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Turning with a Milling Machine

DJ_WANGER

Plastic
Joined
Mar 19, 2017
Hi,

Quite new to this forum and still quite undeveloped in the engineering realm, but i was just thinking...

If i wanted to turn with a milling machine e.g. Mount round bar in the spindle chuck and and manually feed the spindle onto a stationery secured tool, say in a vice at the correct cutting angle would this work. And if it does what experiences have you had with it? Does it generate good tolerances and retain concentricity? I would expect the swarf to evacuate better. Any thoughts?

Obviously this is not for a batch production scenario, but if i wanted to create components using this method without having to buy two machines is this feasible?

Thanks for any input
 
I've done it both on a Bridgeport and with cnc mills in place of a good lathe or cnc lathe. Think of it as a very fast and precise lathe spindle, just don't put as much cutting pressure on it as you would a lathe. I've done up to 3" diameters in tool steel with my BT30 mill with excellent results. I can easily hold a tenth or two. With presetting the stock in the tool holders and access to the tool carousel you could do some production quite efficiently. If you need multiple tools think of a gang tool setup bolted to the table with fixture offsets for each tool.
 
I have done that lots of times with a Boston Digital 14-24 CNC mill. You can clamp multiple tool bits on the table and shift it around to change tools, making it a sort of ersatz turret lathe. The tools don't have to be in a line or the same height because you can program anything you want.

Bill
 
It's routinely done. Keep in mind that a mill spindle typically has some size/weight limit on tools, where lathe chucks can often hold however heavy a part you could possibly get into the lathe.
 
I made an arbor in the lathe for a large diamond grinding wheel to be used on the Bridgeport. I then mounted the arbor in the Bridgeport and "turned" the face dead nuts true with a brazed carbide bit held in the milling vise. I had to hand feed it, as the power feed wouldn't go as slowly as I wanted.
Depth of cut was about 3 thou as I recall. Worked very well... the wheel ran perfectly true at 2000 RPM.
 
I made an arbor in the lathe for a large diamond grinding wheel to be used on the Bridgeport. I then mounted the arbor in the Bridgeport and "turned" the face dead nuts true with a brazed carbide bit held in the milling vise. I had to hand feed it, as the power feed wouldn't go as slowly as I wanted.
Depth of cut was about 3 thou as I recall. Worked very well... the wheel ran perfectly true at 2000 RPM.

Make sure the ways qre covered when you diamond grind on a Bridgeport. The wipers will not sweep all the diamond dust off and it will get under the slide and wear it rapidly.

Bill
 
35 yrs ago I borrowed 10k and bought my first Bridgeport, I used it often mounting stock into the spindle, and putting a HSS lathe tool in the vice. Lord those where the days! Now 35 plus yrs later ,and 30 plus CNCs , wish I where back in my basement, without a lathe.
 
It works fine, but you're limited to smaller diameters and shorter stock.


Screwmachine, I had to smile at your limitation to smaller diameters, because I was already thinking about Johnoder's experience. I seem to recall that he used the horizontal precisely because he needed to be able to handle the large diameter. :)

The limitation to "shorter stock" definitely applies ... but an awful lot of the turning I do is 6" or less in length, so even that may not be that limiting.

All that said, certainly the mill is not where I would first "turn" when getting ready to turn a part; that's what the lathe is for ... but as John illustrates, the mill can sometimes solve a problem that the lathe on hand cannot handle.
 
And to add to some of the above comments: there is one situation in which it is the ideal method to use. If you need to install a drill chuck on a tapered arbor to be used in a particular milling machine, tilting the head to cut the taper in that machine can minimize runout in the taper. That is particularly true if the arbor is locked permanently in its collet and the collet is clocked to the same rotational position in the spindle when reinstalled. I have done this a few times successfully. Similarly straight pins or holes in a collet or tool holder can be centered to run true if cut in situ and clocked the same on re installation.

Denis
 
In a pinch a vertical or horizontal mill can do some lathe turning. I made form tools to plunge from one side then come in from the other side to cut off. But the ability to thread, reach in with measuring tools, steady long work, run between centers, quick change from center to drill and to reamer are just a few reasons to have both.
 
DJ

I'm not a machinist - I'm an ME (and somewhat of a hack who plays with machine tools). My current Clausing lathe swings 12 inches, previous SB was limited to 11 inch swing. On a few rare occasions in the distant past I have used my B'port to turn fairly light wt larger dia part than my lathe would swing, mounting the part on a home made arbor that mounted to the mill spindle, turning the part at LOW spindle speeds. I have also used a rotary table to "turn" parts too large to swing in my lathe. Neither is ideal but I don't have the room for a larger lathe. I prefer using the rotab for "turning" large dia parts rather than mounting them in the B'port spindle - unfortunately even slower than turning w/ the part in the spindle but IMO less chance of a large dia part coming loose and spinning toward my chest.
 
I've done plastic parts to 24" diameter on a knee mill. We currently have a 5" chuck for the Cat 40 spindle. Aloris tool post on vertical bracket on the table. Cat 40 mounting block on front edge of table holds drills, boring bars, and the five inch chuck still holding the turned part for milling! The only limitation is your imagination.
 








 
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