[snikkeldak]

Hello everyone!

My name is Lennert, im from Belgium and i'm converting a HBM 45 PROFI to CNC.
I'm studying mechanical engineering and am currently in the final year of my master.
https://www.hbm-machines.com/product...i-freesmachine

The goal is to convert the machine with as little modifications as possible. It will not be the cleanest conversion, but it will functionall.

I started with the conversion of the Y-axis:
Due to the square shape of the ballnut holder i lose a few centimeters of travel in the Y direction, but once the cnc mill is running i can round over the edges.
The nut holder was made on the lathe with a 4 jaw chuck.
https://ibb.co/iSjJUp
https://ibb.co/g9hu29

The stepper and bearing block are mounted on a 8mm thick steel bracket that was TIG welded:
https://ibb.co/hwmyUp
https://ibb.co/f2LQ9p

The handwheel is not attached yet in this picture:
https://ibb.co/cUnSN9

Once the Y-axis was complete I started with the X-axis:
The ballnut holder was made on the late with a 4 jaw chuck and the side chamfers were made using a hacksaw and file since my mill is in pieces.
https://ibb.co/nDTbh9
https://ibb.co/jYyyvU
https://ibb.co/nGmU29

The bearing block and stepper are again mounted on an 8mm thick steel bracket:
https://ibb.co/khDWFU
https://ibb.co/j8ap29

My TIG welding isn't the best but certainly enough for the application here.
https://ibb.co/fuVdvU

A photo of the 2 brackets side by side:
https://ibb.co/fDVvaU

The steppers are NEMA34 8.5Nm Dual shaft and the ballscrews are SFU2005.

[skrubol]

you'll want to take the crank or whatever it's called off the handwheels. Those throw things way off balance and will shake the whole mill, plus being hard on the stepper bearings.

[snikkeldak]

Yes, I will keep that in mind. I don't know if I'll be using the handwheels often, but i chose dual shaft steppers just in case.
In the meantime I have completed the Z-axis:
Z-axis ballnut mount:
https://ibb.co/dDZ6Ep

Making an 8mm steel stepper bracket:
https://ibb.co/nceHLU
https://ibb.co/cOQrfU
https://ibb.co/h2yoS9
https://ibb.co/cvwWfU
https://ibb.co/iV0Dup
https://ibb.co/i8dcLU

Made a steel bracket and added gas struts:
https://ibb.co/iQEZ0U
https://ibb.co/n0toS9
https://ibb.co/gspTS9
I chose to mount them to the steel table since it was quick/easy and I don't want to make any holes in the original mill.
The head can now be moved up and down the full range of 500mm very easily by hand. Right now I can't rotate the head anymore, I might someday make a new bracket if it turns out to be a problem.
Next up will be adding an oil system and inductive proximity sensors as limit switches.

[skrubol]

Can you rotate the head enough to tram it? Most CNC's don't bother with ever manually rotating the head, as it's such a pain to get it trammed back in, and you can 3d interpolate or whatever to get the same effect.

[snikkeldak]

Yes, I still have about 5 degrees in each direction

[snikkeldak]

I finally have a few days off (and money) to continue working on the mill.

Oil system:
- Added oil connections
https://ibb.co/gjkwk49
- Added manual oil pump + manifold
https://ibb.co/g6nF4Ww
- Added oil grooves into contact surfaces:
https://ibb.co/F4sNyb5

Electronics:
- Added a cross to the base since it would vibrate from left to right to increase stifness:
https://ibb.co/j6QFHD0
https://ibb.co/MPLkhKX
- Mounted electronics box to the rear:
https://ibb.co/yNX5QQ4
- Soldered a (kinda messy) board to use proximity sensors instead of limit switches using optocouplers:
https://ibb.co/9tXPvbw

[snikkeldak]

I have completed all mechanical parts of the mill. The gas struts do remove around 70mm of travel in the Y-direction, which is suboptimal but i can easily change the mounting later on.
https://ibb.co/X8z2kBn
https://ibb.co/r55Yk34

Here are two first test runs at conservative speeds:
https://www.youtube.com/watch?v=iUNV...ature=youtu.be
https://youtu.be/cLdHf_yi0SA

I have tested up to 6000mm/min when the system is well oiled, but it would lose steps sometimes.
Right now maximum speeds are set to 2000mm/min

[snikkeldak]

Ok, I have tuned in all axes and measured the backlash for backlash compensation:

0.06mm in X, got it accurate to within 0.02mm with compensation
0.10mm in Y, got it accurate to within 0.04mm with compensation
0.60mm in Z, got it accurate to within 0.13mm with compensation

Are these acceptable for a homemade machine with a simple chinese ballnut conversion and open loop steppers ?
My biggest problem as of now is the collet chuck, i litteraly have multiple mm of runout on the tool:
https://ibb.co/SKGgdv5

This is probably not how the inside of a collet chuck is supposed to look like ? (the holes are not concentric)

[ninefinger]

Thats an ER style collet nut. You need to engage the collet in the nut first before assembling it to the collet holder. https://125718-359648-raikfcquaxqnco...ers249-427.jpg

[snikkeldak]

Ahh ok, now I kinda feel stupid for asking haha. Thanks alot!

[skrubol]

X and Y backlash don't sound bad, but .6mm on the Z may cause problems. End mills often pull into the workpiece, so when ramping or plunging you may end up with the endmill pulling down that .6mm all at once, potentially breaking the tool.

[Bebbetufs]

Hi, Congratulations on your conversion and thanks for sharing. I am a total newbie, but I have the same mill and I want to do a similar conversion.

Would you be able to tell us how long the ballscrews are?
Also, I would like to know if you feel the nema34 is the correct size for this mill, especially the Z-axis.

[snikkeldak]

Hello, sorry for the late reply!

X ballscrew is 1000mm,
Y ballscrew is 600 (not sure since i lost order email)
Z ballscrew is 700mm.

I ordered them all a little long so I had to cut off small sections as I couldnt find exact lengths i needed.

The Z axis is 13Nm nema34, and together with the gas struts (2x 45kg), it can move very effortless.

[Biribisse]

can I contact you in any way? I would like to buy the hbm 45 profi milling machine, and then convert it to cnc, I would be very happy to have your support, thanks!

[snikkeldak]

Hello,
You can send me a personal message on the forum, or ask your questions in here (maybe the info is also interesting to others)