Machining Motor Casings

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Very interesting Mid! Thanks for the suggestions!

My dad owns two lathes, and he has been using the South Bend Heavy 10" for this casing. The chuck can grab about 8" of 38mm stock, which is perfect for anything up to about 20" max. For longer cases, or 54mm cases where he can only grab 2-3", he will be creating a steady rest.

He gets accurate depths for snap ring grooves in the cases by using a micrometer stop. It's pretty cool. I imagine you know what it is, so I won't go into detail.

Well the nozzle is almost done! After that it's just a nozzle washer and she'll be ready for a test.

After machining the graphite more I have realized it's not very consistant, there are little pockets in it...but I imagine that they will get filled with slag after the first test, I guess we'll see! They may just erode quicker than nozzles of higher quality, but since it's cheap it's not too big of a deal.
 
Originally posted by DPatell
This case is designed to be used with experimental motors. I really wish I could go into detail regarding the propellent, but it's not allowed in this forum.

I do have loads for this case, and will test fire it once finished.

edit: Moderators, will I be allowed to post pictures of the static fire?
Click to expand...

I am no moderator, but I for one would LOVE to see a picture of an EX motor static fire! I don't think EX activities are discouraged on this forum - since they are rocketry related - but rather the discussion of propellant mixtures, combinations, or other information that could lead to accidental injury or death. (ie - mixture ratios, chemical types, etc.) Heck, I think you would get some kudos for showing pictures of your rocket launches at EX events!
 
Originally posted by DPatell
This case is designed to be used with experimental motors. I really wish I could go into detail regarding the propellent, but it's not allowed in this forum.

I do have loads for this case, and will test fire it once finished.

edit: Moderators, will I be allowed to post pictures of the static fire?
Click to expand...
Absolutely! In fact, we'll hunt you down if you don't! ;)
 
Not entirely related to the casings, I did some ignitor tests today. I will be using these for lighting the loads in this case, so I figured I'd post them.

Here's some of the ignitors.
 
This is the first test. A big ignitor with slivers of Blue Thunder tied to it with cotten string. Lit the Blue Thunder right away, so if I can fit it in the nozzle then we will always have instant ignition!
 
This is a test of a smaller ignitor, one that will be used in the 38-220 case. I think this will do the job, but we will see when I static test.
 
the blue-ish light is the blue thunder that was tied to the ignitor. When it lit, the slivers fell off and burned on the saw horse...in a motor that will light the motor much quicker.
 
This is the resulting thrust curve. I have this data about 1 minute after the motor is fired.
 
Very cool! About how much money did you put into the thrust stand? It's a possibility, and something I'd be interested in trying...
 
Originally posted by Evil Prince
Dan, not to be a stick in the motor casing or whatever, but they can only be used for EX. Even if one were to use the "same" materials and anoidizing and machined them to the identical specs, NAR and TRA disallow certified motors from being flown in anything but the manufacturer's - or appointed vendor's - hardware.
Click to expand...

This was the dogma for a long time, but I don't think it's true. At Loki we are going to encourage and support people making their own hardware. All Loki reloads will say something to the effect of "to be used in Loki Research motor hardware, or equivalent". I will post dimensioned drawings of the Loki hardware on the web so that anyone can make their own, or take the drawings to a machine shop and have them made.
 
Jeff - That will be very helpful! Very cool, I'm looking forward to that. I will be patronizing you at any launches that you show up to.
 
Originally posted by Loki
This was the dogma for a long time, but I don't think it's true. At Loki we are going to encourage and support people making their own hardware. All Loki reloads will say something to the effect of "to be used in Loki Research motor hardware, or equivalent". I will post dimensioned drawings of the Loki hardware on the web so that anyone can make their own, or take the drawings to a machine shop and have them made.
Click to expand...

Jeff, You are my Hero!!! :)

Seriously... that is a great way to be.

Will we be seeing you at BALLS in a few weeks?

--Alex
 
Originally posted by Loki
At Loki we are going to encourage and support people making their own hardware. All Loki reloads will say something to the effect of "to be used in Loki Research motor hardware, or equivalent".
Click to expand...

If I could hug you, I would :p

Loki is indeed the GOD of Thunder!
 
Originally posted by n3tjm
In my opinion, I think EX is a valid and wholesome endeavor for the experienced and legal (old enough to be leagally responsible) rocketeer. TRA has an EX program, and in my opinion, NAR should come up with one too. Before 1994, reloadable motors were taboo... now... anyone flying anything above G is pretty much limited to reloadables. Hybrids are now here. So many new things coming up... which is good. Remember.... it's up the hobbiest that become the great inventors of the world ;).
Click to expand...

The hold up in all such progress is far more due to the fear of actions against the organizations by individuals and agencies than it is for any lack of forward thinking.

Anyone is free to build and fly anything that does not contravene existing laws. NAR and TRA rules are not existing laws. Doing so merely means you're not doing so under protection of their insurance, and that implies it's not a sanctioned event (other than the provisionally sanctioned EX events).

Darn near everything above a C6 and the birds that use them was considiered either EX or just "outside the scope" of the NAR at one time.
 
Originally posted by AlexNUMB


Will we be seeing you at BALLS in a few weeks?

--Alex
Click to expand...

Yes, I'll be at BALLS. I'm looking forward to a great launch. If we get weather like last year it will be incredible.
 
It's official, the 38-220 casing is finished! First static fire should take place tomorrow. First a Yellow flame, and then a sparky. Should be interesting!

Here's the parts laid out.
 
Here are the next two casings to be machined...a 15" long 38mm, and a 10" long 54mm. Should keep us busy for a while.
 
wow those sparky grains are nice, they look like they were made by a pro, either that or they are commercial. I dont know which, but they look like they will make a sweet motor ;)
 
Yea, but they might be a little faster than originally planned... :p
 
Hmmm, nice motor!

This could be a practical undertaking if I take shop in high school, or can anyone tell me an expected price range for a 29mm set in a machine shop?

Thanks,

Blue
 
Originally posted by Ryan S.
wow those sparky grains are nice, they look like they were made by a pro, either that or they are commercial. I dont know which, but they look like they will make a sweet motor ;)
Click to expand...

Uhh... they're a little smudged on the sides of the casting tubes... oh, and it looks like the AP percentage and solids loading is a little higher than intended too :D

Good luck Dan. I hope it doesn't dial 1-800-KABOOM (to borrow a phrase from Dave Bullis)!
 
Originally posted by daveyfire
Uhh... they're a little smudged on the sides of the casting tubes... oh, and it looks like the AP percentage and solids loading is a little higher than intended too :D

Good luck Dan. I hope it doesn't dial 1-800-KABOOM (to borrow a phrase from Dave Bullis)!
Click to expand...

yeah but that doesnt matter, plus that was a big batch.

I am sure you could tell the AP percentage just by looking, just a mismeasurement I am sure, whoever made it was probably up at 12 at night, after a long day/

I beleive Neil McGilvery coined that phrase.

btw that motor wont explode.
 

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