Grinding Spade Bits- questions on making templates, etc.

[Kenny]

This is something I've always wondered about, where do you all get the shape and/or templates to grind your spade bits? Do you just come up with a shape that looks good and go with it, or is there something specific I should be shooting for?

My first bit was just rounded on the end, as it was for a poker shape and a conical bit wasn't needed. But now I'm getting into some different shapes (Bulldog) and I'm going to need a conical bit to get the needed wall thickness.

I know some use a computer drawing program to make templates, but you'd still need to know what shape you want to be able to do that.

So I guess what I'm looking for is what the basic I should be shooting for looks like and if what I've come up with will work. Though I'd like to see how what some other bits look like too.

How I've been making my templates is on "Serif DrawPlus", as there is a "badge" template in that program that seems to look like what I would want, so I just went with it. There is a picture of the type of template it makes, though I can stretch them out, make them shorter, wider, basically whatever I want (within reason). Is this OK? Or should I be doing something differently?

[jogilli]

read this

viewtopic.php?f=43&t=5188&hilit=spade+bit

you can email DMI and I'm sure he'd give you the pictures again.. but the text says it all

james

[Kenny]

Thanks, that's basically what I do now. I'd just like to know if my shapes are close to what I'm looking for. From what I can tell from others I've seen in the past, I'm not too far off. But some professional opinions would make me feel a bit better and be more confident.

Thanks again
Kenny

I did PM DMI to ask for the pictures, as that's really what I'm after.

[DMI]

If you add half an inch to the length of the bits in the picture and then redo the curve you'll get a better chamber shape. A short blade with such a sudden cut off could magnify the gouging effects of vibration/judder.

That being said the shape you have gone for is very similar to that in some Ben Wades from the 1870's that I have.

David.

[Sasquatch]

Mine are way rounder than that, fwiw.

[Kenny]

Mine are way rounder than that, fwiw.

If it's not asking too much, I'd love to see a few pictures.

And the picture isn't exactly what I'm using. I just whipped something up to show you the basic shape I'd found. The one conical bit that I've actually ground has a "rounder" point to it, basically being more squat looking at the tip.

As well, I don't make the bit as long as the template is. That's just to give me a point shape. I try to leave as much meat as I can, ie: try not to shorten the paddle up too much. I don't know if this is right, wrong or otherwise, but it seems to work ok. But, I've not made many pipes, so this comes from very little actual experimentation.
I do shorten the shank, and quite a bit too! I try get it as short as I can while still reaching about 1/16" from the bottom of the collet.

As for vibration/chatter, if you look at the picture below, this was fresh off the drill bit, no sanding at all. And the little tear-out you can see at the top was 100% my fault. I thought it was a good idea to start the hole with a forstner bit (maybe 3/8" to 1/2" deep) and then switch to the paddle bit. Wrong! It just gave me a ton of chatter when I initially entered the hole with the paddle bit. I've drilled a couple since without using anything for "pre-boring", and I get excellent results.
(now I said that, I'll get nothing but a chattering mess!)

[RadDavis]

I can't see anything wrong with that drilling.

Rad

[Sasquatch]

LOL yeah that looks okay.

[Sasquatch]

Here is an actual digital representation of the actual bits used in actual Sasquatch pipes. This is major bigtime secret shit so don't tell anyone.







Your chamber looks fine to me. I see very little up-grain tearout which means you got them fairly sharp, and the chamber looks entirely pipe-shaped to my highly trained eye. And yes, the paddles do best without a pilot. Strange but true.

[Sasquatch]

Also it is not mandatory to put painter's tape on 13/16" bits.

[Kenny]

Thanks a ton!

I like how you rounded the tip of your bits, far better than a sharp point. But I can do that when I'm doing my "spinning on the lathe grind" at the end, just before sharpening.

Just as a sort of tip that I've picked up from drilling on the lathe, using collets in the tailstock gives you a much more solid hold on the bit than you get with a drill chuck. You get about 95%+ surface contact with a collet, and less than 50% with a drill chuck. This just adds up to more vibration with a regular chuck, especially when using things like paddle bits.

The collets are pretty cheap too, and easy to use as they fit right in the morse taper (or R8 taper, etc). You can get them for about $10 each, or a set of 7 for $65, and they work very well, as long as you can get a draw-bar through the back side of your tailstock. I got mine from LittleMachineShop.com.

And thanks again for the help, much appreciated!