TOPIC:

As I don't have much experience with these things, I would like to hear other peoples opinions on these CNC routers on eBay. The main use will be for cutting alu, frp and cf (parts for rc-cars, of course). Are these good choices?





Tom

1st off, I know nothing about these ... but I can see things that would worry me If I was in the market for one:

- Price - I know it's a lot of money, but it's still nothing for a CNC machine tool

- Construction - I just can't see aluminium extrusions being stiff enough. Reason I think that it because I set my Unimat SL up in its milling configuration, that's cast light alloy & IIRC a 25mm round steel arm. The deflection was so great & the bit wandered so far off course when I tested it with _nylon_ I decided it wasn't up to the job.

- Description - the word "engraver" is used extensively, and it even says "Our customers mostly use this machine for engraving two colour plastic board signs and copper/fibreglass circuit boards." - i.e. taking a really fine skim off very soft materials. FRP, CFC & aluminium I'm very skeptical about TBH, despite what the description says - I'm just thinking of that Hobbyking "lathe" I bought, this is potentially the same mistake, only a lot more expensive.





ps curiously, I found nothing in the way of reviews for that Hobbyking lathe, just a few people saying it must be rubbish without every even having seen one in the flesh (and I appreciate the parallels ) but 10,000s must have been sold ... I can only assume everyone thought it was garbage too, but didn't was to admit they'd been suckered ... back on point, any reviews/hobby sites raving about it?

Just looking at it I doubt it would do what your expecting it to, and if it did, not very long. Very 'flimsy' looking. You could, for the same price, buy a manual machine of better quality.

Those aluminium extrusions can be very stiff if used correctly. They are used very extensively in industry for machine building and automation.

If you could find a manual machine, it would probably not be a major job to upgrade it to CNC capability yourself. The electronics and stepper motors can be had very cheaply from ebay (from China) and the software (and advice) is available free from many online communities.

I have toyed with the idea of making a 3D printer for a while now - the driving electronics and software are the same, but the construction can be much lighter.

Thanks for your input guys....

What I can find about these machines on various forums is inconclusive. The main complaints seems to be about the electrical parts, like the motors, wires, and controllers. Some actually say they are a good "base" for upgrading to better electronics.

I have no experience with such machines, and not with manual machines either. How does a manual machine look like? I have browsed various forums for home made machines, and as I'm quite handy and technical, I do believe I should be capable of putting something together myself. All the parts and plans are out there and both the mechanical and the electronic aspects seems doable. The only thing is that I'd rather have RC cars as my hobby, and not CNC routers

Tom

CNC routers... go!
The ones you're looking at are fine for chopping wood, vinyl, soft plastics etc & engraving.
No good for aluminium cos the spindle runs way too fast (Aluminium will gall up on the cutter unless you use lube, coolant, sharp tooling & relatively slow spindle speeds). We've got a monstrous industrial one at work & that struggles with even special free-cutting ally.

They won't do mild or stainless steels, they don't have the rigidity or table drive power.

If you need to be making fairly accurate cuts (ie better than 0.2mm accuracy) then you need to go for the ballscrew option, & if you're going to do that, a manual mini-mill is twice as good for a quarter of the money (& will cut steel, ally etc). The Sieg X2 & various Chinese copies can be had for under five hundred quid.

Don't even think about trying to cut GRP/FRP with a router or mill, it will blunt the cutters in a matter of minutes, even carbide ones, & they aint cheap... Been there, done that. I think the professionals probably cut the stuff with water jet.

The other thing to consider is the software & electronics side of things - if you're planning to build one using "electronic modules", it's more complex than the manufacturer's let on, & probably not for the less than electronics complacent garage basher.

The software I've used varies in difficulty - some is easy to pick up, others will leave you stumped. A lot of people are using Mach3, so there's always someone out there to answer questions if you get stuck.
Don't forget though, you still need software (& the ability to use it) for creating the cut paths or 3d models.
I personally prefer to do 2d cut paths, then cut the z-axis with layers of various depth. It's ok for straight-sided engineering shapes, but you need proper 3d for curvy shapes (What I call art)

HI!... I'd like to build one of these. Not quite the same but could make a ton of parts on it.

www.rc10talk.co...39&t=27742

Thanks for the insight. I have done various 3d and 2d cad models, so that won't be a problem. I have used shapeways for 3d printing, and I'm tempted to try emachineshop for alu. Fibre-lyte can make CF parts from CAD files, also one-offs, quite cheaply.

HP,
gomachv actually made some parts for me (FRP and CF) with that machine.