How do I Bridgeport Mill rectangular aluminum tube that is much longer than the vise?

My aluminum tube is 3" x 3" with 1/8" thickness, and it needs to be accurately cut to 47.127". One end is a simple right angle but the other one needs a 52.562 degree angle.

What’s the best way to do this?

Bruce

First you are giving very precise dimensions with no indication of the tolerance. 0.XXX" are typically ± 0.010", Your using a three decimal place angle which is fractional seconds, don’t know what that tolerance might be.

  • Tilt Table: mount to bed after squaring up like you would a vise. Then use the digital angle meter to set angle (check the battery first). 52.562 decimal degrees = 52° 33’ 43.2" fractional. However, our digital gauge is good for ± 0.1 degrees. This may not be anywhere near the accuracy you need.
  • Kurt Vise and 5" vise using our 5" sine bar and a 3.970" stack. This will get you within 1 second of degree.

For the length, not sure how to do this as I have no idea what tolerance you need is. I don’t think the larger caliper can do that. It’s either 36" or 48". You could scribe it’ maximum length, then add the extra and scribe the final length. If done carefully you might get ±.0.010". The add how accurately you can hit mark. I’d say you would be ± 0.015" total. Cut the end with angles first, then the 90 degree, easier to measure and align.

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That’s going to be the most precise stripper pole ever made!
Getting the length cut that precise will be difficult without an accurate measurement tool. You can scribe a line and sneak up on it with the DRO AND LOTS of measurements in between but it is still doubtful you can get under .01 unless you get lucky

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Bruce,
Can you put small divots in the material without worrying about it? Or a couple holes that you can put test pins in?

TBJK,

Sure; really all I’m building here is a cart so we don’t need any great precision.

Within a millimeter or 0.1 degrees will be fine.

Now that I’ve thought about it, I can just measure with a ruler or tape, then get the angle with a digital protractor.

I like your test pins idea though, nice.

Bruce

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If this is the case I believe the cold saw has a miter head for diagonal cuts . A lot quicker and easier than the mill I would think.

Wouldn’t use the cold saw for aluminum. The evolution can do aluminum.

-Jim

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I’d vote for the evolution saw too, it’s likely to be within a half a dagree if you set it very carefully.

This would be the perfect opportunity to use the 5 foot calipers!

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Nice replies all. Can’t wait to try that Evolution in angle mode!

I will not ague that the evolution saw may be the better choice but is there a reason you would not use the cold saw to cut aluminum??

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The cold saw is not designed to cut aluminum. The SFM on the blade is not fast enough to cut it.

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it’s meant for mild steel, brass, and stainless if the wall thickness is .125 or less. It’s not fast enough

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so I get this straight, you will cut mild steel, brass and SS but not aluminum? and you only use it on material 1/8" and lighter?

The teeth will clog, they are too closely spaced and the gullets are too small. Kalamazoo, the manufacturer recommends 1700 sfm for Aluminum, our saw at high speed is about 220 sfm. That’s why we have the Evolution saw: it has a an Aluminum blade and is high speed. It’s the proper cut off saw.

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in addition to what @Photomancer explained regarding aluminum on slower and lower tooth count wheels, the 1/8 wall restriction only applies to stainless steel tubing.

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So you know, the issue with the SS is ii work hardens as it is cut. .125" material can be removed fast enough that the hardened zone can’t be “built up” and ruin the blade, material wider than .125" may be more than the blade can handle. The blades are $150-$190 per blade. We can get them resharpened, but it doesn’t take long to dull them with hardened steel.

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got it, thanks.