Newbie design need advise

[mogu]

Hi everyone!
Greeting from Singapore!

I'm new to both CNC and this forum.
Earlier was doing research and came up with a simple design(post on http://www.cnczone.com/forums/diy-cn...er-design.html before I got to know this forum)

After read up more and research, now came up with new design and seeking advice.






Current design using all steel tube and will be welded mostly.
65x65x3mm
150x75x3mm


12mm steel flatbar for all the plates that you can see on the drawing(Read a lot, most people suggest 20mm aluminum for Z axis, will 12mm steel flatbar work?)


Hiwin 20mm rail for X axis, 16mm rail for both Y and Z axis
2 x 2010 ballscrews for X axis, 1610 for both Y and Z axis


Overall length 1m x 1m(External) due to space constraint.
Cutting area will be ~ 700x700mm


Hardest material to be cut will be aluminum.


Thanks!

[EddyCurrent]

This new design is much better that the first one and it's an excellent first draft.
I'm sure there's more, but two things stand out for me straight away.

1. You need some diagonal bracing between the legs on the base. i.e. on all 4 sides and the bottom.
2. The working position of the spindle looks like it is at the bottom end of the Z axis which means there will be high leverage leading to felexing leading to low accuracy.
Obviously that design gives a good range for Z travel but you should be ready to bring the workpiece closer to the gantry by using an adjustable height bed or as I do a series of sacrificial plywood beds laid on top of each other and skimmed flat before starting work.

[Lee Roberts]

Hi Mogu welcome to the forum !

I have made a design suggestion for your consideration, I think it will serve you better and is what I would personally do.

Please see the attachment.

.Me

[Boyan Silyavski]

Hi,
I believe you have all wrong the long ball screws, the plate attaches to ball screw mount and that moves the gantry.

They have to be adjustable -in all directions, like 3D / the mounts/ and the bracket has to be separate and allow adjustment vertically, oblong holes, after the leveling of rails /epoxy??/ .

Like you have drawn it, what would you do if you need to adjust the screw mount in direction towards the frame? I know you can file it but will be very difficult to adjust it.

IMHO but some may not agree, the correct procedure is this- to level the long rails, then mount then parallel, then mount the gantry , adjust the gantry in all directions. Then mount the gantry side plates. Then mount the ball screws via attaching the housing to the plate. Then move the gantry one end. Then attach the ball screw supports and if there are additional support plates- fix them via clamps. then move the gantry to the other end and repeat. Tick some dots with the welder to fix the additional plates. Then remove the ball screws and gantry and Then solder them and then paint all.
When all ready, the procedure is the same. you will have nice aligned parallel in all directions ball screws that will not need playing with steps in Mach3

Hence the need for additional support plates .

They can lower your ball screw length by the width of the gantry step, say 300mm each side. And also you can fit the motor there.





Of course its up to you. You can do it as you originally intended, it will work but just leave say 3mm below the ball screw ends supports for adjustment . Repeat the procedure as described above and when you reach the moment you can shim them or even better shim and epoxy them.