Very poor large hole result

[stupoty]

When I've used hole saws in the mill I have always found it better to not use the lock pins but alow it to jam hard against the face of the arbor.

This does make them a lot more difficult to get of the arbor but much less "all over the place".

Removing the hole saw from the arbor is normaly in the bench vice with levers and / or pipe wrench.

Stu

 

[talvare]

When I've used hole saws in the mill I have always found it better to not use the lock pins but alow it to jam hard against the face of the arbor.

This does make them a lot more difficult to get of the arbor but much less "all over the place".

Removing the hole saw from the arbor is normaly in the bench vice with levers and / or pipe wrench.

Stu

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

 

[RaisedByWolves]

I can't tell from your picture but did your hole saw have a twist drill to guide it at the center? If yes I really don't have any suggestions beyond getting an annular cutter or boring after the hole is cut.

But, your hole doesn't look right compared to holes I've cut with the same hole saws. Those Lennox hole saws are good in my experience, also did you use any cutting oil?

John

This!

John beat me to it.

Should have been a pilot drill mounted in the center of that hole saw.

And that.

You’re lucky you got away without wrecking that hole saw.

 

[AllenV]

This!





And that.

You’re lucky you got away without wrecking that hole saw.

I did have the pilot drill installed. It is mostly obscured from view in the photo.

 

[GeneT45]

It's been mentioned a couple of times already, but speed kills. When I use a hole saw in the mill, I put it in backgear and just lean (not too aggressively) on the quill lever. It's slow, but it produces a round hole with a much better finish than trying to do it quickly, and your saw (carbide or not) will be none the worse for it. Little heat, and the slow feed really improves the finish. Annular cutters are great, but probably not worth it unless you get a stunning deal, or you're doing production quantities.

GsT

 

[woodchucker]

I haven't read most of the replies. I just got to this thread.
300 seems too fast to me.
Also, take a piece of wood, and cut through with the wood.
Mount the wood to the piece to cut, and use it to keep the saw guided.
Use a vac to clear chips regularly as well as cutting fluid.
Hold steady pressure, and make sure the saw is bottomed out on the flange, don't use the 2 pin method of holding the saw.

 

[Firstram]

Slower speed and a guide block will give better results. Cut a hole in a small piece of 3/4 plywood, with the tubing in the vice locate the ply with the holesaw and clamp it down. This really helps the saw get a good start and can be removed once the teeth are fully embedded.

Woodchucker beat me to it!

 

[AllenV]

Thank you for the plethora of responses. Your collective expertise is very helpful.

My immediate task is to make a number of holes with the current hole saw. Making sure it is tightly assembled, reducing the RPM, chip clearing, lots of cutting fluid. Try guide pins rather than the pilot drill. These are all things you (collective) have mentioned as best practices.

One thing I’ll be looking at is uniform engagement of the teeth. Seems to me that if 1 or a few teeth are proud and first to cut then that might cause the distortion of the thin shell I “think” I observed. I’ll have a look.

Looks like I can put a dozen practice holes in that piece of square tube. Results will influence the next steps.

And, I want to see if I can fit that piece in the 4-jaw and lathe. The 13-inch swing ought to be okay, just not sure if the chuck is big enough. I’ll hold that as a back-up method I had overlooked at first.

 

[AllenV]

I haven't read most of the replies. I just got to this thread.
300 seems too fast to me.
Also, take a piece of wood, and cut through with the wood.
Mount the wood to the piece to cut, and use it to keep the saw guided.
Use a vac to clear chips regularly as well as cutting fluid.
Hold steady pressure, and make sure the saw is bottomed out on the flange, don't use the 2 pin method of holding the saw.

Adding trying a guide block to my list.

 

[D.sebens]

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