Guided Drilling W/ Hardened Inserts

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It'sMe

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PGB,
I saw how a 3/8" drill bit couldn't be centered to drill a hole, but was instead chewing at the hardened insert while the hole was drilled by hand.

For those who have to drill by hand, there's got to be a better solution. A possible solution would be a shorter bit that doesn't have a cutting surface longer than it needs to be. For example, a 3/8" drill bit used for safety selectors has flutes all the way into and past the hardened insert, yet that's way too much fluting. That amount isn't needed and chews the insert.
While searching for bits, there's not much to choose from and prices can be high.
I found this but for $45 before shipping, but the shank looks like it needs to be longer.
1719621990245.png

Does anyone have a better suggestion, or an alternative idea?
PS, does anyone know if the hardened inserts are replaceable, and where insert can be found? The manufacturer spoke of this, but doesn't sell any inserts.
 
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Stone off the side cutters, just enough to dull them? Leave enough to cut the thickness of the frame. Just spitballing.

I think the correct procedure is to drill undersize and ream with a reamer. For me, the various parts are tight enough in the holes drilled with bits. I do see your point about chewing up the guides more than you need to. The guides should be harder than the bit and not a problem but who knows.
 
bkbrno said:
Stone off the side cutters, just enough to dull them? Leave enough to cut the thickness of the frame. Just spitballing.

I think the correct procedure is to drill undersize and ream with a reamer. For me, the various parts are tight enough in the holes drilled with bits. I do see your point about chewing up the guides more than you need to. The guides should be harder than the bit and not a problem but who knows.
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That's an excellent idea to dull the cutting edge of the portion of flutes that are not needed.
I don't know why one hole would be so imperfect when the others turned out fine. Technique didn't seem to change.
Slow speed and moderate pressure.

It was only one safety hole, the side housing the safety detent, that was off a bit. Maybe an ambi safety would hide the error.
 
Drilling soft metal is different than drilling steel. Look up bit sharpening for brass. the angle is very different than used on steel. I modified my drill bits based on a youtube video for drilling brass. It basically scrapes the metal away rather than cuts. The comparison of the finished holes was pretty dramatic in terms of roundness and trueness.

I do know that for drilling rivet holes in aluminum aircraft skins, you spin the bit at a really high RPM. Also you use lubricant, usually Boelube, mostly to keep metal from sticking to the bit. Most drills don't spin fast enough, people building airplanes look for a drill that spins close to 3000 RPM. The result is round and true holes. Slow and moderate pressure is for steel. Same technique in aluminum results in holes that are not round.
 
bkbrno said:
Drilling soft metal is different than drilling steel. Look up bit sharpening for brass. the angle is very different than used on steel. I modified my drill bits based on a youtube video for drilling brass. It basically scrapes the metal away rather than cuts. The comparison of the finished holes was pretty dramatic in terms of roundness and trueness.

I do know that for drilling rivet holes in aluminum aircraft skins, you spin the bit at a really high RPM. Also you use lubricant, usually Boelube, mostly to keep metal from sticking to the bit. Most drills don't spin fast enough, people building airplanes look for a drill that spins close to 3000 RPM. The result is round and true holes. Slow and moderate pressure is for steel. Same technique in aluminum results in holes that are not round.
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What I found was not an angle change, but to purposefully dull the cutter so that the bit wouldn't continually try to drive into the "brass."
I don't have the confidence to change the bit angle, but I am confident that I can dull a but.
 
Looks like you found the same or similar utube.

I didn't "dull" the bit but did hone the cutting edge square to the face. As square as I could by hand anyway. It doesn't take much to get the edge.
 
What
bkbrno said:
Looks like you found the same or similar utube.

I didn't "dull" the bit but did hone the cutting edge square to the face. As square as I could by hand anyway. It doesn't take much to get the edge.
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What sort of speed and pressure do you use?
 
When using my modified bits, I spin trigger pin size bits as fast as I can. With a standard drill bit, you have to go slow and pressure same as steel or the bit will grab and snap. Still working on a 3/8" size hole technique. I would like to drill a smaller hole first then finish it up with bigger bit. I need an insert for the insert. I also use Boelube to keep the build up off the bit. Honestly, drilling bigger holes in aluminum is an annual event at most so I'm not really an expert on this. My brother built an aluminum airplane that I helped on a little. I drilled a few holes for him. Lots of repetition and practice there. That was thin aluminum and small holes.
 
bkbrno said:
When using my modified bits, I spin trigger pin size bits as fast as I can. With a standard drill bit, you have to go slow and pressure same as steel or the bit will grab and snap. Still working on a 3/8" size hole technique. I would like to drill a smaller hole first then finish it up with bigger bit. I need an insert for the insert. I also use Boelube to keep the build up off the bit. Honestly, drilling bigger holes in aluminum is an annual event at most so I'm not really an expert on this. My brother built an aluminum airplane that I helped on a little. I drilled a few holes for him. Lots of repetition and practice there. That was thin aluminum and small holes.
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Maybe for the smaller holes you could get a bit with a smaller point. I don't know what they are called, but look like this:
1719710858844.png
 
That is a brad point bit. I see them mostly for woodworking. I have some DeWalt bits that look like that and are for metal. They didn't impress me.

I will probably use a center drill next time. I didn't know they came in 3/8" but the center drill size is 4 1/2.
 
Use number and letter drills, test drill holes slightly undersized and use a reamer for exact fitting.
 
Pern said:
Use number and letter drills, test drill holes slightly undersized and use a reamer for exact fitting.
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Do you have a video of someone else doing this that you could post? If not, no sweat.
 
bkbrno said:
Both links, different company name, same address and phone number.
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One has good reviews. IMO, both seem legit. I found the 2nd by googling, to investigate, the contact information of the first.

Recently I was trying to figure out what ammo order was in a brown box without opening it, so I searched the sender address. As it turned out Botach is who I ordered from, but another company's name appeared on the address search. Businesses do things to their advantage that may make us question what they are doing.
 
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