13mm motor mounts

[Rob Fisher]

Does anyone know where you can get a 13mm motor mount that will fit a bt-50 body tube?

 

[jflis]

well, it won't be for a few more months, but we'll have them at FlisKits before long... not much help now, but figured I'd let you know...

Also, since this isn't the first request we've had for this, I am looking into ordering the rings for this very soon and will update the forum when I know what we're doing and when regarding them.

jim

 

[wwattles]

I make all of my own LPR mounts out of picture matting. I use a compass cutter I got pretty cheaply at Michaels, but just about any hobby knife will do as long as you can cut the curves and smooth them down to fit.

WW

 

[Rob Fisher]

Thanks for the info Jim, I was asking because I just lost a rocket built like that to a tree today. I built this rocket a few weeks ago but actually found the motor mount and body tube packed in some boxes. I originally got this when I joined "Estes Aerospace Program" way back when (actually like 19 years ago) and it came as a free added bonus rocket with my subscription. I really liked the way this rocket took off slower with a bt-50 tube, and it still got pretty high. Before this rocket the only 13mm rockets I had were bt-20s. I really like the more realistic slower take-off, plus the fact that you get 4-13mm motors for the price of 3-18mm motors. When you offer this mount I will definitely be buying some! Oh yeah, could you please include an engine hook with the kit-thanks.

 

[jflis]

yea, that short engine hook is a problem... we're looking to get them tooled, but for the initial release they will be hook-less... (sorry... )

 

[Fore Check]

Balsa Machining Service (www.BalsaMachining.com) has all the stuff you need in stock.

The mini-engine hooks are $0.50 each, and the centering rings to center a BT5 inside a BT50 are $0.15 each - available both in 0.05" thick black letramax cardboard or 0.125" thick lite ply. They also have a CR35-F which can be used as a thrust ring, made of 0.05" thick cardboard (just insert the engine hook first and glue flush with the engine hook tab.)

For the motor tube, you'll need to purchase a full length of BT5 if you get it from BMS. This full tube is 34" long, so you'll need to cut it into 1.75" lengths. The full tube is only $1.00, so that means you can get 19 tubes cut from it (cost comes out to a shade over 5 cents per engine tube.)

Added up, that's a total cost of about $0.96 per engine mount (minus shipping.)

 

[graylensman]

Ya beat me to the recommendation, Fore Check! I've got a Little John clone built from BMS parts, and it's quality stuff.

 

[jetra2]

You know, if you wanted to cheat a little bit...you could do this.

Take the standard BT-50 to BT-20 (24mm to 18mm) paper wound CR's like you normally get in kits like the Alpha, and the normal thrust rings for 18mm tubes. Glue the thrust ring inside of the standard ring on a flat surface and let it dry. From there you can build as many as you'd like, then use them as normal CR's. You'll likely lose a bit of strength, but I wouldn't worry about it too much - it is a minimal amount.

HTH

Jason

 

[jflis]

Jason,

Just a word of caution about gluing a standard thrust ring (EB20) into a 20-50 centering ring...

The EB20 has an OD that is .026" *smaller* than the ID of the 20-50 centering ring. The EB is designed to fit inside a BT-20 where as it is the *BT-20* (not the EB20) that is designed to fit inside the 20-50 centering ring.

what I *have* done in a pinch is to glue an EB20 (which, in the case of FlisKits, is identical to our CRP-5-20 centering ring) into a scrap BT-20, then I cut the BT-20 down to the length of the EB20 (1/4") then I glue *that* into the 20-50 centering ring. This is the only way to assure that the rings are actually *centered*

jim

 

[jflis]

MAN! it took a bit of searching to find this thread again! LOL

Good news is, we got the CRF-5-50 rings in so I am now able to put together the six-packs of CRF-5-50 as well as instructions for an EMK-13-50 engine mount kit.

Bad news is, I seem to have hosed my disk and won't be able to get a replacement till Tuesday at the earliest... May have to wait till Wednesday before I can even *begin* to work on this (along with getting ready for Whitakers)...

If I get it done, I'll actually bring some of the EMK kits down with me.

I've attached a pix of the rings. very cute

jim

 

[Rob Fisher]

Hey Jim, any word on when the 13mm-50b.t. engine mounts will be ready? I have a top secret cluster scratch-built waiting on them.-thanks.......

 

[shockwaveriderz]

Originally posted by jflis
yea, that short engine hook is a problem... we're looking to get them tooled, but for the initial release they will be hook-less... (sorry... )

Hey guys! Make your own engine hooks...from piano wire....! takes all of 5 seconds with a pair of needle nose pliers.......

 

[Micromeister]

Shockie's right,
I've been making motor hooks out of either music (piano) wire or 1/8"X .050 flat steel or stainless steel stock. Some hobby shops stock the flat strips as well as the music wire. or you can get the material on line at many industrial supply distributors, McMaster-Carr being my favorite. comes in 12", 24" pieces or 100ft reels if you need to make a bunch

 

[kenobi65]

Balsa Machining has mini-engine hooks. Just got one in my shipment from them.

 

[sandman]

Next time you replace the windshield wipers on your car save the metal stips along the rubber.

They are the perfect size and they are stainless steel!

Bend 'em to shape with a pair of needle nose pliers (or better two nedle nose plyers.

Two wiper blades give you enough for 8 to 12 engine hooks (depending on make and model of car).

If I do the rear wiper too on my wifes Jeep I have almost 18 "E" size hooks!

sandman

 

[jflis]

Originally posted by Rob Fisher
Hey Jim, any word on when the 13mm-50b.t. engine mounts will be ready? I have a top secret cluster scratch-built waiting on them.-thanks.......

Not too long after I get my data disk back... (yep, back from Whitakers )

I hope to have the rings up and available this week... I will keep everyone posted on when some new things are coming out as soon as I get my sys back to rights...

jim

 

[scadaman29325]

Originally posted by sandman
Next time you replace the windshield wipers on your car save the metal stips along the rubber.

That's exactly right, I replaced mine about two weeks ago and saw that those metal strips were perfect for engine clips, I just had not taken the time to post it.

Heck, I can't go through the store any more (ANY store) or throw anything away without thinking about my rockets first. Even the sewing store (with my wife, Kevlar thread, Parachute/Streamer material, Elastic shock cord...?) Threw out an old patio umbrella (hum, gimbal joint for launch pad?)

I believe that's in the Rocket Maniac thread somewhere.

 

[powderburner]

I have used the little metal strips from the sides of those washer blades, and many times they work great. Some of the time, however, the metal strip cracks and breaks where I make a bend. Do any of you guys try to heat-treat the metal before you make clips? I am wondering if I anneal it first, will it be too soft? Anybody?

 

[jflis]

Originally posted by Rob Fisher
Does anyone know where you can get a 13mm motor mount that will fit a bt-50 body tube?

Well, a month ago I said it would take a few months... ...i was mistaken...

The EMK-13-50 engine mount kit is now available