Hole Saw - Won't saw all the way through

[Pooh_Bear]

I went today and bought a bi metal hole saw.
http://www.lowes.com/lowes/lkn?action=productDetail&productId=178327-28303-34016-16A&lpage=none

I chucked it up in the drill press and started drilling in 3/8 plate.
Pilot bit drilled real good. Saw had some trouble getting started,
but after it did it drilled good, for about 1/4 inch deep.

I have drenched it in cutting oil. I have cleaned all the chips away from it.
I have tried light pressure and moderate pressure and heavy pressure.
But it won't go deeper than 1/4 inch.

What am I doing wrong.

I have 5 holes started. Plan on doing the other 3 tomorrow.
Then I'm just gonna flip the plate over and drill from the other side.
If it works then that will finish all the holes in that plate.

Then just 10 more holes to go.

Pooh Bear

 

[MrJimi]

I use this kind and I never have any problems
http://www.use-enco.com/CGI/INSRIT?PMAKA=301-0205&PMPXNO=947966&PARTPG=INLMK32

for $10.95 ya cant beat the set
Jim

 

[rswyan]

What am I doing wrong.

Adjust the height of your drill press table (up) - or the depth stop .... you're out of spindle/quill travel.

And make sure that after you do drill the first one all the way thru you remove the cut plug from the hole saw otherwise you will have trouble later once you get enough of them in there.

 

[wushaw]

Adjust the height of your drill press table (up) - or the depth stop .... you're out of spindle/quill travel.

And make sure that after you do drill the first one all the way thru you remove the cut plug from the hole saw otherwise you will have trouble later once you get enough of them in there.

I was going to say the same thing...I have had it happen to me where the adjustment nut works its way down a little and no matter how much pressure you input it just won't cut anymore

 

[Pooh_Bear]

I should have 4 inches of quill travel.
And the pilot bit is 1/2 inch above the plate.
Don't think the problem is not enough quill travel.

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

If I have to turn the plate over and finish the hole from the other side
I believe it will still be faster than using the twist drills.

Pooh Bear

 

[rswyan]

and no matter how much pressure you input it just won't cut anymore

Same here - more times than I would care to admit.

 

[rswyan]

Well 4 inches is pretty good if that's what you actually have .... I only have 3 1/8" on my 17" Craftsman drill press .... and I think it had the largest travel of most of the ones I looked at, at the time (and was the reason why I bought it over the others)

You're using the same hole saws I have here - Lennox. I've hogged out a 2" hole in 1/2" plate several times and numerous 1" and smaller holes with mine.

What speed are you running these at ?

The other thing I have noticed is that sometimes the cutting action will just stop for awhile - I continue to apply alot of pressure and eventually the saw will start cutting again.

 

[GuglioLS]

Perhaps the hole saw is not exactly straight or the metal is expanding and binding against the inside of the hole saw:

 

[Pooh_Bear]

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

 

[3RRL]

Pooh Bear,
a) If you still have travel on the quill and b) If you don't have anything plugged inside that hole saw, then I think you work hardened that steel piece. Now you'll have to use carbide or a plasma torch to cut it or try flipping it over.

 

[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.