RE: [CAD_CAM_EDM_DRO] Taig CNC Mill vs.Homebuilt Machine

Where does one find plans / drawings / pictures of a Stewart Platform? I
would not want to have to design my own from scratch for a first go at one
of these.

John Guenther
'Ye Olde Pen Maker'
Sterling, Virginia

> -----Original Message-----
> From: Carl Mikkelsen [mailto:cmm@...]
> Sent: Tuesday, February 04, 2003 10:04 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Taig CNC Mill vs.Homebuilt Machine
>
>
> Bob,
>
> If you are building home-brew, you might consider a Stewart Platform (aka
> Hexapod) mill.
>
> I'm into construction of my third generation machine. I still haven't
> gotten a head appropriate for milling steel, but I'm well fixed for
> aluminum and wood. I'm waiting for LittleMachineShop.com to get
> a shipment
> which includes an R8 head assembly
>
> Advantages of a Stewart Platform are:
> Accuracy does not depend on long, flat, straight, STONG
> linear ways.
> All forces are compression or tension -- nearly no
> bending forces
> are applied to moving parts.
> Full six axis positioning.
> Possibly lower torque requirements for motors.
>
> Disadvantages:
> Larger physical size.
> Six actuators, motors, and drivers instead of three.
> Accuracy comes from software and calibration rather than
> mechanical craftsmanship.
>
> -- Carl
>
>
> At 03:40 AM 2/4/2003 +0000, you wrote:
> >I have read with great interest many archived and all current
> >postings since joining this Group. I am encouraged enough to move
> >from the periphery and into the fray and would like to know whether
> >there is a compelling reason to buy a mill and modify it for CAD/CAM
> >use rather than assemble one from discrete components attached to a
> >welded frame, whether in traditional mill form or gantry.
> >I have been leaning towards building as it seems to promise larger
> >than "benchtop mill" size and I have several ball screws, linear
> >bearings, motors and drivers. I have believed that the use of these
> >components is inherently better than leadscrew and dovetail ways in
> >obtaining a tighter tolerance and longer life. My specific concern,
> >however, is the linear bearing's ability to withstand repeated stress
> >and my ability to construct a frame to proper tolerance.
> >On the other hand, the temptation to purchase a CNC ready Taig is
> >justified in my research having yet to read a single complaint or
> >regret. I could even us it to build a gantry mill as my second
> >machine.
> >I appreciate this group and have been impressed by its contributors
> >namely Les, Tim, Wes and Jan to name a few.
> >Sorry Bill, is that flaming?
> >
> >Thanks for the consideration,
> >Bob O'Neal
> >
>
> Carl Mikkelsen
> cmm@...
> www.foxkid.net
>
>
>
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