BT50/56 centerimg rings

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

T-Rex

Ordinary Average Guy
TRF Supporter
Joined
Jul 22, 2011
Messages
3,318
Reaction score
324
Location
SE Texas
I am in search of a few BT50 to BT56 centering rings.
I have checked all the usual vendors (eRockets, Sirius, JonRocket, BMS). I can get them through Uncle Mike's via ebay if I order a motor mount kit for $1 (with $6 shipping). Those are some expensive rings. Suppose I could order some other stuff to make the shipping less of a hit.

Tried to make some out of bass wood & balsa. That did not go well. Glued 3 thicknesses of cheap poster board together and tried to cut them. That did not go well either.....

Anybody have any other thoughts? (or have some stashed that you would be willing to part with?)
 
I'm curious what didn't go well?

I would think drill a hole in the piece, get kind of close with a small saw, put a nut and bolt through, chuck it in a hand drill, sand a bit.

That's of course assuming you don't have access to a double fly cutter in a drill press.
 
I have rolled my own centering rings for LPR in the range 13-18 mm and 18-24 mm. In this case the thickness of the centering ring/thrust ring is 2.5mm or 3mm from one tube to the next. For the larger CR-50/56 it would end up being around 5mm. Cutting out a pattern from a sheet in the typical manner is difficult when the thickness is this small, so I roll them like I am rolling a body tube with the length 1/4", cut from strips of cardstock along the bottom short edge of an 8x11 sheet. If you cut along the long edge, the paper will crease when you roll it, paper has a grain. You cut several 1/4" strips, then glue stick one to the inner tube, roll it around. Insert an engine in the BT50 for some support if needed. Keep adding strips until you get close to the inner diameter of the BT56. May need to let them dry a little in between adding layers so they don't slide around on you. When you are done, coat the top and bottom of the rolled CR with white glue. If you think it needs some extra support, print up a CR from PayloadBay.Com on cardstock, easy enough to cut with scissors, and white glue that single layer to the top and bottom of the CR to make a sandwich to keep the laminate layers from telescoping. It should be plenty strong for up to D engines. Your size range is about the size/power limit for which I would use this technique (you did post this in the LPR forum)

here is a 13-18mm engine mount I rolled from cardstock, for example: (half-moon baffle is cut from a box of Girl Scout cookies)
DSC_7395.jpg
 
I'm curious what didn't go well?

I would think drill a hole in the piece, get kind of close with a small saw, put a nut and bolt through, chuck it in a hand drill, sand a bit.

That's of course assuming you don't have access to a double fly cutter in a drill press.

The width of the ring is what didn't go well. The wood ones tend to break at the grain while trying to work them to the correct size. The paper ones I made delaminated while sanding.
Plus I have very limited access to tools at my current location. (no, I am not in jail)
 
The width of the ring is what didn't go well. The wood ones tend to break at the grain while trying to work them to the correct size. The paper ones I made delaminated while sanding.
Plus I have very limited access to tools at my current location. (no, I am not in jail)

Delamination won't happen with the right material. LW found this "presentation board" at an art supplier that almost matches the strength of Letramax. That's the hard fiber CR's Flis sells that I dearly love. This presentation board is similar in that you can use an Olfa circle cutter on it and sand the edges without delamination. Make a pretty good single baffle too. Glue sticks to it quickly also.
 
The width of the ring is what didn't go well. The wood ones tend to break at the grain while trying to work them to the correct size. The paper ones I made delaminated while sanding.
Plus I have very limited access to tools at my current location. (no, I am not in jail)
Makes sense.
 
I have rolled my own centering rings for LPR in the range 13-18 mm and 18-24 mm. In this case the thickness of the centering ring/thrust ring is 2.5mm or 3mm from one tube to the next. For the larger CR-50/56 it would end up being around 5mm. Cutting out a pattern from a sheet in the typical manner is difficult when the thickness is this small, so I roll them like I am rolling a body tube with the length 1/4", cut from strips of cardstock along the bottom short edge of an 8x11 sheet. If you cut along the long edge, the paper will crease when you roll it, paper has a grain. You cut several 1/4" strips, then glue stick one to the inner tube, roll it around. Insert an engine in the BT50 for some support if needed. Keep adding strips until you get close to the inner diameter of the BT56. May need to let them dry a little in between adding layers so they don't slide around on you. When you are done, coat the top and bottom of the rolled CR with white glue. If you think it needs some extra support, print up a CR from PayloadBay.Com on cardstock, easy enough to cut with scissors, and white glue that single layer to the top and bottom of the CR to make a sandwich to keep the laminate layers from telescoping. It should be plenty strong for up to D engines. Your size range is about the size/power limit for which I would use this technique (you did post this in the LPR forum)

here is a 13-18mm engine mount I rolled from cardstock, for example: (half-moon baffle is cut from a box of Girl Scout cookies)
View attachment 342192
Thank you for the reply.
Didn't think about rolling them. May have to give that a go before I spend anymore $ on this thing. It was supposed to be something cheap to use the last of my BT56...
I think I have a couple 29mm thrust rings that I could build up using your technique.
 
