# Clausing Lathe - How to taper past 90 degrees?



## rogerrabbit (Nov 8, 2012)

Hi All:
A little project for practice as a newbie: Machinists screw jacks.



The left is completed, the right in progress..got a chance to finally use the 3" rotary table to mill the flats I got from HF a while ago.

Here is how I set it up, ended up eyeballing the taper as it wasn't critical probably around 5 deg.


The problem with the clausing is that the degree markings only go up to 90, here is the front view.. the indicator is actually on the back side.. its a real PITA to read, even with the light right on it.. 



using this setup, how could I dial in an angle > 90?  the only idea I have so far is to scribe a mark in the front of the compound, but I have no idea how I would accurately scribe it?

thanks!

Roger


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## wa5cab (Nov 8, 2012)

Roger,

If I understand what you are saying, you want to scribe a witness mark on the operator (front) side of the cross slide.  So for that, you need to hold a scribe and move it a short distance vertically.

I'm totally unfamiliar with the Clausing and its accessories but if they made such a thing, do you have (or can you borrow) a milling attachment that looks something like the one made for the Atlas machines (mounts in place of the compound)?  And a second cross slide to mount it in front of the existing one?  If any of that makes any sense, that would give you a means of holding a scribing cutter in an offsetting block (to get it low enough) and moving it vertically.

Robert D.


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## rogerrabbit (Nov 8, 2012)

Hi Robert,
hmm, I have neither a milling attachment nor a 2nd cross slide, so that would be difficult, but I get what you are saying.. I shall have to think more on this and maybe adapt something.

then how would I get the scribe to the right place? I would assume it should be marked exactly 180 degrees from the original?

thanks,
Roger


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## wa5cab (Nov 8, 2012)

Roger,

For determining the required location, the only practical thing I could think of was to assume the 90-0-90 scale on the compound is accurate or close enough and pick up the location of the front 90 line by raising the scribe (cutter) and moving it side to side into alignment.

The rest of what I was thinking , so somone can point out any problems, is first I would lightly grind a vertical flat to scribe the line on.  Then use an inverted 3/8"-square V-nose carbide cutter as a scribe.  The cutter would have to be lower than the vise on the milling attachment will go (at least with the Atlas milling attachment) so make an inverted "L" cutter holder out of 1" bar.  Base of the "L" would be in the vise.  Through the vertical part of the "L" and parallel to the base (i.e., horizontal) you would need a 3/8" square hole with set screws through the side to hold the cutter.  Vertical motion to do the cutting would be handled by the milling attachment.  Side to side by moving the block in the vise.  And depth of cut by either loosening the gib on the added cross slide and moving it by hand or if the carriage dovetail is long enough to get both cross slides on it with the cross feed screw still engaged in the nut on the original, by moving the original in the normal way.  On an Atlas, it looks like the latter might work.  But you would have to load the two cross slides on from the rear because of the diameter of the cross feed screw bearing.

I'll add that although the scale is on the cross slide and the witness marks on the compound, I do realize that the Atlas already has two.  

Incidentally, I noticed this morning that there is another machine-specific forum called I think Clausing-Colchester & LeBlonde.  I don't know what it's about but you might have a look there for any mention of your issue.  And for that matter, you might call Clausing about it.

Robert D.


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## PurpLev (Nov 8, 2012)

The better approach to making this cut is to position the compound at an angle of less then 90 and run the lathe in reverse with the cutter behind the workpiece as you are looking at the lathe. not only will this allow you to set the angle to your desired angle, but it will also position the compound wheel accessible to you as opposed to having to reach across the ways/tailstock which is not a very safe way to work on the lathe. I believe this is also the reasoning for the compound markings to end at 90 as this is how it is designed to work and be used.

makes sense?


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## wa5cab (Nov 8, 2012)

PurpLev,

I'm sorry, but no.  In order to put the cutter behind the workpiece (and run the machine in reverse) in order to taper a part with the small end toward the tailstock, you have to also put the compound behind the workpiece.  So to get at the crank on the compound, you have to reach over the tailstock and/or work.  

With the compound in front of the workpiece and pointed slightly to the left of straight toward the headstock, you can taper a part with the compound crank on the operator's side of the work.  My understanding is that this is what Roger did.  His problem was that he had to guess at the angle because the Clausing has no front witness mark.  And 90 on the scale on the back of the compound was clear of the sole witness mark on a Clausing.

Robert D.


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## Tony Wells (Nov 9, 2012)

You could lock the compound at the 90° mark, and using the QCTP, indicate one of the sides true in either axis. Now loosen and turn the compound 180° and indicate the same side of the QCTP again. Now you can remark a new datum according to the 90° mark in its new location, directly opposite where the original is.


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## rogerrabbit (Nov 9, 2012)

thanks everyone, great ideas here..

purplev, 
possible, when I bought the lathe, the drum switch/motor was wired for reverse operation, maybe this is why.. only concern i have is that the chuck is a screw on type, wouldn't running in reverse loosen it?

Robert,
yes, exactly what I did.  My lathe is movable, so I could get around that problem by standing behind the lathe.


I was looking through one of my pdf's I had collected (how to run a lathe or similar), and they showed pictures of a lathe grinding a 60 degree center facing the tailstock..is this just a bad design on the clausing (no 2nd datum), or is there a technique I am missing?

thanks,
Roger


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## swatson144 (Nov 9, 2012)

One of my lathes didn't have a 2nd datum line. I clamped the compound at 90°, indicated it for a check. and then marked the crosslide on the 0° mark. I just used a sharp chisel since both lathes are imports and that seemed to be what they used on the 1st line.

BTW the 1st line was several degrees off and I fixed it at the same time. Your Clausing is probably right on.

Steve


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## PurpLev (Nov 9, 2012)

wa5cab said:


> PurpLev,
> 
> I'm sorry, but no.  In order to put the cutter behind the workpiece (and run the machine in reverse) in order to taper a part with the small end toward the tailstock, you have to also put the compound behind the workpiece.  So to get at the crank on the compound, you have to reach over the tailstock and/or work.
> 
> ...



It is true that the cutter will be on the other side of the workpiece, but the compound wheel will still be facing the operator (forward) so you won't have to reach over the compound as the feed wheels will be accessible:





My point was more so to clarify that the markings "only up to 90" actually make sense when you consider making tapers this way, and also it creates a work scenario where the wheels and the operations are accessible and convenient and there is no need to stand on the other side of the lathe for this process. 

Sharon.


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## Tony Wells (Nov 9, 2012)

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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## DMS (Nov 9, 2012)

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


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## wa5cab (Nov 10, 2012)

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.


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## Bill C. (Apr 17, 2013)

rogerrabbit said:


> Hi All:
> A little project for practice as a newbie: Machinists screw jacks.
> View attachment 42153
> View attachment 42155
> ...



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


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