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#901 tender

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Posted 21 March 2018 - 16:01

PROXXON MF70 MILL CNC CONVERSION

 

So Part II will be mostly about the software but before going there you need to set a current limit for the steppers.

You need a DC meter (preferably digital) set to about 2vdc full scale and a very small pozi-head screwdriver.

Connect the negative lead of the meter to 0v (- on the 12-36v socket on the shield) and the positive lead to the screwdriver.

 

Plug the three stepper drivers into the 3 axis sockets X,Y,Z of the shield and plug the shield onto the Arduino Uno. Leave the motors unconnected at this stage.

Apply 12v DC to the 12v-36v terminals on the shield, make sure you get them the correct way round.

 

Working with each stepper driver in turn. Adjust the tiny pot on the board with the screwdriver so the meter reads about 250mV.

Theres a YouTube video here showing this but it gets a bit technical. If you set it to 250mV you won't be far off, if later you find the stepper missing steps you can increase the voltage up to about 400mV.

(Fast forward to about 3:30 in the video to see setting the voltage)

 

Back later with the software install.

 

 

 


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#902 tender

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Posted 21 March 2018 - 22:59

PROXXON MF70 MILL CNC CONVERSION

 

​So, for the software I am going to assume some knowledge of downloading and installing software on a PC/Laptop.

​If you're really stuck just ask for help.

 

You need to download and install three packages.

 

The first is the Arduino IDE to talk to and upload the GRBL software to the Arduino.

 

Get it here and follow the instructions to connect to the Arduino Uno.

 

Next download the GRBL installer from here https://github.com/P...hive/master.zip unzip the folder and move to 'Documents/Arduino/Libraries'

 

Start the Arduino IDE and connect to the UNO.

 

Under 'File' -  'Examples' scroll down until you see GRBL and select GRBLtoARDUINO

(if you don't see it goto 'Skecth' - 'Import Library' - 'Add Library' and Select GRBL from 'Documents/Arduino/Libraries')

 

Click on the 'Upload' (right arrow) button. The GRBL code should compile and upload to the Arduino Uno.

 

Next Download and install USG Platform  (Universal G-Code Platform) from here http://winder.github...bsite/download/

Start the UGS (ugsplatform64.exe)

Select the COM port the Arduino is connected to and click on the 'Connect' icon.

You should get the status of the GRBL in the console window of the UGS followed by 'ok'.

 

If you get this far now is the time to plug-in the steppers (power off first) and try moving them with the 'Jog Controller' of the UGS.

but first you need to set the steps/mm for the three steppers.

The Proxxon MF70 has 1mm/turn on all axes and the steppers have 200 step/revolution, we need to set the step/mm to 200.

 

At the bottom of the console window in the 'commands' line type

$0=200.0

$1=200.0

$3=200.0

We also want to limit the speed of the feeds so to start set them all to 50

$4=50.0

$5=50.0

 

Now try the Jog Controller. 

Set the 'XY Step' and Z step to 1

clicking on the X,Y and Z buttons should now move the steppers 1 revolution and if connected to the MF70 move the table/height by 1mm.

 

You now need to generate some G-Code and load it from a file in UGS.

I use Fusion360 (free to download from https://www.autodesk...360/free-trial)as it has a GRBL driver in the CAM to generate the G-code in the correct format for the GRBL interface.

Download the free trail and register for non-commercial use to extend usage.

Lots of tutorials on YouTube. Or you can use your favorite CAD/CAM.

 

Good luck, and if you get stuck just ask.

 

Edit:

I'll try and upload some screen shots later with a video of the system in operation.


Edited by tender, 21 March 2018 - 23:06 .

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#903 tender

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Posted 21 March 2018 - 23:13

PROXXON MF70 MILL CNC CONVERSION (screenshots)

 

Arduino IDE

 

Arduino.PNG

 

UGS (Universal G-Code Sender Platform)

 

UGS.PNG

 

Video, testing operation

 


Edited by tender, 21 March 2018 - 23:34 .

