Softening/Hardening/Tempering 30 thou feeler gauge

[Alan Wood 4Participant @alanwood4]

I have a strip of 30 thou feeler gauge, 1/2" x 2", that I need to drill 2 x1.5mm holes at one end and 2 x 3mm holes at the other end. (Apologies for the mixed units).

The 1.5mm holes are proving difficult so I heated the feeler to cherry heat and slowly backed off the heat and this has softened it sufficient to drill all the holes.

Question – what temperature profile to now harden and temper the feeler back to its former springy self ? I have a small kiln style oven so I can control the temperature fairly closely.

I have four such strips to make so would like an easy life and not too many broken drills.

Edited By Alan Wood 4 on 16/09/2020 17:05:57

Edited By Alan Wood 4 on 16/09/2020 17:06:26

[Alan Wood 4Participant @alanwood4]

[mechman48Participant @mechman48]

Type in the 'Search' box, 'Tempering ' will bring up a few threads for perusal. Just for interest…

**LINK**

George.

[CirclipParticipant @circlip]

Punching holes in existing "H & T" strip works.

Regards Ian.

[peak4Participant @peak4]

Maybe use tungsten carbide PCB drills, available quite cheaply from ebay and other sources in sets of 10 in 0.1mm increments.
Make sure you clamp well, and use a sacrificial steel backing plate, to save the drill breaking through and chipping its cutting edges.

I've just been using one to drill holes in "all hard" hacksaw blades to shorten them for a 9" frame.

Alternatively, if the hole sizes aren't absolutely critical, a new(ish) centre drill works OK, again with suitable close clamping and a backing plate.

Bill

[VicParticipant @vic]

Yes I was thinking carbide drills. Much easier than messing with heat treat. Although carbide drills are easy to break in that size! Good luck with the project.

[Martin KyteParticipant @martinkyte99762]

You get my vote for punching. Clock suspension springs are done that way. Nothing fancy is required just a couple of short peices of strip with two locating pins to align them. Drill and ream through both for the hole dia required and turn up a couple of silver steel punches the corect dia. Harden if you feel like it but for a couple of holes you don't need to.

regards Martin

[Alan Wood 4Participant @alanwood4]

Thanks for all the helpful support on this. I have made one attempt at heat treatment which helped but wasn't perfect and was a real pain.

Working on a Plan B.

Thanks again

Alan

[Ian PParticipant @ianp]

I have used diamond burrs to make holes in shim stock.

I bought a cheap set of burrs (about two dozen of all shapes and sizes) that have 1/*2 diameter shanks, I usually start the hole with a ball shaped one and then change to conical. Square or other shaped holes are possible too.

Ian P

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