help choosing electronics & spindle

[Banana Jack]

so after ages of wanting to build a cnc mill and not knowing where to start, i finally found this: How to make a mini milling machine- manual or CNC!
perfect! it's exactly what i wanted! i'm building it exactly as described, except i'm using mdf instead of birch plywood. (that won't affect anything, will it?)
now i just need some suggestions on electronics and a spindle to use. I will be cutting aluminum and plastic. and some carbon fiber sheet, actually-1mm thick mostly but maybe up to 2.5mm if it can handle it. I'm also considering trying to get one of these to work on my machine: DoughtyDrive
so i'm pretty sure i want 4th axis capabilities. I will be using stepper motors. I've been considering trying to build my own driver board, but if that turns out to be beyond me- i've also been checking out the hobbycnc driver board, and i've heard good things about it, so i'll be strongly considering that(unless you guys have something better...?)
as for the steppers, i want them to NOT be the limiting factor for what i can cut and how fast. I want the design of the machine to be the limiting factor.
also, spindle wise, i've heard good things about the rotozip...that's what this guy used: http://i53.tinypic.com/5f446v.jpg
but the guy soon afterward decided to upgrade, so i dunno anymore...of course, his machine is a lot bigger than mine... edit: i just realized that scheer is on this forum-yes, that's a picture of your machine!

[hemsworthlad]

Hi,
By the sounds of it your on a limited budget because your considering building your own drives so i'll just point out the doughty drives are several hundreds of dollars.!

Personally I wouldn't take the cheap route with drive's or any of the electronics and if you buy wise and are perpared to spend a little more on a quality product like Gecko's G540 then your control side will grow with you as your knowledge and CNC Addiction grows.
Steppers are relatively cheap so they are not so much a big issue and can be upgraded with each machine or upgrade.

IMO it will be money well spent and I would sacrifice building now in favor of waiting and saving if i had too and in the long run it will save you money.
Seen so many people take the cheap route only to regret it later because it's cost them more or even give up all together sadly dissapointed.

Dont know if Kress spindles are available in US but they are very good small spindles.

If you want a 4th axis and dont need super precision then you could always use the machine to build one using timing belts n pulleys relatively cheap.

Also I would for the little extra it will cost use ply wood it will be much better and stronger than MDF will also drill/screw much better.

Good Luck.

[JD_Mortal]

Birch-plywood is a good alternative to MDF, if it is thick enough. However, it may not be as "true" on the flat-surface. (Plywood tends to have un-uniform surface, due to multiple layers of glue and shaved-wood-ply. As opposed to MDF, which has a more uniform surface due to the pressing process and standardized development.)

Mounting will not be as strong, if you are going to use through-hole mounting. However, if you are just going to mount to brackets, then mounting will be about the same. (You do not want to mount anything with screws running adjacent to the surfaces, eg, in the short-side of any plywood.) Plywood, due to multiple layers of varying grain, does not have the same through-hole density/strength. The strength is all from face to face.

(I call it through-hole, but I am sure it has another name. The mounting style used on many prefab desks and cabinets. A hole drilled from face to face, about 1" from the edge, holding a nut. The screw-hole drilled from the edge, into the through-hole, attached to the nut. Used for 90-degree angle mounting, as a replacement for a bulky and unstable mounting block. Also commonly used on most RepRap assemblies that use MDF or birch-ply.)

Can't help you with the spindle part though... I am not at that point yet. I am just going to use all the crap tools I have in my garage until I find a decent spindle.

[Banana Jack]

thanks for the heads up - the doughty drives site doesn't actually list the prices, which i thought was odd. i am on quite a short budget, i might have to borrow money if i want to buy electronics before my next paycheck. maybe the doughty will be a later on addition... or maybe for my next machine. (8020 Al, ballscrews, bearings everywhere, and about twice as big as this one) or maybe i'll just design my own. i just figured a 4th axis would save me a lot of awkward remounting and repositioning when making 3d parts.

how much of a difference is there going to be though? between a hobbycnc 4-axis for $100 and the gecko g540 for $300? and are there any in-betweens, higher quality than the hobbycnc but lesser than the geckos? i've also seen the linistepper which looks pretty good for cheap.
i might end up upgrading to geckos eventually, with a different machine, but i think the hobbycnc will work just fine for the machine i have right now...that's what i'm leaning towards... that and three of these. 222 oz/in for 24 bucks, i thought it sounded pretty good. and a homebrewed power supply, i think i can handle that.

yeah, it looks like i can get a kress from ebay...and i bet they ARE good, they are quite expensive. a 530watt for $250, 800watt for $280. whew. i'm gonna need a variable drive system, too, for any spindle i get, aren't I? does that hook up to the driver board then, to control spindle speed by computer?

i'm hoping for as much precision as possible(making rc car parts - 1/36th scale maybe smaller...so super small.), but don't know how much i'll be getting with this machine.

i'd be using 3/4" wood either way, and i have the mdf already, so if it doesn't make a whole lot of difference that's what i'll be using. and as for drilling/tapping i'll be using 1/2" wooden dowel inserts, glued in, so i don't have to thread mdf directly.