Creative end cuts with no mill

I am looking for creative suggestions to cutting aluminum. I do not
have a mill, and the prospects of getting one in the near future are
non-existant. I have to therefore use other more creative methods. I
am primarily interested in cutting off lengths of 2 types of aluminum
extrusions, the 1st being square 10mm section in a length of about
60mm, and the 2nd being rectangular 10mm x 80mm in a length of about
150mm. I would like to make the cuts square and perpendicular,
holding the length and perpendicularity to .001 inch and with good
surface finish.
I use a technique on the 1st type that is quite effective. Using a
hacksaw and the sides of an old vise as a guide, I rought cut the
material to a couple hundredths of an inch of size. Then I use a file
on the ends to clean up the cuts. Then I put the metal in a vise, the
part being aligned vertically, and place the vice on my drill press.
Then using a circular abrasive disc (like the black+decker variety,
120 grit), and using very light "taps", I clean up the ends. Once the
ends each have uniform "machining" marks on them, I measure with
calipers, calculate how much needs to come off, and repeat the process
using the circular disc. I have a good idea of the number of tap/cuts
are needed to bring the part down a particular distance, and the
process all-in-all is pretty well-defined. I can finish the part in a
reasonable amount of time (for the process that I am using - say 20-30
minutes) and the finish vaguely resembles that of one which was
fly-cut.
Now the problem. With the smaller part, and a light tapping touch,
the circular disc does not flex in a considerable manner. When I try
to use this approach on the bigger piece, there is flex, "stiction",
and general uneven cutting. Therefore, the piece does not clean up
uniformly. Also, having a piece clamped 1.5 inches or so and then
extending upward out of a vise some 4.5 inches causes a good deal of
vibration which further degrades any finish that I might obtain. I am
trying to think of a way to achieve similar results (as the smaller
piece) in this larger piece using some of the more common workshop
tools like a drill, drill press, files, belt sanders, dremel, etc.
Short of marking the piece up with prussian blue and then scraping or
dremel'ing it's perpendicular edge and then uniformly bringing this
perpendicular edge to dimension (and I might get 1 part an evening
done, ugh), I see no decent creative solution. So I am hoping someone
has a good idea that I can try. Thanks in advance.
Reply to
ss
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You can use a table, radial arm, or miter saw with a carbide blade. If set up carefully you can get very square cuts. You can even use a skill saw but the cuts won't be so square. ERS
Reply to
Eric R Snow
I use a table saw with a high count carbide blade and a little bees wax for lube. Looks like a mill cut end. A good miter saw will also do an excellent job.
Reply to
Bruce A. Frank
snipped-for-privacy@ya.com (ss) wrote in news: snipped-for-privacy@posting.google.com:
Miter saw, with fence and clamps, carbide tipped blade and end stop.
Reply to
Anthony
I have little experience grinding aluminum, but it sounds like you are plunge grinding the whole thing at once. If you get yourself a beefy angle plate ground, maybe 6x6x6" then you can clamp that flat to your DP table and clamp your part rigidly to it. Then make a ring to go around your DP column (if you don't have one) and put the ring up under the head of your DP and clamp it tightly, then loosen the bolts holding on the head of your DP. Buy or make an arbor that you can chuck up and that is threaded 5/8-11. Go buy a "cupstone" grinding wheel and put it on your arbor. Buy, make or borrow a cheap surface grinding diamond dressing fixture and clamp it and then fire it up. You will be swinnging the head sideways and lowering the quill a little at a time and then clamping the quill down. Dress your wheel flat, and then it's time to surface grind your part. Do it just a little at a time, feeding the part in maybe 1/8" or 1/4" at a time.
You will need to learn how to tram your DP table precisely square to get results within .001" - that's an awfully tight spec, by the way!
If you have a worm drive saw you can go get one of those miracle blades for about $49 and you can just clamp the extrusion down and saw it off.
Another option is to make a 4" belt grinder, or to buy/borrow a hand belt sander like woodworkers use, and to hold it vertically by its handle in a vise and use it as a mini-belt sander (I did that for years and it works pretty well.)
And WEAR EYE PROTECTION! I once started grinding aluminum on the superstructure of a Navy ship, and I was wearing a face shield but those tiny chips flew inside and within one minute I was in pain and the eye docs had to take seven pieces of aluminum out of my eyeballs.
Grant Erwin
ss wrote:
Reply to
Grant Erwin
without a lathe or a mill, holding + or-- .001 in length and or perpindicularity is a tall order . not impossible tho
Reply to
Wwj2110
Yes, I spoke a bit too hastily. On the small parts, which are utilized kind of like stand-offs, that is to space and support larger flatter pieces, and with the working procedure I had developed for them, the .001 is not so bad because I can bring the dimension arbitrarily close and then tweak it until it is just right. On the bigger piece, yes, those tolerances are practically problematic. As it turns out, the exact deviation from the spec is not so critical, + / - half a hundreth would be fine - but what I meant and failed to say is that tolerance relates to pairs of parts. They can all be oversized .005 just so that each is oversized by .004 to .006, and just so that deviations in the perpendicularity are consistent too.
Thanks for pointing this out, as you correctly imply, the time required to bring a larger part to these spec's by hand would favor one with a good deal of time and even more patience.
Reply to
ss

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