Need Machining (lathe) Help

[AdrianParticipant]

If I had a lathe, I might be tempted. But mostly I’d like to use a certified motor so that I can set a record. I think the I and J records are do-able with our launch site and existing 38mm motors.

Tom said that What’s Up hobbies has the flush rear closures in 38mm. They’re not on their website so I’m emailing them.

Update: What’s up hobbies does not have them. I bounced the question back to Tom. We’ll see if these are made of unobtanium or if it’s a real product that someone can in fact purchase.

[James Russell]

turning an aft closure flush to the AF does not make a motor “not certified”. As long as you do not do anything to the temper of the AL and do not change anything can change the way a motor works you are fine. I think that some of the NAR rules get caught up in others rules and things get polluted. You can not do anything that could weaken the motor case or closures. An example would be welding fins on to a case. If you have the machine and the skills then change you aft closure, if not let someone that does.

[Kenneth ReillyParticipant]

I don’t know if he reads the forums or not, but Dennis Billings would be the one to talk to.

[Warren B. MusselmanModerator]

I have precision lathe capabilities up to 8″ diameter and 13″ long. I’m more than happy to turn factory closures down. Not so happy to make one from scratch since I’ve haven’t learned how to thread things yet..

Personally and not to dispute James, my understanding is that any modification of the motor case or either front or rear closures makes the motor uncertified and therefore not legit. I may be wrong, but I’d like to hear a member of the BOD or Paul Holmes tell me that before I was sure. Definitely not trying to dispute James, but the way I read and hear the rules is that if you mod a motor case and closures in ANY way, they’re uncertified. My logic says it ain’t right, but many clubs apparently take it exactly that way.

…fortunately, NCR ain’t one of ’em. I’d do that if I were you and just make sure it don’t blow up in TOO spectacular a manner when the media are about.

W

[James Russell]

I don’t know if he reads the forums or not, but Dennis Billings would be the one to talk to.

Not sure who Dennis is but the person that makes the call on things like this for TRA is Paul Holmes and if there is any question then it would go to the BOD or maybe the TAP.

[James Russell]

I have talked to Paul, that is were I got my info. see bellow:

“James,

I assume we are talking Commercial motors. The dividing line for yes or no has to do with motor case integrity. If your modification compromises the case it is not allowed. This could either mean a hole through it, taking out the temper, or a thinning of the case enough to cause a bursting.

Not sure why knurling is that big of a deal if left on, but if taking it off, I would recommend not grinding it off and milling it off, instead

I would say a Redrill and an eyebolt threading is fine, except you have to make sure the temper of the case is not compromised, there is no drill through AND the guy doing the modification knows what he is doing.

That’s the crux though, how can we be sure someone did a good job at any modification. That’s why it is frowned upon.

When a manufacturer offers any changes they are supposed to come to me for approval, like the foreword fill/staging closure I approved for Skyripper motors. Then they take the liability if something does not work.

Paul”

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