Starting to design out my build, looking for critique

[MartinS]

First up, I am still driving the gantry on both sides. Just one side is resting on two HIWIN rails, while one is resting on a linear bearing on a smooth steel rod-type rail. Here is the model if you want a more detailed look.

Chrono, apologies for missing the second ballscrew, that makes a big difference. You at least have a brick under the end of the springbard

Most builders here use rails both ends of the gantry to as best they can, constrain "flexy" elements (don't forget, most materials are looking for any excuse to bend, twist or vibrate).



When your spindle is cutting at the 6mm plate end of the carriage, Hiwin rails will help resist the twist on the gantry better than the Igus ones. And either way, increasing the distance "C" between them will help.

I mentioned Boyan Silyavski's build
http://www.mycncuk.com/threads/6457-...my-first-build
not to push you towards steel, Al is fine, but to demonstrate by design, reducing the chance of flex and vibration.

Re. the 6mm gantry end, I think that you mentioned that it is to "...let the machine compensate". I guess that you mean "to accommodate assembly/build errors" One way that others achieve this with rigid side rails and substantial side plates, is to mount the Hiwins on the top so that with clearance holes in the sideplate mounting, they can find their own best position on the carriages. See AndyUK's approach. Again, I am not pushing you to change, just showing other approaches to your best friend "rigidity". Also, bracing across the end is another approach.



I have a background in manufacturing with machining centres and lathes with capacities up to 1200mm, precision grinding and measuring with CMM's in controlled environments. Whether it be a CMM or a cutting machine, we want to be assured that the probe or cutter is in a specified and known position. The difference betwen the two are the forces in the system. Those in a cutting scenario being far greater....

Regarding the side rails, it wouldn't harm if you added one or two extra pillars and fillets per side. Also, bracing across the end is another approach.



I hope that this post is more positive than the last one. There are soooo many ways of getting "there" and you are nearly there, Y and Z look great.

Crack on lad......