# Doing Lathe Operations On A Mill



## barnstormer (Apr 23, 2015)

Folks,

I'm a retired mechanical engineering tech and shop teacher.  (I have some machining background, but still learning). I'm a graduate student at Iowa State University. I have a project to build some hardware that will let kids safely do miniaturized woodworking. (I call it woodworking, but it's closer to using machine shop techniques on soft materials). The working title of the hardware is WIC (Wood Shop in a Can).  WIC will be low feeds, low speeds, low decibel and manually cranked (not motorized).  It will be designed primarily to help the kids explore at their own pace - and ultimately lend meaning to their math and science courses -  by actually using the math and science to machine wood and make something durable.  That's the focus right now.  But the hardware in another form can help other deserving populations to do miniaturized woodworking – folks that  might not interface well with a conventional woodworking shop  –seniors,  children, mentally and physically handicapped - and perhaps especially combat vets who might benefit from woodworking in an atmosphere that is more relaxing and less threatening than a wood shop.  (A wood shop is a wonderful place, but essentially it is composed of islands of activity that involve super-sharp surfaces running at high decibel and high rpm. That is not necessarily therapeutic to some folks that have had traumatic experiences).

The hardware is going to require some industrial grade precision.  That's why I bought the PM 932 (vertical) mill. Money is tight with graduate school. At present, I cannot afford a lathe.  I have a large number of small cylindrical parts to make - some of the steps requiring traditional lathe techniques - turning, parting, grooving, facing, chamfering, knurling. I am purchasing a Vertex horizontal/vertical 8 inch rotary table, tailstock, dividing plate  set and chuck from Fred at Hamilton tool.  I'm seeing the challenges in two different flavors:

With the rotary table horizontal and the cylindrical part chucked or held vertically - (I can do this with parts that will not require any sort of steady rest or tailstock support). With these parts, I will have to move the part into a rotating, spindle mounted tool - and then turn the rotary table. I don't see a problem with this if I can accomplish the right feed using the rotary table crank.

(for turning operations that exceed the length of the cutting tool cutting surface, I would need to move the part into the rotating, spindle mounted tool, crank the rotary table 360, manually feed the tool vertically (don't have power down feed on the quill), crank the rotary table 360, etc. – don't know what this would do to my surface finish - and don't know how truly cylindrical the resulting journal or shoulder would be)

Think this would work with reduced shank square end mills, ball mills, woodruff cutters (for slots).

With the rotary table vertical and the cylindrical part chucked horizontally (center line along the x-axis) - (I would only do this if the part required steady rest or tail stock support) - I'm assuming I could perform turning operations using a side cutting mill.  On the y-axis, I would manually feed the part into the rotating, spindle mounted tool. Then I would need to coordinate turning the rotary table and, at the same time, engaging the x-axis power feed.  Again, don't know what this would do to surface finish or to the finished geometry of the cut.  [would not want to inadvertently be cutting threads ].

(this last scenario disturbs me. Seems like I would be feeding the part obliquely to the end mill – not sure that a helical end mill would be the best choice – maybe a straight fluted end mill?

Understand immediate reaction is "get a lathe" , but really don't have that option now. Would appreciate comments on what I'm proposing above. It's a great project (I'm four years into it) and I think the kids will love it.

Tom


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## randyc (Apr 23, 2015)

Tom, aren't you making this more complex than it needs to be - I don't see a need for a rotary table ?  You said that your parts were small so why not just put the stock in the R-8 collet (in the mill spindle) clamp a lathe cutting tool in the milling vise and operate your mill as a vertical lathe ?  That's not at all uncommon and does a nice job albeit a little slow 

Longer parts would be a problem, both for support and the possibility of running into the table.  But I'd imagine that for the price of a good rotary table, you could probably pick up a used Asian 7 x 12.  Of course if you did this, you wouldn't need to operate the mill as a vertical lathe, LOL.

I don't see the rotary table as being a good alternative.  It would be slow, probably not achieve a good surface finish and the accuracy/roundness of the part might be suspect.  People DO use this technique but generally only for LARGE diameters - too big for their lathe.  Sorry I can't offer better advice


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## barnstormer (Apr 23, 2015)

randyc said:


> Tom, aren't you making this more complex than it needs to be - I don't see a need for a rotary table ?  You said that your parts were small so why not just put the stock in the R-8 collet (in the mill spindle) clamp a lathe cutting tool in the milling vise and operate your mill as a vertical lathe ?  That's not at all uncommon and does a nice job albeit a little slow
> 
> Longer parts would be a problem, both for support and the possibility of running into the table.  But I'd imagine that for the price of a good rotary table, you could probably pick up a used Asian 7 x 12.  Of course if you did this, you wouldn't need to operate the mill as a vertical lathe, LOL.
> 
> I don't see the rotary table as being a good alternative.  It would be slow, probably not achieve a good surface finish and the accuracy/roundness of the part might be suspect.  People DO use this technique but generally only for LARGE diameters - too big for their lathe.  Sorry I can't offer better advice


yup - see your point about creating a vertical lathe.  Will still need the rotary table - but for things that it is meant for.

randyc - much obliged to you


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## Randy_m (Apr 23, 2015)

Use a boring head you can do I.D. and O.D. turning.


