My CNC design

[dex918]

Hi,

I design this after learning from reading CNCZONE.

The specs is

X travel = 18 inches
Y travel = 16 inches
Z travel = 4.7 inches

The distance of the table top to the highest point of the gantry is about 12 inches.
Machine footprint is 35 inches (including motor at the back) x 26 inches and height is 13.5 inches.

I have not finalised this design as I need feedback or comments from you guys. This is my first attemp to build this machine. Any negative or positive comments is welcomed.

[widgitmaster]

According to the picture, the Z-axis leadscrew will be lifting both the spindle motor and the z-axis leadscrew motor! That's a lot of unnecessary work to move all that weight! Your screw and nut will wear out fast!

My 2 cents.

Widgit

[dex918]

widgitmaster,

Thanks for the comments. I agree with you. However, redesigning the Z axis will definitely eliminate or reduce the unnecessary load. This will however reduce the X travel. Furthermore, the it will also reduce the clearance from the table top upward.

But, I will definitely consider your approach.

[rustamd]

if you flip around the Z assy you will not loose any travel and motor will not have to lift itself

[dex918]

after considering your suggestions, I finally decided to re-design the setup and this is what I have for now. Most likely it is final and will start to fabricates the needed parts.

[widgitmaster]

Good design, but don't forget the four adjusters in the corners of the base, so you can level your machine for accuracy!

Widgit

[dex918]

just for updates.. The parts I receive for the machine... It's the parts for Y and Z assembly and the leadscrew mount bearing block.

[IMG][/IMG]

[stevehez]

Real nice keep us posted.

[svenakela]

My machines are running the same config as your first (as many others), if the motor has a problem lifting itself you have too small motors.

Both designs work though, it's just a matter of taste.

Regards,
Sven

[dex918]

Sven,

Thanks. I already re-design the Z assy as shown in the second attachment.

I am now waiting for other parts to arrive. I am using acme screw instead of ball screw due to the cost factor. As for the lead nut, I am still deciding between brass or delrin... which one should I use??

[JMcDonald]

My concerns about using brass, a plastic, or even a soft aluminum (6063) is how accurate they will stay if you preload them or use another method of anti-backlash. It seems that while they would indeed run smoother because of their self-lubricating properties, they would constantly need adjustment due to the threads wearing. Is this true?

[dex918]

This is my Leadnut. I plan to use delrin for it. The width is 50mm and the slit is 3mm wide. I am using 12mm acme, 2mm pitch. I use double row A/C bearing for the Acme mounting block (driven side), with 2 hex nut to lock it to the bearing and normal radial bearing for the floating side to prevent the Acme from whipping.

Now I have a problem where to put my machine since I am staying in a 850sqft flat.

Although I have dedicated room for my hobby works, it's only 5ft x 8ft.