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

[njhussey]

Hi Barry,
Yes that's the way I was thinking of, seemed to be the easiest option but will rely on getting the bearing carriage mounting points dead accurate as Jonathan says you have to get it accurate or it puts stress on the bearings and rails and will lead to premature wear. I'll look at getting a local machine shop to machine the carriage mounting points on the ali so there are reference shoulders to butt the carriages up to...

[njhussey]

I've ordered the Reactive Resins slow curing epoxy (like the West System stuff hopefully but cheaper) and the viscosity doesn't seem too bad. Here's a quick video of me swishing it about in the bottles!!

[EddyCurrent]

How did you get it so quick ?

[njhussey]

How did you get it so quick ?

Next day delivery as standard, can't fault their service...although I've not had a reply to my email yet.

[njhussey]

This is how I'm going to have my fence for pouring the epoxy, I might put an extra cross channel near the front of the frame as an extra channel for self levelling.

[EddyCurrent]

Depending on how good it flows I was thinking about either a central aqueduct (epoxyduct ?) or two, one at each end. Obviously two are more wastefull than one. You don't fancy using the draught excluded idea then for the fences then ?

[njhussey]

I'm going to test on a miniature set of welded steel first using some steel offcuts. I'll weld up a practice piece first like this...



Just hope it doesn't use too much epoxy...

[njhussey]

Additional epoxyduct added....



Might try the draught excluder on the test piece....can see it being messy to get off after the epoxy sets?

[njhussey]

Had a little play at lunch with the pillar drill and a bit of 60x60x5 RSA as I was thinking of making the dummy gantry base out of steel (plenty in the scrap bins at work cou"stock"gh) to cut up and mess with. I printed the hole pattern out on some paper and taped this to the bottom of the angle and centre punched the hole positions (high tech stuff this) prior to drilling them. Used a 6mm drill bit for a bit of clearance as the holes on the carriages are Tapped M5. Bolted the carriages to the angle and I reckon it should work OK and will save me spoiling a good bit of 10mm 6082 Ali plate.

I will get some draught excluder and try Eddie's moat method on the underside of the angle so as to get a level surface to mount the carriages on. I know for the sake of getting the rails parallel I don't need to do this but it means I can try the epoxy out to see how good it is and also try Eddie's foam moat idea at the same time

[EddyCurrent]

I did a test pour today and it's looking good. The draught excluder worked fine but where two pieces butt up at corners it needs a bit of glue between as there was a slight leakage through the joint. I'll do a full report in my own thread after it has cured. Also I'm thinking that when the moat is removed the edges of the epoxy would look a lot better if a bead of liquid nails was run down, like you would with sealant, then run your finger along it to create a nice fillet that will set hard and can be painted over.
It looks like the epoxy did not penetrate into the foam, which was my biggest worry, and I think that's because the foam is waterproof.