My deluxe Island Cutter :-)

[ChrisLX200]

Okay, I'm new to this stuff, but I saw a useful technique on YouTube regarding how to make up small PCBs using the 'Island' (or Manhattan) technique. Using a small cutter of sorts with a plain copper-clad board to create small isolated pad to solder to. Great! But um, where to get a suitable cutter? I saw diamond impregnated hole-saw type things described which didn't really sound suitable to me, so I decided to make my own. I'm more engineer than electrician anyways :-)

For a first attempt I used a piece of 3/8" dia round tool steel (low-carbon Silver Steel) and drilled a 5mm hole in one end and turned the outside to some rough diameter which would create what I thought would be a suitable sized 'moat'. I cut the teeth off-hand (I didn't use any indexing tools, just done by eye), the cutter was a dovetail cutter mounted in my mill and the workpiece only roughly aligned to produce cuts in the end of the tool which would produce relief angles to the cutting edges. This was a 10min job only :-) Then I hardened the steel right out (heat to cherry red and drop into cold water) - no need for tempering.
Well the cutter worked and produced nice round pads (photo).

So that was good but there were a couple of issues: there was no control over depth of cut and it was tricky to cut an island exactly where I wanted it (difficult to judge position). I moved on to a Mk.2 version, and here I included a spring-loaded plunger with a 60-degree point which allowed me to centre the cutter exaclty, and I also added a sleave which controlled the depth of cut (0.050" inch). The sleave is made of rather strange stuff you don't come across often - it is bronze-loaded PTFE, and this stuff has the lubricating properties of PTFE but with much improved mechanical strength. So with this sleave I can ignore worries about cutting depth - just drop the tool onto the board and the sleave ensures the perfect cut depth. Again, the cutter was made from silver steel but this time I tempered the steel as I expect to keep it for a long time. The teeth can be sharpened if needed with a small slip stone or diamond file, fibreglass is very abrasive but provided this cutter is run cool (so it doesn't lose its temper) it should be very durable.

Anyway, I made my first board with it - a crystal tester :-)

[cdev]

I've always wanted one of those things, should get one now that I have a drill press..  I just use chunks of PCB that I chop with a big old pair of shears (or have been exuded by my nibbling tool.)

So is that an oscillator that will work with any crystal?

[ChrisLX200]

Hi, it's w2aew's video on the subject, the example is a crystal tester https://www.youtube.com/watch?v=blalAktxFoI. The circuit has worked up to 32MHz for me.

One other advantage of my Mk.2 cutter is that, if you're prepared to live with using a deep centre-punch mark on your board, then you don't need the drill press as the spring-loaded centre helps prevent the cutter skipping/wandering. Using a drill press is still the safest option though.

[Gyro]

Very nicely done! 

I have a couple of island cutters (no idea where they came from now) which are drilled and split at the top so that they can clamp a small (1mm) twist drill when tightened in the chuck. This allows attachement of a through hole leads of larger components (on the back) and also gives some self centering during cutting.

That loaded ptfe looks very useful, I've never seen that before.

[ChrisLX200]

Thanks :-)  Yes, the pilot drill idea was the first thing that occured to me but I wanted to avoid putting holes in the board at this stage, but if you can live with a hole in the centre of the pad then a home-made spade drill or something (i.e., having a smooth shaft instead of fluted along its length) would work well as a pilot and not chew up the board so much. I think I'll try that, a spring-loaded point can easily be exhanged for a drill point.

There are quite a few modified PTFE combinations - bronze-filled, graphite-filled, glass-filled, and all offer their own advantages/disadvantages. They are ridiculously expensive to buy as new stock materials but I managed to snag some offcuts on Ebay. Bronze-filled PTFE is the hardest wearing version of all and is actually conductive (so considered unsuitable for electronics, well, as an insulator anyway :-) ). It is commonly used to make hydraulic piston rings and washers etc., and I used it to make custom seals for spring air rifle cylinders.

[SeanB]

I normally use Vesconite hilube for cylinder bushes, as it wears well ( or at least it  does not damage the shaft much), is easy to machine and works with or without lubrication. Done some in pure PTFE stock, as it is better in some applications, and prefer these plastics over bronzes or other nylons. Made nozzles in PTFE, as it helps in not having the liquid stick in it.

[w2aew]

Hi, it's w2aew's video on the subject, the example is a crystal tester https://www.youtube.com/watch?v=blalAktxFoI. The circuit has worked up to 32MHz for me.

One other advantage of my Mk.2 cutter is that, if you're prepared to live with using a deep centre-punch mark on your board, then you don't need the drill press as the spring-loaded centre helps prevent the cutter skipping/wandering. Using a drill press is still the safest option though.

Nice job!!  Certainly nicer than the tool I used in the video that inspired it!  Congratulations on taking it to the next level - love it!

[ChrisLX200]

Thanks w2aew - and even more thanks for your YouTube channel and the superb videos! I subscribed of course and am slowly working through them all :-)

ChrisH

[Raj]

Make one by sticking abrasive powder onto it like Ave did ()

use a drill guide or drill press with depth stop.

[CJay]

Now that's impressive, I can see a market for those (and I'd join the queue)

[ChrisLX200]

Make one by sticking abrasive powder onto it like Ave did (...)

use a drill guide or drill press with depth stop.

Wouldn't last long... and the last thing you need on a machine tool is shedded diamond grit floating around, it gets into slideways and bearings and you can kiss the machine goodbye! If I were doing that job then I would have brazed some tungsten carbide bits to a circular steel blank.

Also, I was trying to make a tool that didn't require the use of accurate drill press with a depth-stop, my tool is self regulated in that it only cuts to the depth required. You  can use a hand drill in a pinch :-)

Finally, the abrasive type of cutter doesn't produce a nice finish on a job like this, mine produces perfect cuts and it's very fast (because it actually 'cuts' the copper out).

ChrisH

[ChrisLX200]

Now that's impressive, I can see a market for those (and I'd join the queue)

Thanks :-)  I'll bear that in mind! I fancy making a set of different diameters with the option to insert a pilot drill or pilot centre in them.

ChrisH

[mikerj]

Looks like you re-invented the spot weld cutter

[ChrisLX200]

Looks like you re-invented the spot weld cutter

LOL! There goes the patent hopes... :-)

ChrisH

[mtdoc]

Very nice!

For those who want an easy purchase option.  I've found that one of these work well.  Obviously it doesn't have the centering and depth control advantages of the above.