For such a small project like a dimple, I don't think I'd bother using any lube (and didn't with my AR barrel).

 

How fast are you spinning the bit? Usually if you have the speed too high, or the feed rate too slow, it will burn the bit and cause the problem that you describe.

It's best to start off with a machinist grade bit (cobalt would be great), and turn it at a slower RPM.

 

How fast are you spinning the bit? Usually if you have the speed too high, or the feed rate too slow, it will burn the bit and cause the problem that you describe.

It's best to start off with a machinist grade bit (cobalt would be great), and turn it at a slower RPM.

I'm guessing the $3.60 I spent on a cobalt bit isn't getting me machinist grade steel. But plenty of people seem to have done this with ordinary bits you get at big box hardware stores.

I'm running the drill slow, very slow. Handheld drill with barrel held in a vise.

Check out the video in the first post - how the heck is he carving up the steel so quickly? In the comments he says he's using a cheap bit (does not identify material/coating).

 

Dude,

Its a small notch for a set screw, we are not building a steel bridge here. Get it set and you are good to hook. The depth is not as critical as you think. BTW, stake the screw when done.

John

 

The depth is not as critical as you think.

Depth is not the issue. Current dimple isn't as wide as the tip of the screw, so it won't actually act to resist movement if the barrel were subjected to such.

As mentioned earlier, I can get this done with the cobalt bit I have, but I'd like to understand why it's taking so long and why the steel isn't being carved out as per the video.

 

you may have a different steel in the barrel

this happens to me at work all the time, some screws drill really easy and i can make a nice hole for an easy out in no time, and some i got to cuss at for a while before i make a hole big enough for an easy out

 

To answer your question re: drill press, Yes having a press makes that much of a difference. A bench top drill press isn't a huge investment but it's great to have when you need one. Or of course, live near someone that has one

 

Drypowder I could tell you I have drilled many of these with no issue...but that really doesn't help you. I can tell you how I do it and some will gasp and moan.

Get it str8 and tighten down the screws. Take one screw out and place the barrel and block on your benchtop drill press that have been set up to run as slow as possible. Use a bit that just clears the threads to dimple the barrel. Put that screw back in tight and remove other screw, repeat process. If the dimple is not large enough, remove gas block and use a larger bit to enlarge dimple.

I use a $60 benchtop press and titanium nitride bits all chi-com junk from Harbor Freight. Never had a problem and I always get tailings that would make a machinist proud.

I would have to guess that you are definately running your bit too fast and blinding the bit.

You may have surface hardened the steel with earlier efforts as well, which makes later efforts a real chore. I can't imagine any barrel steel that would require carbide bits, try cutting some 306 stainless and you will imagine this little venture a walk in the park. Lubricating oils often make poor cutting oil. Cutting oil contains sulphur which aids in machining.

 

you may have a different steel in the barrel

this happens to me at work all the time, some screws drill really easy and i can make a nice hole for an easy out in no time, and some i got to cuss at for a while before i make a hole big enough for an easy out

Good point. And yeah, been doing plenty of cussing!

To answer your question re: drill press, Yes having a press makes that much of a difference. A bench top drill press isn't a huge investment but it's great to have when you need one. Or of course, live near someone that has one

Is that because you can apply more force with a drill press without damaging the motor than you can with a handheld/cordless?

Drypowder I could tell you I have drilled many of these with no issue...but that really doesn't help you.

Exactly. I've already linked a video where a guy dimples the barrel in seconds with a handheld drill and what he says is a cheap bit. So I already believe it's possible!

I can tell you how I do it and some will gasp and moan.

Get it str8 and tighten down the screws. Take one screw out and place the barrel and block on your benchtop drill press that have been set up to run as slow as possible. Use a bit that just clears the threads to dimple the barrel. Put that screw back in tight and remove other screw, repeat process. If the dimple is not large enough, remove gas block and use a larger bit to enlarge dimple.

I use a $60 benchtop press and titanium nitride bits all chi-com junk from Harbor Freight. Never had a problem and I always get tailings that would make a machinist proud.

I assumed (you know what they say about that) that any half-decent drill press would be too expensive to justify for once-in-a-blue-moon usage. But maybe not. I'll take a look at HF's offerings.

I would have to guess that you are definately running your bit too fast and blinding the bit.

You may have surface hardened the steel with earlier efforts as well, which makes later efforts a real chore. I can't imagine any barrel steel that would require carbide bits, try cutting some 306 stainless and you will imagine this little venture a walk in the park. Lubricating oils often make poor cutting oil. Cutting oil contains sulphur which aids in machining.

