Milling Aluminum - Rework

I don't advocate this, and don't tell anyone I recommended it in any way, shape, or form, but...

I had a similar problem about 20 years ago, about ten times deeper than yours, and I got away with using a single-edge carbide bit (1/2") in my router. The aluminum was 2024-T4. I set up a very solid and unnecessarily complicated jig, made of birch plywood and with lots of C-clamps, to make sure it was all rigid and wouldn't slip. Through trial-and-error I got to within a couple of thou and then finished it off with a homemade scraper.

Disclaimer: But I think it's all a bad idea. I advise against it...

-- Ed Huntress

Description setup snipped...

LOL

It must all be in the bits. In a fit of naive foolishness about twenty years ago, I placed a router, its bit spinning at 25K RPM against some .062 aluminum sheet, I only needed to shave off a few thou -- BAM!

The bit was trashed, the aluminum was trashed, and by the grace of God no blood flowed. I vowed then and there to never try anything involving hand-held routers and aluminum again.

Ed Huntress wrote:

See? I'm learning about the law and newsgroups. I haven't said anything about this, and it wasn't anything bad, but I wound up in court for a day two weeks ago, subpoenaed as a witness because of something I said on this newsgroup two *years* ago. It's led me to re-think Google's NG archiving. I now hate it.

It's the second time, same issue. The first time, last year, I had to give recorded testimony. This time I had to sit in the witness chair in court.

I don't want to do it again.

-- Ed Huntress

That's probably the smarter course of action. Because of some revious experience I knew I'd need a pretty solid fixture, so I went to some lengths to make sure that was the case. Still, I approached it very carefully, holding onto the router like a drowning man holding a life ring, and cutting in small bites.

-- Ed Huntress

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Been there, done that. So, has it given you the same total disgust of the legal profession I came away with?

Karl

Not in this case. I was really impressed with the judge, a Hispanic woman who gave both sides plenty of room. I also saw two very clever attorneys at work.

I've been in court before, though, and in the past I've come away with the feeling you suggest.

-- Ed Huntress

I have routed aluminum with wood bits and a variable speed router on low speed, worked great, but I advise against doing it! Greg

There's another man who knows the value of caution.

A variable-speed router sounds like a nice thing. When do you use the lower speeds? With bigger cutters, or are there other purposes for it?

-- Ed Huntress

I can't visualise from your description exactly what shape the bits you need to remove are nor do you say what tolerances you are trying to achieve. However, a skilled operator can work to pretty fine tolerances by hand with dremel type equipment. Basically what we do when porting cylinder heads. For very fine work in aluminium I find it easier to use a mounted stone lubricated with kerosene than a carbide cutter. You can shave away a couple of thousandths of an inch at a time with care with these.

Pink aluminium oxide ones meant for grinding cast iron are the ones. Something like a 10mm diameter cylindrical one on a 3mm shank lets you get into fiddly corners. Used dry on aluminium the pores clog almost instantly but keep them wet and they can remove material surprisingly well. For flat surfaces a coarse oilstone also well lubricated with kerosene will remove high spots in aluminium very well.

-- Dave Baker - Puma Race Engines

When the shit settles..some details would be nice.

Gunner

It's better to be a red person in a blue state than a blue person in a red state. As a red person, if your blue neighbors turn into a mob at least you have a gun to protect yourself. As a blue person, your only hope is to appease the red mob with herbal tea and marinated tofu.

(Phil Garding)

It's not a big deal, and it's not something I'd want to discuss in public. It was a contract dispute between two companies I had been involved with. I'll tell you by email.

Imagine my surprise when I was giving testimony in a deposition, discussing the subject for most of an hour, when an attorney pulls out printed copies of three or four of my RCM postings that he had found in Google's archives. I was very glad then that I habitually stick to the truth.

-- Ed Huntress

I've drilled my whole family never to post anything on the internet that you wouldn't want waved in your face 10 years in the future. Appears to be good advice.

Sounds like a job for a file.

Or put some sandpaper on a large flat surface (such a a piece of glass) and sand them off by moving the part .

How the hell did the attorney recognise "truth"? Surely not a concept familiar to most of them?

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At the *bottom* of a pocket?

Enjoy, DoN.

I would say you can use a router to clean up the corners. The trick is to clamp and jig it properly. That is important. It does not take much to twist and scrap your part or draw blood.

You might also consider working the area by hand with some die files if the tolerance specs permit this or perhaps you can relieve the part that fits in the hole on the corners.