber lid stops that I have a generic ones from the hardware store, they may be a bit thinner than the originals (which were missing from my lathe). I have a composite flat belt with metal clips. If I do push the lathe real hard I can make the flat belts slip, which is probably a good thing at least for me.

When I got my 820 it did not come with the rear support leg, mine is the older pipe style. The length of this leg is also critical to getting everything right.

View attachment 235132

It sounds like you have more tension on your belt than I set up with mine. I had no idea how to do it, so I just winged it and gave it what seemed to be a reasonable amount of tension. I could try to tighten
things up a bit and try again.
 
For the flat belt, I would try and bring the right side of rear pulley shaft in a smidge. I think doing that will make the flat belt want to ride to the right (it shouldn't take much). When I had my 200, I had the newer style rear shaft without the adjusters ... never really had an issue with the flat belt (other than slipping).

I did have a similar issue with the motor belt, after I replaced the motor (original pulleys). I really think that is more a trial and error of motor positioning to find a sweet spot that works for both pulleys. I remember beating myself over the head on that issue. With the old motor the belt was easy to flip from one pulley to another, I never did get the same result with the new motor.

Since my lathe has the countershaft adjusters, I did try adjusting that last night to make sure the shafts are parallel. Belt is brand new from Logan, and I made sure the pulleys were clean before I started it up.
I might try a bit more belt tension.

As far a the v-belt goes, the tension difference between the two pulleys is pretty substantial. I'm going to call Logan and see what Scott says.
 
As another point of reference, I also noticed that the adjusting screw on the cover of my lathe is set low enough that the cover has to be pushed down a tad to actually make contact with the bumper stops. I reached under the drive box to check the belt tension (motor off), and it does not appear to be especially tight.

I'm using a 3/4 inch wide serpentine belt and haven't noticed any slipping, but I may not be driving very hard as I'm still using a lantern tool post with a pretty small cutting tool.
 
As another point of reference, I also noticed that the adjusting screw on the cover of my lathe is set low enough that the cover has to be pushed down a tad to actually make contact with the bumper stops. I reached under the drive box to check the belt tension (motor off), and it does not appear to be especially tight.

I'm using a 3/4 inch wide serpentine belt and haven't noticed any slipping, but I may not be driving very hard as I'm still using a lantern tool post with a pretty small cutting tool.

I would imagine the serpentine belt is rubber, so probably less likely to slip. The Logan belt I installed is quite thin (about .050 thick) and glued together. Not sure how it's made, but it doesn't
seem as "grippy" as a a pure rubber belt, so it may be more subject to slip. I called Scott Logan this morning. He thought I had a pulley alignment problem, though he did suggest a bit more belt
tension. When I asked him how to tension the belt, he said only as tight as needed to avoid slip. I went back and tinkered with the lathe some more: made sure that the countershaft was
parallel to the spindle and the pulleys are in line. I also upped the belt tension and rechecked my v-belt alignment. It seems OK now, and I was able to do some more tests. I also asked about the
difference in motor pulley tension. He indicated that there were two countershaft pulleys for the 10" Logan, though he wasn't sure exactly when the changeover occurred. My parts list showed
the early Model 200's had my pulley (LA-141), and the 210's had a different one. Later, they standardized on one part. What I did find is that mine is a larger OD than the diameter that Scott gave
me over the phone, which explains why mine adjusts up as it does. So, it appears that my lathe may have also had a different motor pulley than the one that Scott sells. Had no information
about that, and only has dimensions for one part. So, if I change the belt position, I'll just have to re-adjust the tension. No big deal, really.

So it appears that I have a working lathe. I'd call this job finished, except I have to machine the backplate and mount the Bison 4-jaw I bought for it. Then it will really be done. But, I do want to thank
all of you that contributed by giving me advice and encouragement during this job. I really appreciate all the help you guys have given me.
 
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