Ok so my original idea of a wooden build is out the window and is going to be steel instead. I've got a TIG welder I can borrow from work and I'm currently learning to use it properly at college.
Meantime I've been messing around in Sketchup (learning to use it too) and have started getting my ideas drawn up.
The machine will have an overall size of 1200 x 800 and hopefully around 1000 x 600 ish working area and a 100 Z axis. It will be used for hardwood, plastic and maybe a little aluminium from time to time. I'm wanting to have the ability to add a 4th Axis at some point so I've designed the bed with a space in the centre where it can be added and also space at the end to accommodate an end clamp for woodwork joints.
The base will be build in five parts, two sides held together by the "N" shaped braces. The legs and braces will be 50x50x3 box section the top will be 50x50x3 angle and the lower brace (running parallel to the floor) will be 50x25 box section. The end plates on the "N" sections where they will be bolted to the sides will be 5mm thick.
The bed will be 100x50x3 box section on the sides, with the X axis rail being mounted on the upright pieces. Hopefully this should give good strength. The middle braces on the bed will be 50x50x3 and will be doubled up at the clamp end the idea being that two pieces welded together will be stronger than a single 100x50
I've been messing around sketching (old school style with a pen and pad) ideas for the gantry but really can't decide if it should be steel or aluminium extrusion. Initially the idea was to make it in 3 piece of 100x50x3 box section arranged in a " ] " shape but I'm open to suggestions here......
I forgot to mention I'm looking at SBR20/16 rails with RM1605 ballscrews. With two screws on the X axis probably with a stepper on each.
I think you'll be lucky to get 1000 x 600 out of the current size, wait until you've drawn up the gantry it's surprising how it grows My router is 1300 x 750 and I'm not going to get that much working area, close but no cigar....Ballscrews, for wood you need speed so don't use 1605 ballscrews use 1610, if you need precision then you can always reduce down with pulleys (I'm assuming that you're connecting the stepper to the pulleys with belts to reduce the resonance?)
Gantry, L shape is fine either 2 lots of 100 x 50 box section or C section 20mm aluminium plate, the box section is the easiest and cheapest but you'll need to make sure that it's flat and twist free. If using tooling plate and if machined properly then this is virtually eliminated. Why not use 100 x 50 x 1/4" (10 gauge?) aluminium in an L shape, EddyCurrent and Kingcreaky have both used this arrangement and it's a very neat solution.
Get the gantry drawn up, you'll find that your design will change, and then change, and then change.........Neil...
Are you suggesting I shout use one stepper and a pulley set up on the x axis?
I'm not understanding the resonance issue, is it that there may be a resonance from the ballscrews turning that will be transmitted to the motor unless it is isolated mechanically from it?
I'll have a look for build threads by Eddycurrent and Kingcreaky with the aluminium gantry.
If you connect the stepper directly to the ballscrew with a rigid coupling then any resonance transmitted through the ballscrew, from the spindle/cutter for instance, will be transmitted to the stepper, a belt will help lessen this.Neil...
And give the option of changing ratios along with possibly keeping things more compact by not having the motors hanging out the back. I'm liking this idea!
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