China CNC 6040 - Setup, Testing & Review

[SeanB]

If you are wanting water cooling you need to have a tank and a radiator. I had a brass tank made up by a radiator rebuilder, and put a cheap pond pump in it to move the water. The radiator is a condensing coil and fan from a commercial display cooler, bought from the domestic spares place as a new spare part, came with a base panel and a receiver, but I only used the coil and the fan. Fittings and piping are standard 12mm air line ( nylon quick connect hose and fittings) and some antifreeze in the water to combat corrosion.

[metalphreak]

Yeah I've got parts for a proper watercooling setup. 12V Laing DDC pump and a 2x120mm radiator. I was planning on putting it all in a seperate box with a 24v to 12v switching regulator so I can power it all off the main control box. I'm going to have to ditch the included water pump anyway as it seems to have a small leak in it.

[shebu18]

Great stuff you have there. Please post a pic with the finished PCB.

[FreeThinker]

Just a Tip if this is the first time you have milled a pcb. Fix a sacrificial sheet to the bed and run a cut over the full area (just a few thou deep will be ok) then fix the pcb to this and you will get perfectly even depths of cut when you mill. The Z Axis of the mill is unlikely to be perfectly perpendicular to the bed and this will remove most of the error. Good Luck
 <edit> Just noticed the cut out in your baseboard should work a treat <Edit>

[metalphreak]

FreeThinker: yep Seems to have worked well too.

I ended up just using one of the $2 V cutter bits that came with the machine for a test run (incase I somehow ruin an expensive bit...). Played around with the feedrate and spindle speed a bit while it was going, and ended up with some little burr bits. Not sure if its the cutter, feedrate, spindle RPM, but all tracks tested out fine with a meter (ohms and continuity). I didn't have all the right drill sizes so some holes that were meant to be 0.7xx mm were 0.8mm and the 0.9mm ones are 1.0mm. Accuracy seems pretty good though, as the oversized holes still didn't break out the copper pad Next time i'll increase the pad sizes in Eagle as well. The board hardly has an optimized layout as I did it in about 20mins (inc schematic layout). The values I used in pcb-gcode were really just guesses based on the default values. The two USB traces in the middle are supposed to be 16mil.











Drilling the holes took ~3mins including the time to swap the bit twice

PCB was depanelized with one of those 1.0mm chipbreaker bits Like a knife through butter.

Zip attached with Eagle files (V6.0), G-Code, and Gerbers.

[jasonh]

That looks really good, I only tried one pcb on my CNC and it came out good as well.  I am ordering a new laser cutter/engraver next week to get better engraving than my cnc can do, with a 1500x1200mm bed I can't cut out the pcb's but I have seen that I could do pretty large stencils for etching.  Not sure if I will try that though..

    I am assuming you are using computer watercooling radiators?   just guessing based on the 120mm size.   I am using a single 120mm one on a 2.2kw spindle and it doesnt even really get warm.  I have a large gantry so the pump/resevoir and radiator all ride on the x carriage.

[wkb]

Neat!! Can you post a video of the CNC at work?

[metalphreak]

Just took a couple of videos but I need to edit the footage before I upload it.

I also need to build a proper probe interface for touching off the bits to set the Z height. The paper trick is hardly reliable when you are trying to take off a thin layer of copper. First run was a little bit not deep enough. Second run was fine. Had a bit of a mishap when routing out the board as it came loose so I had to redo the board - in the process of doing so I snapped the tips off two V bits as they went too deep (again, Z height setting issue). The breakout board has a pin header for a probe so I'm just going to wire into that, and use a piece of 1.6mm PCB with some crocodile clips.

Did a bit more reading around on the subject. Looks like I need to crank up the spindle speed to max, and lower the feedrate a bit as well as adjusting the cutting depth.

[metalphreak]

Part 1 of 3

[wkb]

Thanks mate   

As a side note: although I think H&S has gone way overboard, I would be a bit careful with dusting off that epoxy/glasfiber dust mixture.  It is for sure not healthy for your lungs.

[metalphreak]

Part 2 of 3

[metalphreak]

Thanks mate   

As a side note: although I think H&S has gone way overboard, I would be a bit careful with dusting off that epoxy/glasfiber dust mixture.  It is for sure not healthy for your lungs.

Most of it is supposed to be copper material. In any case I have a dustmask and safety glasses on when milling. Some sort of vacuum setup is in the planning. A respirator mask is very important when milling MDF as the dust from that stuff is quite nasty if you're constantly exposed to it. The drilling and routing doesn't create much dust in the air at all. Most of the chips are heavy enough not to float through the air.

A few basic safety precautions are always a good idea. Going in with a hazmat suit and an oxygen tank would be overdoing it

[metalphreak]

Part 3 of 3

[wkb]

Thanks mate   

As a side note: although I think H&S has gone way overboard, I would be a bit careful with dusting off that epoxy/glasfiber dust mixture.  It is for sure not healthy for your lungs.

