Full disclosure: I'm still very new to cutting / fitting tube and I promise to not work on anything structural for quite some time. Right now, I'm working on some basic WAL-bannable offense sliders to replace the crappy tub mounted ones that came on my JKU.
I'm working with 1.75x.120 1xxx dom tube. I'm using a HF tube notcher and so far have only been making 90* cuts. The issue I'm having is burning through hole saw blades at an excessive rate. Also, the cuts are taking longer than I would expect. My guess is I'm doing it wrong and need someone to provide some feedback on my technique.
Here's what I'm doing:
- Take measurements and mark where to cut
- Use the following formula to determine cutting speed:
(4*120)/diameter inches = drill speed
4*120/1.75=~270. My drill press' lowest speed is 300rpm.
- Coat the hole saw with dark thread cutting oil
- Apply constant (not too heavy) downward pressure and let the saw remove material. I keep the cutting edge wet with cutting oil.
- I avoid releasing pressure on the saw for the duration of the cut
- The cut takes 10 minutes or more. I've read elsewhere that it should take less than a minute. For some reason no matter how tight I have the chuck, the cutting shaft seems to drop often -- not what's going on there, but it's annoying.
- I cut all the way through the tube. I don't rotate the tube and cut from the other side
Typically, following those steps will demolish a HF hole saw about 50% of the way through the tube. A Milwaukee or Diablo hole saw will be missing 50% of it's teeth at the end of a single cut. I'm just not sure what I'm doing wrong here but it's costing me $10 every time I want to cut a tube.
I know, I know, the problem exists between the feed lever and the floor, but any tips would be appreciated.