You may be right. I was running the drill faster earlier on (thinking this should be done in under 1 min).

 

You need a solid carbide drill bit if the others are not working. The down side is they are expensive and must be used in a drill press to prevent breakage, any bending and they will snap. What size dimple are you trying to make and I will see if I have one. If so and if you are willing to drive to Fuquay I can let you use my press.

 

You need a solid carbide drill bit if the others are not working. The down side is they are expensive and must be used in a drill press to prevent breakage, any bending and they will snap. What size dimple are you trying to make and I will see if I have one. If so and if you are willing to drive to Fuquay I can let you use my press.

~5/32" / 11/64". I'm almost done with this one, but may have another one to do in the near future. A relaxing cruise over to Fuquay beats the frustration of this first go-around!

 

You are also welcome to stop by my shop in New Hill. I have carbide, cobalt and machinist grade bits as well as a nice drill press and some barrel vise blocks.

 

Nothing wrong with a cheap drill press from Hazzard Fraught tools. They have no place in a real machinist's shop but then I am only an imitation machinist. They are fine for small household projects and light use. I bought mine because of the very things you are writing about here in this thread. Mine sits in the corner of my loading bench and has a multitude of uses including trimmng and deburring cases.
If I can find a coupon I will send it your way, not sure if they have one this month on the small drill press. I will check.

 

Don't use CLP as cutting oil, it has lots of additives whose sole purpose is to prevent what you're trying to accomplish. Clean it all off and try with a new cheap drill and I bet it cuts fine.

 

Nothing wrong with a cheap drill press from Hazzard Fraught tools. They have no place in a real machinist's shop but then I am only an imitation machinist. They are fine for small household projects and light use. I bought mine because of the very things you are writing about here in this thread. Mine sits in the corner of my loading bench and has a multitude of uses including trimmng and deburring cases.
If I can find a coupon I will send it your way, not sure if they have one this month on the small drill press. I will check.

Usually HF has a 20% off one item coupon you can use online or print out for in-store use.

Like this one:

http://www.harborfreight.com/digitalsavings.html

 

You are also welcome to stop by my shop in New Hill. I have carbide, cobalt and machinist grade bits as well as a nice drill press and some barrel vise blocks.

Thanks, I appreciate the offer. I'm certainly curious now to see the difference a drill press makes.

Messing around with installing the gas tube roll pin (with only a roll pin punch, no starter punch), I was thinking I could make myself a roll pin starter punch with a drill press.

Nothing wrong with a cheap drill press from Hazzard Fraught tools. They have no place in a real machinist's shop but then I am only an imitation machinist. They are fine for small household projects and light use. I bought mine because of the very things you are writing about here in this thread. Mine sits in the corner of my loading bench and has a multitude of uses including trimmng and deburring cases.
If I can find a coupon I will send it your way, not sure if they have one this month on the small drill press. I will check.

I know which drill press you're referring to. No need to look for the coupon, I've seen those before and I'm on their snail- and e-mail lists so I'll keep an eye out for it.

Don't use CLP as cutting oil, it has lots of additives whose sole purpose is to prevent what you're trying to accomplish. Clean it all off and try with a new cheap drill and I bet it cuts fine.

Yep, lesson learned. I'm already done with this one, but will definitely get actual cutting fluid for next time I need to drill metal.

Usually HF has a 20% off one item coupon you can use online or print out for in-store use.

Like this one:

http://www.harborfreight.com/digitalsavings.html

Heck I've got a 25% off one item coupon and drill presses aren't excluded.

 

Barrel steel is typically 4150 or similar, around 30 rockwell C. The cheapest drill bit will cut it. One thing to remember is standard drill bits do not cut at their center. The chisel point at the web "pushes" material out to the cutting edges. This takes some force. If you are not applying enough force the chisel point will round quickly and generate heat. Slow is not the answer, a 1/8" drill @ 80 surface feet/ minute = 2400 RPM. A split point drill will help a lot, especially with a hand drill.

standard vs split point

 

Phudd - very good post. The reason that I recommended slow is that it will usually prevent the bit from overheating / rounding over if not enough force is applied.

 

I had a friend over yesterday dimpling his barrel (same make/model barrel).

Things we did differently from last time (still using hand drill though):
1. No use of black oxide bits at high speed. Only used titanium nitride split point and cobalt split point bits.
2. No CLP. Used actual cutting fluid.

End result? Process was sped up by ~25-40%. Still nowhere near the seconds the OP in the video shows - and the guy there is also using a hand drill, no cutting fluid and a cheap bit.

Seems there must be some differences in barrel hardness.