Tapered drill bits - diameter

Karol · Post by **Karol** » Sun Sep 17, 2006 10:27 pm

Hi there, I'm about to purchase some tapered drill bits so I searched in the forum where I found a recommendations around 5/32" - 9/64".

Now, I'm not an expert in these things and I would like to know what is the diameter on the both ends. I asked guys behind the website is selling them but they replied that the number is matching screws that fit into the hole predrilled by these bits. Well, that didn't help... Is the 5/32" diameter of the tip or the butt of the drill bit?

Do you guys mind, if you happen to have such drill bits, to measure the diameters and post them here? Preferably metric but converting imperial is just as easy. Thanks in advance!

Karol

RadDavis · Post by **RadDavis** » Sun Sep 17, 2006 10:40 pm

Hi Karol,

My bit is 1/16" at the pointy end. At the butt it is 5/32".

Hope this helps.

Rad

Karol · Post by **Karol** » Sun Sep 17, 2006 10:46 pm

RadDavis wrote:Hi Karol,

My bit is 1/16" at the pointy end. At the butt it is 5/32".

Hope this helps.

Rad

Rad, that's exactly what I was after, thanks a lot and I really appreciate prompt answer!

That's from (5/32) inch = 3.96875 millimeters to (1/16) inch = 1.5875 millimeters in case someone (like me

) can't do imperial.

Karol

RadDavis · Post by **RadDavis** » Sun Sep 17, 2006 11:27 pm

I'm happy to help, Karol.

rad

ckr · Post by **ckr** » Mon Sep 18, 2006 3:00 am

Rad

I have also thought of picking up some tapered bits. Could I bother you to also measure the taper? How long is it from the point that it deverges from 5/32 to the little pointy end?

My concern is the airflow being restricted before the last inch where the slot begins to widen the hole allowing the same volume of air to pass through.

If the taper is over an inch, is there anything you do to compensate, like adjust the angle of the slot to penatrate further into the stem to form a deeper slot?

Nick · Post by **Nick** » Mon Sep 18, 2006 8:49 am

If i remember correctly, I was just messing with mine lastnight, the taper takes place over a distance greater than an inch. But it would probably depend on the maker of the bit. I'd be interested in seeing any formulae you've worked up for the flow pattern. Its always been an interest of mine.

Post by **KurtHuhn** » Mon Sep 18, 2006 9:20 am

Mind you, it's been about a month since I've seen my tapered bits (moving sucks) but I seem to recall that the taper takes place over about 1.5 to 2 inches. It's a very gradual taper with no obvious shoulders. This is acually idea for pipe stems because that results in far less turbulence in the airway.

What I do is drill the first half inch or so with a regular jobber-length bit, then drill using the taper bit. That first half inch will support the taper bit, since the tips of these things are very flexible. Then bring it to within a half inch of the end of the stem - that way you'll leave enough material for cutting the slot, shaping the button, etc. After the stem is mostly shaped, you can go back and drill sightly further with your tapered bit if necessary, but you will probably find that you don't need to as long as your slot is cut right.

RadDavis · Post by **RadDavis** » Mon Sep 18, 2006 10:09 am

What Kurt said.

The idea is to widen the button end side to side so it looks like a flattened funnel. I don't use a formula, I just widen it until I can feel no resisitance at all when I take a puff through it.

Rad

ckr · Post by **ckr** » Mon Sep 18, 2006 7:30 pm

Karol,
I appoligize if I am hi-jacking your thread, but it is on topic.

Nick,
No formulas, but I think that converting a 5/32 bit to decimal and dividing it in half and doing the pi X R^2 would produce an area size less than a 1/16 slot extending across the diameter of the hole. Hence, the amount of air able to pass into the slot is less than the amount able to enter the hole.

(Back to the problem)

I had made a stem thingy to guide 2 1/16 openings directly into the 5/32
opening for repeatability and to compensate for alcohol shakes - DT's

.

(Especially for pipe makers that do not have a pair of vise-grips for hands)

After finishing the bit I came to the conclusion that rather than have the 1/16 holes enter directly into the 5/32 opening they should be 1/32 to the left and right of the opening (increasing the amount of air *smoke* that
can enter the slot) which would widen the slot further back. The grey is the current cut and the yellow is where I think it should be.

