Model Engine Maker

Help! => Mistakes, muckups, and dangerous behaviour => Topic started by: AVTUR on January 12, 2020, 07:29:05 PM

Title: Broken screw in die
Post by: AVTUR on January 12, 2020, 07:29:05 PM: I have a little problem. How do I get the broken bit of a screw out of a die?

I think the set up to cut the thread was OK. The screw broke at the die during the second pass. The lathe spindle was being turned by hand and a thread cutting lubricant used. The material was mild steel.

I am making 7 screws and this was the fourth. I put it down to pure exuberance; that is, not backing off frequently.

:'( :'(

AVTUR
Title: Re: Broken screw in die
Post by: Jo on January 12, 2020, 07:33:27 PM: 12BA = it is small, so get a jewellers saw out, poke a thin metal cutting blade through the hole in the die and having tensioned the blade in the saw frame carefully cut into the screw. Move the blade into the next hole and cut again into the screw. Repeat down the split in the die.

It should come out ;)

Jo
Title: Re: Broken screw in die
Post by: Jasonb on January 12, 2020, 07:43:20 PM: You can also expand the split die a little and see if you can get the broken bit to turn and screw out.
Title: Re: Broken screw in die
Post by: AVTUR on January 16, 2020, 03:47:45 PM: Jo and Jason

Thanks for the suggestions. I should be collecting two new dies from a local supplier, in the next village, in the next few days.

I think I will encapsulate the die in clear plastic and keep it as a desk trophy.

AVTUR
Title: Re: Broken screw in die
Post by: zeeprogrammer on January 16, 2020, 06:47:33 PM: Quote from: AVTUR on January 16, 2020, 03:47:45 PM
I think I will encapsulate the die in clear plastic and keep it as a desk trophy.

I like that. :Lol:

If I did that for all my most memorable failures...we'd be out of clear plastic.
Come to think of it...some of my stuff should go into opaque plastic.
Title: Re: Broken screw in die
Post by: awake on January 16, 2020, 09:11:24 PM: How small is a 12BA? Yet another option, if you have a mill, is to get some cheap carbide endmills from eBay or other sources, assuming you can find some small enough. Spin the endmill as fast as you can, and peck out the screw.

I had to do this recently after breaking a tap in a part - in my case, 2mm endmills were an appropriate size. Obviously, the larger the endmill, the less fragile!
Title: Re: Broken screw in die
Post by: steamer on January 16, 2020, 09:13:04 PM: I see at least 2 plausable ways to do it. I'd go for the ball end mill myself...but the piercing saw will work if the screw isn't hard.

Dave
Title: Re: Broken screw in die
Post by: tghs on January 16, 2020, 09:36:55 PM: being at under 1/16th for 12BA take a dremel and grind out the threads,chips and burrs in the round holes near where break happened,, then try a #60 drill from the back side,, it may spin out.. no use wasting a HSS die..
Title: Re: Broken screw in die
Post by: Jo on January 17, 2020, 07:53:35 AM: The tapping size for a 12BA is 1mm. Things will happen very quickly with power tools in the die :paranoia:

Jo