- Joined
- Jan 22, 2011
- Messages
- 8,031
But Sharon, rarely have I seen a cross slide have enough travel to do that with the tooling as pictured. However, a boring bar can often give enough reach to turn the back side of a part.
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Clausing Lathe - How to taper past 90 degrees?
- Thread starter rogerrabbit
- Start date
Probably not with a rocker post like that, but I have turned tapers as PurpLev describes on my 7x14 using the quick change tool post I have. It is much easier to access the compound hand wheel. Even then, I was pretty close to the limits of my cross slide. It's really gonna depend on the lathe in question.
To address the original question, I would say, set your compound to 90 degrees using a square, then scribe a mark with a scriber. If things are tight, make a light mark (but take care to make it clean), then remove the compound and firm it up. My new lathe has two witness marks (one in front, one to the left side, 90degrees from one another), it's quite useful.
You should keep in mind that those graduations on the compound are "ballpark". In general, they are close enough, but if the angle is critical, then you will want a more accurate tool to measure/set the angle. One example is turning tapers. Don't even bother using that scale to line up for cutting a taper. For decorative cuts/chamfers, or threading, you should be good.
DMS
To address the original question, I would say, set your compound to 90 degrees using a square, then scribe a mark with a scriber. If things are tight, make a light mark (but take care to make it clean), then remove the compound and firm it up. My new lathe has two witness marks (one in front, one to the left side, 90degrees from one another), it's quite useful.
You should keep in mind that those graduations on the compound are "ballpark". In general, they are close enough, but if the angle is critical, then you will want a more accurate tool to measure/set the angle. One example is turning tapers. Don't even bother using that scale to line up for cutting a taper. For decorative cuts/chamfers, or threading, you should be good.
DMS
- Joined
- Dec 25, 2011
- Messages
- 10,511
Roger,
Yes. In my opinion anyway, running a threaded spindle nose lathe in reverse while cutting is just asking for trouble. If the chuck breaks loose, ruining the workpiece is the least of your worries. Doing it with a workpiece held in a 3AT or 3MT collet would be safe but you are limited to 17/32" and 13/16" diameter respectively.
I don't know how many of the Clausings are still around but it occurred to me that someone might make a few bucks by building and renting a unit to generate the second witness mark.
I will add that you can cut safely on the back side of the work if you invert the cutter and run the lathe in forward. Assuming that you can get the cutter on center.
Sharon,
Now I finally understand what you were saying earlier. But although I've no idea what the situation is with the Clausing, I just tried putting the compound behind the work on my 3996. With the compound set around to 85 deg. (which puts the compound moving away from the work at 5 deg. to the machine axis) and the Yuasa QCTP moved all the way to the back side of the compound and with its two faces parallel/perpendicular to the compound dovetail, the face of the tool holder block is at about 1.4" diameter (0.7" behind the spindle axis) when only one thread of the crossfeed screw is still engaged in the crossfeed nut. Not a good place, and the cutter would have to be peeking out of the holder no more than the depth of cut, and be held with one of the two screws that normally holds the cutter in the other end of the block because the front screw would be over the carbide. Using the original lantern tool post with no cutter holder and a HSS cutter would gain a few threads. The crossfeed nut is 1" long (16 threads). With the crossfeed screw fully engaged in the nut, the maximum diameter that you could cut on the Atlas with the QC is less than zero. I didn't dig out my original lantern type to see what its diameter actually is.
Not that it matters, but I can't get to the back side of my machine as it has a custom made splash guard on the back. From the Oil Patch boom of the 1980's when I used to spend megabucks every year in job shops and got one of them to make it for me.
Robert D.
Yes. In my opinion anyway, running a threaded spindle nose lathe in reverse while cutting is just asking for trouble. If the chuck breaks loose, ruining the workpiece is the least of your worries. Doing it with a workpiece held in a 3AT or 3MT collet would be safe but you are limited to 17/32" and 13/16" diameter respectively.
I don't know how many of the Clausings are still around but it occurred to me that someone might make a few bucks by building and renting a unit to generate the second witness mark.
I will add that you can cut safely on the back side of the work if you invert the cutter and run the lathe in forward. Assuming that you can get the cutter on center.
Sharon,
Now I finally understand what you were saying earlier. But although I've no idea what the situation is with the Clausing, I just tried putting the compound behind the work on my 3996. With the compound set around to 85 deg. (which puts the compound moving away from the work at 5 deg. to the machine axis) and the Yuasa QCTP moved all the way to the back side of the compound and with its two faces parallel/perpendicular to the compound dovetail, the face of the tool holder block is at about 1.4" diameter (0.7" behind the spindle axis) when only one thread of the crossfeed screw is still engaged in the crossfeed nut. Not a good place, and the cutter would have to be peeking out of the holder no more than the depth of cut, and be held with one of the two screws that normally holds the cutter in the other end of the block because the front screw would be over the carbide. Using the original lantern tool post with no cutter holder and a HSS cutter would gain a few threads. The crossfeed nut is 1" long (16 threads). With the crossfeed screw fully engaged in the nut, the maximum diameter that you could cut on the Atlas with the QC is less than zero. I didn't dig out my original lantern type to see what its diameter actually is.
Not that it matters, but I can't get to the back side of my machine as it has a custom made splash guard on the back. From the Oil Patch boom of the 1980's when I used to spend megabucks every year in job shops and got one of them to make it for me.
Robert D.
From your photo I would use a coal chisel and carefully line up the edge with the 90 degree mark then tap the chisel with a hammer deep enough to mark the casting. Good luck