Anyone know the specs on the bottoming tap for our 12mm head bolt holes?

 

Search feature my friend, it's 12mm x1.75: https://www.dieseltruckresource.com/...=bottoming+tap

 

The search feature of this site is unfathomable!

 

Way back in my gun shop days, I sometimes made bottoming taps by cutting square the ends of regular taps that had been broken; you break lots of taps when messing with rifles.


If a bottoming tap is not handy, you can even cut an un-broken regular tap, rather than wait on UPS.

A diamond disc in a Dremel works fine.

 

Good point. I can do that! Thanks!

 

when you go to buy your tap get HIGH SPEED STEEL taps only if it dosent say HS or HIGHSPEED on it dont buy it it will be a Corbon steel tap and they are JUNK. most of the tap I see at the hardware stores Lowes Home depo and the like are carbon steel taps. I found out the hard way about this. I buy and sell a fair amount of used machine shop tooling if I find any carbon steel taps they go right in the scrap metal bin even if they are new. Ken

 

Surprising though it may seem, just about any el-cheapo tap and die set that I have used have good hi-speed steel and seem to last indefinitely.

I have a small SAE set that came from K-Mart many many years ago that has cut thousands of threads and all are still going strong.


Probably ten years ago, I bought a suit-case full of Metric and SAE taps/dies at Harbor Freight and my experience with them has been likewise.

It's kinda funny, but a friend bought an almost identical set off one of those pricey tool trucks; he probably threads one hole to my fifty and nearly all of his high-dollar taps have already broken.


On the contrary, thinking I was doing the "right" thing, I have spent big money on single taps and had them snap like glass in the first hole.

 

If they snap like glass the tap is most likey carbon steel tap ken

 

What kind ov rifles you messin' with that need M12x1.75 bottoming taps? Bofors?
cheers,
Douglas