Thread: Features that Rigid CNC Routers possess.....

Originally Posted by Sterob

After seeing Rods new build, I started looking at DIY CNC Router designs, and set out to discover the characteristics that a good solid CNC Router should have.

I want to be able to cut aluminium like butter, as it were....

Gantry: not sure how to improve that over my 6040. I don't know if just thicker material is required, or if load moments need to be considered..... still looking into this.
Steve

Steve, how much bigger are you planning to make it over the 6040???? This has a bearing on the size of the gantry, if you're finding that the gantry is flexing, what size aluminium are you wanting to cut like butter, in one pass or multiple passes??? Not knowing the size of the 6040 gantry, it is hard to come up with a recommendation for a replacement.
The uprights on the side of the gantry may need to be thicker and wider, to absorb some of the flex in trying to cut aluminium faster, if that is what you're also trying to achieve.
How do you find the 6040 machine, was there much that you had to do to improve it????? If so, what did you have to do?
Asking, as I'm thinking of getting something similar.
Kryn

Originally Posted by KBs PensNmore

Steve, how much bigger are you planning to make it over the 6040???? This has a bearing on the size of the gantry, if you're finding that the gantry is flexing, what size aluminium are you wanting to cut like butter, in one pass or multiple passes??? Not knowing the size of the 6040 gantry, it is hard to come up with a recommendation for a replacement.
The uprights on the side of the gantry may need to be thicker and wider, to absorb some of the flex in trying to cut aluminium faster, if that is what you're also trying to achieve.
How do you find the 6040 machine, was there much that you had to do to improve it????? If so, what did you have to do?
Asking, as I'm thinking of getting something similar.
Kryn

Not planning on going TOO much bigger than a 6040. Not sure yet.
I just want the machine to be very capabile of cutting Ali. Do not require single pass cuts. Not that crazy...lol
I don't know if the gantry is flexing, but you can tell the machine is working very hard.
I think the uprights on my 6040 are approx 12mm thick, so they are quite solid.

The 6040 is a good first CNC machine, but it is built to a price.
Only problem I had was missing steps , after a few hours use due to binding in Y lead screw and 2 of the 4 round linear blocks.
Also I found 2.5 mm offset between y lead screw and ball nut mount ( came from factory like this. )
It had paper shims in it that were wildly inadequate....
If I bought another, I would check all the axis for low friction traversing before I fired it up.
It *will* cut ali, but it is hard work and quite slow, IMO.

So basically they're a kit of parts, already assembled, to ensure that everything is there, strip it down and rebuild it, sounds like most Chinese machinery.
To make the machine stiffer, I'd upgrade the side uprights to 14 mm or even 16 mm just to make sure there's no flexing there. Surprising how 12 mm will flex if the head is travelling sideways and comes to a sudden stop, maybe you wont notice it, but I'm certain it would be there.
Kryn

I know nothing about desktop machines, but work with an industrial router and can give the following observations:

Twin linear guides are standard for X and Y, Z on ours is a single guide but it's twice the size of the X and Y guides

I've never come across a twin ball screw on Y and I think it would be an unnecessary complexity; a fine-pitch ball screw has immense mechanical advantage and should be able to push through anything just fine

Twin X steppers (one on each side) are standard on all high-speed nesting routers and many 5-axis machines as well. They are pretty much essential for rigidity at high speeds, our router is only supported on one end of the gantry and there is noticeable flex with instantaneous direction changes - and it's built from fully welded 15mm steel plate.

As always, overkill is the best kind of kill and there's no such thing as too heavy duty.

I wouldn't strip it down unless you were suspicious.....
I would certainly drop the steppers off and push the axis full travel to make sure they a free and smooth and then, delve deeper if you found something.
In my case, I had to keep going until I found something....lol

I'm not certain of the uprights thickness...I may be wrong.....the machine is somewhere else atm. I will be able to check in a couple of weeks ( moving house )

Which one are you thinking of buying Kryn?

They all look the same but they have subtle differences...Make sure you get ball screws and USB interface and the larger spindle motor.

Steve