How to attach e-bay to body tube

[DragonRocketry]

Here is how I attach my e-bay to the body tube. Hope this helps.

Items needed to attach electronics bay to body tube.

Drill

Drill bits ( I use 7/64 and 11/64 if doing #8 screws)

T-nuts

Buttonhead screws

5 minute epoxy

Thin CA

Masking tape

Mixing board

Tooth picks

Gloves

Sandpaper



First thing mark your coupler half the length so you know where the center is. Insert coupler into body tube to that mark. I like to tape the tubes together so they do not move while drilling hole.



Now find mark on tube and drill through both tubes. I start with the 7/64 for a pilot hole and then drill with 11/64.






Now I remove the tape and pull the coupler out of the tube. At this point I put some CA around the holes I drilled. See pictures. Let this harden up and the sand the burrs off.

 

[DragonRocketry]

After the CA dried and is sanded I insert the screw through the hole in the couple and thread the t-nut on to the inside of the coupler. I then mix up some epoxy and epoxy the t-nut to the coupler. Let this set for about 30 minutes.




After the epoxy is hard I remove the screw and insert the coupler into the body tube. Align the hole up and insert the screw.



Repeat these steps and do the next hole. I do one hole at a time, so nothing gets out of whack.

 

[Hobie1dog]

Thanks for all the great photos.

 

[waltr]

Nice write up and pictures.
I do they same drilling and harden with CA.
However, I use Push-in rivets which are just easy. No need to epoxy a 'T-nut' to the inside of the coupler.
https://www.mcmaster.com/rivets/shank-style~click-lock/
For smaller rockets (24 to 33mm BT) I use one to keep Ebay attached to Main chute section. Larger I use 2 or 3 rivets.

I also use these rivets to attach Nose cone to a paylod bay.

 

[DragonRocketry]

Nice write up and pictures.
I do they same drilling and harden with CA.
However, I use Push-in rivets which are just easy. No need to epoxy a 'T-nut' to the inside of the coupler.
https://www.mcmaster.com/rivets/shank-style~click-lock/
For smaller rockets (24 to 33mm BT) I use one to keep Ebay attached to Main chute section. Larger I use 2 or 3 rivets.

I also use these rivets to attach Nose cone to a paylod bay.

I will never use plastic rivet again. I had them shear instead of pushing the nose cone off.

 

[Sandy H.]

I think the method above is great. The only thing I do differently is to use a Unibit to drill the holes instead of a twist drill. I like the really nice round hole they make in thin materials. Regretfully, the self-chamfering feature that works great on sheet metal isn't quite as applicable to our round tubes, so I make sure to be gentle and not bump the next size when drilling. After the CA, any fuzzies are easy to sand, as you've shown.

Unibits aren't cheap and for cardboard it is nice to get a sharp one vs. the kind of stuff you get at Harbor Freight, so you're stuck getting one that is good quality. Probably not worth it for just rocketry, but they are useful for lots of things, once you have one.

Sandy.

 

[waltr]

I will never use plastic rivet again. I had them shear instead of pushing the nose cone off.

I do not understand...Please explain exactly what you setup and what you expected to happen and then what did happen. Please include BT size and weights of sections.

One problem I have seen on this forum is one person is talking about a smaller Class 1 cardboard rocket and answers come from experience with 50 pound L3 rockets.

I have been using these plastic rivets on a number of cardboard rockets for over a year without issues.

 

[MALBAR 70]

Thanks this was what I was looking for.
I'm building The Black Hole Space Probe and was wondering what the extra hardware was for.

I was also wondering if you could make a post on how you set up the attachment point for the recovery harness on your kits. Thanks.

 

[DragonRocketry]

Thanks this was what I was looking for.
I'm building The Black Hole Space Probe and was wondering what the extra hardware was for.

I was also wondering if you could make a post on how you set up the attachment point for the recovery harness on your kits. Thanks.

Mike. The line with the SW, you will need to drill a 7/32 hole on that mark for access to the switch on the ebay sled.

 

[MALBAR 70]

Thanks.
Where do you suggest the static ports be located? With all the protrusions (rings) the airflow along the air frame will be disrupted quite a bit.

 

[DragonRocketry]

Thanks.
Where do you suggest the static ports be located? With all the protrusions (rings) the airflow along the air frame will be disrupted quite a bit.

I would keep them about 1/2" up from the end of the body tube and do 3 holes. That is how I was planning on doing mine.

 

[Keisling]

The prongs on that t-nut look like they could snag your recovery gear.

 

[DragonRocketry]

The prongs on that t-nut look like they could snag your recovery gear.

no recovery gear in the e-bay.

 

[jhill9693]

Very nice. I'd never considered using CA before trying to remove the burr. That hole really cleaned up nicely after CA treatment.

 

[kavy8]

Dang, that is clean and tidy! Going to try this out on my first DD

 

[SolarYellow]

It's possible to buy tee-nuts without the prongs, just a nice, smooth flange. I'd try to do that.

I'd also use a wood-boring bit with a Forstner-type tip to drill the hole. I find they make cleaner holes in wood, cardboard, MDF, etc., at least on the entrance side. Can still tear out the back a little.

 

[Rob Campbell]

It's possible to buy tee-nuts without the prongs, just a nice, smooth flange. I'd try to do that.

I'd also use a wood-boring bit with a Forstner-type tip to drill the hole. I find they make cleaner holes in wood, cardboard, MDF, etc., at least on the entrance side. Can still tear out the back a little.

Yes, they're called weld nuts.

 

[Pem Tech]

Yes, they're called weld nuts.

Ouch....

 

[Titan II]

It's possible to buy tee-nuts without the prongs, just a nice, smooth flange.

Brad Hole t-nuts. Amazon, Lowes, etc.

https://www.google.com/search?q=bra...IMzMxMWowajSoAgCwAgA&sourceid=chrome&ie=UTF-8

You can also just take pliers and flatten or break off the prongs.

 

[kyle]

It's possible to buy tee-nuts without the prongs, just a nice, smooth flange. I'd try to do that.

I'd also use a wood-boring bit with a Forstner-type tip to drill the hole. I find they make cleaner holes in wood, cardboard, MDF, etc., at least on the entrance side. Can still tear out the back a little.

Where do you get 7/64" Forstner bits? That would be nice to have.

 

[SolarYellow]

Search for a "brad point drill bit."

 

[conneryc]

For my LOC 7.5" level 3 rocket I used the same procedure. Except with the LOC coupler and "stiffy" tube, together they are thick enough to flip the t-nuts around so that the prongs get buried into the coupler. I used a total of six per tube connection to the av-bay, 2 screws at 3 locations evenly spaced around the diameter.

For my 4" and smaller stuff I just use these plastic rivets: https://www.csrocketry.com/building-supplies/small-parts/rivets-12-pack.html

 

[rcktnut]

I use the t-nuts also without the barbs, epoxy them in place. If you happen to have a work bench with a vice, which I do, you can open it up a little to catch the ends of the t-nut place middle of t-nut in opening and hit it with a hammer. I do this and it works very well to conform the t-nut to the inside of the coupler. This works well especially on smaller dia. tubes.

 

[ep29030]

It's possible to buy tee-nuts without the prongs, just a nice, smooth flange. I'd try to do that.

I'd also use a wood-boring bit with a Forstner-type tip to drill the hole. I find they make cleaner holes in wood, cardboard, MDF, etc., at least on the entrance side. Can still tear out the back a little.

PEM nuts also work for this application. Just epoxy them in place. Also, a plain 6-sided nut can be epoxied in place and do the job. I’ve used them multiple times on altimeter boards without issue.