# Lathe Turning Head for CNC mill



## cfellows (Jan 2, 2015)

I've been toying with the idea of making a small, special-purpose CNC lathe, then today I ran across this...

[ame]https://www.youtube.com/watch?v=9Sr9p8tCv_g[/ame]

This seems like an altogether better option and maybe not to hard to make???

Chuck


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## cfellows (Jan 2, 2015)

I already have this 4th axis that I built with a 1600 oz in Stepper...







but the maximum RPM is probably under 100 RPM.  I would need a second, higher speed motor for turning.  The head is made from a solid aluminum block and the spindle is from an Atlas 6" lathe, 1" x 10 tpi thread, mounted in Timken taper roller bearings.  That pretty much leaves the tool holder, which shouldn't be a very difficult project.  The Sturges tool holders, by the way retail for between $300 & $400.


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## cfellows (Jan 2, 2015)

So here is the Sturges tool holder for using their turning head with a milling machine...






And here is my version...
















Mine started out about 1/2" longer, but I broke a tap threading the hole in the end which secures the insert, so I cut it off and reformed the end.

I've adapted a smallish DC motor to my turning head.  It has an Atlas 6" lathe spindle with a 1-10TPI threaded end.  I'm now waiting for the mail man to deliver a ball bearing race which will replace the bronze bushing in the back end of the motor.

Chuck


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## cfellows (Jan 2, 2015)

I finished the turning head today to a point where I could test it.  Here's the video...

[ame]https://www.youtube.com/watch?v=CNSTYXB7JXw[/ame]

I'm really pleased with the results, although I may need a larger motor.  Might be time to start experimenting with brushless DC...

Chuck


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## DICKEYBIRD (Jan 2, 2015)

Great work Chuck!  Was that .010" in the radius or diameter mode?  Not too shabby if  it was peeling off .010" radius on what looks like 1" stock at what sounds like spooling up to pretty a high rpm...like 2000 or more?

I'm curious how you're handling the axis designation in Mach.  Were you able to just make a new (lathe) profile and just set up the ports & pins to make the table left & right be your Z-axis and the Y-axis function as X?  If so you should be able to use the Mach Turn wizards do all kinds of neat stuff.

I love CNC lathe stuff! Thm:


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## cfellows (Jan 2, 2015)

DICKEYBIRD said:


> Great work Chuck!  Was that .010" in the radius or diameter mode?  Not too shabby if  it was peeling off .010" radius on what looks like 1" stock at what sounds like spooling up to pretty a high rpm...like 2000 or more?
> 
> I'm curious how you're handling the axis designation in Mach.  Were you able to just make a new (lathe) profile and just set up the ports & pins to make the table left & right be your Z-axis and the Y-axis function as X?  If so you should be able to use the Mach Turn wizards do all kinds of neat stuff.
> 
> I love CNC lathe stuff! Thm:



Thanks!  The cutting depth was .010" which is .020" off the diameter.  Hard to say on the spindle speed but probably between 1500 and 2000 RPM.  I was using the mill setup in Mach3.  I'm a little fuzzy on axis designation in a lathe, but basically, the mill X was the axial feed along the work and the mill Y controlled the radial feed of the tool (cutting depth) into the work.

Chuck


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## DICKEYBIRD (Jan 2, 2015)

CNC lathes are designated lefty-righty: z-axis and innie-outie: X-axis.  Left or towards the chuck is Z-minus, towards the user's belly is X-plus.  We'd have to think carefully about your setup a bit!


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## RonGinger (Jan 2, 2015)

Nice work Chuck. 

Mach probably didn't execute the last statement in your program because you did not end it with a <return> key. Without that mach does not know it has reached the end of the line. very common error.


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## AussieJimG (Jan 3, 2015)

That looks like something that we could all use. 

But I am glad I am not trying to keep up with you.

Jim


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## kvom (Jan 3, 2015)

Other than straight turning and facing it can be difficult to program contours on CNC lathes accurately by manual means.  When I was learning CNC lathe at school with a Haas, the control supports the G7x canned procedures, but Mach doesn't.

If you ignore the roughing passes, then the issue with the final finishing pass along the profile is the nose radius of the tool.  You'd need to consider it like an endmill of that diameter following a profile.  That means you can't just move the tool to the points along the profile line, but must offset it by the radius.

What this all means is that you need CAM software to generate the toolpaths.  The software I use for CAM, CamBam, has a modest capacity to handle lathes as well for turning.  You draw the half-profile in CAD and define the stock diameter, cutting depth for each pass, feed rate, etc.

I have used this to turn some profiles on my mill with the stock held in the spindle and the lathe tool clamped in the vise.  I had to use the Mach turn screenset to get it to work.


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## DICKEYBIRD (Jan 3, 2015)

kvom said:


> Other than straight turning and facing it can be difficult to program contours on CNC lathes accurately by manual means.  When I was learning CNC lathe at school with a Haas, the control supports the G7x canned procedures, but Mach doesn't.
> 
> If you ignore the roughing passes, then the issue with the final finishing pass along the profile is the nose radius of the tool.  You'd need to consider it like an endmill of that diameter following a profile.  That means you can't just move the tool to the points along the profile line, but must offset it by the radius.
> 
> What this all means is that you need CAM software to generate the toolpaths.  The software I use for CAM, CamBam, has a modest capacity to handle lathes as well for turning.  You draw the half-profile in CAD and define the stock diameter, cutting depth for each pass, feed rate, etc..


Mach comes with "wizards" that will handle quite a few lathe ops.  Here's just one page of them.  I'm not at my shop PC which has quite a few more that were available as free downloads incl. canned drilling cycles, threading, parabola, etc.  The NFS Wizards that are available (Ron G.) offer even more nifty wizards.

The wizards allow you to specify roughing cut depth, feed speed, spindle & coolant on/off and are easily editable to add or take away functions.  As far as tool tip radius comp., Mach does that as well

All these wizards don't take the place of a CAM system but the they will do most of the kinds of work you'll come across in our shops.


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## goldstar31 (Jan 3, 2015)

Somewhere in my 'library' I have details of  a concave and convex attachment which fits a manual lathe. Found it- it is in Model Engineer for 19thOct 1979 and for a Myford Super7 by a Mr R May.

Next to it is Horizontal Milling Attachment for a Super 7- 3rd May 1974. The next was from the workshop of the Late Ken Metcalf and  it is a multi toolholder for the top slide-- which is a far more advanced QCTP but in 1971.

And after all this- Prof Chaddock made ALL the ball handles for a Quorn with a former made from a scrap file -one evening.

Makes me think.


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## Toolguy (Jan 3, 2015)

I once programmed my CNC mill to make a bunch of injection mold cores by using the mill as a lathe. We didn't have a CNC lathe, so had to make do. As I recall, I had to program it upside down and backwards, but it did work. It is hard to explain and hard to wrap your head around but it can be done. I used a collet for those, but now I also have an R8 shank lathe chuck in case I need to do something  similar.


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## cfellows (Jan 3, 2015)

Thanks, all, for the comments and kind words.

I've been working on this project mostly because I think it's interesting and a good learning experience.  I've already discovered some needed changes to the  shape of the tool holder.  And, I'm going to make another tool holder which takes VCMT inserts, like these which have a 35 degree included angle on the tip.






I've also experimented with mounting the work in the milling spindle and the tool bit in a vise attached to the table.  That may be a much better alternative, particularly for short work.  I'll attempt a video of that to post as well.

Chuck


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