All seemed pretty good, but when examining my handiwork and seeing the dead space that cant be cleaned and will collect tars lead me to rethinking the tapered bit bit (intential bit here).

The second is what I think the bore of a taper bit would look and am thinking how far in YOU GUYS extend your slot. Kurt is bringing the bit 1/2 inch closer than a straight bit.

BTW-seems like it will draw fine. But, notice the buldging of the lines of the bore, it is caused by heated acrylic expanding and melting off the sides, need to try cutting fluid.

Now, if they taper as Kurt mentions, not a first hand observation - but based on memory

, the taper is well over an inch and maybe up to 2. If the taper is straigt from 5/32's then I would assume that 1/2 the way down the taper the diameter would be 5/64.

Duh - 2 conclusions :dunno:
a) With a tapered bit the slot must reach back further?
b) 5/32 in not necessary to get a full open draw?

Also noted, to work with a transparent acrylic is very instructive, a foward
motion with pressure to the left causes the tip to remove from the right a
flat left/right movement melts not cuts. Of course it could be my bits but I would recommend for any newbe to drill transparent acrylic and make their own observations.

My hat off to those that can do this effortlessly and anyone who thinks this craft is a cake walk can ..., CUZ it is anything but.

Karol · Post by **Karol** » Mon Sep 18, 2006 7:39 pm

ckr wrote:Karol, I appoligize if I am hi-jacking your thread, but it is on topic.

Oh, the opposite! Anything on this subject has a potential to help me and others to climb up the learning curve faster so it's all good and I'm glad the discussion took off in this direction.

Karol

Post by **KurtHuhn** » Mon Sep 18, 2006 7:52 pm

Duh - 2 conclusions :dunno:
a) With a tapered bit the slot must reach back further?
b) 5/32 in not necessary to get a full open draw?

a) not necessarily. In fact, you can bring the tip of the drill bit right to the end of the button if you so wish. Sometimes you can do this, sometimes not, depending on the shape and thinness of the stem. Since the tip of the bit is very small, it won't make the slot any wider. This all depends, of course, on what size of tapered drill bit you use, and what size you cut your slot - which leads us to....

b) Depending on the pipe, a perfectly good draw can be accomplished with 9/64" or even 1/8". Some pipes, however, may require a 3/16" airway diameter. The longer the stem, the more open the airway may need to be.

ckr · Post by **ckr** » Mon Sep 18, 2006 8:42 pm

Kurt,

b) Depending on the pipe, a perfectly good draw can be accomplished with 9/64" or even 1/8". Some pipes, however, may require a 3/16" airway diameter. The longer the stem, the more open the airway may need to be.

Am I leaving the chamber shape and size out of my suspositions? i.e a smaller chamber requires less vacume to draw the smoke inwards?

How does the length of the stem effect the volume of air passing trhough the airway?

Post by **KurtHuhn** » Mon Sep 18, 2006 10:17 pm

ckr wrote: Am I leaving the chamber shape and size out of my suspositions? i.e a smaller chamber requires less vacume to draw the smoke inwards?

How does the length of the stem effect the volume of air passing trhough the airway?

I have found that a bent pipe benefits from a larger diameter, as do pipes with very long stems - like churchwardens. Especially in the case of churchwardens, you run into what's called "flow resistance". I'm sure Nick or one of these other guys could give you a good formula for it, but I tend to wing it and increase the airway on some of those really long pipes to 3/16" to overcome the problem.

FWIW, the solution occured to me when I was setting up kegs for the first time. In that case flow resistance is a real problem, and you have to balance length with pressure and diamter of hose. I figured that I could come up with a churchwarden that smoked as smoothly and readily as a straight billiard.

