NEW ROCKET IS HERE!!

[rsbhunter]

Ok, enough dramatics. My Madcow DX3 2.6" arrived today. Dry fit fins, sanded and filled (not much needed) and checked motor mount and rings. The fit on the rings semi concerns me. Out of the box they are loose on the tube. Being my first mp rocket, I am wondering how to proceed. Should I use masking tape to build up the tube dia, , or place tape on one side of the tube that will give enough shoulder to stop the ring and square it to the mm tube, place a fillet of epoxy on opposite side, and remove tape when epoxy is firm, but not fully cured? Any tips, suggestions or advice is welcome. I understand this is like smaller rockets in many ways, but then again not! Just want to do it right....rsbhunter

 

[Art Upton]

How loose is loose ? What could you fit in between the tube and ring to get an idea?

Example a human hair or a Kevlar cord?

 

[rsbhunter]

Ok, because of my ocd, the od of the mm tube is 1.200. The I'd of both rings is 1.218. Scotch tape is approximately. 002. The difference between the mm and centering rings equals .009 each side. So 4 layers of scotch tape.picture is centering ring at max angle on motor tube. rsbhunter

 

[MarsLander]

Here is what I do. Wrap the tube with a piece of paper, align the end of the paper so it wraps perfectly. Tape it to itself. Then wrap the end of the paper with blue or masking tape, two wraps is plenty. Having the paper there makes squaring the tape easy. Like this picture, but just put paper on one side of the ring. These rings were sloppy too.



Put the ring against the paper in the proper place. Tack on the ring, using medium or thick CA, two dots, on the side opposite the paper, you don't need a full ring of CA. Hit the CA with some accelerator. Remove the paper and tape from the tube. Epoxy as normal, or whatever glue you are going to use.

Don't forget to sand the tube where you are going to glue.

Don't overthink it, glue it up, the gap won't matter. Being Square matters a bit.

 

[rsbhunter]

Here is what I do. Wrap the tube with a piece of paper, align the end of the paper so it wraps perfectly. Tape it to itself. Then wrap the end of the paper with blue or masking tape, two wraps is plenty. Having the paper there makes squaring the tape easy. Like this picture, but just put paper on one side of the ring. These rings were sloppy too.

View attachment 638942

Put the ring against the paper in the proper place. Tack on the ring, using medium or thick CA, two dots, on the side opposite the paper, you don't need a full ring of CA. Hit the CA with some accelerator. Remove the paper and tape from the tube. Epoxy as normal, or whatever glue you are going to use.

Don't forget to sand the tube where you are going to glue.

Don't overthink it, glue it up, the gap won't matter. Being Square matters a bit.

So basically your using the paper to form a "shoulder " to square the ring up? Could I use tape wrapped ACCURATELY around, 5 or 6 layers to do the same thing? I will still use the paper to make sure I'm 90° on tube...place the edge of paper the width of the tape away from the centering ring? Maybe not clear, but same princible??rsbhunter

 

[Hobie1dog]

So basically your using the paper to form a "shoulder " to square the ring up? Could I use tape wrapped ACCURATELY around, 5 or 6 layers to do the same thing? I will still use the paper to make sure I'm 90° on tube...place the edge of paper the width of the tape away from the centering ring? Maybe not clear, but same princible??rsbhunter

i do it this way also.

 

[cwbullet]

So basically your using the paper to form a "shoulder " to square the ring up? Could I use tape wrapped ACCURATELY around, 5 or 6 layers to do the same thing? I will still use the paper to make sure I'm 90° on tube...place the edge of paper the width of the tape away from the centering ring? Maybe not clear, but same princible??rsbhunter

I used cardstock to cut my tubes to ensure they are square.

 

[MarsLander]

Could I use tape wrapped ACCURATELY around, 5 or 6 layers to do the same thing?

Sure.

The nice thing about the paper with tape over it, when you put the CA on, you just slide the paper off/away/down. No need to unwrap tape.

If you are also smart about it, you can put the paper on ONCE. Tack the first ring, slide it, tack the second ring on, slide the paper and tack the 3rd ring. No multiple tape wrapping sessions...

 

[rsbhunter]

WILL DO. This is why I ask...you guy's know your stuff!!! rsbhunter

 

[MarsLander]

If you are also smart about it, you can put the paper on ONCE.

So you are clear...if you do this^^^, you need to stack all three CR. Then paper and tape. Tack the first one, slide the other two and the paper down, tack the 2nd one, then slide the paper and last CR, then tack it...

 

[lr64]

If it was me, I might build up the spots on the tube where the rings go with fiberglass. Narrow fiberglass tape would probably be convenient. If I was going to do it all at once, with something like the typical slow hobby epoxy glue, I might heat it up after applying, so it soaked into the fiberglass. Alternatively, I might lay up the fiberglass first and then come back with the ring when it was mostly set.

Epoxy saturated kraft paper would probably also work fine for this. But you'd have to saturate it ahead of time. And apply pressure. I have some 110 lb card stock that's .009" thick, but I don't know how it would behave when saturated. In any case, saturation takes a few minutes, and is probably best done from one side, and then the other.

 

[rsbhunter]

Got the forward ring tacked on...should be getting my BSI medium 15 min epoxy in a day or 3, then I will glue the cr to mm with filets. I am using a Aerotech motor retainer, so I need to wait and find out the depth of my to mount the ring...Thanks to everyone who replied, you guys make it easier to do it right...rsbhunter

 

[86mustang408w]

Cool build!


Michael B.