The Mrs aint gonna be happy about this little project!

[Jonathan]

Even before welding, it's questionable whether steel box section is accurate enough to mount round rails on opposite faces, so no matter how good the welding is it's not a good plan. It certainly wouldn't work for profile rails without further machining or shimming.

it certaily ticks the 0.05 accuracy box you mention with ease

How do you know?

[m.marino]

You set up index plates on the top and bottom of the box section which not only would help deal with small distortion of welding But also give you a rebated straight edge with which to create a master index edge for setting up the rails with. This also has the advantage of being able to do dis-assembly and certain types of maintenance much much easier. First you have to decide which edge is you master edge and work from that in the actual building. Though bolting works much better in most cases. This is why King bridges that are bolted together from many plates have been know to last over 80 yrs of active use.

Michael

[r0bsk1]

Due to a change in plan i've settled on a 1200mm for both X and Y. Ill be using 2 lengths of 60mm box section on a back plate with sbr25 rails to form the Y axis. Y is mounted on the X bearings near enough at the mid-point of the Y bearings. I've not drawn them in yet but ill put some diagonal pieces in to support the Y uprights against the X bearing plates.
Would taking the Y uprights below X bearings and box section and linking up with the opposite side of the X bearing plates offer significant more support to the X bearings?
Y bearings appear to be a little out of position. Everytime i move 1 bearing, they all move! I must have grouped them somehow. Going on the bearing blocks are 65mm i have a 20mm space between the 2 which make 150mm from one end to the other on each Y rail. Is this spacing sufficient?
Is it best to drive Y on the main Z back plate or can i use the shorter Z back plate? I'd like to protect the Y screw from any debris.


Attachment 7198
Cheers

[r0bsk1]

Just a quickie in prep for building a PSU. I've got 5 MA860 drivers rated at 7.2A each driving 3.1nm steppers.
When I come to use all 5 stepper they wont all be maxed out at once. What rating of transformer should i be looking for?
I'm looking at 1200VA 2x50 at 12A each. Wire the output in parallel and get 24A. Yes this is below 7.2x5 but would i ever exceed that machining wood/composites/Ali?

[Jonathan]

Bit of a hand waving explanation here, but in short...The the motor coils are rated for 2.1A, and you'll put them in parallel so 4.2A per motor. Due to them not drawing anywhere near full power most of the time, you can design for about 2/3rds of that, so 2/3*4.2*5=14A. 50V, so P=50*14=700W. So you need the nearest size transformer, or combination of transformers above that rating - so most likely 800VA. Plus some capacitors and a rectifier. I've currently got a 500VA and 325VA to power 5 or 6 of those motors.

[r0bsk1]

Ah the ruddy motor windings! New i was missing something. Ta