Nick · Post by **Nick** » Tue Sep 19, 2006 9:13 am

You're absolutly right Kurt. The longer the pipe, stem and shank, the more resistance is generated by the walls of the channel. In short flows this resistance is nominal, but as the length increases, the resistance and turbulence generated increases exponentially. A wide bore ameliorates this effect because with a larger area for the flow to pass through, give a constant draw rate, the velocity of the flow slows down. That is to say, if you're sipping at a rate of X in two pipe, one with a narrow draft hole and one with a wide draft hole, the velocity of the smoke in the narrow will be much higher than in the wide. And because of the change in velocity, along with a change in pressure, the flow will be less turbulent in the wide bore than in the narrow bore.

Too fun!

What would really be fascinating would be to run the numbers that actually took into consideration the changes in shape of the draft hole. As well as the bowl. Its possible with some flow simulation frograms, but their damn expensive. Still, it'd be totally wicked. That, and I'm just a dork. But hey, I'm OK with my dorkiness.

ckr · Post by **ckr** » Tue Sep 19, 2006 2:34 pm

Nick,

I can appreciate dorkiness, it even applies to me at times, a very understandable explanation - thanks.
As for the taper bits bit, I figure I may as well take a trip over the bridge and get me some from JD. I'll try Kurt's 1/2 inch back method with my Stem Thingy method and then Rad's puff and widen method see if I can get it all together so it works for me. At least it will tidy up the area where the funnel meets the airway.

Thanks all for your inputs it has helped, at least if I run into the problem I'll understand a little about what is causing it. I had thought it was just something simple like restriction between the airway and funnel. Hopefully, I will soon be doing more puffing than experimentation.

Kurt, it is funny how many problems in day to day life relate to pipe making and visa virca. "Flow resistance" same thing causes voltage drop to those electrons on a 200 foot run but I never would have thunk it on a pipe stem.

Post by **KurtHuhn** » Tue Sep 19, 2006 9:49 pm

ckr wrote: As for the taper bits bit, I figure I may as well take a trip over the bridge and get me some from JD. I'll try Kurt's 1/2 inch back method with my Stem Thingy method and then Rad's puff and widen method see if I can get it all together so it works for me. At least it will tidy up the area where the funnel meets the airway.

Also known as the "puff and listen for a whistle" method. Sometimes you need to blow through the tenon end and listen.

Hey, if you do venture off your island, let me know and we can meet at JD and drool over tools.

Kurt, it is funny how many problems in day to day life relate to pipe making and visa virca. "Flow resistance" same thing causes voltage drop to those electrons on a 200 foot run but I never would have thunk it on a pipe stem.

Considering I just dropped a 160 foot run of 6-3 cable to the new workshop, I can totally relate. To power the joint I only needed about 20 Amps sustained, but the generator is also out there, and I may need to pull as much as 40 Amps from that when (yes, when) we lose power this winter - so my plan of using inexpensive 10-3 cable was out. Onfortunately, that also meant that I needed to run conduit underground since I wasn't goin to pay for 6-3 UF cable when regular 6-3 was already ongodly expensive. *looks at Lowes bill, cringes in pain*

ckr · Post by **ckr** » Wed Sep 20, 2006 7:32 am

Hey, if you do venture off your island, let me know and we can meet at JD and drool over tools.

Hey dude, I resent that implication! I'll have you know I have been off the island over eight times in the past 20 years! Regardless, I'll be hitching up Bess to the wagon and expect to be there about 11 this Saturday.

w/pipe in pocket

Karol · Post by **Karol** » Thu Sep 21, 2006 4:02 am

LOL, great avatar!

ckr · Post by **ckr** » Thu Sep 21, 2006 4:08 am

8O 8O So basically, I just need to figure... 8O 8O

Well why didn't you guys just say so instead of all this beating around the bush.

Which means that the air closer to the walls encounters more friction and travels slower while the air flow towards the center encounters less resistance and it's velocity increases. So the center channel of the airway delivers the greater volume of air to the slot. :dunno: I guess??

For others that are trying to get a grip on these issues ...
http://hyperphysics.phy-astr.gsu.edu/hbase/pfric.html
... pretty much explains what is going on.

Too Fun

ckr · Post by **ckr** » Thu Sep 21, 2006 4:24 am

Karol wrote:LOL, great avatar!

Smokes like a champ too!