More On Tobacco Chamber Bits

[Frank]

For those of you who prefer a spiral type bit as opposed to my previous suggestion of using router bits, these ball nose end mill bits should also work & won't cost you 100 bucks a pop:
http://www.use-enco.com/CGI/INSRIT?PART ... XNO=947313
or if you prefer cobalt:
http://www.use-enco.com/CGI/INSRIT?PART ... XNO=947844
Drat, I just realized I could have offered them here for $50 each and made a small profit (just joking, I'm always on the lookout for less expensive accessories to aid us all).

I finally received my 4 jaw independant chuck for my lathe. Next week I will be popping into a couple of commercial/industrial machine shops to price the cost of having two of the opposing jaws accurately drilled & tapped for a sharpened machine screw. No need for an explanation, you guys already know what that's for.
The point being, if any of you guys are interested, while I am there, I will price the cost of having a 3/4" Silver & Deming bit ground to a rounded end taper. Hopefully it will cost less than $100 each. What I require are the X & Y dimesions as illustrated here:
.
X=length of taper; Y=angle of taper.
If someone could post these measurements for a 3/4", 7/8" and 1" bit, or a close approximation, that would be a great help, thanks.
If my sketch is incorrect, please feel free to revise it and post the correct profile shape.
I'm guessing that the larger the order, the less the per bit would cost, so if it is feasable, I could get a batch made for all at one time for whoever is interested. Let me know what you think.
I'll post my findings back here.

[LexKY_Pipe]

Let us know how it all turns out.

[JHowell]

I finally received my 4 jaw independant chuck for my lathe. Next week I will be popping into a couple of commercial/industrial machine shops to price the cost of having two of the opposing jaws accurately drilled & tapped for a sharpened machine screw. No need for an explanation, you guys already know what that's for.
The point being, if any of you guys are interested, while I am there, I will price the cost of having a 3/4" Silver & Deming bit ground to a rounded end taper. Hopefully it will cost less than $100 each. What I require are the
I'm guessing that the larger the order, the less the per bit would cost, so if it is feasable, I could get a batch made for all at one time for whoever is interested. Let me know what you think.
I'll post my findings back here.

Commercial/industrial shops will be the most expensive place to have small jobs done. If you have a drill press and the chuck jaws aren't hardened, you can do it yourself. Taps are cheap. Or, try to find a local hobbyist/retiree. I know a retired Westinghouse engineer who helps me with machining problems. He's a treasure trove of setup tricks and fundamental machining principles. You could pay a bundle and have your job done in a 4-axis Haas CNC mill, but doing it yourself could be much more valuable in the long run.

[RadDavis]

Good point, Jack!

I ground my silver & demming bits to the profile I wanted on my bench grinder.

I think it was Kurt, or maybe you, Jack (or maybe both?) who ground theirs on the lathe with an angle grinder as the bit was spinning.

You can easily over engineer this stuff and spend a lot of money when it isn't necessary.

Rad

[Frank]

Commercial/industrial shops will be the most expensive place to have small jobs done. If you have a drill press and the chuck jaws aren't hardened, you can do it yourself. ......but doing it yourself could be much more valuable in the long run.

@Jack
I have a combo mill/drill/lathe with a fairly decent machinist's vice, so I had considered drilling & tapping the jaws myself. Since my machinist experience is virtually all self taught, there remains the outside chance that I may not accurately drill across dead centre of the jaws, or else fail to align the two screws directly opposite each other, then there's no chance of my undoing the screw up.
Of course I could take the "nothing ventured, nothing gained" approach and just go for it.
I realise that setup is the most important aspect of machining, and I have a couple of ideas on how to accurately mark the jaw centres for drilling, but any 3rd party advice in this respect is always welcome.

[KurtHuhn]

I think it was Kurt, or maybe you, Jack (or maybe both?) who ground theirs on the lathe with an angle grinder as the bit was spinning.

You can easily over engineer this stuff and spend a lot of money when it isn't necessary.

I's rather immpresisve to behold - in a horrifying train wreck sort of way. But, with about 30 minutes worth of elbow grease and $20 in materials, you've got exactly the shape of bit you want.