That beveled fin jig guide thing...

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Marc_G

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Hi folks,

It's driving me nuts. For my LPR (mostly BT60 and smaller) stuff, I'm puttering around building a fin attachment jig around the lines of this:

Fin Jig.jpg

I cut a piece of particle board at 45 degrees, but for BT60 the wood was too thin so the body tube rests on the outer edge of the cut wood instead of on the inside angles.

Looking for some more details about wood thickness, use of various angles, etc.. I know several people around here use similar jigs...

Any thoughts appreciated.
 

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I suggest you start with a 6 foot long 2x6. Cut the bevel along one edge, then split it into a 3.5 foot piece and a 2.5 foot piece. Drill holes for the bungee cord pins, and 4 through holes for carriage bolt/wing nut assemblies so that you can incorporate a spacer the same thickness as your fin material to ensure accuracy.

I like the design, I just haven't gotten around to building one myself.

G.D.
 
Hi folks,

It's driving me nuts. For my LPR (mostly BT60 and smaller) stuff, I'm puttering around building a fin attachment jig around the lines of this:

View attachment 35191

I cut a piece of particle board at 45 degrees, but for BT60 the wood was too thin so the body tube rests on the outer edge of the cut wood instead of on the inside angles.

Looking for some more details about wood thickness, use of various angles, etc.. I know several people around here use similar jigs...

Any thoughts appreciated.


Here's my thought, you should take a look at these treads:

www.rocketryforum.com/showthread.php?t=9694

www.rocketryforum.com/showthread.php?t=9859
 
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I built one and it works perfectly. I've used it for everything up to a 4" tube. In that case, I used 1/8" plexi-glass to extend the angle and hold the BT. Works like a charm...:clap:
 
I've made something similar, as well, and use it all the time.

I've found its ok if it sets on the outer edge, instead of the inner angles.

I made one out of 1/2" Corian (counter top material), and I've used it up to BT-60. One of my latest project is a BT-80, and the jig does seem a bit narrow. I (attempted) to use 2x4's to make one for BT-80 and up, but a 2x6 would be a better idea, giving more surface area for the jig halves to meet, (and less chance of losin' fingers)

I made mine about 2 feet long, I figure if at least half the length of the rocket is in the jig, it should be good.

I had wondered, too; as long as both angles are the same, it should be good, right? A smaller angle, like 22 1/2 deg. would be easier (for the saw) to cut. I use a table saw, and prefer to make a few passes to get a clean, accurate angle at 45 degrees.
 
Seems like a great opportunity for Odd'l Rockets, Fliskits, Semroc or some other rocket maker to make a simple & cheap fin bevel jig...
 
Thanks again for the links and all the suggestions.

I'm off to Home Despot tomorrow to get some stuff. I'm not sure exactly what I'll buy.

I need to be able to manufacture the thing with reasonable tolerances. Right now all I've got is a circular saw (standard Skil 7.25" kind). I was able to do a fair job cutting a 4' piece of ?3/8" or 1/2" not sure? particle board with the circ saw and a clamped carpenter's level. Burned the wood a little in a few spots but overall not a bad show.

Maybe I'll just buy a 1" thick piece of whatever material looks non-warpy to me and cut it the same way. MDF sounds like a likely suspect. Not sure if true lumber would be straight enough without me doing something to it like planing it down, attaching something rigid, or what...

Or maybe I'll come home with a table saw, or a better guide.

Some of my jig building has been hampered that I don't right now have good manufacturing setup. My tools, and skills to be sure, aren't quite there yet.

Time will tell wish me luck. I'll definitely turn what I worked on last night into a BT50 and below small scale jig.

Marc
 
I use the Standard Rockets Assembly Tool (www.standardrockets.com). No woodshop required, it stands the rocket upright so it takes up less shop space, and best of all you can do all of your fins at one time.
 
I use the Standard Rockets Assembly Tool (www.standardrockets.com). No woodshop required, it stands the rocket upright so it takes up less shop space, and best of all you can do all of your fins at one time.

Really????:confused2:

If truth be told, on a smaller BT, say BT55 or less, you don't even need the bevel. Just slap a piece of fin stock between two boards and line them up... works perfectly and you still don't need a woodshop. Oh, and you can save $79.99.

I don't want to take away anything from Standard Rockets because they make a nice product, but woodshop not withstanding...
 
I went to Home Despot yesterday in search of wood stock and possibly some tools.

It was truly depressing. Their wood stock was awful. They have definitely gone downhill over the years. Lowes tends to be better but I had a gift certificate for HD that I wanted to use for this.

They had no MDF > 3/4". In fact the only wood >1" they had was 2x6 stock. I measure it at about 1.5" in actuality, which is thick enough for all my tubes, but finding one that was reasonably straight over a several foot length was hard. Eventually pulled out one board that wasn't quite a pretzel.

Also bought a new finish (40 teeth) blade for my circular saw... it's nice and thin, about half as thick as my old one. At the same time I bought a cutting guide that I can clamp on and hopefully ensure a straight cut.