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#904 polybear

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Posted 02 April 2018 - 10:11

Many thanks for taking so much time and trouble to post all this for us :yahoo:

 

Just one point - the link in post 902 appears out of date now:

 

https://www.autodesk...360/free-trial)

 

Cheers,

Brian


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#905 tender

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Posted 12 July 2018 - 21:53

I am really interested also on your work on the Sieg X2 (for the simple reason that I have one in my workshop....)

best regards

Vecchio

 

Well, i've been busy again in the workshop. This time a partial CNC conversion to my Sieg X2Plus.

Only done the X,Y axis so far as the Z axis is going to be a bit more complex as the current drive is via a rack and pinion on the column.

Heres an overview: (excuse the mess) and its very much a lash-up at present.

IMG_0599.jpg

The X axes drive:

IMG_0597.jpg

The Y axes Drive:

IMG_0598.jpg

Both drives are essentialy the same being made from 2 pieces of 12mm nylon sheet. One bored out to 22mm to take a 22x8mm ball race (skateboard), the other drilled 8.5 mm clearance for the screw shaft. This also has the 4 nylon pillars for the motor (NMEA23) mounting attached. Each side of the nylon sheets are a 16x8mm thrust roller bearing to remove any backlash in the motor mounting. The motor is connected to the existing screw shaft using a 'lovejoy' coupling, one side reamed out to 1/4" for the motor shaft the other drilled and reamed to 8mm plus 3mm keyway for the screw shaft. It is also counterbored on the inside to take the M6 shaft nut.

Two M6 bolts mount the unit onto the bed using the existing tapped mounting holes for the old hand wheel drive.

 

The drive electronics for the Proxxon MF70 mill conversion (see above) were not going to be man enough for the steppers on this conversion so a pair of 4amp drivers and 24volt 5amp PSU were obtained from ebay.

IMG_0596.jpg

 

This time I'm using MACH3 software so a USB motion controller and breakout board were used to connect the stepper drivers to the PC. (no limit switches connected as yet)

IMG_0595.jpg

 

Here's a bit of youtube testing for lost steps and the effectiveness of Mach 3's backlash compensation, cycling between x0,y0 and x4.0,y4.0 (backlash in the siege X2 screws were about 0.175mm). As can be seen on the independent DRO mounted on the mill the x and y readings oscillating between 0.000 and 4.000 indicate all's well so far.

 

 

Hope this is of interest.

Ray.


Edited by tender, 13 July 2018 - 09:17 .

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#906 richbrummitt

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Posted 12 July 2018 - 22:44

Thank you. After reading your post on the MF70 and watching a few videos I decided to get on with it. So far I have the motors attached to the shield and stepping away happily when jogged. I did find anything over 350mV and I had missed steps with just one of the motors. Next thing is to try and generate then send some g code before attaching to the mill. Estlecam is probably something I'm going to try after that because it looks perfectly adapted to what I want from the machine - profile milling.

What would be really nice is to be able to run without the computer attached. More research required...

#907 Sandy Harper

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Posted 16 July 2018 - 10:22

Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?

Sandy

 

Edit - on the Proxxon mf 70!


Edited by Sandy Harper, 16 July 2018 - 10:22 .


#908 PatB

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Posted 16 July 2018 - 12:53

Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?

Sandy

 

Edit - on the Proxxon mf 70!

 

If all else fails you could rig a set of digital calipers (or even a set of analogue ones, or a proper DRO scale) to show the head position directly so you're not dependent on the handwheel scale to determine where you are vertically. It's an approach I've decided to adopt on my truly dreadful Chinese mill/drill, which has no reliable connection between handwheel and quill, apparently  :angry: .



#909 Sandy Harper

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Posted 16 July 2018 - 13:16

If all else fails you could rig a set of digital calipers (or even a set of analogue ones, or a proper DRO scale) to show the head position directly so you're not dependent on the handwheel scale to determine where you are vertically. It's an approach I've decided to adopt on my truly dreadful Chinese mill/drill, which has no reliable connection between handwheel and quill, apparently  :angry: .

That's a thought

Thanks

Sandy



#910 tender

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Posted 17 July 2018 - 22:06

Is there a method of adjustment to reduce the amount of 'backlash' in the vertical wheel that lowers the head?
Sandy
 
Edit - on the Proxxon mf 70!

I think the backlash is due to end float on the screw, a bit of packing should reduce it.
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