Spade Bit Grinding

[staffwalker]

Hi, question about spade bits, I have ground several spade bits to a rounded shape at the bottom. On all of these they have preformed flawlessly. They cut clean and smoothly and very fast. On the other hand I have yet to do a tapered/vee shape with any success. All of them start the chamber ok for about the first 1/2 of the bit. As soon as they pass the 1/2 mark and the bit reaches its widest point they begin to flutter. This fluttering, of course, makes groves in the walls of the chamber. I've tried cutting part of the bit shank off to shorten it, no luck. I've tried using a foester bit to cut the first 1/2 inch and finish with the tapered spade. It still flutters.

Does anyone have a special trick when shaping the sides of the bit to prevent this?

bob gilbert

[kbadkar]

It sounds like your taper point is slightly off center. I start out rough shaping on the bench grinder, removing excess material. Then, I know this sounds scary, but try spinning the bit on the lathe or drill and do the secondary shaping with an angle grinder, carefully! Then start your cutting edges by hand with a file and finish on a buffing wheel. Maybe someone has a better method...

[staffwalker]

I think you have it right, I never had thought what having the point slightly off center would do, duh. I'll try another one spinning and see. Thanks'

bob gilbert

[pierredekat]

Yeah, I do it more or less the same way: chuck up the bit in a hand drill, spin it in reverse, and hold the bit up to a bench grinder. (Wear your safety glasses.)

I found that you have to spin the bits in reverse during this process because the leading edge gets rounded, while the trailing edge winds up much sharper.

Along the lines of what kbadkar was saying, it helps if you start with a bit sized at least 1/16 inch bigger than what you need to allow for the fact that the spade bits come tapered the exact opposite of what your trying to accomplish.

Oh yeah, when you're at the hardware store, buy an extra one just in case.

[ArtGuy]

I have a 3/8" standard drill bit that was ground to a chamberesque profile the same whay pierredekat describes. I use it when drilling freehand after shaping. I don't see why someone could not modify a silver and deming drill bit the same way. It might be easier than a spade bit as there would be less material to remove.

[kbadkar]

Hmph, I haven't tried a S&D bit. I guess I figured it would be hard to get a good sharp "spiraling" edge on it. I suppose it's possible with a little patience and file skills. That's why I thunk paddle bits were easier to grind down. You can shape first with a S&D bit? I hadn't thunk of that either, duh... How does it perform with the SF/DS method compared to a spoon bit? I might have to try a 7/8", since Brad's hooking me up with the "regular" spoon set.

[ArtGuy]

No, you need to have spoon bits to drill after shaping. The 3/8" bit I refer to is used after drilling a 4mm pilot for the chamber to open it up a little more prior to using the spoon.

I was simply puttng forth the idea that one could modify a silver and deming bit with a drill and grinder rather than having to use an angle grinder and lathe. The angle grinder just seems way friggin dangerous to me.

[ScoJo]

Why is it that you need to have spoon bits to drill after shaping? Is that that a typical S&D bit would have too much tendency to pull on the stummel when you are drilling? I guess I never really understood this.

[kbadkar]

Using the angle grinder is not that scary, but I'm plenty comfortable with an angle grinder (did my time welding), very respectful, but comfortable. Though next time I'll try the drill on the bench grinder to see which "feels" better.

[KurtHuhn]

I have a 3/8" standard drill bit that was ground to a chamberesque profile the same whay pierredekat describes. I use it when drilling freehand after shaping. I don't see why someone could not modify a silver and deming drill bit the same way. It might be easier than a spade bit as there would be less material to remove.

I've done this on all my tobacco chamber bits. I chuck the S&D bit in the lathe, spin it at about 1800RPM, and use my angle grinder to profile the bit. Works great. Then I grab the dremel with a sanding cylinder on it to relieve the area behind the cutting edge just slightly. So far every bit has come out perfect. I don't even bother with spade bits any more.

Of course, doing this is not without inherent risk, so I don't actually suggest someone *else* do it.

[ArtGuy]

Why is it that you need to have spoon bits to drill after shaping? Is that that a typical S&D bit would have too much tendency to pull on the stummel when you are drilling? I guess I never really understood this.

