Yet another linstock design...

[Terry C.]

Rather than hijack Evil Dog's thread, I decided to start a new one.

I was impressed with his linstock made with copper fittings. I decided I needed one of my own. While mine is based on the same concept and materials, I didn't want to copy his exactly.

I wanted to put my own 'spin' on the project:



I used 1/4" copper tubing and bent it instead of using fittings to make the curve. The entrance end has slight 'bell' in the form of an adapter fitting, to aid in feeding the rope through. The other end has a straight coupling added as a reinforcement. The fittings are a harder copper than the tubing.

The centerpiece of this design is the 1/4" x 1/2" adapter that has been sculpted to cradle the tubing. This gives me a solder joint that does not break the lines of the tubing as a tee would. Here you can see the one ready to use, next to the spare I bought in case I messed up:



The pole is a 3/4" diameter poplar dowel 48" long. I would have preferred oak but Lowe's did not have it in the 48" length. The end has been reduced to accept the cap. Once it's stained and finished, I will secure the head. Haven't decided exactly how I want to do this yet, but I have time to think about it.

The design is based on this drawing. When it came time to bend the tubing I could not get it to follow the pattern exactly. I was using the coil spring tubing bender that I have here at home. I had also originally had the bottom end of the tubing flared and no fittings on either end. But getting the good bender and the flaring tool would have meant a trip to the shop on a holiday weekend. Not goin' there! I omitted the flare and went with the soldered fittings instead:



This is just a portion of the original, but it *should* print to scale.

[Cat Whisperer]

Elegant simplicity!

[Terry C.]

Oh, I forgot to mention that the total cost so far has been a whopping $5.91.

The only thing I plan to add is a spike for the end. I have a couple of ideas but I don't know much it will cost yet.

I already have the finishing supplies for the wood.

[Evil Dog]

Very, very nice.

[Terry C.]

Okay, now for a dumb question:

The mailman delivered my rope and my potassium nitrate today. I bought the rope from the magicians site in the stickies.

Unlike the old piece of sash cord I used to test my linstock design, which was stiff and easily slid up though the tube, the new rope is very soft. Too soft. It wants to 'bunch up' and not slide through the tube. I finally resorted to feeding a smaller cord from the other end of the tube and dragging the rope through.

Once inside the tube, it works perfectly, sliding easily in either direction.

Will the rope get stiffer after it is soaked in the nitrate solution?


(I can already hear the jokes :?)

[Evil Dog]

Even the stiffer sash cord will tend to bunch up when trying to force it through 1/4" tubing.... if you rotate the cord while pushing on it though it will generally go through a lot easier.  You may find that nitrating the cotton rope really isn't necessary.  I've been using generic sash cord from the local hardware store.... what looks to be cotton fiber woven over a synthetic center.  When cut in lengths of 6' or less the synthetic core is fairly easy to pull out.  Have found that the cord will burn quite nicely without nitrating... an inch or so in around 15 minutes.  Try a piece of that cord you have without nitrating and see how well it works (or doesn't work).

[Terry C.]

I've got a plain rope on the linstock now, and another piece soaking that I will put out to dry in the morning, so I should be able to do a side-by-side comparison of the two this weekend, weather permitting.

The extended forecast is the same broken record that it's been for most of the last month. Thunderstorms across the board.

Plus, Hurricane Dennis will be coming in close proximity to us probably Sunday night or Monday morning. The current track shows it coming up through Alabama, but if it turns to the east as it moves up toward the Florida panhandle it will give us serious grief.

[Terry C.]

I got a chance to test a couple of pieces of rope today.

I used two sections about 5" long, one plain and the other soaked overnight in a solution of 1 measured tablespoon potassium nitrate per cup of water.

The point of the test was to see how both samples performed on both FFFFg powder and visco fuse.

In the powder test, there was no difference. For each test, a tiny pile of FFFFg (.3 cc Lee powder scoop) was placed in an old aluminum pie pan. Both matches would easily light off the priming powder. No failures in three tests of each match.