Delamination won't happen with the right material. LW found this "presentation board" at an art supplier that almost matches the strength of Letramax. That's the hard fiber CR's Flis sells that I dearly love. This presentation board is similar in that you can use an Olfa circle cutter on it and sand the edges without delamination. Make a pretty good single baffle too. Glue sticks to it quickly also.

If I can get to an art supply shop/Michaels/Hobby Lobby without loosing too much sleep (12 hour night shifts....) I will see if I can locate some. I remember a post a while back where LW mentioned it. I think what I used was actually mat board, maybe that is why it failed.
 
If I can get to an art supply shop/Michaels/Hobby Lobby without loosing too much sleep (12 hour night shifts....) I will see if I can locate some. I remember a post a while back where LW mentioned it. I think what I used was actually mat board, maybe that is why it failed.

You might find it better to search a specialty art store first. I heard you may not find it at HL or Michael's. But I don't know that for certain. Check at JoAnn's if you have one and certainly look into Blick's. I need to know what I really have here as it was given to me and I only know it to be presentation board.
 
52pt (point) chipboard is an option as well, its commonly used as backing for pictures in frames and such, I cut it partly on my wifes CriCut with a deep cut blade, the last little bit I have to cut with a Xacto knife.
 
Just remembered that someone a while back mentioned using backer boards intended for comics. I'll give Wally World a visit when I get off and see what they have. While I am there, check the craft section for a circle cutter that doesn't break the bank.
Part of the problem with the mat board rings was cutting them with scissors and a razor knife....
 
Uncle Mike's sells 24mm to BT56 (BT-50 to BT-56) centering rings in both plywood and Letramax. Click on Blitz Sale on their homepage and scroll down. Shipping is $8 so you may want to combine it with other parts you may need stocking up on.
 
Problem solved.
Used Google as Gary mentioned and Qualman's site came up. Ordered a set of guides for 1/16" fins and 1/8" fins (already have the 3/32) along with the centering rings I was looking for. The fin guides helped the shipping cost make sense to my brain......

Thank you all for you assistance. Good thoughts and techniques that can be used on other projects.
 
Problem solved.
Used Google as Gary mentioned and Qualman's site came up. Ordered a set of guides for 1/16" fins and 1/8" fins (already have the 3/32) along with the centering rings I was looking for. The fin guides helped the shipping cost make sense to my brain......

Thank you all for you assistance. Good thoughts and techniques that can be used on other projects.

That should have been BRS Hobbies that came up and though they do carry Qualmans, it was the Sunward CR's I was in reference to. $2.19 per 8-pack and he still has 6 packs left. Brian isn't known for keeping his stocked supplies up to speed, so if you really want these you might better jump on it. If he runs out, it may be a while before he re-ups again.
 
I know you pointed me toward BRS. I looked around for a few minutes, trying to find something else to spread the shipping across. When I saw that they had one of the Qualman guides I wanted, it sorta pushed me in that direction.... I don't think there is a big demand for BT56 rings, so if I don't have a shipping notice in a couple days, I'll bite the bullet and order from BRS.
 
I know you pointed me toward BRS. --- I don't think there is a big demand for BT56 rings, so if I don't have a shipping notice in a couple days, I'll bite the bullet and order from BRS.
Brian used to carry the Letramax rings before he let Qualman in the door. I really don't know why he did that. But FWIW, I can order nearly 100 bucks of supplies, tubes, NC's, motors and such, and the shipping cost is usually or always under 6 bucks. He packs very well and doesn't use those gawd awful foam peanuts and he ships the same day USPS. I only wish he stayed better stocked than he does. He truly has some of the best pricing I have ever found.
 
Good to know, I'll be sure to send some of my $ his way in the near future. Just bought a bunch of BT60 tube and cones off eBay, so I'll be needing rings there as well, as soon as I figure out what it is going to be...
 
Terry, this is a heads up. I was HL today and checked out their presentation board. Yes, they have some but it's not what you want. This stuff has layers and you don't want that. You need a fiber board to make good centering rings. Chances are Michaels doesn't have it either.
 
Back
Top