Shaping spars, etc. with an electric drill

AVS 03-02-08 Shaping spars 1 (Small).jpg

This is the text of a post I made in the LSS forum while building my AVS.

CONSIDER THIS A "POOR MAN'S LATHE" Smile

Working on the spars, gaff and boom, I came up with a method of tapering that works for me and may be of some use to others. I have had a good deal of success with tapering masts on my drill press by supporting the free end in a hole drilled in a piece of scrap 2 x 4 clamped to the drill press table. This is impractical for doing the spars, etc. due to the fact that both ends must be tapered plus the fact that they are such slender dowels to begin with. I was considering how to do them and one of the problems I have read about and have experienced first hand is that it is very easy to turn a round dowel into an oval dowel when shaping by hand. So one solution is to spin the dowel. I decided that I could spin the small dowels in my 3/8" drill but needed a method to keep from crushing the end that is clamped in the chuck. The answer was right before my eyes. I merely placed a 1" piece of silicone tubing over the end of the dowel and chucked that in the drill. The tubing keeps the dowel from being crushed and also provides an excellent grip on the wood. Then it is simply a matter of folding some sandpaper over the dowel and pulling the trigger.

This silicone tubing is available at most any hobby shop that deals in model airplane engines. It is sold, generally by the foot, as fuel tubing and comes in small, medium and large sizes. I used the large, which has an i.d. of about 1/8". You do NOT have to crunch the chuck down tightly on the tubing/dowel like you would on a drill bit. It is still possible to smash the dowel by doing so. I'd recommend getting some dowel from the local Big Box or lumber or hardware store and doing some experimenting to get a feel for the technique before you attack the kit wood. The added advantage of the tubing is that it provides a sort of crude universal joint, so that if you get slightly off center while sanding, the tubing distorts rather than the dowel breaking.

I used 100 grit sandpaper for the gross shaping. Use moderate speed on the drill (assuming yours is variable speed). If you get going too fast, you'll know it 'cause the sandpaper will get real hot under your fingers. (Remember the Boy Scouts and starting a fire by rubbing 2 sticks together? Same thing...only I personally was never able to start a fire that way!) Once I get down to within a millimeter or so of the final size, I switch to 150 grit and then finish with 220 grit.

I determined the middle point of the dowel (lengthwise) and marked it with a pencil before starting so that I knew where to not sand. After that it is simply a matter of concentrating more towards the ends and less towards the center to achieve a nice parabolic taper.

Using this method I was able to taper each end of the spars, etc. in about 10-15 minutes/end. The nice part is that you wind up with a nice smooth finish and perfectly round spars. The flats for the jaws and the little shoulders on the ends of the topmast and the boom still have to be formed with good ol' carving and hand sanding. I also recommend a final hand sanding using 220 grit lengthwise with the grain on any of the spars that you turn with a drill to eliminate the little sanding scratches around the circumference of the spar.

Posted: Tue Mar 04, 2008 5:55 am • Post subject:

Silicone Tubing = Brilliant! Very Happy

Posted: Tue Mar 04, 2008 6:05 am • Post subject:

Nice one! I've added this tip to the links section in Masts and Yards in the MSD.

If there have been any other tips that folks have found useful, make sure you let us know so we can add the links to the MSD.

Rich

Posted: Tue Mar 04, 2008 6:18 am • Post subject:

I've always rounded and tapered my spars by hand and, you're right, it's very easy to end up with a nice ovel mast!! Mad

This looks like a great idea - I'll have to give it a try.

John

Posted: Thu Mar 06, 2008 5:58 pm • Post subject:

I've used this method in the past but the tubing idea is brilliant! I was leaving marks on my masts that had to be sanded out.

Ed

Posted: Mon Apr 21, 2008 5:13 am • Post subject: Mini Lathe

Hi Folk

This is a simple and cheap lathe that I have used for the making of masts
spars and other deck fittings.
It consists of a drill press extended by a length of aluminium
tube. I have used an old drill that has fwd, and reverse as well as speed variation. The end opposite the chuck is adjustable for all lengths and
the base plate takes several sizes of collars to handle diameter sizes.

I employ the usual methods of shaping with files and sandpaper glued to various timber shapes.

The cost was minimal at $20 for the stand plus some parts of another stand. I have purchased the Dremel saw with the hood and will have a go at converting this gadget to a drop down saw.

Posted: Thu Jan 22, 2009 4:14 am • Post subject:

Excellent - thanks!

Posted: Mon Jan 26, 2009 10:27 pm • Post subject:

Les,
I used to use 4-5 rounds of masking tape for the same purpose but the polyethylen tube is a much better idea. I had some marks from the chuck jaws sometimes while using the masking tape.
Janos