Forstner bit facing wavy?

[Dixie_piper]

I'm currently still limited to only my drill press, and using prefab stems. I've tinkered with this press to spin it true yeat again, the "wobble" is down into the .001 of an inch range, drilling nice tight mortises.
Problem being, when I attempt to face a stem. I get everthing lined up, locked down, double checked and... still getting shoddy results. The stem face looks to be "wobbly," as in a dip on 2 sides. My bits aren't "precision ground," but this is effin pathetic! Do y'all prefer a certain style forstner? These are plain jane, 2 straight cutting edges, but work great on briar w/ patience
I'm using some JH Lowe rubber bits for these first trial runs because I'd rather kill a cheapo stem over a good one. Is this the fruit of a rubber stem? Or could I just have bad bits?
Secondly, drilling a rubber stem; speed? I've used from 250RPM - 700RPM, and the bit still catches, which F.U.B.A.R.s my mortise.
Any advice? This is all that's holding me up on completing my first fire wood pipe and I'm stumped.

[KurtHuhn]

From the description. it sounds like maybe the wobble is coming from worn spindle bearings on your drill press. Even a cheap forstner should make a flat surface, and you'll just have to clean up grooves.

For the airway, you have to go slowly with molded stems, and clear the flutes of the bit often. Otherwise the heat and pressure will build up and cause the bit to catch. When I use a molded stem, I prefer to drill by hand with a tapered bit. the bit will follow the existing airway, and it's easy to clear the flutes. Just chuck the bit in your lathe or drill press and advance the stem onto it. Don't try to drill it all in one shot. At a minimum the tenon will end up FUBAR, but you also run the risk of cracking the stem body as well.

[kkendall]

Silly question... do you face the shank with the forstner before you drill the mortise - or after you drill the mortise? It makes a difference!

[Sasquatch]

It sounds to me like the briar end is okay, but that the problem is in facing a stem prior to inserting a delrin tenon?

If the question is really "how do I face a rubber stem" I would first ask how well clamped (how near to the business) you have it. If it's moving around under the forstner that would cause all kinds of grief.

[Dixie_piper]

I face before the mortise, or at least attpempt to. I think the clamping or the spindle bearings are gonna be the culprit.
I'm working on new soft wood jaws slightly tapered grooves. I realized after posting, that with just a V groove, the tapered stems are only making contact in one small spot.
Also gonna try some with a half circle, one 1/2 way through the top slightly larger than the one on bottom.
If it is spindle bearings, I know a machinist who MAY be able to fix that for a reasonable fee.
Thanks guys!

[Grammaton]

I face before the mortise, or at least attpempt to. I think the clamping or the spindle bearings are gonna be the culprit.
I'm working on new soft wood jaws slightly tapered grooves. I realized after posting, that with just a V groove, the tapered stems are only making contact in one small spot.
Also gonna try some with a half circle, one 1/2 way through the top slightly larger than the one on bottom.
If it is spindle bearings, I know a machinist who MAY be able to fix that for a reasonable fee.
Thanks guys!

I'm still not sure what you're trying to say, but it's almost always loose stock rather than worn bearings.

You need to clamp things down securely.

[RadDavis]

I'm still not sure what you're trying to say, but it's almost always loose stock rather than worn bearings.

You need to clamp things down securely.

Very true. I once turned an oval stem on my lathe. I thought, "How the hell did I do that!?"

Rad

[Dixie_piper]

It's the clamping. I tried facing a saw cut dowel rod today with decent results.
I've got the press bolted to a steel table with grade 8 bolts and rubber bushings, and the drill press vise in place with bolts and lock washers. I tried mounting another stem in the vise today, and realized it was impossible to mount it 100% securely with the current wood jaws I have on there.
Where I messed up is too little contact with the taper stem and straight jaws. Kind of a "da-huh" moment
Thanks again fellars!