Re: Linear Actuator 4-Axis Robot - into a CNC router

"firstyear55" firstyear55@... firstyear55 wrote:
Date: Mon Jun 21, 2010 10:26 am ((PDT))

Hi Guys,
Thanks for your response its really appreciated.

Well the scary news is...I bought one.
Not that particular one, but pretty much the same; and luckily only for a third of the price!

[Great - now you're ahead of the game!]


Im not a pro by the way, so happy to be mistaken on this learning curve.. Im planning on making a DIY CNC using as many existing parts as possible with the aim of turning it into a super cheap 5-axis cnc muncher for wood and foam.

[I'd say see if you can get 3 axes working first, then start adding more as you gain confidence.]

I've been doing a bit of research and they do seem to be very well made linear actuators, made to go all day every day.
Withstanding over 100kg force on each face; with speed/rapids measured in G's also possible (up to 1000mm/s?). So strong/fast.
Backlash is about 0.02 or 0.002 cant remember but good enough for me.

I did notice the lack of support on the X-axis so that will be one of the first "fix's".(would be funny if the wrong code sent the Z axis flying off the X handle).

[If the configuration is the same as the first one you showed us, you might want to disassemble it and support the actuators in a different way. If they are cantelievered out into space, they'll work better for positioning applications than for routing, which requires more rigidity. As was, they will probably be able to cut foam, but wood might be more problematic. We made a router out of linear actuators by building a heavy steel frame and attaching them to it; that works pretty well.]

But first things first I'm working on how to control the robot using G-CODE...eeek!

Apparently they can receive and follow ASCII code so that might be an in.

Or

I'm looking at either keeping the encoders, ripping out the existing driver board and finding another driver (gecko?)

Otherwise just ripping out the AC Servos and replacing them with a cheapo ebay 5-axis nema stepper motor and driver combo?

[The existing AC servo motors might be more hassle to figure out than they're worth. These robots are generally supposed to be run within a proprietary environment, with all the components supplied by the manufacturer. If you lack any part of their system, you might find that it's more expensive and difficult to replace it than simply to scrap it and start over with more decipherable components. But blindly purchasing something similar off Ebay just because it seems cheap is likely to only increase your pile of useless junk. Instead, getting a driver system that comes with support (it's hard to beat Gecko drives in this respect) and motors that are recommended to work with them would be a better plan. Get Mach3, which will install into a standard computer and turn it into a motion controller capable of running G-code, and you're all set (except for the CAD and CAM software, of course...)]


Any ideas.

Dont laugh, Im on a mission to make this work so if you have any ideas, let them rip as I'm going to need all the help I can get..

Cheers
Firstyear

[It sounds like you've got a good start on this - let us know how it goes, okay?]

Andrew Werby
www.computersculpture.com