Odd drill bit

Mike_K · Feb 1, 2021

Hey,

I have an odd drill bit that I won as part of a lot at an auction. It's a 4-flute but the flutes are not evenly spaced around the diameter. 2 of the flutes are paired relatively close to each other and the other 2 also but on the opposite side of course. It has a W-B-D logo on it with M-S under the logo. I could not find any info for WBD on the Internet. It's marked as 47/64" x 3/4" (that's the oddity to me). It also has these markings A-7 and 197D. It is 3" FL and 6" OAL with a ~0.346" shank.

Any help in identifying it would be appreciated.

Thanks,
Mike

Mtndew · Feb 1, 2021

Core drill maybe?
It still only has 2 cutting flutes,so it's not a 4 flute.

Scottl · Feb 1, 2021

My first guess is that the bit is for drilling some sort of very gummy material and the design is to ensure stiffness with minimal friction.

The grind angle(s) should give some clues as to intended material.

DDoug · Feb 1, 2021

mike_k said:
hey,

i have an odd drill bit that i won as part of a lot at an auction. It's a 4-flute but the flutes are not evenly spaced around the diameter. 2 of the flutes are paired relatively close to each other and the other 2 also but on the opposite side of course. It has a w-b-d logo on it with m-s under the logo. I could not find any info for wbd on the internet. It's marked as 47/64" x 3/4" (that's the oddity to me). It also has these markings a-7 and 197d. It is 3" fl and 6" oal with a ~0.346" shank.

Any help in identifying it would be appreciated.

Thanks,
mike

f-o-c-u-s !
.

Booze Daily · Feb 1, 2021

Subland Step Drills Manufacturer - Subland Drill (2-2) | RTS Cutting Tools, Inc.

cyanidekid · Feb 1, 2021

Obviously not a step drill or a "core drill".

( side note; four flute "enlarging" drills are often called "core Drills" even by the manufacturers, but they should NOT be, they do not produce a core)

if the additional lands are the same diameter as the primaries, as it looks, they are for additional guidance and stability when drilling. perhaps in something prone to dig and chatter, like brass?

the 3/4" could have been the original shank, and it got turned down at some point?

sfriedberg · Feb 1, 2021

Physically, it's a dual land or sub-land drill. Given that 47/64" is 1/64" less than 3/4", I strongly suspect if you put a micrometer across the leading set of lands you would find they are 47/64", and the trailing set of lands is 3/4" diameter. If this is the case, this drill was intended for combined rough and fine drilling in one pass.

Other uses of sub-land drills include step drilling (with a larger difference in land diameters) and stability in tough/interrupted condition (no difference in land diameters).

David_M · Feb 1, 2021

Another drill that uses double lands is a brad-point drill.

Mark Rand · Feb 1, 2021

cyanidekid said:
( side note; four flute "enlarging" drills are often called "core Drills" even by the manufacturers, but they should NOT be, they do not produce a core)

No insult intended, but:-

This is another case of the original definition being completely changed as people come into the trade*. Core drills are used for drilling out cored holes in castings. Anular cutters and hole saws are used when it is desirable to leave a core.

Exactly how is a "core drill" used?

*Like the practice of calling rotating centres live centres

rustyironism · Feb 1, 2021

I would swear that I have a similar drill bit here somewhere, but these are as close as I have found.
one is 27/32 and the other is 31/32
F.B.Tools
Speedicut HS
Made in England

Brit. Pat. 699716
US Pat. 2769355

...from google patents..

US2769355A - Fluted cutting tools
- Google Patents

Invented by William Henry Crisp and assigned to Firth Brown Tools, Ltd. in the 1950s.

a small paragraph from the patent..

"It is an object of the invention to provide on a tool of the kind described simple means for breaking up the material removed by the tool into small pieces and thereby to facilitate the clearing of the material from the flutes.

According to the invention a tool of the kind described is characterised by a rib extending lengthwise of each flute and on the rearwardly directed face thereof (considered in relation to the direction of rotation).

Preferably the rib is spaced, in the radial direction, by only a small distance from the base or root of the flute."

Another patent by Mr. Crisp reads similar, but no drawing shown..

CH327036A - twist drill - Google Patents

..now I have to drill some holes to see how they work!

Mike

EPAIII · Feb 1, 2021

The RTS web site claims that the double flute system allows two steps to be optimized for each diameter so that size and concentricity are improved. That makes sense if it is sharpened as a step drill, which yours is not.

Another thing that I see is that it can function as a reamer in that the extra flutes will help in keeping the hole round, rather than three lobed. You can mike the two sets of lands to see if they are the same, which would support this idea, or different.

It is probably an expensive drill bit.

sfriedberg · Feb 1, 2021

rustyironism said:
I would swear that I have a similar drill bit here somewhere, but these are as close as I have found.

Ah, now those are a bit different. What you have there is a flute design with sort of a built-in chipbreaker. I would not group those with dual land or sub-land drills, because there is only one actual land.

juergenwt · Feb 1, 2021

Could be somebody had a reamer and made it into a drill. Reamers are often unevenly spaced. Check out your MHB under "uneven spacing for reamers". This is done to prevent chatter when using even number flutes on reamers.

richard newman · Feb 1, 2021

Booze Daily said:
Subland Step Drills Manufacturer - Subland Drill (2-2) | RTS Cutting Tools, Inc.

I'm thinking it was one of these, and then someone ground off the 47/64" portion. The grind looks kinda sloppy to me.

Limy Sami · Feb 2, 2021

Over here and back in the day (and they were very old school then!!) we knew very similar looking things as reamer drills as in to get a more accurately sized hole in one op.

IIRC / somethings nagging - they were an invention of / made by BSA.

Asquith · Feb 2, 2021

Limy - The 1952 BSA small tools cat. shows 'BSA Blue Arrow double diamter drills'. They had extra flutes, and a short smaller diameter drill portion at the tip. 'Developed for double diamter drilling and so designed as to enable the drills to be reground and maintain their original construction. These drills are manufactured in a number of sizes with 3/8" diameter pilot as a minimum.'

Similar aim to the Subland drills, I suppose.

Limy Sami · Feb 2, 2021

Thanks Asquith :cheers:

Mtndew · Feb 2, 2021

cyanidekid said:
Obviously not a step drill or a "core drill".

( side note; four flute "enlarging" drills are often called "core Drills" even by the manufacturers, but they should NOT be, they do not produce a core)

No shit Sherlock. They are typically used to enlarge holes in castings. And normally they are 3 flute.
:rolleyes5:

Hardplates · Feb 2, 2021

Wow everyone seems to have an idea but I have yet to see anyone post (in all fairness I didn't read very carefully) that is simply looks like a double margin drill

Mike_K · Feb 2, 2021

Both set of lands measure nearly identical at ~0.743". No telling what it was originally but you might be right.
Due to less than vigilant sharpening no telling what it was originally. The largest OD I can get off the body is 0.7485". So ideal for 3/4" hole drilling with a reamer follow up.

Thanks,
Mike

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