Makesmith CNC, capable of routing PCB

[geekabit]

Hi guys,

Have you seen the Makesmith CNC yet? It's a cheap desktop CNC router on Kickstarter. According to the website it's able to cut circuit boards as well, as long as it's not too tiny. Do you guys think it's any good?
https://www.kickstarter.com/projects/makesmithcnc/makesmith-cnc-the-most-affordable-desktop-cnc-rout
http://makesmithcnc.wordpress.com/

Cheers,
Maarten

[GeoffS]

It's made of MDF so isn't going to accurate enough for PCB routing.
Perhaps a nice toy if you want to learn about CNC but not a serious tool

[johansen]

any serious attempt at this needs to use rails and not floating solid rods. they are simply too floppy.

the mdf machine base can be spruced up with some nice solid I beams on the sides, but i can't guess how much that will improve things, compared to the fact that the table can be pushed in X and Y too easily. Z can be pushed up and down but that's not as serious for pcb milling.
grind a flat on one side of the round rod, and bolt it from the backside to something really solid, and really flat, like, an aluminum extrusion, or, something you flycut on a large milling machine. you can still use cheap bronze bearings, they just have to be backed up by something that can preload them properly. 

i have recently thought about the prospect of using connecting rods to push around a granite slab on top of another granite slab with ballscrews or precision ground threaded rod. you would have to correct for the tangent error however, and you would need 2 ballscrews per axis to handle the torque produced on the granite slab by the cutting tool.
it would have incredible Z axis rigidity, but only in one direction.

[Kean]

Thin MDF construction, cheap threaded rod, and a "dremel" spindle are all choices leading to poor CNC accuracy.
But using hobby servo motors to drive the axis?  Wow! that will be really SLOW and inaccurate.

[scientist]

As I said before, nothing much to see here. All the best to the KS campaign runner, but he really needs to up his design skills and get with the times. 2mm plywood is not robust or rigid enough for a circuit milling CNC unless your track spacing is >5mm.

[David_AVD]

I wonder if the OP is part of the KS campaign?

[scientist]

No real way to tell. Sometimes it's the founder trying to stir up sponsors, other times it's actually just some random guy. I prefer when they declare that they are affiliated with it so that we can ask them design questions. 

[Fred27]

His first post is about a Kickstarter? I suspect he's not just some random guy letting us know about something he found interesting. In fact if I could be bothered to search, I'd guess I'd find that exact first post word for word on other sites to.

[poorchava]

I have done some stuff with homemade cnc machines and here are a few thoughts:
-use supported linear rails at least. They are cheap and much easier to mount than "hanging" rods. Unsupported rails may work, as long as you construction allows for pre-loading of the reails so that they don't wobble or resonate. I doubt plywood or mdf is strong enough
-the material used is very thin, which makes me think that the machine is very light (unless the base is filled with sand, concrete or something like that). A machine which is light and obviously not very rigid will no be capable of rapid accelerations. I mean my first machine weighed ~50kg and is used to jump up slightly when the carriage was doing a full-speed right angle turn.
-mdf is very tough (eg. relatively hard to crush or push objects into), dense and heavy. I think it's one the heavier wood derivatives per volume (and pretty cheap too). But it's prone to tearing and shaving, which released quite nasty fibers. It will also swell and deform from moisture, so this machine has to be stored in a perfectly dry room

This is a toy, not a CNC machine. Good to cut cardboard, plastic and some softwood with, but such machine can be made for far less than $175+shipping. Actually the machine with equivalent capabilities could be made from inkjet printer scrap and $10 worth of cheapest plywood. Won't be backing that one.

[geekabit]

Hi Guys,

Thanks for all the feedback!
I have been looking for an alternative to toner transfer, and cnc looks prompsing. Finally I found a cnc mill I could afford, but maybe I'd better save up for something better.

Cheers,
Maarten

[CanadianAvenger]

I wouldn't really consider clearance routing with a CNC as an alternative to etching a PCB, except for simple boards, with wide spacing. Also note that you do not want to use FR4 when clearance routing, the fiberglass dust is quite hazardous. [phenolic is a safe option]