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## barnstormer (Apr 23, 2015)

Randy_m said:


> Use a boring head you can do I.D. and O.D. turning.


thanks randy_m - a follow-up question - I could see having a boring head with R8 shank for use in the mill spindle.  then buying or making an R8 to MT3 adapter for mounting the boring head vertically in the rotary table centering hole.  Seems a good way to hold the boring head?  But don't understand how you release an item from a tapered centering hole in a rotary table.  Where is the knock out?


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## Randy_m (Apr 23, 2015)

I dont know on your table. Put your project in a fixture of some sort, put the boring head in the mill, bore your O.D. and I.D. remove from fixture, cut it off with a saw, remount and face saw cut.


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## Randy_m (Apr 23, 2015)

You dont need a rotary table for this.


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## barnstormer (Apr 23, 2015)

Randy_m said:


> You dont need a rotary table for this.


ok - maybe I get it.  boring head is in spindle.  boring bar is vertical, but faced in to toward the part - to bore the od of the part? trying to figure out whether I would need to grind a new rake and relief on the cutting tool - or buy a bar specially configured for boring od's.


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## Randy_m (Apr 23, 2015)

Same bar I.D. or O.D.


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## Randy_m (Apr 23, 2015)

And yes you get it. Sorry im at work and dont have much time to explane it all.


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## timvercoe (Apr 24, 2015)

I've turned OD with a boring bar in the mill.  It works great and I didn't have to make any special tooling grinds.  I am really confused by the discussion about the rotary table use when holding work in spindle of mill. Can't see why you would rotate cutter in relation to work turning in spindle.  Is my imagination lacking?  I've used my lathe as a mill, and used a horizontal mill as a lathe.  Never thought of using my verticle as a lathe.  Interesting concept.


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## barnstormer (Apr 24, 2015)

timvercoe said:


> I've turned OD with a boring bar in the mill.  It works great and I didn't have to make any special tooling grinds.  I am really confused by the discussion about the rotary table use when holding work in spindle of mill. Can't see why you would rotate cutter in relation to work turning in spindle.  Is my imagination lacking?  I've used my lathe as a mill, and used a horizontal mill as a lathe.  Never thought of using my verticle as a lathe.  Interesting concept.


I got off on a tangent.  I see now that spindle mounting the  boring head is the way to go.  But just for the  mental exercise:   suppose I have a rotary table already mounted  horizontally on the milling table of a vertical mill.  Suppose the rotary table has a MT3 center hole.  Now suppose I have a boring head  with MT3  shank. I don't see why  I couldn't  mount the boring head vertically in the centering hole  and  mount the workpiece  in the  mill spindle.  So, (locked down)rotary table becomes lathe tailstock and  mill spindle becomes lathe  head stock .  I suspect the problem is there is no easy way to remove the boring head from the rotary table.  Would have to unbolt the rotary table, turn it to vertical position and knock out the boring head from the small end of the center hole taper.  Still, a pretty secure way to hold the boring head - in a situation where it is easier to hold workpiece in the spindle than on the mill table. Has anybody run across such a situation? Just curious.


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## Ianagos (Apr 24, 2015)

I'm confused why do to need a boring head at all unless you are mounting it in the spindle.


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## randyc (Apr 24, 2015)

barnstormer said:


> I got off on a tangent.  I see now that spindle mounting the  boring head is the way to go.  But just for the  mental exercise:   suppose I have a rotary table already mounted  horizontally on the milling table of a vertical mill.  Suppose the rotary table has a MT3 center hole.  Now suppose I have a boring head  with MT3  shank. I don't see why  I couldn't  mount the boring head vertically in the centering hole  and  mount the workpiece  in the  mill spindle.  So, (locked down)rotary table becomes lathe tailstock and  mill spindle becomes lathe  head stock .  I suspect the problem is there is no easy way to remove the boring head from the rotary table.  Would have to unbolt the rotary table, turn it to vertical position and knock out the boring head from the small end of the center hole taper.  Still, a pretty secure way to hold the boring head - in a situation where it is easier to hold workpiece in the spindle than on the mill table. Has anybody run across such a situation? Just curious.



Why in the world would you want to do that ?  You're just creating a much more complex and flimsier way of holding a cutting tool rather than just clamping the cutter in the vise !  Machining, as in almost everything, works best when the K.I.S.S. rule is followed, no offense


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## barnstormer (Apr 25, 2015)

yup - I'm rusty.  forgot that the R8 uses both a key and drawbar to secure the tool in the spindle... much more secure than a knockout morse taper.  thanks


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## compact8 (Apr 30, 2015)

Thanks for sharing !


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