I can’t fly RC planes any more due to the lock down, and I’ve got a backlog of unflown planes, so my needle cutter is a bit pointless. Instead I ordered some Rennie router bits that was the only recommendation I could find for bits in the UK, and a 1/8" collet for my old Bosch router, printed a mount from Thingyverse and had a go at wood.
I got a bit confused in Estlcam and instead of five 1mm steps, it dug right in and cut 5mm in one go, but otherwise seemed fine. The edge was fairly neat, even before the finish cut.
There are slight marks on the bottom - is that normal, or does that mean my router is not vertical? Or deflecting as it cuts?
The marks at the top of the picture are where I was impatient waiting for the bits to arrive and experimented with an old countersink bit, just trying to cut a straight line. A 2mm depth of cut wandered all over the place, but a 1mm DOC was at least straight. The line under that was a test with the proper bit.
I have several but a) live too close to Gatwick to fly anything bigger 250g and b) it’s illegal to fly anything with a camera within 50m of anyone else’s house, so I can’t even fly the small ones in my garden. I can fly inside my house but flying the same course repeatedly gets boring with no one to race.
Actually, I’m not entirely sure that being inside my own house allows me to fly within 50m of my neighbour. The laws are quite poorly written…
I bought the shortest bits (8mm), on the assumption that I’ll probably do something dumb and break them soon enough. Overall they’re only about 40mm long, which leaves about 15mm sticking out of the collet.
Indeed, Rennie router bits are the best i could find locally, and being based in Stockport - Manchester means that i can get them on my way home from work!
Ive built both the Lowrider and the MPCNC, and those bits are the best i could find.
Thanks for the recommendation, it’s worked out well!
So now I’ve got it working with conservative settings, how do I know how far I can push it safely? I’ve read several reports where “it just went ‘ping’” with no warning - is that normal, or do you normally get some chatter or missed steps first?
I can’t claim any artistic input for this, I just found an image on line, turned it into a path in inkscape, then cut it.
The small F in the middle was actually slightly too small for the 3mm bit, and Estlcam wouldn’t cut the horizontal parts, but it wasn’t too hard to move the machine around by hand (with the steppers off) to cut them. Is there a better solution? (other than a larger piece of wood!)
The vacuum hose is positioned to hold sheets of foam down while needle cutting, but it’s actually quite convenient to slide up through the bracket for milling wood. Similarly the speed control is for the vacuum, which doesn’t need to be at full power to hold a sheet of foam, but I guess I could use it for it’s intended purpose at some point. Rather bizarrely it came with a belt clip on the back, and no way to screw it to the bench. What do people normally do with them?
Also, now I’m cutting wood, I should probably think about keeping the chips out of the electronics (and my printer!) - would a low fence work, or is anything less than a full enclosure a waste of time?
In Inkscape, after converting the image to a path, you could use the “Edit Paths by Nodes” tool (icon is a arrow with blue dot at the tip) to adjust the path to accommodate the tool diameter…
It’s designed to fit a 500x760mm sheet of foam-board (the stuff that plane is made from). The tubes are 800x1050, overall it’s about 50mm bigger so the wires clear the walls. The foam sheets fit inside the wooden ‘corners’ that you can see on the base board.
It’s quite easy to deflect the router a few mm when it’s in the middle of the table. The gantries bend slightly and the central assembly twists, magnifying the movement. This isn’t a problem for the needle cutter, which has almost no load, but I imagine it would lead to the bit wandering around if I tried to take a heavy cut in a large piece of wood.
I’m still not sure how deep a cut I can take with a carving bit, but 1mm z steps was definitely over-cautious - and I should have spent some time with the artwork making sure all the gaps were the same size!
I picked it because it was attached to the center assembly, not the z-axis, but I don’t like the flimsy 1mm thick tabs into the XYZ bracket, or that it limits both Y and Z travel.
It’s about 6" high, so everything is quite small. I’m trying to squeeze too much into the available space. Also the surface wasn’t quite flat, so initially some features didn’t work. I carved it deeper, then sanded down surface in the areas where it was too deep.
In places the paths aren’t quite smooth, or cross each other and confuse Estlcam. After this I spent a while watching yet more Inkscape tutorials and cleaned up the image, then had another go on a larger piece of wood. The carving came out much better but I discovered that there was a load of woodworm just under the surface
I surfaced the boards with a 1/2" two flute bit, which seemed to cope with 2-3mm DOC, but threw the chips out too fast for my vacuum shoe to catch. Most of it was milled with a straight 3mm bit, except the chick, which was carved. It’s spray painted black and then sanded, but I left some of the paint in the grain of the top surface. Varnishing the deep, parallel sided letters on the bottom plank was a pain - I should have carved them instead.
Some progress on the vacuum shoe attachment - I drew up a new bracket that attaches to the 65mm bolts that connect the XY and XYZ pieces, and attempted to tuck the pipe into the gap between the router and front roller.
The bottom bracket was my first attempt, it’s a bit too long, and not as stiff as I’d like. The top one is the right length, and the little flange below the nut really stiffens it up. Also you can see how using a bottom bracket on this bolt limits the thickness of wood I can fit into the machine - there’s only about 40mm between the bottom of the shoe and the table.
And I need a new shoe, the one I have was designed for 30mm pipe, and I’m using a 35mm (from an old vacuum cleaner) and bent the shoe with a heat gun to make it fit. And I should probably reprint my lower router clamp at some point…
Here’s a top view, showing how it just misses the front roller:
