Thread: CNC Design and advice
Good day all.
Due to lack of funds, I have decided to look at making my own smallish cnc unit mainly from MDF, unto such point that I can afford otherwise.
The unit is going to be mainly used for milling and drilling PCB boards, but I would also be using it for Acrylic, and maybe small alu jobs.
I already have 4x Astrosyn MY103H702 stepper motors, 1x 4 Axis TB6560 stepper motor driver board, 1x 24volt 12amp switch mode power supply.
I have been trying to come up with a design using solidworks, and here is the current design.
I have only been using solidworks for just over a week now, so please bear with me.
The design is by no means finished, and is subject to change depending on what feedback I get.
When I 1st started designing this unit, it was meant to be quite small, but the more I design the bigger it has got.
Any advice you can give me to help finalize the design would be grate.
Thanks for your time.
Best Regards."If first you don't succeed, redefine success"
How much travel are you hoping to have on the Z-axis? I think the spacing of the linear bearings on the Z axis looks a bit close at the moment. I'd extend those triangular pieces on the side of the Z-axis up to the top of that sheet - it should stiffen it a lot. If you don't then I think that the sheet of MDF will flex too much, resulting in poor accuracy.
What pitch screws are you intending to use? You'll struggle to get a good feedrate with those motors on only 24v. Their inductance is too high. They work well on 70V though...
Here's a drawing in solid edge of the motor you're using...might find it useful! You should be able to open it in solid works, if not let me know and I'll convert it.
Astrosyn 1Nm Size23.zip
looks a bit tall and flimsy on the gantry sides... if your making a moving bed you can afford to beef up those gantry sides
also id be tempted to look at puting the spindle over the centre of the X axis so the bed is only needing to travel half its own lenght either way (if that makes any sense) besides that it looks like a classic design and that seems to be the way to make a winner
Last edited by blackburn mark; 17-09-2010 at 01:14 PM.
17-09-2010 #4bearings on the Z axis looks a bit close
edit: sorry jonathan i thought you meant the X axis,,, im with you on the Z axis
Last edited by blackburn mark; 17-09-2010 at 01:13 PM.
That looks nice. I was about to say it looks like a very sturdy machine...then scrolled down and realised the sides are nicely painted MDF not aluminium!
I bet that would be good for milling aluminium if the MDF was replaced with aluminium/steel and shouldn't cost too much more.
I would suggest. for a first machine and primarily PCB milling/drilling to keep the z-motion quite small... no more than 50 - 75mm .. This design looks a tad top-heavy. What are the overall dimensions?
Jonathan: thank you for the stepper motor files, I will use that to update my next rev of the design.
As I am going to be using the TB6560 stepper motor driver board, <30volts is a must otherwise you end up smoking the board and or chips, so I have settled for 24volts.
Speed would be nice, but for now just a working unit will be grate.
If can afford it I will be using balls screws and nuts from Gary, but otherwise it would have to be threaded bar M10 or M12.
There is an error with the Z-Axis in that 1st design, The Z-Axis is meant to be 300mm with 150mm of travel.
Here is the updated version (Rev1.1)
Last edited by Mad Professor; 17-09-2010 at 07:10 PM."If first you don't succeed, redefine success"
rather than use M10 or M12 threaded rod, use TR12x3 trapezoidal. its not much more expensive and will give you 2.5x performance as M12 threaded is only a 1.25mm pitch. Still think the Z travel too much..
What are you proposing for the table to run on? and how bigs the table?
Agreed on the Z travel being too much. Maybe you could make just the Z axis using aluminium plate? It wouldn't cost too much more....What do you need to make with 150mm of travel.
This reminds me of everyone trying to persuade me that 400mm is too much travel on my Z-axis! But I'm using 20mm aluminium plate and supported rails now so it should be ok....
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