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

[njhussey]

Picked up a 2200 x 950 x 10 sheet of second hand (holes in the edges) Aluminium from flebay for the princely sum of £52 the other week.



Finally got round to taking it to a local sheet metalwork shop to get guillotined into smaller peices.



I've now got 5 pieces:

2 off 1000 x 5000 (going to be bolted together and then bolted to the steel base to make the router base, holes don't matter as they'll be out of the cutting area)

2 off 1000 x 450 and 1 off 950 x 205, pieces to get the gantry sides, brackets etc. out of.

Now going to do 2 routers. One is purely for cutting 1000 x 100 balsa sheet and will be a combination of MDF and aluminium. All the items I have so far purchased will be used on this. I will then be able to cut my teeth on this to get used to using the CNC and whilst the machine is hopefully generating some money cutting balsa plane kits I'll be building my other router.

Balsa Router.



The "proper" router will have 3Nm steppers, 80V drivers, 20mm supported rails, 1610 ballscrews belt driven etc. etc. Rough picture below, the 12mm Trapezoidal screws and smaller steppers are still shown here as I've not re-drawn it yet.



If anyone feels so inclined to do so I'd appreciate any feedback, comments etc...

[Jonathan]

Picked up a 2200 x 950 x 10 sheet of second hand (holes in the edges) Aluminium from flebay for the princely sum of £52 the other week.

Not fair! I hope it doesn't turn out to be a difficult grade to machine.

Be careful with the amount of Z-travel on the MDF/aluminium machine. Clearly you want to have as small a Z-travel as possible to reduce the deflection from having a relatively weak Z-axis and gantry, but there still needs to be room to change tools. This could be a problem if you need to use drills, unless you buy short drills and/or have a hole in one corner of the bed which you jog the machine to for performing the toolchange.

[njhussey]

Not fair! I hope it doesn't turn out to be a difficult grade to machine.

It was far less than I was prepared to pay so was well happy.....I'll find out if it is difficult when I send some pieces to Haydn to machine for me. I've still got to do the calcs and design the bearing housings etc. Where would the best place be to have the ball screws on the X axis, they seem to be sticking out quite a long way. Would it be better to have them under the 50x50 box that the rails are sitting on?

Be careful with the amount of Z-travel on the MDF/aluminium machine. Clearly you want to have as small a Z-travel as possible to reduce the deflection from having a relatively weak Z-axis and gantry, but there still needs to be room to change tools. This could be a problem if you need to use drills, unless you buy short drills and/or have a hole in one corner of the bed which you jog the machine to for performing the toolchange.

As the tallest piece of balsa is likely to be 1" I'll look at lowering the gantry and reducing the travel. Want to reduce the gantry size anyway as the sum of all the lengths is just over 5m in length so just more than 1 length :)

Below is the sort of thing I'm looking to cut on the MDF router. No drilling, I'll be using mostly 2mm cutters (somethinig like this I guess 10x Carbide Drill PCB End Mill Engraving Bit CNC 1.2mm | eBay )in the E50 Proxxon I have but yes will look at height for tool changes.

[njhussey]

Well after work I stopped by our local steel and Ali merchant (not the one we use at work) and got 3 x 1.5m lengths of 25mm x 25mm 10g Ali then went to B&Q and got an 8 x 4 sheet of 18mm MDF which they cut down into manageable lengths. Liberated a couple of 1.2m lengths of 3/4" medium red band pipe from work today (we haven't used it for 7 years) so this weekend unless I get collared to do DIY I'll be marking out and cutting out bits for the cheap crappy router I'm doing ;)

[njhussey]

Didn't get much time on the build, only an hour or so this evening tut...anyway I've cut some of the MDF down and routed a channel out for the pipe to sit in. Found out that my tools are crap so been struggling to get accuracy. Also cut some of the Ali sq down to size. Just need to drill and tap the Ali for the skate bearings but won't get a chance to do that till Tuesday.

[njhussey]

Just picked this up today to help drill some holes :) Need a better vice as that one is really crap (but was given it so better'n a kick inna fork...so to speak ;) )

[njhussey]

Had a couple of hours out in the garage today and have put together the base with the rails bolted to them. Used my new digital angle gauge to make sure the rails were level and perpendicular to each other...end plates for the base to cut then I can start assembling the gantry. Now need to jump on the lathe at work and machine my lead screw ends and work out how I'm going to machine the aluminium bearing plates.

[njhussey]

Too many other things getting in the way of working on the router at the moment. Had an hour or so out in the garage tonight, was a tad cool out there..

Started one of the gantry sides but the brain wasn't working and it's not as good as I'd like so will buy some more Ali and do it again, but better!

[kingcreaky]

I admire your determination and self critisism sir. Looks perfect to me Im sure there is some time wrapped up in those pictures.

Been anxiously awaiting an update....

[njhussey]

Unfortunately I didn't get any time on the build over the Christmas period as I was away, only had 1 night at home and that was only really a pit stop to dump presents and pick up more on the way to the next relative.

Planning on getting another length of Ali on Friday and re-doing the skate bearing pieces. Will probably take it into work Sat AM and use the metal saw there to get them exactly the same length. Hopefully I'll not have brain fade this time so the holes will line up correctly!

The top picture in the above post of mine shows one side which in the photo looks OK.....however in my rush to get something done I assembled and drilled it back to front and the bearing holders were upside down, about as wrong as you can get!! Less haste, more speed comes to mind!! The top one should be the fixed with the bottom one able to be clamped up to the pipe to eliminate play.

Should have some updates on the weekend for you, hoping to get quite alot done as no plans for the weekend :)