Improvised milling machine

Back working on my bat house mold. Envision a large rectangular sink made of
5/16 thick cast aluminum... I'm 'milling' a shallow slot in the middle with out
a milling machine. A router with a carbide bit actually works (slowly!) as long
as I take light cuts and keep it lubed up with stick wax. Running into a
problem getting the slots all the way into the corners.
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Have already booked some run time at my local rotational molder next month and
would like to connect the slots before then. Only real machine shop I can
possibly afford (semi retired relative) is not open on my normal days off and
my day job is oddly wide a** open. Running out of time and ideas so I'm asking
here.
Reply to
William Bagwell
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I suspect that in the olden days such a slot would be cut with a chisel (not a wood chisel), also suspect that would still work today...
Reply to
Pete C.
Die grinder + burrs?
Reply to
Spuckle
Even if you had a mill, you probably could not make that cut all the way into the corner.
Some one else suggested using a cold chisel which might be the best option in your situation, although it might not look so pretty.
Other options could be: 1. Cut the sides off, then mill the slots, then screw, weld or braze back together. 2. If you did not mind making the part smaller and had not already milled most of the slot, you could have welded or screwed in sheets of aluminum to raise the flat surface rather than mill the slot. 3. Make a jig to guide a hand-held dremel or die grinder. You could either use an end-cutting bit or an abrasive cutting wheel. It depends which corner you want the radius to be on. 4. Cut out the center section containing the slot. Weld in place a thinner piece to form the slot.
BTW, I assume you know that the vertical edges of the slot should be angled slightly to let the part pop out of the mold more easily.
Reply to
anorton
You suspect correctly. The end slots which were already existing in the original cast molds (my mold is a weldment of cast pieces) were modified using the same 'router as mill' technique and the *much* smaller remaining triangles were removed with a long, very sharp, cold chisel.
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Or the whole page if anyone wants to see it,
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Searching for a faster way...
Reply to
William Bagwell
Inadequate air compressor. Would probably be faster than a chisel if I sprung for a few new burrs.
Reply to
William Bagwell
True. Could probably get closer than my router by angling the head.
Too late for that. Originally was two parts and joined (with a backer bar) where I'm now putting the slot.
Out of time, will reply to the rest this evening.
Reply to
William Bagwell
Do funds allow for a cheapy electric die grinder?
Reply to
Spuckle
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Watch how quickly he chisels the lettering into the high-carbon sword steel. If you can't/won't buy modern machinery you could fall back to the pre-industrial hand tool skills like learning to shape, harden and temper chisels suited to the work. jsw
Reply to
Jim Wilkins
Like, maybe, an air hammer with a cold chisel tip?
Reply to
whit3rd
Do you have one of the many oscillating/multi-tools? Like this:
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These cutters would probably cut aluminum okay (get extras):
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Should look a bit better than chisel work, maybe...
Reply to
Leon Fisk
Have seen this done. Has issues and the better it is welded, the harder it is to repair when it eventually fails.
Only new idea I could think of before asking here was to make a wedged shaped end shoe for the smaller of the two routers I have been using and use a pointed end bit. Think they are made for plunge cuts so I'm not sure how well they would work cutting flat.
Wish I had done this to begin with. Originally *was* two pieces! Had access to TIG then... My MIG warped it way more than I expected building up a pad on the outside so the wall thickness will remain the same.
Oh yes! Though rotational molding is probably the most forgiving of any process. I have seen simple cubes and cylinders made in zero draft molds. Absolutely not recommended for any complex shaped part.
Reply to
William Bagwell
Started watching while I was eating dinner... Did not realize it was so long so might not finish until the weekend. What I did see was quite interesting!
Reply to
William Bagwell
Might be able to borrow one. Still have the too small compressor problem...
Reply to
William Bagwell
Hmm, have seen those plugged in and ready to play with at Home Depot. Can not imagine them taking a heavy cut in aluminum, but it might be just the ticket to clean up the mess left by what ever method I end up using.
Reply to
William Bagwell
You'd be surprised. BTW, the single-speed version is on sale for $15 right now, with coupon. You can't afford NOT to have one. I'm sure the blades will cut aluminum (I've cut iron/steel screws with them with no apparent dulling), but if you're not sure, get the bimetal, diamond, or carbide half-moon blade. Keep the swarf from building up in the cut and it cuts extremely fast.
Question: Doesn't the metal bat house get too warm for the critters? And what do you use for condo separations inside?
Reply to
Larry Jaques
What? Does he have aluminum bats, or something more exotic? ;-)
Reply to
Michael A. Terrell
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I have 2 of the single speed units. They actually work very well. With aluminum the problem becomes heat related. The aluminum actually heats up enough that it gets gummy and bonds to the teeth. I just applied some common ivory soap to the teeth and it made a big difference. Darn thing does come in handy at times.
Reply to
Steve W.
Perhaps a metal shaper with a properly shaped bit in it?
Good Luck, DoN.
Reply to
DoN. Nichols
Bought a variable speed this morning... Tested it on a 3/4 X 1/2" square 'boss' left from cutting with different sized routers. (Large one cuts smoother, small one gets closer to the corner.) Pleasantly surprised at how well the new multi tool worked! However, that was tiny compared to the four ~2 X 3" areas that will need to be cut before the slots intersect.
Running out of time so will remove these in stages so to keep unfinished slots symmetrical.
You do realize this is a mold to make plastic bat houses? Each chamber will be separated by wooden baffles. Though I am experimenting with an all plastic bat house.
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Probably need to put a few pictures in the drop box for folks who don't click on web links.
Reply to
William Bagwell

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