Help with Tiny build

[Harry Mueller]

Hello folks,
As a relative newbie I’ve been working on the Tiny frame and was just putting the finishing touches on the crank retainer. The plans show a .086 diameter hole for the thread portion and .146 dia for the screw head relief. Unfortunately, I drilled the .086 hole all the way through into the body and of course that hole is now too big for a 2-56 thread.
Is there some conventional way to fix this? I could turn some aluminum down to .086 and loctite it in. Or do the same with some brass tubing that is close in size.
Any comments would be appreciated.
Thanks, Harry

 

[gbritnell]

Just go to the next size up 3-48. That should work.

 

[Harry Mueller]

Thanks, that would be an option and I’ll keep it in mind. Unfortunately, I don’t have any machine screws that size, only 4-40 and 2-56, and getting them locally would be difficult.
Harry

 

[kf2qd]

Unless there is a clearance issue you could use any size that would fit. Only person that will know is you, and you have learned something that will be helpful on the next project.

 

[gbritnell]

OK here's the next option. Drill and tap it for 4-40. Thread a piece of rod 4-40 with the thread length just long enough so it doesn't bottom out in the hole. Now screw the rod in until the threads bind up (tightly) Now cut the rod off and mill it flush. Redrill and tap for 2-56 thread. I don't care for Loctite with aluminum.
gbritnell

 

[Harry Mueller]

Thanks, really like this idea. I’ve put in aluminum plugs with loctite but hopefully I can drill them out tomorrow. Or can I pull the plugs out if I heat the aluminum; they extend above the aluminum flat For now. I used red loctite. The lessons continue….
On the threaded rod, should I make them out of aluminum or can I use a machine screw (The black kind)?
Harry

 

[almega]

On the threaded rod, should I make them out of aluminum or can I use a machine screw (The black kind)?

I would suggest using the same material as the parent material. If it is aluminum, then that is what I would suggest.

 

[bob shutt]

Thanks, really like this idea. I’ve put in aluminum plugs with loctite but hopefully I can drill them out tomorrow. Or can I pull the plugs out if I heat the aluminum; they extend above the aluminum flat For now. I used red loctite. The lessons continue….
On the threaded rod, should I make them out of aluminum or can I use a machine screw (The black kind)?
Harry

Harry
Just make a new base. You have the knowledge from the first one and a fix will always bother you.

 

[Harry Mueller]

Well, I’ll see what the morning brings in terms of getting those plugs out. Makes sense to use the same material.
Bob, my intention has always been to build a second version of this motor; this first one is all practice. Although there are a number of “oh crap”s on the frame they are all cosmetic so far. I’d like to keep working on this one until a fatal error is made.
Harry

 

[L98fiero]

Harry
Just make a new base. You have the knowledge from the first one and a fix will always bother you.

John Dobson, the guy that made home made sidewalk astronomical telescopes popular made his primary mirrors out of porthole glass. He made the mirrors sitting on a bench and hand grinding them and said there's no such thing as a failed mirror, worst case is you can't fix it so throw it against a hydrant and start over.