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Re: CNC Design and advice
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.
Attachment 3119
Re: CNC Design and advice
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
Re: CNC Design and advice
Quote:
bearings on the Z axis looks a bit close
not sure i agree jonathan,,, they look about right to me... to far out and the middle will sag under pressure
edit: sorry jonathan i thought you meant the X axis,,, im with you on the Z axis
Re: CNC Design and advice
As far as small and simple goes this is the best I think I've ever seen...
http://www.cnczone.com/forums/showthread.php?t=109390
probably not up to Ali but maybe you can borrow some ideas :)
Re: CNC Design and advice
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.
Re: CNC Design and advice
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?
Re: CNC Design and advice
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)
http://www.mad-professor.co.uk/Misc/...20(Rev1.1).jpg
Re: CNC Design and advice
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?
Re: CNC Design and advice
Quote:
Originally Posted by
irving2008
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..
M12 is 1.75mm pitch...still I agree that's too small if you're not using pulleys to compensate.
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....