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szicree

Well Known Member
I have a band saw, chop saw, table saw, and hack saw. All of the power tools have various wood blades. What is my best bet for cutting some 4130 tubing to length. I'm willing to buy the approriate blade but will probably only need to use it a few times. I'd like a smooth straight cut.
 
A metal cut off wheel (the abrasive, non-toothed kind) in the chop saw makes short work of this. The metal dust that results can get into the works of your saw so be prepared to take it apart for a good cleaning after.

If you only have a small amount of thin wall, a hacksaw with a fine tooth blade does a decent job at less cost.
 
A high quality tubing cutter, like you would use for copper pipe works great. I cut almost all of the tubing for a Sonerai II this way. Saves a lot of hacksaw blades if all you are needing are square cuts. No dust and no noise!
 
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There are carbide toothed metal cutting blades that exist for installation on a common woodworking compound miter saw. A guy I know uses one for cutting steel tubing (round and square) to make tables. It makes much straighter cuts, especially if you are cutting at an angle, than an abrasive chop saw blade does. He says it looks scary but cuts great and he's had no issues with binding or kickback.

There's a number of makers of these; check "metal cutting saw blade" on Amazon.com for examples.

Mark Olson RV-7A F1-EVO Rocket
 
Bi-metal hole saw...

szicree said:
I have a band saw, chop saw, table saw, and hack saw. All of the power tools have various wood blades. What is my best bet for cutting some 4130 tubing to length. I'm willing to buy the approriate blade but will probably only need to use it a few times. I'd like a smooth straight cut.
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..the same diameter as the mating tubing. A great way to avoid the time it takes to "fishmouth" the tubing. For square cuts an abrasive disc on you chop saw would work great. Band saw blades always seem to wear on one side more than the other, then they will drift as the cut through the tube.

LarryT
 
Might not want to use a chop saw on 4130...it's an air hardening steel. That means when cooled quickly (quenched) it gets very hard.

When you use a chop saw the cut end gets red hot. The rest of the tube is cold, acts as a heat sink, and quenches the end as soon as the cut is finished. Now if you must do some minor fitting with a file, saw, or similar....you can't. The quenched end is too hard.

Even more funny is the guy who chop saws to rough length, then tries to fishmouth near the quenched ends with a Joint Jigger or similar. Needless to say, the guy buys a lot of hole saws for his Jigger.

If you're sure of the finished length and the cut end is weld-ready (common with square tube structures), then the chop saw is fine. If you do ALL your trim and fit with abrasive tooling, it is also fine. And a chop saw is great for mild steel; it doesn't air harden.

BTW, the hardness disappears when you weld, assuming you cool slowly post-weld.

You'll want to outfit a bandsaw for steel if you're doing a tube and rag project....lots of sheet fittings to cut out. Try a Lenox Diemaster M-42 Bi-metal in 14-18 tooth variable pattern. Don't force the feed...let it cut at its own rate and it won't wear crooked.
 
A vote for the bandsaw

I have found a bandsaw to be quite useful with 4130 tube and plate projects. A chop saw works on simple cuts but is messy (sparks, abrasive dust, and 'flash' at the cut) and perhaps less precise. Not ready to part with either of my band saws or chop saw. Different tools for different opportunities...
 
I have a band saw, a lathe, a tubing cutter, and an abrasive chop saw.

I use the band saw and tubing cutter because of the mess and noise.
 
tubing

Dan is correct about air hardening with a chop saw. For thin wall I prefer hacksaw, and if you need a smooth end, disc sander. Don't let the tubing get red hot and it won't air harden.When using the sander, sand a little bit and dip end in water. For shaping ends that will fit to another tube, rough cut with Wiss left and right cutting shears and finish with a file. I do use the chop saw for miter joints that will be welded.The welding process takes care of the air hardening. Typical hardware store hacksaw blades don't last very long. Quality blades from an industrial supplier are best. I have best luck with 32 tooth per inch blades on thin wall.
 
I'm finishing a tube and rag project so have cut a lot of 4130. The best method I found was an abrasive cutoff "blade" in my table saw. Lots of sparks and noise (full face protection a must!) but the disc cuts through thin-wall 4130 like butter.

Sam' Legal Eagle project

There are no problems with "air hardening". After cutting to rough length I start fishmouthing with common aviation snips. Sometimes these trims will be fine tuned with a bench grinder but the snips can get you very close after developing an eye for the process. This is a lot faster than setting up some sort of joint-jigger.

Dipping hot 4130 in water is a major no-no.

The cutoff blade and snips is the technique taught via the EAA videos on this subject (Earl Luce) and also in the TM Technologies DVDs (also featuring Earl) which I found very useful. It worked great for me and I have no reservation recommending it.
 
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4130

I agree that dipping a red hot FINISHED PART in water is a no-no. However, using a disc or belt sander and dipping the tube frequently BEFORE it gets red hot will not hurt a thing.
 
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