Very poor large hole result

[AllenV]

This forum is simply unique. So much expertise willingly offered in good spirit.

 

[AllenV]

If you have a face plate for the lathe you can use milling hold downs to hold it to that. Might be easier than the 4 jaw

I do have a face plate. Still slathered in cosmoline for some 17 years. Might be time to bust it out.

 

[stupoty]

I have arbors both with and without the lock pins. The the ones without work ok on smaller holes, but when you start cutting larger holes (probably 2" and up) I've had them strip the threads out of the hole saw because of the increased torque generated. Just food for thought.
Ted

Yeah they can hang up quite badly if the feed is slightly above optimal. The largest I have done is a 6" hole in 3mm sheet for a wood burner flue to go through. Wasn't fun but worked ok.

All the arbors I have are either starrett or bosh brand ones. I've had massive issues with the runout or wander when not using them this way.

I used the dark brown cutting oil.

Stu

 

[AllenV]

I took a close look at the hole-saw. I found that it was not even close to round. This one has a welded seam. At the weld location what ought to be a cylinder has a sort peaked shape with a larger local radius. I went to my drawer where I have 8 or so different hole saws of various size and brand. All the welded-seam style have his same feature. The one I was trying to use is the worst of the bunch as the seam put a tooth right at the widest part. The other type of hole saw I have look to be made in a die press. These are seamless and at least look like circular hole saws .

Seems to me that the proud tooth at the weld seam grabs the metal and pulls outward.

I have decided to abandon hole saws for metal work.

I bought an annular cutter, 1-1/8 x 1 inch, and a Weldon to R8 shank. Both from Accusize.
I did not use a guide pin.

This did a nice job but care IS required. Ran at 200 RPM with lots of Relion fluid. Just enough pressure on the quill to make long curly chip. The moment I felt some chatter, stopped to clear out swarf and flood the circular groove with fluid. Carry on cutting. About three repeats to break thru the 1/4 inch steel. Didn't even take 1 minute to cut a hole.

I measured the ID of one of the holes with a telescoping gauge at 1.128”

Thank you all the suggestions and advice. This helped a great deal.

Photos

 

[Firstram]

Annular cutters don't like chips under the teeth. Once the teeth are started, give firm pressure for a few seconds and a slight pause will break the chips, rinse and repeat while oiling continuously.

Hougen's website gives feed and speed charts that are crazy fast. 1 1/4 at 300 rpm x .001/tooth x 6 teeth= 1.8"/ min, that's 8 seconds to drill through 1/4 steel plate! I hate replacing the broken ones so I go slower than recommended but, going too slow does dull them.