3020T- DJ CNC Users thread

[Landins]

Yes spirits/alcohol is what I meat. I dont know why I used an old swedish word for it. Probanly underslept. Have 4 weeks baby   The spirits can also be an indicator for heat. See how fast it evaporates.

I also find f&s a mystery. The webz is clattered with non-coherent info on this and chipload charts sends the machine into feeds I find risky. But making the tool cut and not rub is a good thing.

 

[Andy Peters]

I just have a manual micro mill. I've found tapping wax to be the easiest, least messy, work best combination. I have no experience with automated lubrication/flush systems.  I also keep a chip brush handy and use it often. 

Paul, which mill?

For front panels and such, I don't see the need for CNC.

-a

 

[Gold]

Paul, which mill?
For front panels and such, I don't see the need for CNC.

It's a Taig. It's too small for most things. I can't trim the edge of front panel sized stock. in one swoop.  I've thought about automating it but the 3040 is the right sized machine to work on front panels. I would get a 3040  if I got serious and had room to put a machine.

 

[Rochey]

neither of which is 19" - so what do you do then?

 

[Gold]

neither of which is 19" - so what do you do then?

The 3040 has a 20" x axis travel. It's good for front panels.

 

[Rochey]

I thought it was 30cm x 40cm cutting area?

what did I miss?

 

[Gold]

I thought it had a 40" slide with a 20" travel. One of the popular Chinese mills is like that. Maybe I'm confused.

 

[Landins]

Its 40×30cm travel.

 

[dirtyhanfri]

I make 19" panels in a 3020, just need two passes, never had a problem about misalignment, and I'm doing it by hand, you could build a jig to be sure you always have the panel in the same exact position.

About the coolants, I use 96°Alcohol, nothing fancy, with aluminum it helps a lot reducing the noise, improving the cutting quality and evaporates leaving no residue.

For aluminum I use to work at maximum 0,5mm depth of cut and feedrate around 100-150mm/min, using a 400W spindle and a 1,5mm bit.

 

[ruffrecords]

About the coolants, I use 96°Alcohol, nothing fancy, with aluminum it helps a lot reducing the noise, improving the cutting quality and evaporates leaving no residue.

In the UK denatured alcohol seems to be called methylated spirits. Do you use a spray or aerosol or just squirt it on?

For aluminum I use to work at maximum 0,5mm depth of cut and feedrate around 100-150mm/min, using a 400W spindle and a 1,5mm bit.

That is just the sort of info I need. My 3020 only has a 200W motor. I wonder if I need to upgrade? What spindle speed do you use. Right now I just turn it right up.

Cheers

Ian

 

[dirtyhanfri]

In the UK denatured alcohol seems to be called methylated spirits. Do you use a spray or aerosol or just squirt it on?

I Just squirt it on the cutting zone, I gathered materials for a automatic pumping system but I have to build a timer circuit for open and close the solenoid

That is just the sort of info I need. My 3020 only has a 200W motor. I wonder if I need to upgrade? What spindle speed do you use. Right now I just turn it right up.

Cheers

Ian

I worked with 200W some months with no problem at all, but the spindle died after a long time working (more than 48h without a pause) and I decided to upgrade it, they're cheap and easy to find in ebay, just search for cnc spindle, I think I spent 80€ in mine.

 

[ruffrecords]

I worked with 200W some months with no problem at all, but the spindle died after a long time working (more than 48h without a pause) and I decided to upgrade it, they're cheap and easy to find in ebay, just search for cnc spindle, I think I spent 80€ in mine.

That's good. Did you have to upgrade the motor drive as well?

Edit: I just found this one that includes a driver:

http://www.ebay.co.uk/itm/CNC-400W-Spindle-Motor-ER11-Mach3-PWM-speed-controller-Mount-engraving-set-/111938787450?hash=item1a1012587a:g:U~EAAOSwT6pVxVxR

Cheers

Ian

 

[ruffrecords]

I just ordered some 3mm thick coloured acrylic panels from eBay. I thought they would be handy for making prototype front panels. It is not any cheaper than aluminium but I expect it to be easier to machine.

Cheers

Ian

 

[Gus]

Plastics can be tricky to machine. 
When drilling the bit can seize.
When cutting with a end mill etc. it can melt.
You often will need cooling cutting some plastics

Also look up the MSDS of what plastics you are cutting some plastics release nasty things when heated

 

[dirtyhanfri]

That's good. Did you have to upgrade the motor drive as well?

Edit: I just found this one that includes a driver:

http://www.ebay.co.uk/itm/CNC-400W-Spindle-Motor-ER11-Mach3-PWM-speed-controller-Mount-engraving-set-/111938787450?hash=item1a1012587a:g:U~EAAOSwT6pVxVxR

Cheers

Ian

Yes, I updated the motor drive too, indeed I think I bought exactly the one on the link you posted.

About milling acrylic sheets, I've read somewhere is way better to use special bits with the flutes reversed and the spindle turning in CCW direction, this configuration pushes the acrylic against the table, while doing it with regular bits and spindle in CW direction, the material tends to climb the bit and usually breaks.

I guess this happen with so thin sheets, maybe with 3mm depth there's not an issue, not sure....

 

[ruffrecords]

I make 19" panels in a 3020, just need two passes, never had a problem about misalignment, and I'm doing it by hand, you could build a jig to be sure you always have the panel in the same exact position.

