Thread: Threading spadebit

If I understand you correctly, you wish to use the spade bit as a two-spur drive centre, with the shaft threaded to engage the drive wheel. It might be simpler to keep the all-thread, and use a coupler nut with one end ground to fashion two or more spurs to pierce the wood. Use another coupler nut, or a regular or jam nut, to lock the modified coupler nut onto the all-thread. The down side of this is finding a bit to match the coupler nut OD for drilling the workpiece; the corners of the coupler nut could be ground slightly to suit an available bit size. If the hole in the workpiece is shallow enough, it won't matter which style of nut is used to lock the spur-modified one.

In your original proposal, the chisel end of the spade bit would need modification to function properly anyway, and threading the shaft would be tedious.

Cheers,
Joe

Originally Posted by SHIPPERS

My Q is can i thread a spadebit. ?
Do i need to temper the steel first?

You might be better off softening it as far as it will go. Heat it to cherry red and let it cool off by itself. For what you are doing I wouldn't even bother to reharden it.

Bob and Joe thanks for your replies.
I think I will give your idea a go Bob.
If my idea doesnt work then what the hell. Its only time

Couldn't you just grind the business end of a bolt to a sharp point, and either glue a nut into the frame or use a t-nut? So it works something like the tailstock on a lathe?

Or are you working on the other end, which'd need to spin with the wood for indexing?

(I'm just confused... )

Skew,

Its the indexing end.
The other end i have already done as you advised.
I just thiught the spadebit rejig would be an easy option

Ah. Gotcha.

I don't know about how it'd work on your jig, but I've found that a 2-prong drive tends to slip a lot on a lathe, especially if the end is not dead square. Which can be a problem when indexing. A forstner or saw-tooth bit would be better, but they'd be just as hard to tap (without tempering) as a spadebit.

Perhaps a small flange/faceplate would be easier to make? Maybe a 1 to 1 1/2" dia. x 1/4"(ish) metal disk, drilled/tapped in the middle to fit a length of all-thread, with smaller holes drilled around the flange?

Then you could either screw through the faceplate for a "solid" fixing, or use small nut 'n bolts in the faceplate - with pointed ends, like the tail-spur - to give multiple "prongs." (I'm pretty sure uses similar "faceplate converted to spur drive" jobs when turning some of his bigger trees. )

Hmmm... I wonder whether an 18mm thick ply disk would work as well?

Andy's (Skew) T-nut, with a lock nut, would be superior to my first suggestion, but a DIY faceplate could be better than either. On a smaller scale, I've used wood screws in a plywood disk to purchase something or other. With a T-nut and lock nut holding the disk to the all-thread, use two or more wood screws to hold the workpiece. Let the all-thread project into a pre-bored hole in the workpiece for initial alignment, and then drive the screws. End grain isn't perfect for strength of nails or screws, but should be adequate for the task at hand.

All that tempering and threading seems a PITA.

Cheers,
Joe - temporarily on the road to Canuckistan