Didn't have a lot of time to play with my purchases last night but I did install the new blade, and chopped my 8' 2x6 into two four-foot lengths. One is a little warpy (by about 1/8" over the length), the other is pretty straight. I'm testing first on the slightly warped piece. I clamped my guide in the correct place so the saw with angled platform will cut the right bit of wood off.

Now I have to find something to mount the wood to while I cut it. I will probably get to this tomorrow. I don't have a proper work table but may do it in the garage (instead of basement) where I've got a router table that may serve. But it's cold in there!

Wish me luck.

Marc
 
Wow what a timely thread!
I've been working on a 1/4" aluminum fin guide for micros cut on a 45° angle 2 piece stacked and shimmed design very similar to these. Amazing how Things that work seem to evolve. Something things this simple just seem never to come up in conversation...like they've alway been around.

Very interesting idea using wood on the larger versions tho I'd more then likely use a more dimensionaly stable material like bendelex (Phenolic barrier board in 1" or better, or perhaps 1-1/4" clear acrylic just to have some secruity knowing the base boards wouldn't warp or distort over time.
 
In my prior post I metioned getting a piece of 2x6 and chopping it into 2 four-foot parts.

I set the first up on a routing table with a sacrificial spacer board between the 2x6 and the router table. Clamps held the board to the table and smaller ones held the saw guide straightedge in place.

IMG_4363.jpg

IMG_4364.jpg

I made a test pass with the circular saw a couple inches over the board to make sure my cord wouldn't get bound up or anything. Then, with the saw base set at a 45degree angle (according to the guide --not the most precise measure...) I started cutting, being careful to stay up against the guide. The first few inches were'nt all that straight, as expected, but then I had the whole saw against the guide and aligned straight. It went fine for a few more inches until I hit the first clamp. When I did the test pass I was too high and missed it but now on the real pass I was stuck. I pulled back an inch and let the saw spin down. Removed the clamp (it was tight enough with just the other one) and continued the pass. Swapped clamps when I fetched up against the second clamp. Then all was fine until for some unexplained reason I couldn't push the saw through the last four inches. I'm still not sure what I was hitting up against but I called it quits.

Using a big miter/chop saw I cut off the first few inches and last few inches, then from the remaining straight stock I cut it so the long side was around 6 inches bigger than the side. Shown is the shorter waste piece and the two pieces I will use.

IMG_4365.jpg

I then aligned the two good pieces as well as possible, and checked them with a 90 degree angle (2x45 should add up to 90). It was clear that the angle wasn't perfectly set, but as long as top and bottom were equal (from being part of the same stock) it should be fine. I clamped them together and put some 1/2" holes in and fed dowels through, then glued the dowels into the lower part.

Here are some pics in theoretical use. I just used some elastic I had on hand; I'll use a thicker piece after I pick some up. And that blue BT-60 is from an old blue ninja kit that I bashed various parts from. And the fin is a reject from another project, and I didn't put shims in yet (just open space in there...)

It actually looks pretty good, but unless I trim it a bit it won't work for 4 fin BT60-or-smaller projects due to overhang of the angle bit.

IMG_4366.jpg
IMG_4368.jpg

I will probably make another one out of thinner stock (1") which would be just as easy. Very good learning project, and this one would be fine for BT 70/80 project I'm considering.

Oh, I didn't put wingnut hold-down screws in this yet... I may or may not do it on this one but probably will on my next version.
 
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While I typically just eyeball the fins, especially on TTW installations, I do finally see the value of what this design offers. I'm embarrassed to say, but I read the other threads when they first came out and kind of wondered what the big deal was, but for some reason it clicked this time and I guess I finally appreciate the whole point. I went back and looked over the other threads again and really wonder where my mind was at the time. . . .

Seems like a very functional, reasonably easy to construct tool for taking the effort out of fin alignment.

Sandy.
 
I misunderstood. I thought you were making or looking for a fin beveling tool.
 
I've actually now completed (more or less...) three of these jigs. The first was documented above and is made out of wood about 1.5" thick (it started life as a 2x6, the one board in the pile that was straight enough to be usable). The second was made out of particleboard that was much thinner (about 3/8th inch thick).

My most recent one is made from 1" (actual dimension) pine that was sold as a stair tread (got it from home depot). In the stair tread pile, there were a bunch of very warpy ones which were made from a single piece of wood each. There were a few treads in the pile that were made from multiple blocks of wood joined together. These were all nice and flat and uniform, so I grabbed one of them.

All of these jigs used approximately 45 degree angles; I cut one long piece at the angle, then do a 90 cut to make it into a longer and smaller section. This makes sure the upper piece and lower piece are at exactly the same angle since my circular saw is not a precision instrument.

The only problem with my most recent one, desigend for BT-60, is that I'm not sure if a 4-fined rocket will fit... might need to cut a bit of the angle off to make room for it under the fin table.

Marc
 
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