Repairing a thread in a blind hole

SteadyRed

SteadyRed

Western Thunderer
Repairing a thread in a blind hole.

Just opened my Metalsmith rivet press, upon assembling it, discovered the blind threaded hole which takes the depth stop screw thread is damaged.

The start of the thread is flat so the screw cannot get a grip.

If the hole wasn't blind & I knew what thread I could run a tap down it to clean up the thread.

Any suggestions.

I should add the threaded material as a light alloy.

Dave
 
Steve Cook

Steve Cook

Flying Squad
Dave
As you have the fixing screw then you can measure that to determine the thread size. Outside diameter plus the internet should hopefully sort that out.
Two options spring immediately to mind for the hole:
1. Counterbore the top of the thread to get rid of the damaged part using something like a 5mm drill. You will have to pick the start of the thread out using a knife blade, small file or end of a scriber, but if its a soft alloy it won't be too bad.
2. Just try and work back up the thread with either a small triangular file or tools as above. I 'm assuming from your description that the thread is present, its just the top part that is damaged.

The other alternative is to send it back and ask for a replacement or ask Metalsmiths advice.

Cheers
Steve
 
Arty

Arty

Western Thunderer
It's M4 x20mm dp, so presuming it's the very top of the tapped hole is damaged, running a taper/second tap down should solve the problem.
If it's any worse than that, you could always drill out 4.5mm and tap M5 and replace the screw and lock nut.
 
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