Help drilling a hardened sear

peter2772000

peter2772000

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I need to increase the diameter of the hole in my sear (from a Hi-Point 45). I managed to drill halfway thru but have snapped at least 5 different titanium bits doing so. Yes, I was using lubricating oil. I realize that the hardened metal is the culprit. Can I heat the sear red-hot, allow it to cool and then drill as required?
And afterwards, can I simply re-harden by heating red-hot again and dropping the sear in oil or water?
 
peter2772000 said:
I need to increase the diameter of the hole in my sear (from a Hi-Point 45). I managed to drill halfway thru but have snapped at least 5 different titanium bits doing so. Yes, I was using lubricating oil. I realize that the hardened metal is the culprit. Can I heat the sear red-hot, allow it to cool and then drill as required?
And afterwards, can I simply re-harden by heating red-hot again and dropping the sear in oil or water?
Click to expand...

Annealing and hardening are best done when you know what steel you are working with. Some steels are water hardening, some oil hardening, some air hardening. Quenching a water hardening steel in oil won't harden it, quenching an oil hardening steel in water may cause it to crack.

A carbide bit might do the job for you. It is most important the work piece he held solidly.
 
When you mention lubricating oil, I presume you mean "cutting oil". If this is what you meant, please disregard my post.

Please also keep in mind that repeated drilling attempts will significantly heat the metal to the point that the hardness of the sear might be changed.

Good luck!

Duke1
 
guntech said:
Annealing and hardening are best done when you know what steel you are working with. Some steels are water hardening, some oil hardening, some air hardening. Quenching a water hardening steel in oil won't harden it, quenching an oil hardening steel in water may cause it to crack.

A carbide bit might do the job for you. It is most important the work piece he held solidly.
Click to expand...
yes carbide drills. awful expensive. however u can buy the cheap masonary carbide drill bits and sharpen them in my drill doctor and it will drill right through planner blades
and bearings. use a mild steel backing so as not to
chip the bit when drill through. u can also grind the sides
in on these masonary bits to get the exact size u need.
 
as jbunny said get a masonry drill bit, they are tipped with brazed carbide. they are dirt cheap, five dollars or so for one. if your sharpening it on a grinder make sure to cut a fair bit of clearance on the heal.

this is basically what your looking for
steinbohrer1.jpeg
 
Yes, cutting oil & no, I didn't insist on overheating the metal while trying to drill through. ;)


jbunny, I don't have a drill sharpener. But if you think a drillbit sharpener would do the trick, I'm willing to try it. It's just that the last time I used one of those contraptions just to sharpen bits in general, the results were...how should I say, less than stellar :redface:


iconfig, I know what the cement bit looks like. I'm just wondering what'n hell kinda grinding I'd have to do on it so's to allow it to drill hardened steel.

GAIRLOCHIAN, you're 100% right. Far as I'm concerned, slow's best all the time. Slow with moderate weight and lotsa cutting oil is what has allowed me to use the same titanium drill set for the last 4 yrs.
 
FYI, Peter2772000,

The "titanium" on drill bits, is a coating, not the material of the drill bit itself.

Mostly it makes low grade drill bits shiny and stops them from rusting in the sea can trip from their homeland (usually China).

Titanium Nitride, Titanium CarbNitride, and a couple other "titanium's" get vacuum deposited onto the product to supposedly increase tool like, and reduce wear. Mostly, these days, it amounts to marketing gimmick.

If you ever get a chance to spend any serious time drilling holes, spring for some decent name brand drill bits from a tool supplier that deals with machine shop supplies (rather than the hobby guys, like Busy Bee, or most of the products sold at the big retailers like Ctire and Home Depot) Cleveland is good, there are lots of others.

Do you have a diamond grit knife sharpener?

You can shape carbide, slowly, with them. A dremel tool, and some diamond grit disks (steel disk with diamond grit on it) can do it too, also slow.

Either will allow you to sharpen up a small carbide tip of a masonry drill bit, if you can get one small enough to use for your hole.

Carbide end mills are sometimes cheaper than carbide drills in the small sizes, and can sometimes be fed down an existing hole to finish up what has been started in a case like this. Worth a price comparison, anyway.

Expect the drill or end mill to be trashed in the process. Contemplate the cost of a new part, vs. the cutting tools, too!

Cheers
Trev
 
Aneal the metal you need to remove by instaling a broken drill bit shank upside down in the drill press. Lower it into the hole you have already started (make sure you have removed all the oil from before, you want it dry). Now keep light presure on it and let 'er spin until a small amount of metal around the hole starts to turn red. Let the sear cool as slowly as possible. It should drill okay and as it only anneals a small area there is no need to retemper.

I've used this method to drill and tap hard recievers (03's p14-17) with good results.
 
Wow, thanks to everyone for all the tips. I'll be trying some of them out this weekend and will post the results!
As far as why I don't simply order another sear, the reason is this. Hi-Point parts aren't as of yet readily available here in Canada. But I will contact Kodiac Outpost to see if they've made any headway in rectifying this issue.

Again, thanks lots, guys. I appreciate the input! :bigHug:
 
If you choose to anneal the part first, you need to increase the thermal mass because small parts cool too quickly to anneal well. I have put small parts in a welded iron box filled with dry sand and then put that in the forge and heated it red hot. DON'T LEAVE IT RED TOO LONG or the sand will melt into glass. Anyway, once red hot just leave until everything is cool again.
As to the issue of what type of steel; when ready to retemper, heat red hot and just let it sit. When cool check with a file; if it is air hardening, it will be hard. If still soft, try oil and if that fails quench into water with 1/4 of oil on top and failing that into water.
Finally unless air hardening, draw the sear to dark brown after hardening

cheers mooncoon
 
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