The fuse test was another story. I cut a dozen 2" pieces of the 3/32" fuse and stuck them up in the ground. I first tried try to light six pieces with the plain rope match. Then I lit the other six with the treated match. I imposed a ten-second time limit on each attempt.

I had a LOT of difficulty getting the plain rope match to ignite the fuse. The only way to get the fuse to light was to get one of the smoldering strands (which tended not to cooperate) to touch right on the end of the fuse. Easier said than done. In one instance, I actually snuffed out the match on the end of the fuse I was trying to light.

The treated match performed flawlessly. Unlike the plain rope which would smolder at the end of the strands, the nitrated rope would form a 'coal' (for lack of a better term) about 3/8" long that was firm and extemely hot. Touching any part of this glowing ember to the fuse would give reliable ignition.

Of the six pieces of fuse I tried to light with the plain rope match, only three ignited within the time allowed. A 50% failure rate.

The treated match lit all of its fuses without fail, and then lit the three that failed in the first test just to make sure there was nothing wrong with the fuses. 100%+ success rate.

The only downside is that the treated rope burns about 4 times faster than the plain. But then I have oodles of rope and more KNO3 than I will probably EVER need.

I have two completed 6' matches, another two soaking, and enough rope for about a dozen more...

[Evil Dog]

One thing you might want to give a try.... when you cut the fuse, cut it at an angle rather than squarely.  That exposes a larger area of the fuse core making it even easier to light.

[Terry C.]

I have the pole finished now.

I stained the poplar dowel with Olympic 'Golden Oak' stain. then applied two coats of Formby's Low Gloss Tung Oil.

One of the things I had yet to do was fashion a way for the end of the linstock to be stuck into the ground. I had envisioned a metal spike of some sort, but in the end I decided that simplicity was the best approach and turned the end of the dowel down to a smooth tapered point.



The head is a pretty tight fit,  plus I have it affixed with a single #4 stainless steel oval-head screw (the same screws I use in my Stratocaster pickguard). Because it's countersunk flush with the copper fitting, you can't really see it from this angle. If the stem was turned directly toward you you could.



Sorry for the crappy picture. I'd wanted to get outside with it, but it's been bad weather for like the thousandth day in a row here.

[Rickk]

if you are looking for Potassium Nitrate to make quick match, and don't want to deal with mail order hastles, check your local hardware store....

Spectracide's Stump Remover, and also Grant's Stump Remover are 99+% Potassium Nitrate.

For what it's worth, "Bonide Stump-Out" is Sodium Metabisulfide... different stuff.

There may be other stump removal products that are KNO3 as well... read the label or find the MSDS sheet before you buy it.

I found an empty space on the Home Depot shelf for Grant's, but I found Grant's in stock at a local ACE hardware store - $4.99 for a pound.

Also, 14-0-45 fertilizer is... guess what?... 100% Potasium Nitrate (KN03). I havn't gone looking for that yet, but if it is readily available, it should be a cheap source as well.


I sorta snickered when I saw 5# sulphur bags in the gardening section, and charcoal was in the store as well. I wonder what I could make if I mixed them all together?

[Terry C.]

I've been doing a little cleanup. This thread was filled with dead links, the hosting site I was using when I first posted this has long since gone belly-up. Since this thread is linked in the stickies, it needed to be repaired.

Also, I have since refined the design of my linstock. The one I use now is slightly different.

The main change was the addition of a supporting ring. The original head was pretty sturdy in actual use, but it did get bent a few times during transport and storage.

I also changed the length and angle of the tubing somewhat, and went with the flare on the bottom end instead of the fitting (which was my original plan).






This new linstock head has served me very well for over a year now. You can see it in action in some of my newer videos.

[Artilleryman]

Reminds me of the device used in church to light candles.

[Evil Dog]

You use a cannon to light candles in church ?  Now that must be impressive !!!