hsracer201
Hot Rolled
- Joined
- Oct 24, 2015
Hey, guys. I'm going to walk y'all though what is going on to see if anyone can help with this lathe. Bear with me, it isn't short, but I'm systematically eliminating common things in all the research I've done. Trust me, I've researched, I've tested, I'm stumped. I'm not chasing tenths or worried about minor tool or workpiece deflection, I'm trying to find out what is BIGGLY wrong. Also, for the sake of pictures I've used a set of calipers to show the readings instead of a mic.
This lathe came up on eBay back in late Oct or early Nov, I don't remember. It was only about 4 hours away, the pics looked good, the price wasn't bad so I bought it. At pickup there was no 3-phase to test anything and I knew that going in. No big deal. When I got it home it was pretty crusty so I tore it down to about every single nut and bolt for a good cleaning, inspection, new wicks, etc. This is somewhere around a '57 so it has a little wear as expected, but generally in very nice condition, and certainly capable of cutting decent parts, right?
Everything was done correctly to the best of my knowledge. I've done this before and I'm familiar with shims, bearing clearance, bed "leveling"/twist, etc. Right off the bat it was cutting a taper. Please note that up until the very end of this whole post there is not even a tailstock on the lathe. All of this has to do with chucked up work pieces. On about a 4" piece I was getting .016" taper. The part was larger at the chuck and decreasing in diameter as it headed toward the tail end of the lathe. I shimmed up what should have been the offending leg with no measurable change. It was shimmed once to the point of having a leg complete off the ground without any noticable change in taper. Next, a whole list of common things were done to try to rule out the problem but nothing changed.
- changed cutting tools, no difference
- changed tool holders (all Aloris), no change
- changed tool posts (all Aloris), still no change
- ran tests in a 3-jaw
- ran tests in a 4-jaw
- ran tests in a 5c collet
- made cuts with and without the taper attachment binding lever tight (taper attachment clamp is not on the lathe, just in case anyone was wondering.)
- used a different saddle, no change
Everything was still the same. Once upon a time I had a cabinet style heavy 10 that developed a taper in it after it was moved with a forklift under the bed. Chad recommended relaxing the bolts that held the lathe to the cabinet and it fixed it. So I relaxed all the bolts, let it settle, tightened everything back up. Nothing. I removed the chip pan. Nothing. I removed the headstock and checked for chips, burrs, squirrels, and replaced it. Nothing. Still cutting the same freaking taper.
Finally I got another headstock, spindle, bearings, everything and did a complete headstock swap with correct bearing shimming, just knowing that would somehow take care of my problems. Nope. Still cutting the EXACT SAME TAPER.
So here we are with a few pics. The offending lathe in question with the 2nd headstock assembly on. I was trying to measure across the face of that plate but I don't think the plate is consistent enough to test.
The following are just a few pictures of the ways and the under side of the saddle to give you a general idea of the condition of the lathe. Certainly not anything that would drag and cause such a taper.
I started over at this point and began taking some pictures. Here's the bed twist from one end to the other. Not "level", but I understand that level doesn't matter, but there is no twist. (A leg has been shimmed .035" to achieve this)
Heastock end, note the bubble position.
Tailstock end as far as the carriage will travel. Same bubble position, so we have an untwisted bed to work with.
First test cut after "leveling". You can actually see the taper. This is in a 3-jaw.
Up near the chuck it is .841"
Near the end it is .817"
Next we chuck up a two collar test bar in the 4-jaw and make an equal pass across both collars.
The collar closest to the chuck is 1.870"
The 2nd collar measures at 1.830"
At this point I just know all the guys on Practical Machinist are going to blame the swapped over headstock assembly, so I switch it back over. While I have it off, I snap some pictures of the bed ways underneath and also the v-ways underneath the original headstock that's going back on.
This lathe came up on eBay back in late Oct or early Nov, I don't remember. It was only about 4 hours away, the pics looked good, the price wasn't bad so I bought it. At pickup there was no 3-phase to test anything and I knew that going in. No big deal. When I got it home it was pretty crusty so I tore it down to about every single nut and bolt for a good cleaning, inspection, new wicks, etc. This is somewhere around a '57 so it has a little wear as expected, but generally in very nice condition, and certainly capable of cutting decent parts, right?
Everything was done correctly to the best of my knowledge. I've done this before and I'm familiar with shims, bearing clearance, bed "leveling"/twist, etc. Right off the bat it was cutting a taper. Please note that up until the very end of this whole post there is not even a tailstock on the lathe. All of this has to do with chucked up work pieces. On about a 4" piece I was getting .016" taper. The part was larger at the chuck and decreasing in diameter as it headed toward the tail end of the lathe. I shimmed up what should have been the offending leg with no measurable change. It was shimmed once to the point of having a leg complete off the ground without any noticable change in taper. Next, a whole list of common things were done to try to rule out the problem but nothing changed.
- changed cutting tools, no difference
- changed tool holders (all Aloris), no change
- changed tool posts (all Aloris), still no change
- ran tests in a 3-jaw
- ran tests in a 4-jaw
- ran tests in a 5c collet
- made cuts with and without the taper attachment binding lever tight (taper attachment clamp is not on the lathe, just in case anyone was wondering.)
- used a different saddle, no change
Everything was still the same. Once upon a time I had a cabinet style heavy 10 that developed a taper in it after it was moved with a forklift under the bed. Chad recommended relaxing the bolts that held the lathe to the cabinet and it fixed it. So I relaxed all the bolts, let it settle, tightened everything back up. Nothing. I removed the chip pan. Nothing. I removed the headstock and checked for chips, burrs, squirrels, and replaced it. Nothing. Still cutting the same freaking taper.
Finally I got another headstock, spindle, bearings, everything and did a complete headstock swap with correct bearing shimming, just knowing that would somehow take care of my problems. Nope. Still cutting the EXACT SAME TAPER.
So here we are with a few pics. The offending lathe in question with the 2nd headstock assembly on. I was trying to measure across the face of that plate but I don't think the plate is consistent enough to test.
The following are just a few pictures of the ways and the under side of the saddle to give you a general idea of the condition of the lathe. Certainly not anything that would drag and cause such a taper.
I started over at this point and began taking some pictures. Here's the bed twist from one end to the other. Not "level", but I understand that level doesn't matter, but there is no twist. (A leg has been shimmed .035" to achieve this)
Heastock end, note the bubble position.
Tailstock end as far as the carriage will travel. Same bubble position, so we have an untwisted bed to work with.
First test cut after "leveling". You can actually see the taper. This is in a 3-jaw.
Up near the chuck it is .841"
Near the end it is .817"
Next we chuck up a two collar test bar in the 4-jaw and make an equal pass across both collars.
The collar closest to the chuck is 1.870"
The 2nd collar measures at 1.830"
At this point I just know all the guys on Practical Machinist are going to blame the swapped over headstock assembly, so I switch it back over. While I have it off, I snap some pictures of the bed ways underneath and also the v-ways underneath the original headstock that's going back on.