Making single flute D bit

[FTlatheworks]

The borax just keeps the steel from oxidizing and pitting when you do your heat treat. As far as I know, it plays no other role in metallurgy. Removing stock with a regular drill and finishing the profile with a D-bit will make it easier when you are going for a flat bottom, but no pilot hole is needed for a D-bit if you grind a relief on the bottom edge from center on the non-cutting side. Just extend the 30 degree relief in the diagram below all the way to the center and it will plunge and leave a flat bottom. For more info, read the attached Deckel manual for a brief, or check some of the texts like Moltrecht if you have a copy, or the Workshop Practice series available on our H-M download library.

Awesome, thank you.

 

[FTlatheworks]

If you search this site you will find a video where I drilled a steel plate with a flat bottomed drill. I drilled straight into the plate without a starting hole. The drill cut about .005 oversize. I used a new Harbor Freight drill that I cut shorter to make it more stout. Jimsehr

That’s not bad. Unfortunately this hole needs to be perfect, so I will be making a couple thousandths under 5/8 when I make this d bit.

 

[Jimsehr]

That’s not bad. Unfortunately this hole needs to be perfect, so I will be making a couple thousandths under 5/8 when I make this d bit.

I wish you well with your d bit. I can make a flat bottomed drill in about 10 to 15 minutes. So I could make an undersized flat 5/8 and follow it up with a flat 5/8 if I had to be sure of finished size.
Jimsehr

 

[FTlatheworks]

I wish you well with your d bit. I can make a flat bottomed drill in about 10 to 15 minutes. So I could make an undersized flat 5/8 and follow it up with a flat 5/8 if I had to be sure of finished size.
Jimsehr

How did you grind that so nicely. I’m at the mercy of my crappy grinder mounted in a dumb place at work. I want to design a surface grinder with an XYZ vice using a cheap bench grinder, or any motor for that matter. I have tried to match your clearance angle and it still doesnt cut worth a damn. Is it possible I have burnt the bit up grinding on it. Maybe I took some hardness out? You guys are making it seem so easy, but I have never seen anyone do it nicely in person and have it come out like a pricey flat bottom bit, D bit, or End mill holes. I should also mention I am drilling this hole 1/2 inch depth at a 10 degree angle.

 

[Janderso]

If you search this site you will find a video where I drilled a steel plate with a flat bottomed drill. I drilled straight into the plate without a starting hole. The drill cut about .005 oversize. I used a new Harbor Freight drill that I cut shorter to make it more stout. Jimsehr

Yeah, I found that Jim.
Pretty sweet. It looks like a center cutting end mill made from a broken drill bit.
A keen eye for sure.

 

[FTlatheworks]

How did you grind that so nicely. I’m at the mercy of my crappy grinder mounted in a dumb place at work. I want to design a surface grinder with an XYZ vice using a cheap bench grinder, or any motor for that matter. I have tried to match your clearance angle and it still doesnt cut worth a damn. Is it possible I have burnt the bit up grinding on it. Maybe I took some hardness out? You guys are making it seem so easy, but I have never seen anyone do it nicely in person and have it come out like a pricey flat bottom bit, D bit, or End mill holes. I should also mention I am drilling this hole 1/2 inch depth at a 10 degree angle.

Alright, I get it now. The angles on a drill bit are much more complex and the pics don’t capture what really needs to happen. I think I understand d bits and making a flat bottom from old bits. Here it is guys! Thanks for sticking with me to figure this out . I will show the bit, then the results in a little bit… no pun!

 

[FTlatheworks]

Did better, not great. I think I could get the bit better with more work.

 

[Jimsehr]

Did better, not great. I think I could get the bit better with more work.

If you mail me a drill I will sharpen it for you. And that way you will have a model. So that you can learn to sharpen your own. You pay postage both ways and it’s a deal. Jimatcf@hotmail.com
How you learn practice, practice, practice.
By the way ANY drill will probably cut 3 or 4 thousands oversized.
Most important thing grinding a flat bottom drill is splitting the point.
Jimsehr

 

[FTlatheworks]

If you mail me a drill I will sharpen it for you. And that way you will have a model. So that you can learn to sharpen your own. You pay postage both ways and it’s a deal. Jimatcf@hotmail.com
How you learn practice, practice, practice.
By the way ANY drill will probably cut 3 or 4 thousands oversized.
Most important thing grinding a flat bottom drill is splitting the point.
Jimsehr

I’ll take a pic, but I got it down last night. I appreciate the offer though.