.png)
Tweet
Hello all:
As the title to my post says, I am now the proud owner of a Craftsman/Atlas metal lathe. I'm pretty excited to learn how to use it; looking back on the past dozen things I've had done by machine shops probably 10 of them could be done on this lathe if I had the skill. It belonged to my wife's grandfather, and came with a HUGE variety of "parts". Tool holders, bits of various sizes, chucks, backing plates, steady-rests, drill chucks, centers, and a whole lot of other things I've yet to identify. I've done some introductory reading as it came with the original Owner's Manual, and I've ordered a copy of the Southbend "How to Run a Lathe" book. The other evening I hooked it up to power, and cleaned and oiled it. It seems to run just fine. There's a chart inside the headstock gear cover showing various gear combinations to achieve different screw and feed rates and...this is odd... I don't seem to have a lot of the gears required. For instance, a 60-tooth gear is specified for a number of ratios, but I only have 56-tooth gears. Maybe my screw feed compound gear sets are from a slightly different lathe? I'm assuming that the gear that drives the compound gear sets rotates at the same rate as the headstock... it appears to be a 32-tooth gear on the end of the headstock shaft driving a 24-tooth driving a 32-tooth. So can I believe the screwfeed ratios on the plate on each compound gear set, or do I need to perform some calculations to determine "equivalent ratios"?
Next I mounted up the 3-jaw chuck (Kobiyashi/Victor) and popped in a piece of 3/4" steel stock. It had a highly polished shiny silver finish, but other than that I had no idea what it was made of. I set the belts for the slowest rotational speed (166 rpm which should give me about 33 fpm), mounted up a 3/8" right-handed cutting tool, and fired her up. The first thing I noticed was that the chuck seemed to be off-center... I could see a wobble. I put the dial guage on it and the variation was 0.006-0.008". Quite a lot, from my reading... I was expecting 0.003" or less. What are my options to true it up? I've read about putting a shim (slice of a beer can) between the offending jaw(s) and the work. The chuck is mounted on a backing plate, which is female threaded to connect to male threads on the headstock shaft.
Well, I figured I'd true it up by turning. I set up the feed rate at 5-thou and a cut of about 30-thou, but the cut was less than successful... the non-concentric workpiece almost seemed to move the tool as it skated up and over the work rather than cutting. Increasing the depth of cut actually bound up the workpiece and made the belt slip. Retreat. The tool did not have any HSS marking on it, rather it said "cobalt" on the size. I am guessing this is a soft tool and I am trying to cut a very hard metal. I also had a bunch of 3/8" tool mounts with the triangular carbide tips, so I tried one of those. It made some fine particle shavings but I still had what I'd call chatter (not really sure). I inherited a fairly extensive inventory of metal stock, but none of it is labelled. There's aluminum, steel, brass, all kinds of stuff in various sizes (lengths and diameters). I am hoping I can use it by going with rotation speeds at the low end of the scale for each metal.
I also inhered a very nice grinder so I tried my hand at grinding my own tool from the uncut end of one of the 1/4" tools... it was pretty easy and seems sharp although I'm sure my freehand angles were all over the place! I tried it on the steel I had mounted and it deformed the tool very quickly... looks like I had ground the cutting edge vertically on the section applied to the work.
I finally resorted to trying a piece of aluminum. I needed a win to keep me going. Again, it was off-center, but by slowing down the feed rate to 0.0024" and using a depth of cut of 0.020" I was able to generate some long shavings like ones I saw in various videos using my home-ground tool. Success! However, I didn't seem to be able to get anywhere near the depth of cut in the videos... of course the lathes in the videos were much larger than mine so maybe that's all my 1/2hp motor is going to give me.
I'm hoping that the Southbend book may help me out with things like how to accurately center punch and drill as I'd like to try turning between centers... the piece of aluminum I was working on was far too long to mount in a chuck with the far end unsupported.
As the title to my post says, I am now the proud owner of a Craftsman/Atlas metal lathe. I'm pretty excited to learn how to use it; looking back on the past dozen things I've had done by machine shops probably 10 of them could be done on this lathe if I had the skill. It belonged to my wife's grandfather, and came with a HUGE variety of "parts". Tool holders, bits of various sizes, chucks, backing plates, steady-rests, drill chucks, centers, and a whole lot of other things I've yet to identify. I've done some introductory reading as it came with the original Owner's Manual, and I've ordered a copy of the Southbend "How to Run a Lathe" book. The other evening I hooked it up to power, and cleaned and oiled it. It seems to run just fine. There's a chart inside the headstock gear cover showing various gear combinations to achieve different screw and feed rates and...this is odd... I don't seem to have a lot of the gears required. For instance, a 60-tooth gear is specified for a number of ratios, but I only have 56-tooth gears. Maybe my screw feed compound gear sets are from a slightly different lathe? I'm assuming that the gear that drives the compound gear sets rotates at the same rate as the headstock... it appears to be a 32-tooth gear on the end of the headstock shaft driving a 24-tooth driving a 32-tooth. So can I believe the screwfeed ratios on the plate on each compound gear set, or do I need to perform some calculations to determine "equivalent ratios"?
Next I mounted up the 3-jaw chuck (Kobiyashi/Victor) and popped in a piece of 3/4" steel stock. It had a highly polished shiny silver finish, but other than that I had no idea what it was made of. I set the belts for the slowest rotational speed (166 rpm which should give me about 33 fpm), mounted up a 3/8" right-handed cutting tool, and fired her up. The first thing I noticed was that the chuck seemed to be off-center... I could see a wobble. I put the dial guage on it and the variation was 0.006-0.008". Quite a lot, from my reading... I was expecting 0.003" or less. What are my options to true it up? I've read about putting a shim (slice of a beer can) between the offending jaw(s) and the work. The chuck is mounted on a backing plate, which is female threaded to connect to male threads on the headstock shaft.
Well, I figured I'd true it up by turning. I set up the feed rate at 5-thou and a cut of about 30-thou, but the cut was less than successful... the non-concentric workpiece almost seemed to move the tool as it skated up and over the work rather than cutting. Increasing the depth of cut actually bound up the workpiece and made the belt slip. Retreat. The tool did not have any HSS marking on it, rather it said "cobalt" on the size. I am guessing this is a soft tool and I am trying to cut a very hard metal. I also had a bunch of 3/8" tool mounts with the triangular carbide tips, so I tried one of those. It made some fine particle shavings but I still had what I'd call chatter (not really sure). I inherited a fairly extensive inventory of metal stock, but none of it is labelled. There's aluminum, steel, brass, all kinds of stuff in various sizes (lengths and diameters). I am hoping I can use it by going with rotation speeds at the low end of the scale for each metal.
I also inhered a very nice grinder so I tried my hand at grinding my own tool from the uncut end of one of the 1/4" tools... it was pretty easy and seems sharp although I'm sure my freehand angles were all over the place! I tried it on the steel I had mounted and it deformed the tool very quickly... looks like I had ground the cutting edge vertically on the section applied to the work.
I finally resorted to trying a piece of aluminum. I needed a win to keep me going. Again, it was off-center, but by slowing down the feed rate to 0.0024" and using a depth of cut of 0.020" I was able to generate some long shavings like ones I saw in various videos using my home-ground tool. Success! However, I didn't seem to be able to get anywhere near the depth of cut in the videos... of course the lathes in the videos were much larger than mine so maybe that's all my 1/2hp motor is going to give me.
I'm hoping that the Southbend book may help me out with things like how to accurately center punch and drill as I'd like to try turning between centers... the piece of aluminum I was working on was far too long to mount in a chuck with the far end unsupported.
Comment