holes in aluminum diamondplate?

Are you serious? 7/64" holes with a plasma cutter? Have you ever looked at a guitar pickguard? This isn't a manhole cover, it has to be pretty!

GWE

Michelle P wrote:

Have you tried a good sharp center cutting endmill? The mills rigidity will probably also help keep the soft aluminum from yanking the bit/endmill in too fast.

Pete C.

How about a Unibit step drill? Greg

Grant Erwin wrote in news: snipped-for-privacy@corp.supernews.com:

from the backside

What Pete said. That's a no-brainer. Even if you don't use the end mill to drill, make certain that you spot face the diamond protrusions to drill diameter so they don't deflect your drill. It would be wise to cover the surface with masking tape if you don't want any swirls from the chips showing up on the finished product. That is almost always a problem. The tape will get sticky and release in areas if you use kerosene or other lubricant, but you should be able to finish the job before it has released completely. Clean up in mineral spirits when finished, which will remove the stickiness left behind from the masking tape. You should be able to pick up the punch marks with a wiggler through the tape. Be certain to mark them before setting up, while you can see them easily.

Harold

That often just changes the nature of the problems at hand. In this instance, the burr you raise drilling on the edge of a diamond would be far more difficult to remove, and it could deflect your drill as it breaks through. All depends on where the hole falls. Maybe the deflection wouldn't be a problem, but deburring it sure to be. Also, if the plate was supplied with the center pops already in place, that wouldn't be much of a solution.

Harold

I think thats what I would use also. Held in the mill.

Gunner

The ones which I have are not ideal for holding in a mill -- at least not in a collet or an end-mill holder. They have three equally-spaced flats which are designed for gripping by a standard drill chuck.

Of course, of you intend to use a drill chuck in the mill, this should work well enough.

Enjoy, DoN.

Thanks to all who responded. I delivered the pickguard tonight to a very happy young metal band. The first one was free, every one from now on will be $150. I got a lot better with a wiggler, and Harold's tape trick worked perfectly. It turned out a lot of the holes were oddball sizes so I had to drill them, not having every diameter of end mill. I wound up freehanding the countersink, and it didn't go too badly. All in all it worked out pretty well.

Grant

Of course in the chuck Though they do work in a collet. Been there, done that.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

countersink.

It wasn't uncommon for me to use that very procedure when building tooling, but it was always in a mill, never a drill press. That alone makes a huge difference, primarily in rigidity. I agree, it works fine, but it's easy to get in trouble, especially with end mills. My only advice is to work carefully when using them in drill chucks. They'll never run as well as they do in a collet, but as you've found, they work well enough for spot facing. It's a different story if you try machining sideways with them.

Harold

It also depends on the size and rigidity of the drill chuck and the drill press itself. The shop has both a hefty benchtop woodworking drill press, as well as a dedicated 3phase floor drill press that weighs over 1000 lbs and has autofeed, infinitely variable speed, etc. Basically a mill missing the table. It even has a drawbar and standard taper so it could be used with collets for holding end mills.

This is a Bridgeport mill I'm talking here, not a drill press ..

GWE

They will work not badly if cutting sideways also. But not with an un-drawbarred morse taper.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

They cut fine, but the minimal support they have from three jaws tends to allow them to hook easily. The additional length of the chuck and the small (chuck) shank doesn't help the cause, either. It's not a good policy to hold end mills in chucks, regardless of how rigid the machine is, or what material one is machining. Still, many of us have, and will, do it and manage to live through it. Still, I never recommend it to anyone.

Harold

Very true indeed and wise words. Which is why I said " will not work badly". I always use a bigger chuck than most folks would in the first place, so the jaws are bigger and one can apply more pressure. And Ive had em move in the chuck..usually digging deeper into the work..damnit. But Ive had the same thing happen with collets as well, though admittedly, less often.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Yep! Hardened jaws gripping shanks that are over 62Rc makes for a poor holding device, particularly when the width of the jaws is so narrow at the point of contact. Collets do grip better, but they still offer problems under adverse conditions. I recall, way back in '67, scrapping a template for the Boeing 747 that was being roughed with a 1" end mill that walked out while I was taking a serious cut. There are times when end mill holders can be a valuable asset.

Harold