Milling on a lathe

[Lynn Standish]

I don't have a mill, nor do I have a place to put one. I do have a Palmgren milling attachment for my 13 x 40 lathe. I avoid using it unless there is no other way.

I would like to bevel the corners on some square and rectangular pieces at 45*. The face of the bevel would be 1/8" or 3/16". That would mean the depth of cut for the 1/8" face would be .0625, and for the 3/16", it would be .0938.

Since cutting these bevels would not involve the whole end mill being in constant contact with the work, I don't know how to figure speed/feed/DOC. Would it be okay to do this in a single cut? If so, what would you recommend for speed and feed? Also, I assume a 4-flute end mill should be used, but should it be the largest or smallest possible?

Thanks for any help.

[dsergison]

good greif man, quit dancing around it and CUT IT!

whith WHATEVER IS AT HAND, at your regular speed.

-I just think you are worrying too much.

have fun Dan

[vmil3]

Hi Lynn,
We need more information here, from you, Ok.

1st. What sizes are your pieces you want to cut, large small, are they rough castings? length x width x height.

2nd. What are these bevels for, are they critical,are they welding bevels,are they decorative bevels? your sizing (.0938") Is tenth's of a thou, Do you need this much accuracy required?

3rd. What are you using to hold the milling cutters? (type of holder, in a chuck, bolted to chuck face, does the holder have a draw in bolt.

4th. Does your compound and or cross slide have T slots?, is the cross slide top surface machined or cast?

5th. Do you under stand what the term "climb milling" means?

6th. Do you have access to a shaper?

7th. Is there a company near you that sharpens cutters for machine shops? eg: end mills, shell mills, milling saws

To offer advice I/We need (more information) or answers to the above questions, from you to help. Ok


------------------
Doug

[Evan]

There are two thing I have found to be important when milling on my SB9. First, cutter rotation as it addresses the work should not be tending to lift the carriage. Second, cutter rotation should not be tending to pull the work in the direction of cross slide travel.

These two items are more important than the issue of climb milling on a lathe.

[This message has been edited by Evan (edited 02-28-2005).]

[dsergison]

7 points consider to a chamfer?

(esp).
"Is there a company near you that sharpens cutters for machine shops? eg: end mills, shell mills, milling saws"

ARE YOU SERIOUS? you are considering suggesting he has a company to make him a CUSTOM MILL for this!

what has this world come too?

/end pissed off mood.

sorry, I'll behave better now.

Oh, yeah. Evans post is helpfull. good. see, just cut the stuff, and follow Evans general advice if you can. Git 'er done!

fixturig will be the toughest part. clamping the stuff secuely at a 45 angle.

that would be the reason to splurge on a 45 chamfer tool. (looks like a countersink)




[This message has been edited by dsergison (edited 02-28-2005).]

[Lynn Standish]

To try and answer some questions:

The job doesn't warrant the expense of a special mill cutter.

The material is 303 stainless, with max. length of the cut being 3.75". The dimensions of the cut are not critical, i.e. the .000X" measurements are just what the calculator shows me for the height of a triangle (DOC) with a base of either 1/8 or 3/16. They are just for chamfering the edge of these blocks - not welding or anything, and not critical, so I might even eyeball things to see what looks right.

The Palmgren attachment can be set at 45 degrees to present the work to the cutter at that angle, so an endmill should work. To avoid the climb, I'd think the work should be presented to the top half of the cutter (with the lathe in forward rotation).

No, I don't have any sort of collet holder for the cutter -- Was planning on just chucking it in a 3-jaw.

As to speeds, I was thinking of 500 - 600 RPM, but don't know if this is correct and/or what the feed rate should be.

In essence, I guess I don't even know enough to know what I don't know, so maybe the question should be ignored.

[SGW]

Yeah, I think you're worrying too much. Try it and see what happens.

But: I know what you mean about "avoid using it unless there is no other way." Milling on the lathe is not for heavy-duty operations. You should be able to do what you're describing without much trouble though.

