Anyone know what this is

[SteviegtrParticipant @steviegtr]

I stole a cache of drill bits on ebay the other day. Most are only what i could call miniature centre drills. Some are only 1mm dia. Up to around 5mm. There were 22 in total all pretty much unused & most are solid carbide.

One drill a 4 flute is to me a bit strange in form. Can anyone tell me what it is. I have not done any google etc yet, but thought i would share with you guys. I am guessing as me some of you will not have seen this profile before. So for those that do know, Prey tell.

Steve.

[SteviegtrParticipant @steviegtr]

Can anyone shed any light on this drill bit.

[Dave SParticipant @daves59043]

Suspect it's a combo drill/ mill bit for PCB manufacturing.

Dave

[Bill Davies 2Participant @billdavies2]

Is it a core drill? More rigid than a two fluted drill, used instead on removing material from a cast hole. But I haven't seen one with cutting edges to the centre. But no, the size is far too small.

Bill

 

Edited By Bill Davies 2 on 31/07/2021 23:04:43

[SteviegtrParticipant @steviegtr]

I still have no idea.

Steve.

[Kiwi BlokeParticipant @kiwibloke62605]

I think it's rather pedantically called a 'carbide 4-flute drill mill'. Examples shown on http://www.maritool.com website. Sorry, I can't tell you any more than its name, but it gets one's search engine going. Hopefully, the indefatigable MG will be along soon, with more information, patents, etc.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Kiwi Bloke on 01/08/2021 02:14:38:

I think it's rather pedantically called a 'carbide 4-flute drill mill'. Examples shown on http://www.maritool.com website.

[…]

.

From whence we learn: Carbide Drill Mills are great for chamfering, countersinking, spotting, and profile milling.

and are invited to: Save tool positions in your machine by using this versatile tool.

Probably convenient in some production scenarios.

MichaelG.

[JasonBModerator @jasonb]

The angle of the end of Stevies does not make it look like the sort that can be used to chamfer and csk as it looks to have a shallower point not a 90deg one which the multi purpose ones have. Just looks to have a 120-130deg point.

The code number is similar to an ITC tooling one but the catalogue doe snot corrispond with the tool shown here, Stevie, what is on the shank just before the size as that may be the maker but can't see due to glare.

[jimmy bParticipant @jimmyb]

I can't help on this one, but have seen carbide drills with 2 extra "flutes" to give additional strength.

Any chance of some close up pictures of the flutes?

Jim

[Michael GilliganParticipant @michaelgilligan61133]

The whole thing [diameter and tip-detail] looks like a custom re-grind to me

What manufacturer would produce a stock product with part of its identification number ground away ??

MichaelG.

[MichaelRParticipant @michaelr]

Looking at the flutes it looks like it may be a modified masonry drill.

MichaelR.

[old martParticipant @oldmart]

The difference in the surface finish either side of the step, and cutting off part of the laser etched characters makes me suspect it has been modified for a special job. I think they started life as normal end mills. Having both drill and mill characteristics makes them very versatile for home use.

Edited By old mart on 01/08/2021 15:53:08

[SteviegtrParticipant @steviegtr]

Posted by JasonB on 01/08/2021 07:11:53:

The angle of the end of Stevies does not make it look like the sort that can be used to chamfer and csk as it looks to have a shallower point not a 90deg one which the multi purpose ones have. Just looks to have a 120-130deg point.

The code number is similar to an ITC tooling one but the catalogue doe snot corrispond with the tool shown here, Stevie, what is on the shank just before the size as that may be the maker but can't see due to glare.

Jason i also found the near No in the ITC cat. Also similar in the Widia range. It appears to be a 4 flute end mill. Although the strange graphic before the S.P No does look a bit like the ITC logo. With a tapered section i guess to cut grooves. ?????.

Steve.

[JasonBModerator @jasonb]

Which part is tapered? or do you mean the "point"

One quick way to tell if it's a regrind may be to have a quick measure of the diameter at the business end and see if it is the 5mm dia engraved on the shank

[Howard LewisParticipant @howardlewis46836]

Certainly two of the edges appear to have been ground like an end mill, or a four facet drill.

Quite a fast helix, so was for some special purpose, not jobber drilling.

Possibly a one off regrind for a specific purpose, known only to the original owner!

Howard

[Nick Clarke 3Participant @nickclarke3]

Perhaps a tooth chipped 5:00 Friday with a job due out Monday so the chipped tooth is ground back to avoid binding/scoring?

Certainly if the lowest ground tooth is to cut it would suggest a 3mm depth of cut for the other teeth which is unlikely with a 5mm cutter.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Dave S on 31/07/2021 23:01:04:

Suspect it's a combo drill/ mill bit for PCB manufacturing.

Dave

I like Dave's theory best.

• Has a drill tip, so can plunge.
• 4 flutes, which are for rapid swarf removal and side cutting,
• Made of carbide, which is good for abrasive materials.
• Secondary edges are good for removing wisps of fibrous material; some wood drills are like this.

Printed Circuit Boards are made of a highly abrasive insulator, such as fibre-glass, bonded at high pressure in resin. The boards typically make short work of HSS, which is too soft, and are drilled and milled with carbide cutters run at very high speed – 20000rpm or more.

Two mill-drill features are common on PCBs: mounting holes and anti-tracking/isolating slots

Not an obvious example compared with many but the bottom left mounting hole above, one of four otherwise drilled cleanly, has been widened and ovalled slightly by waggling the cutter. The purpose is allow slack during assembly, rather than go to the trouble of precisely aligning four pillars with four holes.

In the next example, the cutter has made four long slots, which are used to prevent high-voltage tracking or to improve signal isolation via an opto-coupler. No whiskers allowed.

I think these requirements are met well by Steve's cutter. The fibre trimming feature won't add any value but otherwise I think it should cut metal OK. Try and see. Looks OK in Steve's picture, but if it's been used on PCB, the cutting edge might be blunt.

Dave

[SteviegtrParticipant @steviegtr]

Posted by JasonB on 01/08/2021 07:11:53:

The angle of the end of Stevies does not make it look like the sort that can be used to chamfer and csk as it looks to have a shallower point not a 90deg one which the multi purpose ones have. Just looks to have a 120-130deg point.

The code number is similar to an ITC tooling one but the catalogue doe snot corrispond with the tool shown here, Stevie, what is on the shank just before the size as that may be the maker but can't see due to glare.

I think you nailed it Jason & others. The main shank where the writing is measures 5mm exactly. The rest is 4.52mm.

Steve.

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