Re: Dremel alternatives

Ian,

(snips,inserts below)

> Firstly I'd better describe what I'm building. It will be a fairly
> low end, bridge style machine, built out of MDF.

Neil Gillies has built a couple (one bridge, one gantry) of MDF
machines. He's on this list, and if you do a Yahoo search of Seagull
technologies, his website (with pics) will show up.

> For example, the "screws" are going to be stainless steel
> threaded rods available at home depot.

You must have a hi-end home depot. The ones near me dont have SS
screws! But they DO have plated allthread. If this is what yours has,
you need to run a die down the length to clean up the plating.

> Steppers for this one are only going to be Nema 17 size, 12v (yea I
> know probably too small)

These ARE too small (based on what you say you wnt to do below). Size
23 motors can be had for 5 bucks, and will be a MUCH better choice.

> Am I correct in assuming that gearing, or gear and timing belt type
> options increase my torque forces similarly?].

Yes. However, a gear reduction, or timing belt drive will ALSO "cost"
power from the stepper. And 12 volts will limit the speed, since the
stepper will already be turning relatively slowly, compared to a
higher voltage drive.

>I plan on very light "bites", slow speed, and multiple passes.
>
> Secondly, my applications. I want to try everything! :{) Well
> really, a little circuit board milling and drilling.

Your two statements above are at odds with each other! PCB drilling
needs hi rpms, and fast feeds to prevent epoxy smear. Pcb milling is
similarly improved by higher speeds/feeds. And with a "non-stiff"
machine, taking light cuts can make the cutter work HARDER, as it
deflects to a scraping/rubbing action instead of cutting. For copper,
this is bad.

> Oh yea - cutting some shapes out of tin (roof flashing type of
>thickness).

This will "want" to be done at LOW spindle speed (unless using a
rotary "burr" type cutter). Also, it will require a stiffer machine
than your other mentioned apps. Use aluminum, and save the steel
(Tin) for your Mk. III machine!

> Thirdly, budget and choices. I want to keep the tool down to around
> $100 Canadian or lower if possible. Listed below are some of the
> choices I've seen around, along with some of the pluses and minuses
> of each.
> Ian C.

LOTS of entry level machines use a Dremel successfully! Direct drive
5 buck, 60 oz. steppers with 1/4-20 or 3/8-16 allthread running from
a 12v, unipolar drive. So it can be a good choice for a Mk. I
machine! You need to keep in mind that the WEIGHT of the tool will
have a large effect on your machine, which will be non-stiff and low
powered (axis drive). Dremels are light.

The lam trimmers or electric die grinders will be better for a Mk.II
machine... But much heavier than a dremel.

I'd Keep It Simple on the first go-around. Have fun!

Ballendo