I'd go with a 45 degree chamfering cutter. Or if you're a cheap sort (like me) you can even use a 90 degree included angle countersink.

Try it in one pass. If that turns out to overload things, back and take two passes! Probably about 500 rpm, maybe? That is probably on the slow side, but you're not going for production rates here. Don't be afraid to experiment!

[dsergison]

yep. youre all set up. just go with it.

either:

you'll burn up the cutter in a smoking red ball. = too fast. (and not likely at 500 rpm)

or, it'll chatter and gouge = so take more passes, slower feed. (most likely scenario)

or, IT WILL WORK JUST FINE. (you'll never know until you try)

cheers.

or, use a file/beltsander

[vmil3]

Evan,
You just described "climb milling on a lathe" is when the cutter pulls the work into itself(the cutter via pulling the cross slide because of slop in the cross slide nut and screw).
Do you have a different meaning for climb milling?

dsergison,
I asked the question about a tool grinding shop because they often have under size cutters with damaged teeth (corners burn off) the orginal owner of the cutter doesn't want to pay the higher cost of sharpening to sharp square corners and he doesn't want a under size cutter with champhered corners, he tells the grinding shop to "just keep it". The grinding shops around here champher the corners (easy to do)and let them go for cheep. THAT is why, I asked the question.

Lynn,
You gave the lenght of cut but how thick are the pieces, and how wide are they, heavy thick pieces are held one way,and light flimsy pieces are held a different way.
You state the material is 303 stainless, well cutting surface speed for the cutter would be 50 ft/min. That is not the RPM of the cutter, to find the speed (RPM of cutter) the little formula is cutting speed ft/min = 50 x 3 divided by the diameter of your cutter, example 1"dia cutter has a starting RPM of 150RPM ,a 2"dia cutter is run at 75RPM, and a 1/2" cutter is run at 300RPM. The RPM of the cutter is dependant on what material your going to cut and what the diameter is, of your cutter.
You dont have a proper holder for an end mill , then stop right there, trying to do milling in a lathe using a 3 jaw chuck or worse a drill chuck to hold a milling cutter or a 45آ° counter sink will land you in the emergency ward of your local hospital, these holding devices are not meant to hold milling cutters, or 45آ° counter sinks, cutting with "side pressure" (like your milling job). Yes you use countersinks in a drill chuck when countersinking, the "downward pressure" of the tool forces the countersink up into the drill chuck, you are applying side force. The only safe method to hold a cutter with a hardened shank is in a tool collet chuck, or a end mill holder, if mounting in your lathe spindle via the morse taper these holders must be equipped with a draw in bolt assembley, other wise even these holders will come loose from your Morse taper lathe spindle.
If you had access to a shaper, it would be done faster than even a real milling machine.
You state your lack of experience for your post, that OK, there are many Experienced people here, but "dsergison" is NOT ONE of THEM, on the other hand I earned my living for over 30yrs in a machine shop, replys like "dsergison", if followed will get you to the nearest ER ward if your lucky, if not that type of advise, if followed can, and has Killed before.
Please answer my renaining orginal questions as best you can, that is the only way someone with past experience can help you by recomending advise from his or her experience.
And you are right in saying" I guess I don't even know enough to know what I don't know, so maybe the question should be ignored".

But an old machinist saying goes like this
Ignorance we can fix, BUT STUPIDITY is forever.
So "lets fix YOUR ignorance", "THAT" is DOABLE,



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Doug

[This message has been edited by vmil3 (edited 02-28-2005).]

[This message has been edited by vmil3 (edited 02-28-2005).]

[J Tiers]

I am in no way saying "vmil3" is wrong. I actually agree, particularly about the holder.

I will say, for this job, emergency ward or morgue isn't terribly likely.....but it can be done, if the job is rushed and no care is taken.

In any case, I have used the chuck, or a collet, before, and with some care at watching what you are doing, you can finish the job. I don't recommend it, I have seen the cutter creep. Hard steel on hard steel does not hold well.

