I'm working on building my own version of the 'blind chicken racing' tubing bender. I'm planning on making some 1" and 1.5" holes using some hole saw bits I just picked up to mount in my drill press. The side support pieces are made of 0.25" steel plate and to keep things as symetrical as possible, i'm going to clamp together both sides when making the holes. Are there any tricks or techniques I should pay close attention to when making my way through 1/2"+ of mild steel? I know there will be one issue, the hole saw calls out a recommended RPM of 200 while the lowest belt setting on the drill press I have is about 600 RPM.

Thanks for any input.

 

Here is a link to a RPM lookup table based on the material and hole diameter:

http://www.magbit.com/xref_hole_speed_rpm.php

 

I always recommend a small pilot hole to guide the holesaw bit, but a center punch will do.
Make sure to clamp pieces down securely, or clamp vise down with pieces in it.
Use some coolant,cutting fluid, or a mix. The rpm is triple, but it's not the end of the world, your saw just won't last as long.
Besides that, just moderate-light pressure, keep it cool, and away you go.
Hopefully somebody can add to this...

 

Cold rolled I presume you're using? For starters be ready for quite some time standing there to cut through a 1/2" plate. Personally I would sway away from the hole saw and use drill bits in steps. I've drilled 1" holes in 1" steel plate with a 1" drill before and it worked fine. Start off with 1/8" and work your way up in increments. Best advice I could give; any way you choose; is GO SLOW AND LUBRICATE! Do not allow the cutting media to "overheat." As far as drill bits go (and hole saws) is you get what you pay for. Start off with a good SHARP bit and it will cut like butter.

 

stay away from lenox hole saws. the end where they mount to the shank will bend if it binds. i was cutting holes really slowly with a milwaukee corded drill and when it locked up it bent the holesaws so they wouldnt drill straight. i ended up putting a 2X4 down on the ground and hitting the back of them with my hammer and it straightened them right out. either way lenox sucks

 

[QUOTE=bigTom] For starters be ready for quite some time standing there to cut through a 1/2" plate. QUOTE]

I cut through four 1/2'' stainless plates with 3'' hole saws i bought from ace hardware and it took me about 3 minutes a plate to get through them completely on a cheapo drill press. No guide holes, no steps, just a center punch. If done properly and lubricated properly its actually quite easy and doesnt take much time. Should be faster on mild steel too.

 

I have lots of success with Starrett and Greenlee hole saws. I probably have 200+ cuts on my 1.5 in hole saw. I cut through steel tubing, aluminum and steel sheet with no problems.

Typically for steel tubing I spin them to 350rpm they don't seem to bind as bad as they do when run at a lower speed.

 

I have always had issues when using a hole saw on tubing. Does anybody have any tips for making this easier than I am doing it?

 

(((TRY THIS AND REPLY BACK)))
It may sound like extra work but its worth it !!! first let the hole saw score the material, then drill 2 , 1/4" holes , just tangent to the inside of the score line. This will give the "chip" somewhere to go and will "cut" the cutting time less than half !!

 

I cut .5 inch steel with whatever brand lowe's hole saws and a 14 yea rold makita drill. The makita drill ended up seizing and overheating, then finished the job with a Snap-on drill.

As long as you maintain some decent pressure, and a good amount of lubrication for the saw you should be good.