MMX Launch Rack

[JAL3]

I removed the tap and tried the screw. It threaded fine.

 

[JAL3]

Best of all, it securely held the MMX rod in place!

 

[JAL3]

To mount the launch heads onto the racks, I decided to make a mount of of 1/8" x 3/4" aluminum angle (L1/8x3/4x3/4). I purchased a 36" length from Lowes and marked sections 2.5" long.

 

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The first of the 10 mounting brackets was cut out with a hacksaw. That got old very quickly and a Dremmel cutoff wheel was used to slice the rest.

 

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Considerable time was spent with the 10 "2nd prototypes" moving the hardware around and trying to come up with what I thought of as the best arrangement. Finally, I got things settled in my mind and took measurements to transfer to a CAD file for the final template. I generated one set of templates for the launch head and another for the mounting brackets.

View attachment mmx launch head template.pdf

View attachment mmx launch head bracket template.pdf

 

[JAL3]

The final launch head template was printed out and applied to the 1/4" plywood with a glue stick.

 

[JAL3]

As before, a jigsaw was used to cout out the rough blocks.

 

[JAL3]

Also as before, a sander was used to reduce the rough blocks to the final external outlines.

 

[JAL3]

The igniter notches were rough cut with the jigsaw and finished with files and sanding sticks.

 

[JAL3]

Similarly, templates for all the mounting brackets were printed, cut out and taped into place on the aluminum brackets.

 

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All of the 5/32" holes to mount the brackets to the heads were then drilled.

 

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When that was done, I randomly tried a few of the brackets with a few of the heads to make sure things were lining up as I thought they should.

 

[JAL3]

It was then time to drill the holes for the 5/16 mounting bolts. Since these were quite a bit larger in diameter, I drilled a small pilot hole first.

 

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The full diameter holes were then drilled.

 

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With that done, the mounting brackets were complete and the templates and tape were stripped away.

 

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I think I mentioned that the igniter notches were cleaned up with files and sanding sticks.

 

[JAL3]

The heads had all of their 5/32" (#8) holes drilled...

 

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...followed by the 7/64 (#4).

 

[JAL3]

I had always intended to paint this system and decided that the first coat would go on before the next step in assembly. The templates were stripped off and balsa filler coat was applied to all of the plywood heads to fill some of the grain.

 

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All of the brackets were then primed with white Dupli Color primer

 

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The launch heads were likewise primed.

 

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Everything then got sprayed with a coat of red.

 

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When the paint dried, things began to move more quickly, especially since most of what was left just involved assembly line acts that had been done before. The clips to hold the rod receivers were loosely bolted into place.

 

[JAL3]

The receivers that had been fabricated for the second prototype were retained and fit into the clips. Once they seemed straight, the bolts were tightened down.

 

[JAL3]

The mounting brackets were then bolted into place and all that was left was to take care of the electrodes, the launch rods and put it all together.

 

[kullas]

looks great cant wait to see what it looks like compleated

 

[JAL3]

looks great cant wait to see what it looks like compleated

Believe me, that goes DOUBLE for me!

 

[JAL3]

The key to my whole system was the electrode system to handle igniters for MMX. OF course, this is where I ran into most of my problems. My first prototype had worked for ignition and holding the igniters in place but was not very durable, was unwieldy an and a royal PIA to mass produce. I had intended for the electrodes to be connected directly to the launch system in place of the normal lead wires. One of the revelation that came to me is that this would violate my intention of interchangeability between racks; in a pinch, I would not be able to use the MMX leads for another pad or vice versa. Then I realized there was no reason to get rid of the electrodes. I would just have the clips connect them. That way the clips would still be present for other sorts of launches if needed.

I rethought the electrodes and was frustrated by trying to electrically isolate the pair. I had visions of a sheathed, insulated bolt to hold them in place but quickly found that there was nothing extant that I could find to use. I did not want to rely on wood screws that might pull out and the project languished while I tried to figure what to do. Eventually, I realized that the electrode could be bolted on just one side and still stay in place. I just added a bit more material to one side for the holes. Since the electrodes would go on opposite sides of the head, they would clear each other. I drew up a template and printed it out.

 

[JAL3]

Another change I made on the modified electrode was to choose a thinner gauge of brass. Instead of using strips, this time I bought a sheet of 0.01" thick stock.

 

[JAL3]

I taped the template to the brass sheet.