How do you set X0 Y0 Z0 for each pass?

Cheers

Ian

 

[ruffrecords]

That's good. Did you have to upgrade the motor drive as well?

Edit: I just found this one that includes a driver:

http://www.ebay.co.uk/itm/CNC-400W-Spindle-Motor-ER11-Mach3-PWM-speed-controller-Mount-engraving-set-/111938787450?hash=item1a1012587a:g:U~EAAOSwT6pVxVxR

Cheers

Ian

Yes, I updated the motor drive too, indeed I think I bought exactly the one on the link you posted.

Did you upgrade the power supply or use the one in the controller? Mine is the type with the huge toroid transformer and a couple of PCBs.

About milling acrylic sheets, I've read somewhere is way better to use special bits with the flutes reversed and the spindle turning in CCW direction, this configuration pushes the acrylic against the table, while doing it with regular bits and spindle in CW direction, the material tends to climb the bit and usually breaks.

I guess this happen with so thin sheets, maybe with 3mm depth there's not an issue, not sure....

I just got some 3mm perspex so I will try it out and report the results.

Cheers

Ian

 

[dirtyhanfri]

How do you set X0 Y0 Z0 for each pass?

It depends, I think the best is to explain my whole workflow:

When doing half a panel I divide it in two processes; cutting and engraving.

I place the workpiece in the table over a sacrifical board, clamp it and be sure it will not slip (I HATE when a work is ruined cause my bad clamping).

After that I take the desired bit and fit it in the spindle, out of the workzone and with the whole machine turned off. In this step I check if there's enough clearance between the spindle collet to avoid possible obstacles like screws holding the piece or such, if possible, sometimes you just have to avoid them in programming step.

Then I move manually the X & Y axis to piece X0 Y0 and lastly Z axis, then I do some readjustment to get it right. At this point I turn on the machine but not the spindle, as the bit is touching the material (well, if it's a pcb or a piece which is not gonna be shown I don't care to turn the spindle on and mark the material a little) and set the three axis to zero in the software (Mach3 in my case)

Then I get Z axis some mm over the piece and start the spindle, and run the cutting program.

After that I move the X & Y axis, this time using a software order to 0, and Z to 3mm over the workpiece, just for safety be sure you move Z axis first of all if your program doesn't finish with Z over the workpiece, which is pretty usual.

I turn off the whole machine and change the tool, moving manually the Z axis, after that I set again Z axis to zero manualy and then do it in software. start the spindle and run the program.

Finally I unclamp the piece and I have half a nice front panel. Then I start again with the second part, taking the zero from the opposite corner you took it the first time. Second part is usually shorter than first one.

Keep in mind for this you have to split the design in two parts and then turn one 180º in CAM step, once you're used to it's easy.

Also, looking at the design and construction of the machine, extending the Y travel to 500mm. shouldn't be so hard or expensive, just replace the trapezoidal screw, linear guides and L shaped aluminium extrussions (this part will be better and cheaper with steel or iron I think), the only problematic part is the T slot table. Not so crazy mod for the usefulness you achieve.

Did you upgrade the power supply or use the one in the controller? Mine is the type with the huge toroid transformer and a couple of PCBs.

Cheers

Ian

Yes, I had to buy a pair of SMPS, one 48V for the spindle and one 24 V for the drivers, took out the Toroid and power supply / spindle controller pcb and mounted the SMPS's instead.

I discovered one important thing about machining successfully is the tooling, making jigs for the pieces you usually do and get a nice and fast way to clamp and set to absolute zero your pieces. then is just change pieces and readjust Z axis...

Did you try to make Pcb's? I found it quite harder/frustrating than panel making...

 

[ruffrecords]

How do you set X0 Y0 Z0 for each pass?

Then I move manually the X & Y axis to piece X0 Y0

I understood everything in your post except this part. X0 Y0 is a corner - how do you know the end mill is exactly on the corner?

I was thinking of doing something like this. With the machine off, manually move until the end mill just touches the left edge of the work piece. Turn on machine and zero X. Turn off and repeat for Y.  After this you still need to tweak X and Y to take account of the mill radius.

For Z I move to an X Y over the work piece and , with no end mill, go to Z0. Turn off machine and fit end mill into chuck and adjust Z so it fits nicely in the chuck but loose. Turn on, so motors set and then tighten chuck.

Did you try to make Pcb's? I found it quite harder/frustrating than panel making...

Not tried that yet but I do want to. I saw one video where a guy had to make a height plot of his table to get PCB etching to work.

Cheers

Ian

 

[dirtyhanfri]

I know it's in the corner by eye, using V bits is quite easy, for round bigger bits it gets a bit trickier but just need to get used to it and work in a well illuminated space.

There's people using a camera attached to the spindle to set the X Y zero, not a bad idea, but useless for Z axis

For the Z axis, which sometimes is harder to get correctly, lastly I'be been placing a smoking paper (quite thin) between the bit and the workpiece, when the paper doesn't move I know Z is in 0.

There is also the possibility to set up a auto height detector with a pair of wires, a crocodile clamp and a small piece of metal sheet of well known depth, Googling "Auto height detector CNC" should give useful results. I tried using similar stuff but in the end found them giving me more problems than solutions.

Not sure if I specified it, but for engraving aluminum I'm using 0,4mm 30° V bits, works nicely removing powder coating on panels, also on raw aluminum.