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.