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Ken Nicholas Photography Astronomy & DIY CNC

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July 16, 2015

Hi all,

Its been a little while since I posted but there’s a bit going on.

The dust hood hasn’t been as big a success as I would have hoped for due to the router fan pushing more air into the hood than the vacuum can pull out so it winds up blowing out from under the brushes, so I need to look at redirecting the air from the router somehow. A work in progress.

Next on the list was to level the bed and I had done this to the main bed, a 25mm thick piece of MDF with some brass shims to within about 0.006” and that’s not bad for a piece of manufactured wood over an area 450mm by 650mm but as I have a need to do some 0.005” deep engraving into Perspex sheet over a reasonably large area I needed it to be perfectly flat so I ran a 16mm end Mill “Router Bit” as a fly cutter over the sacrificial bed a 19 mm thick MDF panel and now it is perfectly flat as needed.

The weather here has been horrendous so I’m not spending as much time in the shed as I would like, went out there today and it was 4º C, that’s fridge temperature.

I had tried a couple of different tools for doing the engraving from a 90 and a 60 deg V bit both running and stopped like a diamond drag and neither was very good as the finish was rough and not desirable at all.

So looked at what was available on the net and saw that there was a tungsten drag bit with a 120º point

and a YouTube demonstration that showed it to work quite well on Perspex as I need.

So as I like to make what I can and I just happened to have a nice piece of tungsten handy, “a broken ¼” straight router bit from an earlier post”, I set about putting a an approximate 120º point on it.

As it was only very short it was difficult to hold while grinding so I put it into my cordless drill and that allowed me to not only hold it but rotate it at a very steady slow speed at my Greenstone wheel, this the special grind stone for tungsten.
I am very happy with the result, not quite 120º, more like about 85º I think but the test I ran on another template for my wife’s quilt making it worked quite well with a finish that is quite acceptable.

So now with the bed leveled and my custom engraving tool all I need to do is put it to the test.

This is the Quilt templates piece that I will be engraving and cutting, it’s the same as the ten and five inch I’ve done before but it's a smaller set for an 8.5 inch pattern as can be seen and this will be cut all at once, this is approximately 18 inches in the X axis and by 10 inches in the Y axis. This will be the next job on the bed and with the new engraving tool a better finish will be achieved.

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