CNC Router V1.0 (For Cutting Multiple Materials)

[biketrialsdave]

3mm it is!

Yes, still a bit of work to do on the gantry (motor mounting etc). The profile is 80x40. If I can mount the motor on the outside of the gantry end plates then I was going to put another piece of horizontal profile in to enclose the back completely.

While I'm here, what brands of welding rods do you guys recommend? There's plenty of "Super 6" ones on Ebay (6013) for a good price?

[Lee Roberts]

Dave,

See screen shot, i had 5 mins spare. The red and green sections would fix to your side plates and then to each other, the profile is 80x80, the plate is 20mm, note the datum for the rails on the front plate.

.Me

[biketrialsdave]

How did you manage to edit that, Lee? Thank you! My only concern with that design is that I thought the rails were better off not being on there side?

[Lee Roberts]

How did you manage to edit that, Lee? Thank you! My only concern with that design is that I thought the rails were better off not being on there side?

Hi mate, I pulled your image into the software I use for Web Dev then did some cut and paste magic with what was already there :).

For these rails it's not as important, open round type bearings, then yes that would be correct. You could still mount them at the top and bottom, the choice is yours really but the objective is to get and keep the bearing units as close to the cutter as you can, that being said the the difference here would probably be negligible. I did a few version's of the mock up and one had the rails as suggested, if you prefer that design add plates to the top and bottom, as well as the back, I forgot to say that the back plate didn't need to be 20 mil though, also going with the top/bottom arrangement also means that the spindle plate/assembly stands further away from the bearings due to the lead screw interference with the ali profile.

[Lee Roberts]

Dave slapped this together for you quickly so you can see approximately what you may end up with, without needing to get down and dirty in CAD.

Nothing is to scale obviously as it is just a drawing, note the X Axis screw mount position and that it would probably need moving back (away from spindle) to allow for clearance of the nut and mount (at the spindle plate), side plates would need to be bigger and other plates also bigger, bigger side plates are not a bad thing outside of additional cost because you really don’t want to go any less then 2-250mm centres for your rail bearings, both designs pretty much force you in that direction anyway so I didn’t mention it before but I thought that was a little bit ignorant of me, so here it is.

You could close things up with datum’s and pockets for the rails and bearings and so on, keep an eye on the proportions as well, if you look at the original image I’m working from, the gantry looks small next to the spindle, if something looks small, it probably is...resize to match the proportions if you can.

Also, others will probably say it’s not as important as getting other things right, and they are right but try and keep everything lined up and parallel, so your rails, lead screw and nuts. On the Y Axis (bed) the nut could be moved back towards the spindle in my previous image, vertically aligning it with the rails and lead screw, the middle of that plate “looks” nice but would it be better for the loads, if they are all inline?, they all come together to work as one.

Just my thoughts...What do I know...hope it helps!

.Me

[JAZZCNC]

No need for that box design around gantry it add's very little but expense and more potential for binding. Also with this design the ballnut won't fit between the Z axis backplate and gantry. Those wide top n bottom plates with rails sat back just make long levers acting upon the bearings which will could cause binding.!! . . . . Not a design I'd go for.!

Your design in post #67 will be ok. Don't waste money or time on the box around gantry setup no point or bennifit IMO unless bracing sides.!

[Jonathan]

The significant advantage from putting the rails one the top and front of the top and bottom beams respectively (as Jazz suggested earlier), is that you can make the rails a bit longer and thus increase the spacing of the bearing blocks a bit without widening the machine or loosing travel. I'd certainly recommend that since the stiffness due to the bearings is proportional to the bearing spacing squared (assuming what they're mounted to is rigid etc), so every little helps.