Question on Cesaroni Pro38 Case Dimension

I'm currently working on a 3D printed motor retainer design for a 38mm Cesaroni powered rocket. I have prototypes of threaded retainer fitting well to the motor tube right now, but I still have not ordered the case itself. I searched for information on this dimension, and did not readily find anything.

If someone could provide me dimension B per my sketch below, it would be most appreciated. A caliper measurement, in either inches to 3 decimal places, or millimeters to one decimal place would be really great.

Thanks.

1.618

The .375 x 1.618 part shown in the diagram is not part of the case. It is the rear closure supplied with the motor. Just in case you did not know.

Titan II said:

1.618

The .375 x 1.618 part shown in the diagram is not part of the case. It is the rear closure supplied with the motor. Just in case you did not know.

Click to expand...

I'm assuming he wants to know the knurling dimension so that his retainer fits over it.

Titan II, no I had not fully realized that it was a separate piece associated with the motor itself. But I figure the motor retainer would bear down on the rear closure to prevent rearward ejection.

Thank you, this is what I needed. Here is Blender screen of what I am doing. Basically up-scaling a 29mm design I found on Thingiverse.

ecarson said:

Titan II, no I had not fully realized that it was a separate piece associated with the motor itself. But I figure the motor retainer would bear down on the rear closure to prevent rearward ejection.

Thank you, this is what I needed. Here is Blender screen of what I am doing. Basically up-scaling a 29mm design I found on Thingiverse.
View attachment 317679

Click to expand...

Kind of looks like a big Estes 29mm retainer.

Beware of motor heating and 3d printed material. 38mm motors can get the arft-end of a rocket pretty toasty, especially long-burns.

These are just prototypes from PLA to check scaling fit. I printed with full support structures, and even though the motor tube threads look rough from the trimming work, the two pieces thread together perfectly. A future functional piece will be printed from a more heat resistant plastic.