Hello all,
Having fooled around with lasers and 3D printers for a few years now, I figured it was time I graduate to some sort of CNC mill/router. I have built go karts and gadgets and the like all my life and the temptation to make parts out of usable material is far too tempting. Though I have not built either my laser nor my 3D printer I feel I'm familiar enough with the components to at least draw something up.
The first picture is an electric wagon go kart I built while still in high school. The next is a just a little cardboard throwing star off the laser.
I haven't put toooooooo much thought into the actual dimensions of the machine though this is close to the size I'm looking for. Mostly still conceptual at this point. I'm looking for some validation from people who have a better idea than I do. (why I'm here!) Let me know if this shape/component combination is something worth pursuing. I've done some reading, forgive me if I ask a frequently answered question.
Design Objective:
-Cut aluminum relatively quickly.
-cut steel? (is this a dream?)
-Desktop-ish size
-$1500 range budget
-no frills, hopefully easy to use
So far:
A fixed gantry configuration made of welded 2"x 2" by 0.25" wall square tube. My plan was to weld the pieces together in such a way that I can fill the whole frame with sand (i.e. drilling large holes to 'connect' the members before I weld them together so the sand can fill the entire volume of the frame). I chose this configuration as a compromise between rigidity and build volume while maintaining a reasonable "desktop" size. At present, the spindle is the generic 2.2kw model I found on GrabCad though I am interested in a belt driven brushless setup I've seen some members use. I've heard the high speed spindles are much too fast for some materials. Rails are 20mm square type, ball screws are 1605 type. Steppers are 425oz-in nema23s (mounting remains undecided as you can see in the model). I made the frame more 3D printer shaped (cube) as I would like ability to slide poly-carbonate panels into grooves just on the interior of the machine to create a chip/coolant enclosure. Many of the routers I've seen online cut using only air or the fogbuster style sprayer. Is there a reason more builds don't use typical CNC coolant? In the picture I have the machine sitting on an angle-iron frame that I will enclose to catch chips and coolant. I think I like the Gecko G540 4-Axis all-in-one controller. I've heard good things about it, but it is a little spendy.
Travel is roughly:
x:19"
y:8"
z:4"
Questions:
I know every one of these questions is a huge can of worms to get into, with many things that factor into the answers.
1. Do you think this type of fixed gantry configuration and geometry is rigid enough to mill aluminum relatively quickly? (mostly: whats your overall opinion of how it looks)
2. I have no intuition about the size of the steppers required. I figured that this is a smaller machine and I wouldn't need much more than 425oz-in? Is this fair?
3. Talk me into or out of the Gecko all-in-one thing. I see significantly cheaper options that appear to the same thing. At this level of machine, is it worth it?
4. Is cutting steel on a machine like this a pipe dream? With a different spindle maybe?
5. 1605 ball screws large enough? Or would stepping up to the 20mm be worth it?
6. Asked above: Is there a reason more builds don't use typical CNC coolant? At least the ones I've seen...
7. What your concerns with my design/component selection so far. What are some things you think I may have overlooked or not thought about?
Thanks for your help in advance!