Wood inserts to hold Rail buttons

On the 7.5" nike smoke I am building I was thinking about using 8-32 wood inserts to secure the rail buttons so that I could adjust the size of the standoff for the buttons based on the length of the rail. I would secure the wood inserts in both the aft centering ring and the forward centering ring. Does anyone see any issues with this?

First- do you mean you would use 8/32 t-nuts? Or are these threaded screw inserts and how thick are your rings? Are you flying off a 1010 rail?
What motor size are you using? This may be a better fit for a 15 rail and a little larger buttons depending on weight. I have ( and do ) epoxy in hardwood spacers to mount rail buttons into and for bigger birds double or triple up the centering rings (depending on thickness) to mount to esp the aft one. I would ask somebody who can eyeball it for you what their opinion is and what you have for rails. I'm a little unsure what the length of the rail has to do with the standoffs,because you should just clear the lip on the nose cone. The rail should never be shorter than the rocket(okay-weird exceptions, but-). I think you're on the right track tho'. Straight smoke and good chutes! Send us a pic! Just my farthing's worth.

These are what I will use (not exactly what I purchased b/c I bought the wood inserts from ACE hardware)
https://www.google.com/imgres?um=1&...&tbnw=151&start=0&ndsp=12&ved=1t:429,r:10,s:0

My rings are 3/8" inch thick and are very solid. I am flying off a 15 rail because the liftoff weight will be around 40-50 lbs. The largest motor I envision launching in this rocket is a AT 75/7680 M1850W or a 6 grain Cesaroni M. The rings definitely feel strong enough. The wood insert will be fine.

I have used such inserts to hold the Kaplow clips on my birds. Not quite the same stress load as would be on a rail button but I liked the installation process.

I would epoxy the wood insert into the hole I drill into the centering ring.

Aris said:

These are what I will use (not exactly what I purchased b/c I bought the wood inserts from ACE hardware)
https://www.google.com/imgres?um=1&...&tbnw=151&start=0&ndsp=12&ved=1t:429,r:10,s:0

My rings are 3/8" inch thick and are very solid. I am flying off a 15 rail because the liftoff weight will be around 40-50 lbs. The largest motor I envision launching in this rocket is a AT 75/7680 M1850W or a 6 grain Cesaroni M. The rings definitely feel strong enough. The wood insert will be fine.

Click to expand...

A 3/8" thick ring won't be thick enough to hold that insert. Even if you hit it dead center, it's still not thick enough. Besides using a thicker ring (1/2") you can build up a thick spot on the 3/8" ring by adding another piece of ply at the edge. That will make it a lot easier to hit it and it will have more material to resist splitting.

Or, you can add external plywood to receive the insert. Here's what I've done on a couple of rockets. Inside the hole is a brass insert. HTH. Doug .




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plano-doug said:

A 3/8" thick ring won't be thick enough to hold that insert. Even if you hit it dead center, it's still not thick enough. Besides using a thicker ring (1/2") you can build up a thick spot on the 3/8" ring by adding another piece of ply at the edge. That will make it a lot easier to hit it and it will have more material to resist splitting.

Or, you can add external plywood to receive the insert. Here's what I've done on a couple of rockets. Inside the hole is a brass insert. HTH. Doug .

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Click to expand...

I gotta remember this trick, Doug. Planning to use rail buttons on a big 4" tube fin rocket and your method neatly solves the problem of using a standoff so the rail clears the tube fin.

Thanks!

o1d_dude said:

I gotta remember this trick, Doug. Planning to use rail buttons on a big 4" tube fin rocket and your method neatly solves the problem of using a standoff so the rail clears the tube fin.

Thanks!

Click to expand...

So I would cut a rectangular piece of plywood thick enough so that I will not need any other form of standoff then glue that to the body tube. Then I should form fillets with like wood filler on the sides of the plywood right?

Aris said:

So I would cut a rectangular piece of plywood thick enough so that I will not need any other form of standoff then glue that to the body tube. Then I should form fillets with like wood filler on the sides of the plywood right?

Click to expand...

I think I actually glued up some thinner ply to get there, but, yes, you need maybe 3/8" thick material to start with.

I cut the piece to width, then bevel cut the ends. Next I wrapped some 150 or 100 grit sand paper on the airframe, then sanded the back side of the mounts to contour to the airframe. The piece was then drilled, and the insert was mounted. I put a dab of epoxy on the threads to secure it in the wood.

One key here is to make the footprint of the mount large enough to spread the load out over a large area. This adds much strength to guard against pulling the mount out. (Altho buttons don't see all that much force except when being loaded onto the rail.) These are about 1" wide by ~3" long.

The piece was mounted to the airframe. Yellow glue works fine for a paper-wood joint. I put a thin piece of glass cloth into the joint on either side of the wood to further spread the load. After that, the sharp edges of the wood were sanded smooth, and the the area around the mount was further smoothed with some wood filler.

HTH.

Doug

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o1d_dude said:

I gotta remember this trick, Doug. Planning to use rail buttons on a big 4" tube fin rocket and your method neatly solves the problem of using a standoff so the rail clears the tube fin.

Click to expand...

I used a simple method on my "YouBee" that you might consider. I didn't need a stand off, but I wanted a way to securely attach the rail buttons since they both had to be very low on the rocket.

I took a strip wood about 1" wide and routed out the interior of one side of it, making it a long square u-shaped strip - a channel. You could form the piece from multiple pieces of wood using a flat piece for the top and two thin strips along the edges.

I mounted the strip to the body tube with the open-side down. The u-shape forced it to align straight on the body tube. I both glued and screwed it to the body tube then I attached the rail buttons to it.

In hind sight, it might have been better to attach the rail buttons before attaching the wood to the body tube, but it worked.


You could use a thicker piece of wood to make the standoff distance larger. I used one piece of wood for both rail buttons. But, you could use a short price for each button.

-- Roger

I'm not sure they'll help for your particular applications, but the following web site sells some nice-looking rail button stand offs:

https://web.me.com/bmc_custom/DogHouseRocketry/Rail_Buttons.html

-- Roger

Thanks for the link, Roger.

Those standoffs just might work for my tube fins. I've got to position the rail buttons away from the inside of the tube fin so the rail will fit inside.

Very cool.

I don't know the exact size of the standoff I need for the nike smoke because I am not at home, but I like the standoffs shown in the the link you provided