Comments sought on new build: A CNC Router for RC Gliders and Planes

[njhussey]

how are those parts cut ?

Which bits? The wing ribs are nested so I can fit them on a 400mm x 100mm sheet (small packet post sixe) and ive got holding tabs on them to keep them in the sheet. The ply pieces are done the sane making sure the grain is in the right direction. The fuselage sides are done in 2 pieces and I cut them in half with a spline line so they can again fit in the packet for a small parcel and then fit perfectly together again and make a side. The balsa ribs and fuz sides were done with a 1mm cutter and the ply with a 2mm.....think that's about it.

[njhussey]

Quick question to those who cut balsa (and lite ply)....I use these cutters...http://www.shop-apt.co.uk/single-1-f...us-metals.html

Which cut it OK, however they do lift the balsa and on soft balsa tend to rip it when cutting across the grain. What cutters do you use? I was thinking of trying some down cutters but was wondering if there were better ones out there?

[routercnc]

Hi Neil,

I use 3mm 2 flute TCT router bits but have a similar problem on balsa. I also thought about down cutters but never tried it in the end and where possible I use lite ply instead and have larger cutouts to keep the weight down. Lite play tends to leave a thin layer of whiskers which is easily removed by running around with a scalpel to leave a clean finish.

Thanks

[njhussey]

Thanks for that Barry, I prefer cutting lite ply as it cuts better, yes those little furry bits clean off on with a sharp craft knife. I'll have a play with different types of cutter and see which give the best cut.

[njhussey]

Well been playing with the Router in work. Going to make small plastic (going to be Nylon) samples so I've been drawing them and cutting on the CNC router. Not getting the best finish on flat bottom pieces, looks like it's rubbing but ok on vertical sides. Using both single flute and 2 flute uncoated carbide cutters.



The same is true in Aluminium, sides are OK but the base is a bit rough. Used WD40 and air on the Ali, just Air on the plastic.



I've just downloaded the 30 day trial of HSM Advisor and as if by luck on the plastic I was using 14000 RPM and a feed of 1950mm/min which is not a million miles off what they are suggesting (1790mm/min) so clearly needs some playing with to get the best results....

Need to make dust/chip extraction as the stuff is being flung bloody everywhere......need to finish off the machine/control cabinet....need to make the vertical stand for it as kneeling down is a pain (literally) and leaning over the machine is also a pain......just need another 6 hours in the day to do this!!!!!

[Clive S]

Looking good Neil its great when you start making bits for real

[njhussey]

Cheers Clive, been making lots of RC kits that I'm selling on eBay and now making bits for work. Had the idea this morning, drew it and made it by lunch....snapped 2 4mm cutters with a school boy error in not thinking about cutter clearances but apart from that all good. Pleased the boss anyway!

Below are some RC bits I'm doing for me...

[routercnc]

Hi Neil,

Nice work there. Often thought about selling kits on ebay but never got round to it!

With regard to your earlier post - the bottom finish on aluminium pockets is never perfectly smooth to the eye. I think your photos look OK but hard to tell with the light reflections. Can you feel ridges with your fingernail?

Here are my pockets which I'm pleased with - on a machine which is less stiff than yours:

[njhussey]

Hi Barry,

I'm drawing up a few more planes at the moment, a 3 CH old timer and a low wing Acrobat. The top one in the picture is based on the ugly stick and I'll eventually have that on eBay but want to build and fly it first!

The bottom of the pocket is rough, not ridged but rough as if its been either tearing or rubbing it...I think it's just a case of getting the speed and feed correct. That's the first bit of ali cut on the machine so long way to go yet!

[Clive S]

Do you remember the planes with the mighty midget motor and the unitone tx with the xfg1 triode(I think) valve in the rx with 4 wires