Where can I find hole saws that will cut 16g sheet metal - and do so without dulling after a few uses? Specifically, I'm looking for a 4.5" saw to be used with a large drill press. I've used a normal Lenox version from Lowe's that went dull after two completed cuts. That's a horrible ROI for $35...


Andreas

 

Brother Andreas

While the lenox bits arent top of the line, they should last a few more cuts than two... My initial though was too much heat (teeth loosing thier temper)... that could be caused by 1)not enough lube 2)lube too thin, or more than likely, 3) too much speed.... So a quick search... a 4.5in hole saw should be turning 75 RPM for mild steel.... I dont know a drill press that can turn that slow....

Better question though... whatch ya cuttin' ???

 

Brother Scott,
I tried a variety of speeds, as low as 300. And I kept the cut lines well lubed. Sounds like I may need to sprinkle some carbide into the mix...


16g steel.


Andreas

 

You can appreciate this....
My grandfather ( the epitome of a gear head) had an 8 foot tall drill press frame that he salvaged from a manufacturing plant…. He proceeded to scavenge up a 10hp electric motor and two 4 speed car transmissions that he put in series… This thing would spin a 5 in twist drill bit at 10 or 20 rpm and 4 bazillion ft/lb of torque… it was amazing… to change speeds you simply shifted gears...

 

Awesome! That should be in your garage, next to your five-foot-long torque wrench...




Andreas

 

Slow down the speed even more, perhaps 150 rpm. -- more than likely the cause of this. For steel, use oil.

 

second thought, use a punch press

 

Andreas,
That is a large hole for rather thin metal. You may want to get a nibbler and cut near the line and finish with a file. How many holes do you have to make? Is the steel in a flat form? You could have a machine shop laser cut it. I have cut holes with the sheet metal sandwiched between sheets of wood th keep the hole saw from wandering and the metal from bending up as you cut thru the metal.

Good Luck!!!!!

 

Ah.... even better.....

 

Looked around my shop and came up empty handed....


Andreas

 

Actually, I'm cutting a number of discs, so repeatability is key. Although the hole saw simply stopped cutting after the second hole, the teeth still 'feel' just as sharp. Probably meaningless...


Andreas

 

Flip the sheet over - they're usually softer on the belly side ....

 

Now thats funny !!

 

It might be helpful to let us know what you're working on, Andreas.

I assume that the size isn't too important, becuase a 4.5" hole saw gives you a OD 4.5" hole, not a 4.5" blank. The circles you're making are two hole-saw-material-thicknesses smaller in diameter.

Just given what I know, I would make a center punches, scribe the circles with a divider, make a rough cut with hand shears, and then do a final trim with the same.

Have you had a tetanus shot in the past ten years?

 

This.

Andreas