I would not try to use the end of teh cutter held in a chuck. Too much chance of a dig-in from creep.

And, with the Palmgren , you have to watch out. The *&^%$ thing WILL loosen up under vibration, and flop over, breaking things, ruining work, and sending shards of cutter around. Seen that too.

The 13 x 30 has more oomph than the Palmgren can really take. Too many degrees of freedom. So take it easy.

Lock the vertical slide, if you can, and use crosslide for movement. Replace the middle screw if you need to for easier locking. The slide likes to creep.

DO NOT "climb mill". Just don't. That will cause a lot of problems. The cutter should rotate against the work movement.

Don't take a deep cut. It ain't a mill. I try to avoid over an 0.020 depth, in steel, certainly, although there is always the thought in my mind that the dang thing will shift on pass 3. It has. With deeper cuts, that is more likely.

I'd give real thought to fixturing the piece on the crosslide table, if that is an import that has one. It would be a lot sturdier, and would be a straight cross-slide movement.

It would be a lot easier to swap parts for "semi-production" operation and get them lined up etc, also. You said you had a number of them. The Palmgren sucks for that, working the &^%& vise tends to move the setup.

I thought 303 machines OK, but I may be thinking of another type. Stainless generally has a bad name for work hardening with shallow cuts, and being a pain in the rear.



[This message has been edited by J Tiers (edited 02-28-2005).]

[vmil3]

JTiers,
I know Lynn will benifit from you, sharing your knowledge and experience with him, you JTiers also reminded me of another question for Lynn that I forgot to ask........by your statement

I will say, for this job, emergency ward or morgue isn't terribly likely....

#8 Lynn,
Have you, and "PLEASE be honest at least with yourself", been wearing your Safety Glasses at all times while working in your new found metal hobby. You can post any reply you wish here, BUT only "You know the real answer to my question", and it is "YOU who will pay the price" for fibbing to yourself. I wish you every success in your new adventure, and I, as well as others here, are here to guide you in the safe enjoyment of your hobby. We have been where you have yet to go! And we know how to fix Ignorance
Take Care

------------------
Doug

[DICKEYBIRD]

I don't have the wealth of experience of those above but I do mill things successfully with a home-made milling adapter on my little 8x16 Chinese lathe all the time.

I had chatter trouble until I locked down the carriage and adjusted the gibs as tight as possible on the cross-slide and the vertical slide. My adapter just uses the lathe's top slide mounted vertically on a cast iron angle plate bolted to the cross-slide. It works well as long as you take it slow.

[Lynn Standish]

This job is nothing that can't be done with a file, and I'm not going to spend the money to get set up with collets and draw bars, etc. for doing it one time. Since I have 6 pieces that need to have all edges chamfered, it will be tedious. They are .75 x 1.5 x 3.75, FWIW. Thanks for your interest.

[J Tiers]

If that is what you need to do, and high precision isn't important, sounds like a job for a belt sander. I think it would go quicker than milling on the lathe, with setup etc.

You wouldn't need the collets or holder for that job on the lathe. But a $25 end mill holder from Victor machinery, plus a scrap-bin or all-thread drawbar, and you'd be set up for future lathe-milling work.

I had a different impression of what your task was originally. But I'll stand by the milling info.

Here is a pic of the palmgren 250V on a Logan 10". You can see the way it sticks out, and the resulting good chance for "bounce" and cut problems due to flexibility.

The Atlas and S-B type are undoubtedly much more rigid, but at least the Atlas won't rotate on a horizontal axis as the palmgren will



[This message has been edited by J Tiers (edited 03-01-2005).]

[Rex]

I regularly do jobs very similar to this on my 9" Logan lathe. My "Milling Adapter" is usually my Phase II toolpost or something cobbled up on the spot. I would have a 1" endmill in the 3-jaw for this particular job.
I'm shopping for a milling machine, but so far I've been able to finish most of the things I've been confronted with using the above. Most recent project was a toolpost for an Atlas, all of which was machined on the Logan lathe. Always thoughtful setups and light cuts.