Boring aluminum rod

How about putting a 1.75 inch diameter end mill in your tail stock? Might be tough getting one that would fit, but it's worth a look.

I'm just an armature, but I would trying a boring bar.

Do what Machineman said. Forget the other bullshit. Don't stick a honkin end mill in the freakin tailstock. That is asking, no, demanding trouble.

michael

I must admit to doing the endmill thing a lot. I always drill a good sized clearance hole for the web of the two flute endmill, then plunge with the tailstock. This is pretty common in the CNC world as well when a flat bottom hole with sharp corners is desired. I occasionally use a

Id not suggest doing this with a light duty lathe or particularly the AA lathe. It needs to be a rigid lathe.

I also use a two flute end mill quite often when Turning plastic in place of a turning tool. makes for great chip control.

Gunner

"A vote for Kerry is a de facto vote for bin Laden." Strider

I use BP style end mills up to 1.5" all the time in my tailstock. 16" SB lathe. Other than they leave an oversize hole, they are great for roughing. I can't think of a time when I have used them in steel, but in aluminium no problems. I tend to put the set on my bench and go up in 1/8" or 1/4" steps from 1" to 1.5", after drilling to 31/32" (happens to be my largest S&D drill bit), then I go to a boring bar or a big old tool I ground out of 3/4" square HSS.

Do what gunner said or if you don't have an endmill, drill with the biggest S&D drill you have and then take that drill and grind it to a flat bottom drill. Bore it the rest of the way with a boring bar.

"A vote for Bush is a vote for moving jobs offshore"

I agree. That's a very high production method and who's got a hundred dollars for a huge end mill to be used just once?

Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

Read about my physics project at NVCC:

Now one thing you can do, OP, to compromise between Machineman's advice and Gunner's, is chuck an end mill in your boring bar holder with the flute tip dead level. Then set up a stop.

In/out feed the cross slide to exactly center the end mill to start so it cuts well balanced. Set a depth stop on the carriage, or set the compound parallel the ways. Then use the end mill first as a drill, then a boring bar, all the way to the bottom. Out feed 1/3 the diameter of the end mill, and feed again. Repeat until close and finish to the same stop. One setup, one cycle, one job finished reasonably well.

A hard carriage stop will produce better results than feeding the compound parallel to the ways.

Oh, by the way, don't chuck the whole block of stock. The thin sides will bend. Chuck the full depth of the end of the cap plus that much again. You'll have solid metal under the chuck jaws when you are done with this setup, and you won't get a fatal slip as you near completion. Just make up some spacers to lift the stock block in the chuck jaws and use double sided tape to stick them in place.

Face the outside of the top and sides first, then chuck with a bit of paper to protect your nice finish. Bore as above, and feed easily, and there'll be no trouble.

Aluminum will weld to a cutting edge. Kerosene or WD-40 helps a lot. But basically what you do it let it build a little, then pick it off with a knife blade leaving a sharp HSS cutting edge. In other words, you keep an eye on it as you progress.

That's my advice. Worth what you paid.

Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

Read about my physics project at NVCC:

What Michael (& Machineman) said. If you understand what a chip breaker is, grind a right hand boring tool with a decent positive rake chip breaker, then bore and face the cup after you've drilled the largest hole possible. Normally, drills remove stock faster than a boring bar.. Use some kerosene to lubricate the tool as it cuts. You can use an acid brush, or a small paint brush. All you have to do is keep the cut moist and it shouldn't gall on you. Maybe the only thing that wasn't covered is the inside radius of the bore. You'll want to grind and then hone an acceptable radius on the boring tool so it leaves a better finish. Don't leave a sharp corner unless you need one.

Good luck. Tell us how it turns out.

Harold

It's worse than that, though. This guy has been deadly honest in telling us that he has no experience. Large end mills can be serious trouble, especially if used in light-weight machines. My recommendation is to learn to walk before trying to run. There's no doubt the end mill will work, but considering the rake angle, it can get away from the user quite easily. He risks scrapping his project, plus doing damage to either his person or the machine, depending on how poorly his results could be.

I'm with Machineman & Michael.

Harold

Thanks Harold. The (in)experience factor was a major reason for my comment. Dunno why I did not actually mention it. Must be getting....uh...what was it we were........

I think I was supposed to be doing something in the shop, it'll come to me.

mj

OK, I use end mills to rough holes before boring to size all the time, and you guys have me scared :) Why, beyond "Don't stick a honkin endmill in the freakin tailstock. That is asking, no, demanding trouble." is this a bad idea? Is it the self-feed potential of the helix of the endmill?

I have been home-machining for 10 years, the lathe is a 16" SB, the end mill is a BP style with a 3/4" shank that I hold in a Jacobs drill chuck. I've never had the end mill spin in the chuck, and no, I don't hold endmills in a drill chuck on my BP. I run at about 100 fps, usually, and I normally go from around a 3/4" drill to a 1", then 1.25" then 1.5" endmill, at which point I go to a boring tool ground from 3/4" HSS stock. My "normal" depth of cut in aluminium is .100 - .200 under power feed for most roughing purposes (normal turning, not drilling), although I sometimes try to just not stall the machine (actually, the belt slips) when I have a lot of material to hog off. that is about .400 deep cut, at 100 fps and .003" feed (about, I tend to use the suck it and see method of determining DoC and feed, as taught to me by Teenut those many years ago).

Brian

Combined with the self-disengage potential of the Morse taper when the mill starts to self-feed, it could make things a wee bit exciting.

Your belt slippage is keeping you out of trouble. Not really a problem, but consider what would happen if using a geared machine with lots of H.P. Like sucking the E.M. into the work such that it is in turn pulled from the chuck.....Things get scary when the tool sucks into the work, whether on a lathe or mill.

That would be my concern, plus the fact that end mills do not clear chips well when used as a drill. If you're opening an existing hole you have better luck with the chips, but cutting an almost full diameter creates lots of chip movement problems, although not necessarily danger. As you reduce the amount you're cutting via a pilot hole, you then increase the risk of the end mill hogging in. Also, don't lose sight of the amount of energy needed to take large cuts. Small machines generally don't have the type of power often needed. If you scratch away at the cut instead of feed at a decent rate because you're under powered, you're putting undue wear on the end mill. Probably not a big deal, either, but it's not a bad idea for folks to learn to use machines somewhat as they're intended and do a job like this with a proper boring bar. For example, you might haul, with some degree of success, a load of cow manure in the trunk of your car, but you'd have far better success with a pickup truck. One can not deny that both systems work.

Harold

If he had a machine that would handle a 1.75 inch end mill, he'd use a milling machine to do the part.

A boring bar is how this should be done.

Jim

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