Hole Saw bits

[stick]

So I heard that I should expect to go through a few bi-metal hole saw bits while cutting my tubing. I was wondering if the is true no mater what or if it is a funciton of the agressiveness of cutting and the amount of lubricant used?

With the assumption that the first statement is true, I did some research on diamond tipped hole saws. For those of you that don't know- DON'T USE THEM. They are soluble in iron at higher temperatures- just what temp, I don't know. I think what this means for us is that if you used them you could impart more carbon into the steel tubing making it harder, but more brittle. Please correct me on this if I am wrong!

A little more research and I found something called Cubic Boron Nitride (c-BN). Looks like a similar idea to diamond tipped tools without the solubility problem. Has anyone seen hole saws like this, and where could they be picked up from? Almost more importantly- has anyone used a hole saw like this, and does it work well for cutting tubing?

Thanks guys
Mike

[oahupilot]

I found that hole saws last longer if you run them at the correct feed rate and rpm, with a good lubricant. The rigidity of the tooling and support of the material is also very important to improve life of the bit. I just use regular bimetal hole saws and get a pretty good amount of use from it for the cost.

[splischke]

Bi-metal hole saws work very well for cutting 4130 tubing but the brand of hole saw matters. I found that Lenox hole saws are high quality, last a long time, and are no more expensive than what you can get at the box stores. In fact, I used just two Lenox hole saws with my tube notcher to cut an entire fuselage. I have a video on YouTube that demos the process.

www.youtube.com/watch?v=_qp70IWnnwg

-Scott

[schines]

Hi Mike,
It may be just my incompetence with the hole saw jig, but I found it much easier to cut the tubing to the approx. angle with the band saw and finish it up on the bench grinder than to try to set up the drill press for the hole cut. I only wish I had realized the necessity of the band saw before I was halfway done with my fuselage! Just a thought.
Scott

[n3480h]

Though I picked up a started project, I found the bandsaw and bench grinder to be well worth the investment. In addition to the tube cutting and shaping, there are many tabs and pieces of plate to be cut. I can't imagine cutting and forming an entire fuselage without these two tools.

Tom

[oahupilot]

I now much prefer cutting my flat stock with a laser, while sipping my hot chocolate and amaretto ;D

I don't know how spent so much time on a band saw.

Scott is that a harbor freight tube cutter?

[splischke]

Nov 7, 2011 21:30:36 GMT -5 oahupilot said:

Scott is that a harbor freight tube cutter?

Yes. I had to do some minor shimming to get the tube holder "V" centered with the cutter shaft but otherwise it works very good. With Lenox hole saws, mine operates smooth and the cuts are darn near perfect.

[hans]

Nov 7, 2011 21:30:36 GMT -5 oahupilot said:

I now much prefer cutting my flat stock with a laser...

as long as you don't need to bend the pieces afterwards, laser cutting is ok. Please note that the heat changes the temper state locally, which edge-hardens the pieces. Bend them on your brake, and every so often you will find small cracks in the laser cut edges... For this reason, we went the water cutting route for our IBIS projects (see my remarks here: ibis.experimentals.de/buildingmaterial/metalalloy/metalalloy.html )

cheers
Hans

[oahupilot]

Hans lots of sheet metal gets cut by laser and bent up later, the trick is to dress and polish the edge which you should do anyways regardless of cutting method. This ensure a high endurance life as their is less stress concentration points in the materiel. Water jets are nice but I only have a laser at the moment. Also I am referring to sheet aluminum and not plate stock 4130. If you did cut of a thick plate gauge of 4130 you could just heat it back up with a torch and normalize it. Also lots tubing is now cut with laser with plenty of success. Also the strength of your pulse plays a major part in being able to cut thicker stock properly.