29mm thrust ring dimensions

[Mike S.]

Could anyone give me some outer diameter dimensions of aft thrust rings on 29mm single use motors, reloadable casings, or step down adapters?

I'm building a 38mm White Wolf and thought about using a threaded rod with washer/nut instead of the wood screw/washer method called for in the instructions. However, there is only about .140" thickness of the centering ring and I wanted to be sure I could clear the aft thrust ring of the motors with the threaded rod before going with that method.

Thanks in advance. Seems like this should be easy info to find, but got tired of searching.

 

[Art Upton]

Are you talking about making a motor retention with a threaded rod/washer nut?

If the body is 38m and the motor mount 29mm, you should be able to use a nice screw on retainer. Even the Estes style one would work if you don't want the metal

 

[Mike S.]

Are you talking about making a motor retention with a threaded rod/washer nut?

If the body is 38m and the motor mount 29mm, you should be able to use a nice screw on retainer. Even the Estes style one would work if you don't want the metal

Art,
I should've mentioned I already glued the motor tube assembly together. I did think of using the screw on retainer, but the motor tube wasn't long enough to slide aft, and I didn't feel like ordering a longer tube. And I wasn't sure about shifting the CG aft. I always tend to over think things and told myself to just build the damn thing, drill the hole, and install the rod (#4 thread). But forgot about the aft thrust ring clearance.

 

[RokitFlyr]

Go to the Aerotech website. All the information is there. And if you're tired of looking for the information, why do you think someone should do it for you?

 

[SolarYellow]

CTI also publishes nominal case dimensional drawings on their website.

 

[Art Upton]

This may help. Lighting is difficult.

This is a phenolic 38/29 adapter, and in it is a new single use G125.
And at near the bottom you can see the hole in it that I put a screw in so it's screw head would hold a motor in. The 38mm tube would be right on the rear edge of that adapter ring. They are both the same OD.

Now I just friction fit it

 

[Mike S.]

Go to the Aerotech website. All the information is there. And if you're tired of looking for the information, why do you think someone should do it for you?

I did, but they just give length and width of the main body of the motor. And that's why it was an ask, not a demand. Just looking for a little help from experienced rocketeers.

 

[Mike S.]

This may help. Lighting is difficult.

This is a phenolic 38/29 adapter, and in it is a new single use G125.
And at near the bottom you can see the hole in it that I put a screw in so it's screw head would hold a motor in. The 38mm tube would be right on the rear edge of that adapter ring. They are both the same OD.

Now I just friction fit it

View attachment 682343

Thanks Art. If I'm understanding your photo, your adapter would be similar to what my build would look like. In my case, the body tube, centering ring, and motor tube (tube that motor slides into) all flush.

So what I'm looking for is the widest measurement of that G125's black casing. I called it the thrust ring in my original post, so hope I got my terms correct.

 

[RokitFlyr]

I did, but they just give length and width of the main body of the motor. And that's why it was an ask, not a demand. Just looking for a little help from experienced rocketeers.

They have the dimensions of every motor they make.

 

[Art Upton]

Thanks Art. If I'm understanding your photo, your adapter would be similar to what my build would look like. In my case, the body tube, centering ring, and motor tube (tube that motor slides into) all flush.

So what I'm looking for is the widest measurement of that G125's black casing. I called it the thrust ring in my original post, so hope I got my terms correct.

My caliper , if I am reading it right, says 1.25 across the modeled thrust ring.

it is not intuitive to find, as it is on the parent web site here: https://www.rocketmotorparts.com/page/single-use-motor-designs

It says on the G125 AFT END slightly different 1.120 I found this after I measured

 

[Art Upton]

Thanks Art. If I'm understanding your photo, your adapter would be similar to what my build would look like. In my case, the body tube, centering ring, and motor tube (tube that motor slides into) all flush.

So what I'm looking for is the widest measurement of that G125's black casing. I called it the thrust ring in my original post, so hope I got my terms correct.

The print says AFT end is 1.125* and I measured 1.25

* It is not counting the thrust ring

 

[Art Upton]

The G125 is a molded case, the G12 has a 3D glued on thrust ring
they don't seem to give a thrust ring size on either

https://d3l66gvjdr7rqw.cloudfront.net/Templates/170652/myimages/g125t-14a_rcs_assembly.pdf

 

[Art Upton]

I found the RMS reload case does show 1.25 on the aft closure in the print

https://d3l66gvjdr7rqw.cloudfront.net/Templates/170652/myimages/rms 29:180_1698856114309.pdf

 

[Art Upton]

My concern is there really is not much room between this thrust ring and the 38mm tube.
You can even see in this adapter I used before that the screw "swelled" the hole

 

[Mike S.]

They have the dimensions of every motor they make.

Yeah, I went back and scoured the site. I finally found it under "resources". I was originally looking at the "specifications". Thanks.

 

[Mike S.]

I found the RMS reload case does show 1.25 on the aft closure in the print

https://d3l66gvjdr7rqw.cloudfront.net/Templates/170652/myimages/rms 29:180_1698856114309.pdf

View attachment 682403

Thanks Art! Great info. I'm going to err on the high side of 1.25". So like you mentioned, might not be enough room for the threaded rod. Probably go with friction fit and maybe a backup screw, if I can fit one. And pre drill a pilot hole to maybe reduce the "swelling." Thanks again!

 

[bad_idea]

I once measured the thrust ring of an Aerotech G8 (so same thrust ring as an H13 or an I205) at 32.2mm, so about 1.27".