7' X 4' Combi

[Ricardoco]

Cheers Jazz

Don't like the fact the Z axis bearings are so far up the back plate, your creating probably 70mm more leverage. Reducing this flexy leverage is more important than having a slim Z axis any day. .

Jonathan had pointed this out to me as well, so putting them either side is a good bet as in your drawings.

The 300mm for Z axis front plate is a bit of waste has well and will make more work for the stepper and reduce feeds/accel at 30mm thick. 200mm width is fine so thats effectively 540x100x30mm and £23 of wasted plate and if 6 series ali 4.3KG of weight thats not required.!!.

The 300mm will be needed so i cannot odds that, and the weight will be offset buy putting Holes/Pockets where i can removing excess material in the back plate and on the rear of the front plate, i was going to draw that but it crowded the drawing and made the concept difficult to see, I know its a waste but i can live with it.

If you must have narrow Z axis then I'd go with some thing like the pics below.
It's wider on the Y axis by 60-70mm were bearings are located but slimmer on the rest and Z axis front plate but more importantly the bearings are lower down. .

I will have to look at the extra 60-70mm to see if i will lose work space as the spindle is going to be mounted on the right side of the front z plate. Im not thinking it will be a problem..

Also it's actually slimmer at approx 70mm from gantry, will be much lighter and estimate approx 10-12KG lighter over all and will probably use less material depending if you can use the same shortened back plate.

Ive no problems making it slimmer but i would like to mount the stepper with spindle pointing upwards and running a belt to the Screw, the motor is 100mm long (nema 24 (4nm Claimed) ) so would need at least that much to clear the top of the gantry, effectively front plate and back plate level at the top of its travel. the rails i have are 520 or 540mm long cant remember of the top of my head, but that should give enough travel, the Y axis bearings will be 150mm from center of bottom bearing to Center of top bearing

Obviously I've had to guess and used 20mm linear bearing models and dimensions here so depending what your actually using things could workout slightly different.

Well they are 15mm rails for the Z as thats what i have, the Y well they could be 15 or 20 mm depending what i buy/procure..

Im not going to be doing any heavy Machining Of metals other than the odd bit of ali sheet, so i suspect 15mm will be ok if i can reduce the final weight of the Z axis assembly by pocketing as much out of it as i can without compromising on the strength to any great degree.

Rick