Where to get a BT-50 to BT-20 boat-tail tail cone?

[shockie]

To expand this thread: Does anybody have experience with drilling balsa nose cones? And if so what kind of drill bit and speed is used? I would guess you would first drill a small hole then drill a bigger hole? DRill from the base to the nose cone tip direction?

 

[Marc_G]

I completely mangled a balsa BT55 cone once.

I had cut off the tip and put it in a jig of sorts to hold it vertical on a drill press. Pilot hole went smoothly. Switched to a big bit and pretty quickly the bit caught the fibers somehow and ripped it to shreds. To be fair I didn't have much slack around the edges versus bit radius. Press was on sort of mid speed; not sure exact figures.

I did a similar project a year or two later after soaking the cone in Minwax hardener and letting it set up for a while (a week... Just sat in the garage until I got around to it). Went off without a hitch.

 

[shockie]

I completely mangled a balsa BT55 cone once.

I had cut off the tip and put it in a jig of sorts to hold it vertical on a drill press. Pilot hole went smoothly. Switched to a big bit and pretty quickly the bit caught the fibers somehow and ripped it to shreds. To be fair I didn't have much slack around the edges versus bit radius. Press was on sort of mid speed; not sure exact figures.

I did a similar project a year or two later after soaking the cone in Minwax hardener and letting it set up for a while (a week... Just sat in the garage until I got around to it). Went off without a hitch.

I suspected that harder wood would drill better than a softwood like balsa.

 

[cwbullet]

Does it need to be wood?

 

[beeblebrox]

PM me with tube sizes you want and lengths. I know you want 20 to 50 but if there are others let me know, I can 3d print them for you. Single wall with no seams.

Hi folks,

I've got a rocket in my brain and it's time to let it out.

It's nothing special but it will require a tail cone that I can't find for some reason. The body tube will be BT-50 and the engine tube will be BT-20, and I'd like a traditional boat tail shape. I'm not picky on length.

I figured I would grab it from the Semroc collection at eRockets (gotta love eRockets!). But the tail cones section looks pretty thin, and didn't feature what I need:

http://www.erockets.biz/tail-cones/
And some of the cones I might use for an upscale in BT-55 were out of stock. :-(

I fired off an email to Randy to see what he might be able to do.

Meanwhile, I checked out Balsa Machining Service. They have a few boat tails but their only BT-50 size one is bored with a BT-5 hole, not a BT-20 hole. It looks like they do have a BT-55 with a BT-20 hole in it.

Any idea why this is so hard to find and where else I might check? Doesn't have to be balsa... maybe plastic would be better anyway, since the amount of wood would be pretty thin given the closeness in diameter of my desired tail cones.

Somehow my simple projects lead to difficult challenges... before they even get off the ground.

I'm contemplating taking a BT50 nose cone and chopping sufficient tippage off of it to effectively allow it to be a tail cone, if I can't buy what I need.

PM me with tube sizes you want overall length desired and length of shoulder for the larger sized tube. I know you want 20 to 50 but if there are others let me know, I can 3d print them for you. Single wall with no seams. Can be made such that the shoulder is also the centering ring for the smaller tube. I could make you one for the BT-20 - BT50 for free. Additional ones/bigger ones for a nominal fee (No large quantities, I'm not a manufacturer)

 

[JohnCoker]

I'd say the easiest way these days is 3D printing. Here's one I made for my MR scratch building intro video.

 

[Marc_G]

PM me with tube sizes you want and lengths. I know you want 20 to 50 but if there are others let me know, I can 3d print them for you. Single wall with no seams.



PM me with tube sizes you want overall length desired and length of shoulder for the larger sized tube. I know you want 20 to 50 but if there are others let me know, I can 3d print them for you. Single wall with no seams. Can be made such that the shoulder is also the centering ring for the smaller tube. I could make you one for the BT-20 - BT50 for free. Additional ones/bigger ones for a nominal fee (No large quantities, I'm not a manufacturer)

Thank you so much for this kind offer!

I think I'm ok for now though. I've adjusted my plans to use an existing PNC50 cone I have that I can cut down to allow a BT5 motor tube and give me the look I want.

I'm curious what sort of printing rig you have. It would be a whole 'nother hobby for me to pick up so it's unlikely I would do it, but I remain interested!

 

[Alan15578]

To expand this thread: Does anybody have experience with drilling balsa nose cones? And if so what kind of drill bit and speed is used? I would guess you would first drill a small hole then drill a bigger hole? DRill from the base to the nose cone tip direction?

I have done this as an effective way to hollow out balsa nose cones. I used a drill press at low speed with ordinary twist drills. Yes, the smaller diameter can be drilled deeper than the large diameter, to remove more of the balsa mass.

 

[Marc_G]

I made progress over the weekend. Here is the current state:

 

[Marc_G]

Comparison of the original tail cone cut down to BT20 and the new one with steeper curve cut to BT5 that gives me the look I wanted:

 

[Mugs914]

I made progress over the weekend. Here is the current state:

That looks really sharp!!

 

[Marc_G]

Thanks. It will be coated in mirror paint so I wanted a simple shape that would be easy to smooth to create a good base for the shiny paint.

 

[Marc_G]

See further discussion at this thread: https://www.rocketryforum.com/threa...et-with-mirror-paint-by-stuart-semple.165660/

 

[shockie]

From Quest Tomahawk kit...try scaling or different curve as needed.

View attachment 455899

Post as pdf?

 

[teepot]

According to Bill at BMS to drill balsa use a sharp bit and high speed.