BSD Thor - My L2 Rocket

Built this starting back in the Summer and finished up paint a week ago. I built it with an E-bay and removable rivets as I plan to use it for Dual Deploy eventually. Taking my test next month and if I pass, my flight will be in November on a J435. I plan to add a vent to the booster, I'm thinking 1/8" inch but I'd love some input. The only issue I'm currently running into is the coupler that goes into the booster is still very tight. I've been sanding it down with 60 grit for like ever and don't seem to be getting anywhere with it. I will vent the upper tube and the e-bay once I decide to use dual deploy.

Maybe you could try briefly 24 grit then go back to 60?

It crossed my mind to go lower, although the lowest Home Depot near me has is 36 grit in a sponge. Someone told me to peel the outer layer off, however I don't want it too loose to where it won't stay straight up and will fall

Harbor Freight carries 24 grit in sheets don’t know if one of those is near you.

I do have one near me. I'll stop by there

Very cool!

I have a scratch built 4” Thor and used pml phenolic tubing and had the same issue with the coupler being too tight but I had put a light coat of paint on it as well. I’m the end it’s still sticky, but the ejection charge with blow it and the shear pins just fine so I’ve left it.

This one is so tight, I can barely get it on and off. I'll just keep sanding until it fits right.

Arsenal78 said:

This one is so tight, I can barely get it on and off. I'll just keep sanding until it fits right.

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I literally had to bang this one on the ground to get it to close up all the way.

Atm I have the LOC 38/54 heavy-as-hell adapter thing with the Z-clips but I plan to get a 54mm flanged Aeropack with an adapter to replace it because it's just too damn heavy of a system. I wish I could do a regular Aeropack but this kit is older than those and the motor mount tube only has like 1/4" exposed at the end, just enough for z-clips but not enough for a standard Aeropack.

Nice paint job. I like it

You definitely don’t want any connections to lose enough to wobble though. Seen wobbles in stages destroy rockets. Sliding freely is good, lose is bad. You probably already know that.

I’d peel a layer then add tape as needed to snug it up. Once a charge or two goes off and coats the inside of the body tube, it will get even tighter over time. After peeling a layer, give it a light coat of poly clear coat.

Check your paper as you sand. Sometimes, the sandpaper clogs pretty fast, and you're just polishing instead of removing!

Still, a pretty sweet build!! Haven't seen a THOR in a while!! happy flights!

The more coarse the sandpaper the less contact the cutting surface has. Use fresh #180 and keep it clean, it should sand down fairly well. Great looking rocket by the way!

Are you sanding a bare coupler or did you "seal" it with a layer of CA first?
I usually put a layer of water thin CA on the coupler first, then sand. Makes it a hard surface that sands well without getting fuzzy. When you get the size you want polish it with a little 400 grit to polish...

I’m sanding a bare coupler. Would the thin CA allow me to take enough off to make it fit?

As others have said, user finer grit paper. A cool trick is to mount the offending part on either a drill, drill press or lathe (eliminate what you don’t have ) and then gently hold sand paper against outside of spinning part.

Pretty soon, bee-ute-if-full fit. This way you get an even surface, uniform contact of the coupler with the airframe, and the shine of a job well done. Priceless. Good luck.

Arsenal78 said:

This one is so tight, I can barely get it on and off. I'll just keep sanding until it fits right.

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careful when you try to seperate it, my fiberglass level 3 rocket would not come apart until it suddenly did. 8 stitches.

Probably goes without saying but do the sanding evenly so it doesn’t have tight spots. That’s how mine is now and I need to go back and hit those areas up again.

I used the flanged Aeropack motor retainer on mine too and it works fine. I think I did the same thing and didn’t leave enough room on the end of the motor mount but that was eight years ago and I can’t remember for certain.

I also coat paper with thin CA before sanding. It will soak through several layers of paper, and the exterior you sand off will be smooth. 60 grit is extremely course for cardboard tubes.

You can also give the same CA treatment to the inside of the tube as well.

For booster and payload vents, 1/8" - 1/4" is good. Depending on the size of the rocket. That vent is less precise than your Avbay vents need to be. I will start with a smaller 1/8" hole , then coat that hole with CA glue . Then drill the hole to the next size up . I just put it on the backside of the rocket where no one will see it.

DM1975 said:

Probably goes without saying but do the sanding evenly so it doesn’t have tight spots. That’s how mine is now and I need to go back and hit those areas up again.

I used the flanged Aeropack motor retainer on mine too and it works fine. I think I did the same thing and didn’t leave enough room on the end of the motor mount but that was eight years ago and I can’t remember for certain.

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This rocket kit is about that age. The motor mount that came with it was only long enough to put all the rings on and use the z-clips.

Eric said:

I also coat paper with thin CA before sanding. It will soak through several layers of paper, and the exterior you sand off will be smooth. 60 grit is extremely course for cardboard tubes.

You can also give the same CA treatment to the inside of the tube as well.

For booster and payload vents, 1/8" - 1/4" is good. Depending on the size of the rocket. That vent is less precise than your Avbay vents need to be. I will start with a smaller 1/8" hole , then coat that hole with CA glue . Then drill the hole to the next size up . I just put it on the backside of the rocket where no one will see it.

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This rocket is 7ft 2" with the bay installed and 4" wide. I've also heard 1/8" hole in the booster and payload from someone else.

Arsenal78 said:

This rocket kit is about that age. The motor mount that came with it was only long enough to put all the rings on and use the z-clips.

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I scratch built this one but I did it as true to design as I could.

Arsenal78 said:

I’m sanding a bare coupler. Would the thin CA allow me to take enough off to make it fit?

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Yes the CA will cause it to fuzz up a little, but since it becomes a hard surface it sands very well. When you get close, finer grit will polish the joint (especially if you do the tube and the coupler) making it nice and smooth.... qquake2k has stated the he goes as fine as scotchbrite to polish his, but the he is also usually spinning the parts on a lathe.

Unfortunately I have no way to spin and sand (unless there’s a way to spin it with a hand held drill) so I have to hand sand it

+1 on the tip for using CA. I've done this a few times on tight couplers, including small ones (BT-60 size). Make sure to use the water-thin CA. Do NOT use a gap filling CA or you will be sanding forever. Also be sure to give it plenty of time to dry before sanding. Otherwise, it turns into a complete mess (ask me how I know this). You can use a CA accelerator if you have it, but I prefer to let it soak in and dry on its own.

Once you have it sanded and fitting good, I like to put a little baby powder in my hands and then rub some on the coupler. Go easy on this. Baby powder can clump up if you use too much (ask me how I know this). I also use this trick on my PML pistons.

BTW, you've got a great looking rocket. I've always liked that design. Let us know how your flight goes.

--MARK

Good looking rocket, much success to you for the test and flight!