Arbors

I was wandering if someone could point me in the right direction. If it isn't obvious I'm new to machining in general. I have a Nichols horizontal mill that I want to uses as a tube notcher, but I'm not exactly sure what parts I need to hold the hole saw. If you check out the link you will see exactly what I want to do. http://antbikemike.com/images/Building/step3big.jpg

Thanks Larry

Larry, that pic link looks to be a NMTB40 or Cat 40 or BT40 (all very similar) endmill holder which is coincidentally holding the holesaw arbor.

I would shoot for a 3/8" dia round arbor if possible. I think there is a heavy-hex arbor common, but it will be more difficult to adapt.

That part in hand, look for an appropriate endmill holder that has the right ID.

Usually it will have setscrew(s) for retaining the endmill, you can file a small flat on the round arbor to help provide a better seat for the setscrew.

Other Nichols owners can probably point you exactly in the right direction (knowing the spindle taper, etc).

Larry:

I tend to agree with Matt but I think I'd look at making that arbor 5/8" dia minimum, 3/4" would be better. Except for the smaller sizes most hole saws have a 5/8" X 18 threaded hole. Just turn and thread one end to fit the hole saw and file or mill a flat for the set screw and your ready to go.
Another option might be to obtain a hole saw arbor. The heavy duty ones are usually 7/16" or 1/2" hex. If you measure across the corners you might find an end mill adaptor close to that so the arbor will slide in or with a little filing or turning can be made to fit. Then again, lock the set screw against one of the hex flats.
TS

A related question, sort of. If you use a hole saw arbor, the pin drive type, do you like to run the saw hard up against the arbor or do you let it float and let the pins drive it? Does this change depending on how rigid the setup is, like drill press vs vertical mill? I've done it both ways and sometimes one cuts better than the other, but not always as expected.

Jimbo

Nichols use a 40nmtb taper.

As for the hole saw. Allow it to float on the pin. THey get REALLY tight if you just screw them down. Although they seem to work better screwed tight. Is a good hole saw arbor available from msc industrial or enco ( do a google search for them)
with a round shank? Then hold it on a endmill holder with the hole that matches the shank and you should be ready to go.

Also if you can afford it a rotobroach may work.

PS is that your nichols? From what I can see it looks beautiful.

Jimbo:

Use the pins. I found out the hard way what can happen if you screw it tight to the arbor. The threads can strip in the saw and they are a pain to get off when that happens.
TS

Larry, I love your bikes. Your designs just strike me. Good for you, man.

Seems to me that because the cutting forces are not balanced using the hole saw that way, it should be tight on the arbor somehow. I haven't had the experience of one over-tightening, but I can sure see it being a pain. I would want to have it snugged up securely on the threads, then pinned so it can't tighten more. Probably not a lot of meat to work with on any standard holesaw arbor to accomodate your own pin drilled to suit, though.

I would be making my own arbor for the holesaw, with a backing flange large enough to turn a recess into for the holesaw to light press fit into. Then drill and tap a central hole for a bolt, which will be able to hold the saw into the recess with a made-to-order washer. I would still use a pin to prevent the saw from spinning, and that will prevent the bolt from becoming over-tightened as well. The pin could be press fit into the flange, or it could be part of the homemade washer, and fitting through the saw and into a hole in the flange. You wouldn't need to use the threaded mounting hole in the saw at all.

At least this gives you a rigid setup, and some support to keep the saw concentric. For any size of holesaw that's longer than it's diameter, you can afford to have some of that length buried in a recess in the backing flange. For wider holesaws, where the length of it has to go partway through the tubing in order to complete a cut, you wouldn't be able to use the recess idea. But in that case, the flange could also be wider and would give some room for you to drill and tap for more than one socket head bolt. I would still use a homemade washer sized to suit to sandwich the holesaw to the flange, for best rigidity of the setup.

Thanks for the advice guys. Alot of what your talking about is over my head so I will have to do some research.

And Gregg K, I wish I could claim the bikes. But I can't. The owner of this company was once part owner in one of todays nicest custom frame builders.