Most of it is supposed to be copper material. In any case I have a dustmask and safety glasses on when milling. Some sort of vacuum setup is in the planning. A respirator mask is very important when milling MDF as the dust from that stuff is quite nasty if you're constantly exposed to it. The drilling and routing doesn't create much dust in the air at all. Most of the chips are heavy enough not to float through the air.

A few basic safety precautions are always a good idea. Going in with a hazmat suit and an oxygen tank would be overdoing it

Yeah    Like I said "a bit careful". 

[robrenz]

If you want your machine to last longer, vacuum up the dust right at the work zone, don't spread it around with a brush.  That glass fiber dust is very abrasive and will get into all your slides and screws and spindle bearings and cause you a lot of grief.  If you want your spindle collet taper to stay in good shape you should remove and clean the nut, collet, and taper each time you change a bit.  Dust gets into the grooves of the collet and when you just change the tool you smash that grit between the collet and collet seat in the spindle.

[IanB]

I also need to build a proper probe interface for touching off the bits to set the Z height. The paper trick is hardly reliable when you are trying to take off a thin layer of copper. First run was a little bit not deep enough. Second run was fine. Had a bit of a mishap when routing out the board as it came loose so I had to redo the board - in the process of doing so I snapped the tips off two V bits as they went too deep (again, Z height setting issue).

It seems like the optimum answer here would be some kind of feedback control on the Z height of the milling turret, something like the laser tracking system that DVD read heads use.

[metalphreak]

Keeping the board flat is the most important part. Most of the commercial stuff uses a vacuum table, or a foot attachment around the spindle that pushes the board flat to the baseboard as it moves around. At the moment I have to manually move the Z axis down until the bit touches the board, which is difficult to do accurately by eye. The breakout board in the control box has a probe port which I plan on bringing out to the front panel as a pair on banana sockets. The idea is, you connect the input pin (which is buffered to the parallel port and also tied to +5V via a pull up resistor) to a piece of copper board, and then connect ground to the milling bit. When the bit touches the copper board it pulls the input low and Mach 3 knows its touched. Since the board is 1.6mm thick, you set the Z axis home to the current position minus the 1.6mm thickness, and that's the surface of your actual material you are cutting.

1oz copper board is only 1.4mils thick so even the tiniest error effects your cutting depth. You want to avoid cutting any further into the fibreglass substrate than necessary.

[jasonh]

You will like the touch probe when you have it set up.    I have my entire machine grounded with the BOB and safety earth so I only need to worry about the touch plate and not having to have anything on the cutter. 

    It makes life very easy.  In mach3 you set up the height of the touch probe, 6mm in my case and when it touches it sets z to +6mm.

   oops, re reading you are using mach 3 as well.

   A new machine I will have coming soon has a vacuum pump and table.   

   For those that don't know you do not put your work straight down on to the vacuum table, you have a spoilboard , eg 18mm mdf that doesnt matter if you mark it, cut it etc.

   The vacuum pump actually sucks right through you 18mm mdf and hold the parts tight against that.

[george graves]

subscribed!

[vl400]

How is the CNC going?

Have you tried it on aluminium? Am looking for something to mainly do enclosure cutouts and front panel engraving.

[metalphreak]

I haven't tried aluminium yet, but it should work fine for that Cutting wood and acrylic with 1-2mm passes only shows about 0.2A peak on the motor controller which is ~50W. The spindle itself (800w) is more than capable of handling harder materials and/or deeper passes.

Not really "EE" related, but I decided to make a fan grill design so I can test cutting with acrylic. Turned out pretty well Need to polish the edges and it should be shiny

      

It's actually smoke-grey / clear-black 3mm acrylic, not solid black. Excuse the poorly lit iphone snaps...

[BenGW91]

Hello metalphreak,

I am new to the CNC world but am interested in buying the CNC 6040, but I have a few questions.

How do you set the origin on this machine for each workpiece? - I will be using Vectric cut 2D and 3D with Mach3. Is it as simple as manually controlling the position of the mill bit to the corner of your workpiece before "Zero-ing" the Mach3 software somehow?

Thank you
Ben

[metalphreak]

Hi Ben,

You have two sets of co-ordinates within Mach3: Machine Coordinates and Workpiece Coordinates.

On a machine with axis homing switches (something I will be adding), you can automatically zero the machine coordinates. These are used to basically track the machines position so it doesn't run past axis limits. 

The Workpiece coordinates are set manually to where ever your material is within the machine coordinates. Basically, I just move the machine manually to one corner of the acrylic (or whatever material) and make that the zero/home for workpiece coordinates.

Whatever you set to be the workpiece coordinates will match up with the home/origin within vectric.

I might make a series of videos eventually as there isn't all that much material available for complete beginners. Most websites assume you have a background in machining, milling or woodworking.

Perhaps its time to invest in a proper video camera instead of using my DSLR 

[steve_w]

Do you do this for a hobby or for work?

[metalphreak]

This is just a hobby for me. I'm actually a uni student completing my final year of a BE & BCom in Electrical/Electronic Engineering and Management