drilling HSS

[Douglas JohnstonParticipant @douglasjohnston98463]

I am in the process of building a PCB cutter using a pair of HSS planer blades picked up on ebay. In order to mount the blades on a carrier it would be beneficial to drill the blades but do not know if this is possible.

 

The blades are about 300mm long and 20mm wide with a thickness of 3mm. Is it possible to cut a 4mm hole through HSS of this thickness with any sort of carbide or diamond cutter.

 

Doug

[Douglas JohnstonParticipant @douglasjohnston98463]

[WeldsolParticipant @weldsol]

You could consider spark erosion I’m sure there must be a company local to you that would do it.

 

Paul

[Keith LongParticipant @keithlong89920]

Hi

Have you thought about clamping the blade to the carrier with a back ledge for the blade to locate against – pretty sure the guillotines that we had where I worked used this principle for both metal cutting and pcbs.

Keith

[Douglas JohnstonParticipant @douglasjohnston98463]

Hi Keith

 

What you say is pretty much what I had in mind, but the problem is how to hold the blade in position without any clamping device protruding from the surface which would interfere with the fixed blade. Perhaps superglue might do the job if I can’t drill the HSS.

 

Doug

[mgjParticipant @mgj]

You could use superglue, or one of the rubber loaded epoxies by 3M, but one has to ask why use HSS at all.

 

The only advantage of HSS is that it retains its temper/mechanical properties at high temperatures, which a guillotine chompingg PCB is not likely to impose (is it continuous production?)

 

If temperature is not a problem in use, I’d use gauge plate. Drill and thread and then harden as normal. It’ll actually end up harder than HSS, so it could well score both ways.

 

 

 

Edited By mgj on 20/02/2011 19:07:51

[chris stephensParticipant @chrisstephens63393]

Hi Douglas,

What MGJ says, but if you do want to drill HSS a solid Carbide drill should do it. There is a warning about carbide drills, they are very brittle and best not used free hand. Oh and they are not cheap, either.

chriStephens

[Hugh GilhespieParticipant @hughgilhespie56163]

Hi Doug, You can drill almost anything using abrasives. I used to be involved in making a telescope mirror and the abrasive technique was the best method for drilling thick (2 inch) glass blanks. You use silicon carbide abrasive, say about 240 grit size and a bit of copper or brass tube as the ‘drill’. The tube size is chosen to give whatever hole size you want. Just cut a piece of tube a couple of inches long with a fairly square end. Stick the tube in a chuck, set for about 100 – 200 rpm. Now make a little plasticine or whatever circular dam on the piece to be drilled and fill it with the SiC and water – sort of a thin slurry. Start your drilling machine and very gently lower the quill onto the work (actually the very gently stuff is for glass, probably doesn’t matter too much with HSS). Keep a firm pressure on and in a pleasingly short time you will have a through hole. If it takes a long time, you may need to change the brass/copper tube – it wears away fairly quickly. The hole is slightly larger than the OD of the drilling tube but not by much.

 

Have a go!

 

Regards, Hugh

[David ColwillParticipant @davidcolwill19261]

When I did this I hung a weight off the drill handle and pottered around while it happened.

Edited By David Colwill on 20/02/2011 23:32:52

[Ian S CParticipant @iansc]

Hugh, you beat me too it, I made a mandrel with a spring on it that presses the bit of tube against the work so that you just lower the drill press so that the tube presses lightly on the work, with some grinding paste under the tool, switch on and go and do some thing else. I tried it out on the hardened face of an automotive valve lifter, it took quite some time, but went through ok, and left me a small hardened cylinder. It drills glass even easier. I think I used bottom speed on my mill which is 90rpm. Ian S C

[Douglas JohnstonParticipant @douglasjohnston98463]

A lot of good ideas for me to think about. The reason I went with the HSS blades was mainly the low cost (ebay is a wonderful place) and the convenience of having the cutting edge ready formed. I did previously think of using gauge plate but was put off by the thought of hardening it without distortion.

 

The more I think about it I feel I might get away with superglue since the main cutting force will be provided by the stepped carrier. Perhaps loctite 603 might be used here instead of superglue so I must do some experimenting.

 

Doug

[Chris TriceParticipant @christrice43267]

Don’t glue them. The bond with superglue or epoxy starts to break down at barely above the temperature of boiling water. In fact you can use a soldering iron to heat a metal component that’s been glued specifically to break the adhesive bond.

[Paul Jarvis 2Participant @pauljarvis2]

Hi Doug

You could use a 4mm screw drill, these carbide drills are employed to remove HSS taps etc and are available in 4 mm from companies like Cromwell tools ( usual disclaimers) they are not cheap however.

Don't bond the blades as they will definitely come off if the blade gets hot. I would also advise against clamping them without some retaining method as I have experience of them coming off at high speed when core carving with a vertical spindle with major consequences.

Paul

Paul

[Neil WyattModerator @neilwyatt]

Why should the blade get hot cutting PCBs?

I'm assuming the project is just to make a small but robust guillotine?

Neil

[Roy MParticipant @roym]

Doug, if you can look at my previous posts, you will see a simple way of drilling through HSS. If you can't find the post, which included a sketch, then I could re submit it if you message me. I may even have a drill. Roy M.

[Speedy Builder5Participant @speedybuilder5]

Its a bit late, but my Axminster 330mm blades have holes in them already.

[MWParticipant @mw27036]

Why not just use a dremel type disposable grinding bit? Would've been my first port of call. 

Michael W

Edited By Michael Walters on 11/11/2016 20:17:05

[Roy MParticipant @roym]

Paul J. If you look at my previous post, you will see that the design of the drill for HSS is based upon the screw drill. Carbide blanks are cheap on fleabay. Roy M

[Neil LickfoldParticipant @neillickfold44316]

Roy , I make my carbide drills similar to the sandvik ones in the link here,

I use air to keep flushing out the micro chips and on the small ones under 4 mm use about 800 to 1200 rpm and hand feed normally in as ridgid as I can drill or mill. I cheat and increment the feed stop each cut about .1mm at a time.

Neil

[Roy MParticipant @roym]

Neil, mine are just cheap imitations! I think the cutting geometry is very similar, but I make them off-hand.Roy M.

[Ady1Participant @ady1]

Why not just use a dremel type disposable grinding bit? Would've been my first port of call.

I've chopped up hss with a dremel type tool as well. Mounted everything securely on the lathe for stability, started it running and used the cross slide/saddle to slowly chop through with a dremel, it was surprisingly easy and you didn't need much pressure, unlike with a carbide drill

GL

[Jon GibbsParticipant @jongibbs59756]

I've had success drilling HSS with cheap TCT spear point tile drills. You can often pick these up from the pound shop. Plenty of pressure is required and they do chip in use but you can get two or three holes per bit if you're careful.

Another option would be to cut 4mm wide slots from the back of the blade with a Dremel cut off wheel.

HTH

Jon

[Douglas JohnstonParticipant @douglasjohnston98463]

Well that was a blast from the past and it is now 5 years on from when I posted that question. I used a solid carbide drill and that worked a treat. I even managed to countersink the holes so the bolt heads were flush with the blade.

​ My first pcb guillotine was not a success as it was not rigid enough but the mark 2 version has been wonderful and slices through glass fibre pcb board easily. The only decent commercial pcb guillotine I could find at the time cost the best part of £500 and my diy one was made for less than £20.

Doug

[Neil WyattModerator @neilwyatt]

Could you be persuaded to write it up Douglas?

A PCB guillotine would be handy round here!

Neil

[Douglas JohnstonParticipant @douglasjohnston98463]

Hi Neil,

​ pm sent

Doug

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