Homemade Motor Retainers

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qquake2k

Captain Low-N-Slow
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Can you guys show me pictures of your homemade motor retainers? I need ideas.
 
This is what I usually do, but I put the flange of the T-nut on the inside of the rear centering ring (i.e., facing the nose of the rocket) since that's the way T-nuts are supposed to work. I still use epoxy as this gent does just to make sure they're never pushed inward accidentally. However, I use epoxy under the T-nut before it's driven home with silicon grease inside the threaded area to prevent epoxy migration into it, then more epoxy around the T-nut just as he does, but more liberally:

https://www.rocketreviews.com/featured/tip_featured4.shtml

There are many more tips here:

https://www.rocketreviews.com/cgi-bin/resources/tips.cgi?motors
 
I do the same thing. Use T-nuts in the CR and clips with screws to hold the motor in. I use different size clips for different size rockets or motors. You can get that at any hardware store, Lowes, or Home Depot usually by the electrical section. They are the clips used to hold conduit to a wall.

...Fudd

DSC_1299.jpg

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I do the same thing. Use T-nuts in the CR and clips with screws to hold the motor in. I use different size clips for different size rockets or motors. You can get that at any hardware store, Lowes, or Home Depot usually by the electrical section. They are the clips used to hold conduit to a wall.

...Fudd

That's an awesome looking nozzle! Is that a 54mm? What kind of motor is it?
 
That's an awesome looking nozzle! Is that a 54mm? What kind of motor is it?

That's a Medusa nozzle for an AeroTech 54mm reload. AeroTech uses those to reduce mold costs -- it's a "one size fits many" nozzle. Depending on the reload used, a different number of nozzles will be drilled out, and the throat size will vary on them, as well.

Regarding the question about PVC, I've seen PVC used as a motor retainer. It holds up amazingly well.

-Kevin
 
When I can I simply use a hose clamp. I extend the motor tube aft an inch so that I can get a hose clamp on it. I think I'm the only guy that does this. It's cheap and never lets go.
 
A couple of barrel nuts, long hex bolts and a few nuts and washers..Parts list of the motor retention on my 3" Thor and my Excel Plus..These are a couple of pictures from the Thor..

Motor Retention 001.jpg

Motor Retention 003.jpg
 
I just epoxied two pieces of ca hardened balsa, drilled and screwed inserts into balsa. 2 threaded inserts,2 button head screws and 1 drawer repair piece $2.00
mercury_integrator_02.jpg
 
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I just epoxied two pieces of ca hardened balsa, drilled and screwed inserts into balsa. 2 threaded inserts,2 button head screws and 1 drawer repair piece $2.00

Now that's a first -- I've seen all the other methods before, but that's the first time I've seen someone use an angle bracket.

You just scored points for originality. And it's inexpensive, too!

-Kevin
 
That's an awesome looking nozzle! Is that a 54mm? What kind of motor is it?

Yeah, those Medusa nozzles are cool. The aerotech J275W 54/852 is a medusa motor, puts out an awesome plume at lift-off. My Devastator on one at Red Glare

DevastatorJ275RG7.JPG
 
Clotheshanger wire clips? Is that the motor hook in your photo? Where do you get them?

That is a motor hook in the photo, but it is not what I am talking about. I will have to take pictures of the clotheshanger wire setup I use.

As for where to get them, I start in the closet.:cyclops: Once I have found a suitable wire clotheshanger I cut and bend two pieces (one for each side) so that one end is a circle (screw goes through that) and the other is kinda hook shaped (that goes on the motor)
 
I like the way this retainer looked. Untill I launched it without a standoff and charred the epoxy!

motor retainer.jpg
 
I saw an easy, inexpensive and seemingly effective retaining system on a 38mm recently. It was just a hose clamp tightened down around the motor tube.

It worked.
 
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Screen door clips, a pair of screws, and a pair of T-nuts. All from Ace hardware.

Now this might be a bad thing depending on how you look at it, but I don't have to ever remove the screws. Simply loosening them allows me to turn each clip in the opposite direction (one up, one down) and rotate the motor casing and slide the motor out. I can slide the motor back in the same way. When I tighten the screws, the clips don't twist any more though, so I think it's pretty secure in there. I suppose I could prevent the ability to twist with a bit of epoxy to either side of the bottom of the clips
 
Motor retention in my Maverick. It featured a 29mm mount in an ST-16 tube, which meant that there was not much room for blind nuts and machine screws. But I made it work. The blind nuts and socket screws are 2-56. After installing the blind nuts in the ring, I had to grind down the flanges with my Dremel and I had to reinforce the ring by laminating it with a few extra rings cut from 1/64" plywood. There was very little material holding the ring together after I drilled the two holes for the blind nuts.

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The rear ring mounted on the motor tube.

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MK
 
For the retainer itself, I picked up a 1" x 1.5" bushing at the hardware store, and drilled a pair of holes in it.

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MK
 
I had also constructed a 24mm to 29mm adapter for that mount. Here it is with a spent E9 casing inserted in it.

DSCF1067.JPG


For its retaining ring, I used an electrical conduit washer that I purchased at Lowe's.

DSCF1059.JPG


The OD of the washer was 1.75". I had to grind down the outer edge so that it would fit the ID of ST-16. I used my Dremel for that. The process put a groove into the edge of my grinding attachment.

DSCF1054.JPG


Here is the adapter inserted into the 29mm mount, with the retaining ring screwed into place.

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MK
 
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That is a motor hook in the photo, but it is not what I am talking about. I will have to take pictures of the clotheshanger wire setup I use.

As for where to get them, I start in the closet.:cyclops: Once I have found a suitable wire clotheshanger I cut and bend two pieces (one for each side) so that one end is a circle (screw goes through that) and the other is kinda hook shaped (that goes on the motor)
Sheesh, for some reason "clotheshanger" wire clips came out in my mind as "clothesline" wire clips. :bangpan: I now completely understand what you're talking about.
 
Screen door clips, a pair of screws, and a pair of T-nuts. All from Ace hardware.
Thanks for that source info! I've had trouble lately finding them since my local Lowes and Home Depots now only sell plastic or otherwise inappropriate screen door and mirror clips.
 
I had also constructed a 24mm to 29mm adapter for that mount. Here it is with a spent E9 casing inserted in it.

DSCF1067.JPG


For its retaining ring, I used an electrical conduit washer that I purchased at Lowe's.

DSCF1059.JPG


The OD of the washer was 1.75". I had to grind down the outer edge so that it would fit the ID of ST-16. I used my Dremel for that. The process put a groove into the edge of my grinding attachment.

DSCF1054.JPG


Here is the adapter inserted into the 29mm mount, with the retaining ring screwed into place.

DSCF1069.JPG


MK

VERY NICE!!! Thanks!

Mike
 
I use a 6" to 12" threaded rod. Epoxy it along it's length to the engine tube so that it extends about 1" past the end of the engine tube. I then use two nuts and a small washer to hold the engine in. The nuts go on either side of the washer to clamp it in place, and the washer is placed so it is just touching the motor.

This works great and is simple. I got the idea from another contributor when I was building my first HPR. It flew great and the engine stayed in.
 
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