Sturdy and Fast all Steel CNC , my first build

[routercnc]

Hi Iman,

Best to start a new build thread for your design questions.

Have you built a cnc machine before, or have other building experience? 2500x2000x600 is a very large machine, especially for machining aluminium. Machining aluminium requires a stiff machine and having 600mm Z travel makes that very difficult, especially with a single gantry and large overhang.

1- I've not used rotating ballnut design but the stiffness of the axis is dependent on the AC bearing stiffness/quality so it will be a factor.

2- The simplest analysis to perform is to work out the stiffness at the collet in the X Y Z directions. The axes have to be locked in some way to stop them sliding when you do the analysis. 10-20 N/um (Newtons per micrometer) would be considered a very stiff / commercial machine. You need to apply 1N at the collet and get the software to work out the displacement. I don't think what you have drawn will come anywhere near that value.

3- Design and assembly. Make sure it can be built in a particular order so you can access the bolts as you build it. It is easy to design a set of parts which can't be put together especially if bearing blocks are near each other for Y and Z axes. Also, make sure you have slotted holes and adjustment in multiple planes. Assume the stock you buy will not be flat or straight or free from twist (although aluminium ecocast / tooling plate should be pretty good).

To give you some idea of commercial machines, here is the Mori Seki. Look through the pdf file and note the travel (way less than your dimensions), and note the weight.




pdf:
pm0uk13-nmv5080-pdf-data.zip


Also have a look at this thread :
http://www.mycncuk.com/threads/9809-...zed-CNC-router