Hole Saw - Won't saw all the way through

[Pooh_Bear]

That sounds reasonable.
How can I prevent that from happening.
I already drench the bit with cutting oil.

I get the impression that after the bit goes deep enough to be below the teeth
that the chips can no longer be expelled and the bit loads up.
Forcing it further may be causing work hardening.
Keeping the chips clear has been a real problem so far.
The oil just makes a gummy mess of all the chips.
I could use an air hose to blow the chips off but that would make a huge mess.

Only 3 more holes to go in the 3/8 plate.
Then 6 holes in a 4x4x.25 square tube. I expect it to cut this no problem.

Pooh Bear

 

[ultrarunner]

Back in my machine shop days... we would have drilled 1/4" pilot holes, followed by maybe a 5/8" and then finished with the 1" if being slightly oversized was not a problem.

You can count on a drill "Always" drilling a hole larger than it's nominal size. More exacting work was always reamed to the final size required.

In addtion to cutting oil, cutting speed is very important. For a 1" drill we would have run it around 320 rpm... the smaller the drill, the faster the speed.

Normal cold rolled Steel, or Hot rolled for that matter, should not work harden. Work Hardening could be a real problem with stainless and tool steel.

 

[MrJimi]

My lowest speed is 240 RPM.

MrJimi, I have a Silver and Deming drill bit set from Harbor Freight.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=527
I will be using it for a couple of 3/4 and 7/8 holes I have to drill.
I drilled one 1 inch hole with it and it did ok. The hole saw is smoother.

Pooh Bear

Thats good to hear, I have never used a hole saw on steel, just on wood. Your set looks just like the Enco version, I bought 3 sets and so far so good
Jim

 

[PineRidge]

Hope the slugs aren't hard to get out once I do get a complete hole.

There should be a series of slots on the side of the Bi-metal blade. After the plug is cut you can use a screwdriver blade in those slots to help you remove the cut plug.

 

[scott_vt]

Mornin Pooh Bear,
Just to add to what Rob said allready, what RPM are you running that saw?

And you included a link to a 1" saw, is that the size saw you are using?

Slow, with adequate oil, as you said your using and it should be no problem. I like Lenox hole saws myself, but thats just a preference !

You may have work hardened the steel but I think if you did that then your saw would be dull also.

 

[HomeBrew2]

Continuing with 3RRL's comment and adding an answer to your question, I've had the same prob ... in the future keep more pressure on the saw from the beginning so it is continually cutting, ie, don't LET it work harden the piece. Use a chip brush if it's loading up bad ... or what ever it takes to get the chips out.
Cheers!

 

[Pooh_Bear]

Hey IT WORKED !!!!

I took a small allen wrench and reached in and cleaned out the hole real good.
Poured some more oil in it and drilled some more. Then cleaned again.
Then drilled some more, and cleaned and drilled and cleaned and drilled.....
Finally it drilled through. Then I drilled the rest of the holes same way.
And the little round slugs just fell right out.

I guess after you get into a depth below the teeth that the chips have no
where to go. So it just loads up the teeth with chips and you are just
pressing on the chips creating heat. Clean the chips out and keep drilling.

Six more one inch holes to drill. All in 4x4x.25 square tube.

I might be done drilling all my holes by tonight sometime.

Pooh Bear

 

[cyberknight]

Just a little note. I save the slugs from hole saws. Got a whole box of different sizes. They come in handy for weird washers and other projects. Glenn

 

[wushaw]

I use a shop vac from Wally World for picking up the shavings, it works real good.

 

[mlauk]

I haven't tried this yet, but I read this tip in a wood magazine. Drill two-1/4 inch holes just inside the diameter of the large hole to clear the chips.