Specialty Dirll Bits

I am working on a design project the will require specialty drill bits to make the project economical.

I have to bore flat bottomed holes (like a Forstner bit makes) 1/4" deep in various diameters from 3/4" to 2" and then drill a through hole that is centered on the flat bottomed hole in various diameters from 3/8" to

3/4". These holes sets will be drilled in 1X4 soft wood.

Ideally I would like to find Forstner bits that have 3/8" to 3/4" centers instead of brad points. Are there such tools? And as long as I am wishing, if the Forstner section of the bit had replaceable carbide cutters it would make things much easier. So has anyone seen such a tool or have any ideas where I might be able to get tools like this made?

For the prototype I used the appropriate sized Forstner bit to make the counter bore hole and then drilled a through hole with the standard twist drills of the appropriate size. To make this project most economical, I need to drill both the through hole and the counter bore in 1 operation. The scope of the project is huge and we will be making millions of holes so any way to combine operations will be very beneficial.

Thanks in advance Greg Postma

Reply to
Greg Postma
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If you are really going to do millions, then making your own tooling is the economical way to go.

Not too difficult to make your own custom carbide bits. Brazing bits of tungsten carbide onto steel shanks can be done with a propane/air torch and

45 pct silver brazing rod and fluoride flux. Grinding and sharpening requires a tool grinder and diamond wheel. Your compound cut might be best arranged as a compound tool (several concentric pieces connected by setscrews).
Reply to
Richard J Kinch


You might see :

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My ability to make production tooling is very limited. I've been doing prototyping and if it takes me hours to make a part that in a production atmosphere will be made in seconds, so be it. I know the limits of my ability and I have neither the ability nor the background ( machining, metalurgy, heat treating,etc) that would make me think that I could design and manufacture dependable and economical tooling. That's why I am hoping to find "off the shelf" tooling that will meet our needs.

I agree with your assessment. I should be a relatively easy project to make custom carbide bits, but not for me. Again, I acknowledge my short comings and for skilled tool maker this should be a simple task. But tooldesign and tool making are not my professional fields. By rights I am a salesman, I often make prototypes of parts or packaging for our customers. My biggest asset is that I am aware of many differant manufacturing techniques and yet since I am far from an expert in any field, I am not burdened with the knowledge that "You can't do it that way". It has been said that aerodynamicaly it is impossible for a bumble bee to fly, but the bumble bee doesn't know anything about aerodynamics, so it just flies. Just think of me as a large bumble bee. I usually know what has to be done, but I am not burdened with a history of making parting an a particular manner, so I seek out the simplest method that meets the quality and economic needs of the project and attempt to design a manufacturing process that meets these needs.

Thanks for your help

Greg Postma

Reply to
Greg Postma

Thanks very much, the drills ictured here are much like what I thought I should be able to find, but didn't know where to look. I'll try to contact Precision on Monday to see if the make the size combinations I need.

It never ceases to amaze me the wealth of knowledge found on the news group. Thanks,


Reply to
Greg Postma

Hey Greg,

Sure sounds like a CNC router/engraver set-up to me. A single lip cutter is easy to come by in quantity, and if a 3/8 is used, you'd be able to do all the sizes you mention. The big problem of course is heat. Not so much heat the hurts a carbide cutter, but if it gets hot it will burn the wood. If this is to be a commercial operation, I suggest you contact an production wood-working machinery company.

Take care. Good Luck.

Brian Laws>I am working on a design project the will require specialty drill bits

Reply to
Brian Lawson

So long as the CNC is programmed not to leave the bit standing still against the wall of the hole, it will work fine. I know, because I have done similar work with my woodworking CNC router

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I'm not sure why Brian thinks a single lip is the best bet - I generally use 2 or 4 flute spiral carbide cutters for straight work.

For literally millions of holes, custom ground drill bits might make sense; they will require custom sharpening, too. The CNC router can do the same work with off the shelf bits (and if the programmer is any good, undersized regrinds are no problem - the size of the bit is just a variable that is adjusted when a new bit is installed). But the drill would be faster per hole.

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There are people out there that do such stuff as a specialty. Having a drawing of what the hole needs to be is often enough for them to work from. I'll also note that there are systems of quick change fasteners for tooling that will make changine a particular bit out for another real fast.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

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Bob May

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