thinking of building a CNC machine

[animus_divinus]

hello everyone, im thinking of building a CNC router soon, i have many materials already.. i have four rather powerful little motors, a 5-axis controller, a power supply, i have 6 feet of lead screw, anti-backlash nuts, various bearings.. and well, i was wondering what sort of machine i should look into making

id like to make it out of wood, or plywood, i dont like MDF because it tends to warp much easier.. so wood or plywood

id like to go with a 4x2 travel.. i believe i have the components i would need for that except for rails

one other thing.. is i would like it to be able to mill steel if at all possible, just small steel components not more than 8 inches in length and a few inches wide with accuracy.. it might be better to build a smaller machine for that i guess..

but im looking for inexpensive materials for now, and would like to have the rails be a bronze bushing on a piece of tube steel if thats possible..

now would it be better to have a raised gantry above the table, or build raised rails on the side for the machine to ride on?

my biggest concern is the raised gantry models either need a piece underneath, or dual leadscrews.. and well, they dont seem as rigid as i would like.. it seems id have to buy steel brackets just to hold the pieces together at a right angle with any kind of strength in the joint

so any advice as to what is should be looking for would be helpful

[ger21]

1) you won't be cutting steel. If you need to cut steel, buy a mill.
2) Imo, most plywood warps far more than MDF. MDF will sag, if not stored properly (flat). Plywood will warp and twist even if lying flat.
3) I think you'll need precision ground shafts for your bushing idea to work.
4) As for type of machine, that's a matter of personal preference.

I'd recommend spending a few weeks reading through all the build threads here to get some ideas.

[animus_divinus]

im going to avoid the bronze bushings and go with linear bearings instead.. for the fact that id be dealing with a lot lof saw dust, and that could gum up the bearings

[animus_divinus]

question, does anyone sell the fiberboard parts as a kit?.. i dont really have precision tools to cut and drill those without a lot of effort.. could i buy the MDF boards already cut and drilled?.. if not, is anyone here able to do it if i were to pay them?

[ger21]

Welcome to Joe'sCNC.com

[animus_divinus]

im actually nearly finished designing my own... doing an initial design first, then im going to study it and find areas where i can simplify.. then edit the design.. this is going to be small enough where i should be able to make all parts from a single piece of 3/4 inch MDF...

[animus_divinus]

well, ive been doing some thinking on my design. and used some inspiration from other designs and i believe i have what i need... travel is only going to be about 2 feet by 1 1/2 feet by 2 inches... im going to attempt to extend this a bit more to 3x1.5 feet, with 4 inches of vertical travel, ill make it out of MDF, however, im going to epoxy glue angle aluminum to the edges of the table for added support, and quite possibly along the vertical lengths of the gantry, and on a support piece between the gantrys.. all to add greater rigidity, and durability to the mdf

i think ill use some of these angle iron pieces to hold some abec-7 ball bearings i have and theyll ride on ground steel rod... im not sure if ill support the grounded rod, im not sure its neccessary for the length of table im working with, itll be kinda small... so im undecided about that, and with the design in my head that im working on in 3D, i can add supports later

on another note, i do want a machine that can do metal, however, for this im going to buy a hobby size manual milling machine thats capable of the travel i need, which is like 6x3x1.5 inches i guess... its not much, and then ill remove the hand cranks on those, replace them with new motors... and use that for CNCing hard metals

[animus_divinus]

for the record.. heres what i have designed so far.. itll have roughly a 30x18x4" travel... tell me what you think... btw, i left the table top off for now so you can see how it rides on the rails underneath... rails for the gantry in this rendering are 20mm, and for the other axis' is 12mm