Well after seeing those crazy pics of that guy holding a stummel with one hand, operating a drill press with the other, all the while using a spade bit... I suppose anything is possible. However, every carver I know who shapes prior to drilling uses a spoon bit to carve the final profile of the chamber. I just don't want anyone to misunderstand my post and hurt themselves

[ArtGuy]

I have a 3/8" standard drill bit that was ground to a chamberesque profile the same whay pierredekat describes. I use it when drilling freehand after shaping. I don't see why someone could not modify a silver and deming drill bit the same way. It might be easier than a spade bit as there would be less material to remove.

I've done this on all my tobacco chamber bits. I chuck the S&D bit in the lathe, spin it at about 1800RPM, and use my angle grinder to profile the bit. Works great. Then I grab the dremel with a sanding cylinder on it to relieve the area behind the cutting edge just slightly. So far every bit has come out perfect. I don't even bother with spade bits any more.

Of course, doing this is not without inherent risk, so I don't actually suggest someone *else* do it.

I just imagine the angle grinder getting crooked, hitting the flat part of the spade, leaping twards me and cutting a huge gash in my chest before I have a chance to react. However, then again I have never used an angle grinder.

[KurtHuhn]

I just imagine the angle grinder getting crooked, hitting the flat part of the spade, leaping twards me and cutting a huge gash in my chest before I have a chance to react. However, then again I have never used an angle grinder.

Oh, trust me, there is *no* way I would attempt this with a spade bit. There simply isn't enough grindable surface area to make it safe.

[ScoJo]

I've done this on all my tobacco chamber bits. I chuck the S&D bit in the lathe, spin it at about 1800RPM, and use my angle grinder to profile the bit. Works great. Then I grab the dremel with a sanding cylinder on it to relieve the area behind the cutting edge just slightly. So far every bit has come out perfect. I don't even bother with spade bits any more.

Of course, doing this is not without inherent risk, so I don't actually suggest someone *else* do it.

I would love to learn how to do this. Unfortunately, I also have this aversion to going through the remainder of my life with less than 10 fingers. Any chance you would be willing to post a video of this process?

[bscofield]

I have a 3/8" standard drill bit that was ground to a chamberesque profile the same whay pierredekat describes. I use it when drilling freehand after shaping. I don't see why someone could not modify a silver and deming drill bit the same way. It might be easier than a spade bit as there would be less material to remove.

Awww... son of a bitch! I just drilled 9 holes in my hand trying this!!

[kbadkar]

For angle grinding a paddle : do initial grinding on bench grinder, only fine tune with angle grinder, full lathe RPM, proper grip and body positioning, no angle grinder guard to obstruct view (someone just moaned!), never set trigger lock, fully perpendicular angle of wheel to ground, remove a tiny little bit at a time, respect the tool. Of course, it seems simple and safe enough to me, but I know people who won't use a table saw because getting their hands near a blade freaks them out. (Yes, of course I use a push stick on skinny rips too.) I don't suggest anyone just play around with an angle grinder in this manner, nor do I suggest that someone play around with any tool if they don't have years of power tool usage (initially under supervision) and proper safety principles under their belt. And some people just weren't meant to plug in a power tool at all. Then I see an old Barry Jones shaping on a table saw with all 10 fingers! Yeah, and that big German guy freehanding with a spade bit. On the other hand, I read about the guy who died using a angle grinder or Rad skewers or heads and hands yanked into drive belts and shafts or blades because of loose clothing or hair. And in regards to ScoJo's question, that's why I haven't tried using the S&D bit for freehanding... I'm just afraid it will snag and spin the stummel wildly. Everyone draws their own line, and that one didn't seem safe to me. It comes down to what you are comfortable with and the scars to prove it.

[KurtHuhn]

I would love to learn how to do this. Unfortunately, I also have this aversion to going through the remainder of my life with less than 10 fingers. Any chance you would be willing to post a video of this process?

I will be working in the shop all weekend, so I'll try to find a moment to film something. I also have promised shaping a stem, from start to finish. I'll try to get them all squared away this weekend.

[Nick]

One time, while I was working in the mail room, I got my tie stuck in an envelope opening machine. YEOWCH! Jerked me across the room. I came to work wearing a bow tie, and have done so ever since.