Thanks for add. I come from a background of building 3d printers so I have a good understanding of the motion systems involved but I have some questions regarding capabilities limitations. I currently have a left over azteeg control board and 3 nema 17 and 5 geared nema 17 so I’m thinking of using it for a desktop CNC. Can i use the geared nema 17 to drive my motion? Is it possible to make a system that can cut aluminum without use of oil? If not how much oil is needed? What do I use as a tool head? I currently have a dremel but it seems bulky. How do you hold material still? Is there some good guides you can recommend to get me on the right track?
you can run the axis with geared nema17 they will provide enough torque, but speed for rapids may be lacking. Non geared nema17 may not have enough torque, specially if you use belts (but ShapeOko uses nema17 and belts … at least some people use nema17)
you can cut aluminium without oil, but that may not be the best way of doing it nor it will ensure long life for your tools or better finish.
3)dremel is noisy. long jobs can take hours, not sure how long your dremel can keep on working non-stop. not sure how long can you keep on hearing the noise. AC power tools tend to be noisy too. 3-phase spindles are the way to go in terms of power and noise but they are heavier, bulkier and definitely costlier than a dremel, plus you will need a variable frequency drive too, so it may be something you can plan for the future.
you can hold the material still by screwing it to a wooden base.
http://cnczone.com forums is full of useful content, shapeoko forums can be very useful too.
In my opinion, for what it’s worth, a dedicated spindle motor would be a better choice. I have read that dremels have an issue with runout because their output bearing will get sloppy after a time. I am curious whether your azteeg board understands all of the required g and m codes specifically the speeds and feeds for the spindle. To cut metal you need an extremely stable frame. I would imagine on a desktop mill you’re depth of cut will still be limited. If you plan on cutting in three dimensions, you will need some kind of CAM software. I would also suggest some ball nose cutters. As for other cutters, there are speed and feed calculators online. A single flute end mill will require more speed than something with more flutes. More to the point, what cutters you require is controlled by the machine they are used on.
I see no reason you couldn’t use geared steppers to drive your machine, but, I have little to no practical experience.
Generally speaking the speeds and feeds are a lot different for CNC. Also a CNC needs a lot more rigidity. Cutting metal is more about horsepower. I wouldn’t use nema 17 motors. Minimum torque should be about 640 oz-in. Aluminum is pretty gummy material, cutting fluid is highly recommend. At least a spray mister, but flood coolant is better. Material is usually held in a mill vise or clamped down in a fixture.
@Derek_Schuetz I just finished putting together my OX (see http://blog.davehylands.com/2015/04/ox-build-part-6-spindle-and-first-cut.html). It uses 175 oz-in NEMA23 steppers, but I’m only running them at half current right now (so effectively about 90 oz-in). I don’t see why a n ungeared NEMA-17 couldn’t work. A geared one will definitely increase the torque (at a reduced speed). How fast you can rapid doesn’t really affect things too much. For example, even though my OX is currently set to rapid at 400 mm/sec (945 IPM), your typically cutting speeds will be more on the order of 400 mm/min (15 IPM).
I also have a Sherline mill that I’ve used quite a bit for cutting aluminium. I normally cut aluminium mostly dry, perhaps putting very small amount of lube on the cutter (a drop here, a drop there). Your finish will be better with lube, and the lube helps to keep the aluminium from sticking to the cutter. Pure aluminium (hardware store variety) is very gummy and I try to avoid that. 6061 is readily available and I tend to use that a fair bit. Its still a bit gummy and you may need to clean off your cutter periodically. 7075 is harder and machines nicer.
I normally hold my material down with clamps, or use a vice. Sometimes I’ll even machine special fixtures. It really depends on exactly what you’re cutting.
Ok so my Geared motors are rated for 283 oz-in holding and 566 oz-in moment. @Kyle_Kerr as for the g and m codes to control the motor how is this generally hooked up, i would assume that the azteeg x3 would be capable considering the amount of expansions available. could someone provide a link to a decent starter spindle motor kit? @dhylands by the looks of it i just need to bye a tooling plate and then build my frame to that out of extruded aluminum v slot?
@Derek_Schuetz re: g and m codes. Doors your control board understands S and F codes (speed and feed)? Thinking about it, it can probably manage feeds and speed control for the spindle would be up to how you drive your spindle.
You can do a lot with what you have listed. Would it be perfect? Probably not. Should you go ahead and do it? Why not?
With that small of steppers, you will most likely need to go with something that gives mechanical advantage like a screw drive instead of a direct drive. The gear drive depends on how much gear reduction they have but also there is most likely more backlash than is easy to accommodate.
The dremel? My personal opinion is that dremels suck for this application. You would be better off with a $20 Harbor Freight laminate trimmer. They both are noisy and have lots of runout but at least the laminate trimmer has a bit of power. Anything from there up would be an improvement. It is easy enough to upgrade the spindle later. If the dremel is all you have? Hey, go for it. A lot of people use them. Just don’t expect really good finishes or long life.
Aluminum is easy to cut (not much different than some woods) but has it’s own difficulties. Biggest being that it will stick to the cutter and cause problems without taking measures to stop it. Powerful cutters that eject the chips well, air flow, and lube/coolant are the usual approach.
Holding stuff down can be done a lot of ways. Screws, double sided tape, clamps, glue and a vise are all the usual first choices. Workholding and fixturing can sometimes be more of an artform.
@Derek_Schuetz Using the tooling plate was just an example. I used SlatWall (aka slot wall) on my OX. You could use a piece of MDF with holes and propel nuts to create an MDF “tooling plate”. You could use T-track. I’ve seen people us extrusions as a form of T-track. There are lots of options. It really depends on the types of things you plan on cutting.
So look around at other people CNC machines (routers, mills, etc) and see the methods being used.