Desktop sized CNC

[JAZZCNC]

As for rails, I think to use MGN12 rails with MGN12H carriages for Z and X axis. For Y axis HGR15 with HGW15CA (or other type, depending on final design) carriages.

I have concerns if MGN12 with MGN12H will be enough for Z and X axis ? (even though I have seen those used in small cnc machines).

You will be better with HGR15 or better still HGR20. The bearings are easier to work with and not so tiny.

I really liked the CSMIO/IP-M 4-axis Ethernet Motion Controller, but in specs it shows that the spindle axis is not supported ?

No this means you can't control the spindle has an Axis like you would if using Servo Motor with Encoder, say for Spindle orientation with ATC or ridged tapping. But it does have 0-10v Speed control with Relay Output for On/Off.

As for stepper drives, I will go with DM556 (or if needed - AM882). But what about steppers ? What torque I would need? (I plan to use pulleys and make 2:1 gearing or just leave it 1:1). The size is important too - smaller steppers are better for my design :)

Well difficult to say exactly without knowing Mass etc but like Lee says 3.1nm will give good balance of power and speed so often used. More important is that you choose Steppers with Low inductance to give good torque at speed.

Do I need closed loop steppers and drivers ? are they worth the money[/URL] ? )

No you don't need them and provided you match the electronics correctly and don't overtune motors you won't lose steps.

But if you can afford them then there are some advantages other than the closed Loop.? . . Three phase motors are much smoother and give more torque across the speed curve. They also handle resonance much better.

Thou I'm not sure about those Drives/motors has I've never used them and not all Closedloop are the same. You'll also need at least 2Nm, ideally 3nm.

[TadasM]

Gents,

thank you for your comments.

Lee: is there any other decent controllers (usb or eth) I should consider besides the JAZZCNC recommendation ?

I found these steppers: 57HS22 Leadshine, they are 2.2nm motors and has only 1.8 phase inductance. Anybody has experience with these steppers ?

Belts and pulleys: is it enough to have 6mm belt width or should I go for 10mm or 15mm ? (15mm width pulleys looks too big on desktop sized machine :) ).

I have found this Kickstarter project, they claiming that theirs machine can do aluminium. And they seems using MGN12 rails ? Is this means that it is enough to have MGN12 or their machine more like "toy" compared to more robust DIY machines ?

[TadasM]

Hello again :)

Have not decided on controller... Found PoKeys57CNC very interesting.
Do some one have experience with PoStep60-256 + PoKeys57CNC ? Or should I better stick to Leadshine DM556 ?

Thank You.

[TadasM]

Hello everyone,

Bit more than a year passed from my first post and intentions to build a desktop size CNC machine. The design took longer than expected, but this CNC machine is not only about functionality, but about the design too. Machine is designed to have a small form factor but with biggest possible cutting area and be able to cut various materials, including steel. I hope You will like it as much as I do.

MMC - Mini Mighty CNC:




Some numbers / info about my CNC machine:

• FULL Work area X/Y/Z: 480 x 600 x 110 mm
• Foot print: 416 x 778 mm (to outside of the foots)
• Machine dimensions (L x W x H): 830 x 650 x 640 (height measured when Z axis UP at maximum, width measured at maximum width of X axis)
• Weight (kg): approximately 100kg (control cabinet not included)
• Rapid speed X/Y/Z: currently tested with 10000 mm/min showing very good results
• Acceleration: X/Y - 2000 / Z - 1200
• Repeated accuracy: 0.01 mm (check video below)
• Linear rail types: HIWIN 15mm with carriages HGH15CA
• Drive train X/Y/Z: Belt driven 1:1 ball-screws for all axis (1610 for X and Y axis, 1204 for Z axis)
• Spindle: Currently installed 800w water-cooled spindle. (Can be upgraded to 1,5Kw spindle)
• Drive motors: Steppers NEMA 23, 3.1NM (60BYGH301B)
• Home/limit switch's: Inductive Proximity Sensor type
• Sacrificial MDF bed with 54 pcs of 6mm threaded points for material fixing
• Built entirely from Aluminum
• Software: UCCNC 1.031 (show the new layout for UCCNC)
• HB04 Wireless Remote Handwheel Controller MPG Pendant

Control cabinet:

• Stepper drivers: Leadshine AM882 Digital Stepper Drive With Stall Detection
• Motion Controller: UC300ETH-5LPT ethernet motion controller
• BOB: HDBB2 breakout board
• VFD: Schneider Altivar 320
• Toroidal traff: 230V/2x24V 2x12.5A = 68V DC to Stepper drives
• Capacitors: 2 x 20000/100V
• And other electronics...

I made a few checks of machine accuracy and repeatability.

Here is videos for Z and X axis (Y axis has same accuracy, I did not made a video cause I feel it will boring to watch anyway :) )

Z axis test:



X axis test:






Testing my new CNC machine:

Very first testcut:




Material size: X= 285.000, Y= 305.000, Z= 4.500

Rapid CNC move feedrates:

X axis: 8000 mm/min
Y axis: 8000 mm/min
Z axis: 6000 mm/min

First toolpath:
Tool: Solid Carbide V-Bit 90 deg 10 mm
Cutting Feedrate:1500 mm/min
Spindle speed: 18000 rpm
Total depth: 1.2mm (Two passes: first pass at 1.0 mm, second at 1.2 mm) The two passes strategy was chosen in order to check repeatability of machine witch showed perfect results.

Second toolpath:
Tool: Solid Carbide End Mill 6 mm (1 flute @ 25degree)
Cutting Feedarte: 1000mm/min
Spindle speed: 14000 rpm
Total depth: 4.6 mm (Two passes: first pass at 3.6 mm, second at 4.6 mm. 1x10 mm tabs to hold peace in place were generated)



Next time, for such thin material, double sided tape will be used to avoid any material vibration during machining.

Looking forward to cut some Aluminum and Steel.


I have also designed and tested a PEN holder, and made some nice gift cards during holidays. Please feel free to download, print and use it :)

download link to Thingiverse: http://www.thingiverse.com/thing:1847711

Currently I'm working on additional features for this machine and hopefully I will be able to post the results faster than next January :))) :

• Dust shoe
• Auto tool zero probes (stationary and handheld for semi automatic tool changing)
• Mist system

I'm very thankful to all of You, who gave me some kind of advice and support.

[Clive S]

Looks like a very nice machine its a credit to you. Its always nice to see the first cut.

[JAZZCNC]

Looks like a very nice machine its a credit to you. Its always nice to see the first cut.

+1 on that.

Lot of work and thought gone into the finer details of that machine which others might not see or appreciate well done. .

[A_Camera]

Nice machine. Now you need a dust shoe so you can leave it alone working on it's own...

[TadasM]

Gents,

I have tested aluminium machining. It is a first time that I have machined/cut aluminium and I'm not very happy with result.



In the attached picture the blue line indicates the pocketing path and red line profile cut path.



pocketing path settings:


Profile cut path settings:


Spindle speeds and feeds are from HSM advisor:


Pocketing toolpath on part looks really good - shiny finish. But on Profile path - looks like crocodile just cut with his teeth...

Could someone point out where is the issue here and how to get same surface finish as per pocketing toolpath ?
Thank You

[JAZZCNC]

You'll never get nice finish on slotting profile toolpath without using Finish pass. So leave material offset and do full depth 0.2mm finish pass.