Cheap CNC router to use with 3D printer toolchain

ArcEye wrote:

The 3020 I'm looking at is more like this model,

For instance this 3040, which is cheaper than your 3020, but exactly the same build and even the picture is almost identical.

www.ebay.co.uk/itm/PROFESSIONAL-CNC-3040...&hash=item4d0a0601f1

If general 'rip-off Britain' criterea apply, I would be surprised if you could not get a 3040 for the same dollar price as the £ price here and have a bit more flexibility in terms of what you can machine

Unfortunately, I'm not seeing that. The 3020 is under $500 shipped, but the 3040 starts at around $625 with shipping (although you'll see it without electronics for $500 and free shipping or for $500 + $500 shipping complete) :

www.ebay.com/itm/3040T-CNC-ROUTER-ENGRAV...&hash=item3cf1beda71

Worse still, I've noticed that the 3040 is usually packaged with a different driver box in the US. The 3020 has the same controller that the EU 3040 has, with BNC connectors for the individual motors. However, in the US, the 3040 has a different (blue) controller box with what looks like a single centronix connector for all the motors... which looks a little scary to me in that I don't believe that style connector was designed to handle much current. Am I right to be worried about the connector?

However, in the US, the 3040 has a different (blue) controller box with what looks like a single centronix connector for all the motors... which looks a little scary to me in that I don't believe that style connector was designed to handle much current. Am I right to be worried about the connector?

I found plenty of 'blue boxes' with individual connectors just the same as the 'black boxes'.

I use a screw down version of these connectors on my small mill, for motor and limit connections, which have worked fine for the last 8 years.

The max amperage for the advertised motors is approx 3A and quite honestly you can put 13A @ 240v AC through a single strand of wire ( a fuse) quite happily, so a soldered pin 30x thicker does not seem a problem to me.

regards

ProfHankD wrote:

I didn't think LinuxCNC could take OpenSCAD or STL files into G code, but that is definitely part of the toolchain I want, so I was hoping to hear some "I use this for that" type comments....

I basically use two CAM-packages besides handwritten G-code:
- The CAM360 that comes builtin in Autodesk Fusion360 (which is free for noncommerical use)
- CamBam. Much more low-end than Cam360, but it gives you exactly what you ask for and it can do quite a lot. Exceptional value for money.

I don't like it, but for your purposes DeskProto could be great too.

All in all milling is a more complicated process than 3D printing, and toolpath generation strategy depends on the actual feature to be milled. This is a bit different from 3D printing.

and simply use 3M double-sided tape to secure most parts for machining

Works fine, I use the double-sided carpet tape trick quite often although I often prefer hotmelt on a metal carrier.

ProfHankD wrote:

Are you talking about a vacuum clamping system or vacuum dust removal?

You certainly want dust removal when milling wood.

(for that matter, what coolant does one normally use with this class of machine?).

Personally I consider flood coolant obsolete with modern cutting tools on a hobby machine. I mill mild steel, stainless steel, tool steel, aluminium, brass, etcetera using only compressed air and in case of aluminium an alcohol mist for lubrication/chip removal/cooling.

I was talking about vacuum clamping.
Trying to remove adhesive residues gets old fast if you are making more than one or two of something.

I guess I had assumed dust collection was a given.

I ignored vacuum clamping; topicstarter is looking at a $500 mill. A vacuum pump + table that can reliably hold down a 200x200mm piece of wood when a contour is milled or a few holes are drilled is going to cost the same amount of money or more.

I use a fairly low capacity vane vacuum pump, but that limits me to a couple of small vacuum pods only.



Those pods were a rainy sunday afternoon project, but I actually like them and their flexibility.
I run a sacrifical piece of MDF on top (actually more inside; only 0,5mm sticks out on top) of these small pods and screw them onto the table where they can do their job best.
Two or three of these is the max I can run, and then I cannot have much leakage. But they sure beat glue or double sided tape for holding down things like PCB's etc.