if you can't get a Helicoil maybe you could make an insert with an internal thread 1/4x32 and an external thread of what ever you have
drill and tape the head for the insert and then screw the plug into that, just a thought
EDIT: I missed the rest of the post sorry disregard
Progress on the Demon has been a bit slow, I have been working on a 3 cylinder radial as well, I will put a build log up about the radial soon
This is a few of the parts I have made for the radial
This site has been around for a while, I have not had anything to do with them so I don’t know if they actually sell the casting and plans, but someone on here might know more about it
http://modelenginecastings.com/engine-casting-kits.html
Michael
Hi David
Im not familiar with sherline machines so its a bit had for me answer that
I would think if you took it slow with small cuts maybe you can do it ok
It may pay to ask the question in the forum, and someone with experience with those machine will be able to give you a better answer
Sorry...
I have found that 99.9 percent of the people that come to my place have absolutely no interest in the engines or anything else that I have made or seeing the workshop, I get mostly the same questions as timo_gross
Why I became interested in model engineering
I used to fly and race RC aeroplanes with my father, he had a lathe and mill
We would make different heads and tuned pipes for the racing planes and various other modifications
I purchased a lathe and a milling machine for my self as I moved...