Re: [CAD_CAM_EDM_DRO] MachMotion vs. DIY for a Bridgeport

Well, I haven't seen the Bridgeport, but after having gone through this...

(See previous answer for the Taig guy)
A single Gecko G540
48v 7.3A power supply from eBay

>200oz square-bodied steppers. NEMA23 type.

Desktop PC with a parallel port, one with a video card not just on-board
video (though you can get around this by adding a video card). Mach3
software to control it.

The ONLY real tricky part here is you need NEMA23-sized motor mounts
that specifically fit the Bridgeport. I can't help you there, if nobody
here knows and eBay gets you nowhere go to CNCZone forum.

I'm not sure what shortfalls in steppers you're referring to. Servos
CAN be faster, but probably not for a mill. The G540 can drive already
steppers faster far faster than many types of commonly milled stock
could ever even be machined at, and it's beside the point because the
steppers can already meet or exceed the maximum recommended speed for a
lot of milling machines. The big routers which have high-speed transit
capabilities, and use wood stock which can (and generally should) be
routed at >100ipm are where the servos become useful. A Geckodrive
seems to get around all the hardware problems and pains that would cause
steppers to stall or lose steps.

This setup is pretty much guaranteed to not only work without
complications, it'll actually deliver some top-notch performance. It
will also be surprisingly cheap. That setup should be under $500 in
parts, not including motor mounts which I can't estimate.

Danny

danieltmedlin wrote:

> I have a Bridgeport Interact CNC mill. It was one of those great eBay
> deals. Bought the machine from a vo-tech school for $300, but they
> had been using this particular one for spare parts. Needless to say I
> have none of the CNC controls.
>
> After searching the Internet far and why I see where some people
> would use stepper motor systems, but apparently they do have some
> shortfalls in performance, on the flip side they're affordable if you
> can decide what components are compatible we teach other. Another
> solution is to collect the necessary components for a servo control
> system. The performance is better, a bit more expensive and more
> difficult to tune.
>
> This is my dilemma I'm not an electronic guy. I've been trying to
> learn enough to understand the nomenclature from each breakout board
> manufacturer, but this seems to be overwhelming for me. What I'm
> scared of is buying a couple thousand dollars worth of parts and then
> once I start sitting down to wire everything things are not
> compatible and "magic smoke" starts pouring out of things. This is
> the chance when you DIY. I do everything myself except electronics.
> Making the brackets for motors etc. is no problem but selecting
> electronic components that are compatible is a problem.
>
> My dilemma is do, I buy a complete system from MachMotion, or do I
> attempt to DIY. The Mach Motion system will run around $6,000, but it
> seems to be pretty close to state-of-the-art for a guy that has a one-
> man machine shop. I figure I could do is stepper system myself for
> about $2500, or attempt to servo system for about $3500. The $6,000
> price tag is a little bit out of my budget but not enough to where I
> couldn't scrape up a little extra money here and there.
>
> I'm sure some of you have built stepper systems for a Bridgeport that
> work very well, and others have built servo systems that do just as
> good. When you consider the amount of time that you spent assembling
> the system versus simply purchasing a complete turnkey system, what
> does hindsight tell you?
>
> So what's your opinion?
>
> Dan
>
>
>
>
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