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  #1  
Old Mon 21 July 2008, 16:57
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
MechMate Gantry on a Moving X Table?

As this is my first post, I'll give some kudos to Gerald. His design, engineering, and materials sourcing skills have been lauded by others. I'd like to point out that the right moderating touch on a forum site is also a master level skill. Let me test that skill with a crazy idea:

I'm a hobbyist type with a background in technical theatre. I can't dedicate the 90 sqft of floor space that I'd like to have for a full size
MechMate. So I started thinking up crazy options: I could share a 9' x 17' x 8' high garage between a car and an MM. But which do I drive on top of
the other? I could try for some kind of vertical design, or perhaps a "Murphy Mech Bed" that folded out of the side wall of the garage, but it didn't really appeal.

This, a glance at recent SB products, and some consideration that my typical parts are less than 2' x 4', and I started thinking about modifications to the
MechMate. I still didn't want to give up on eventually, or occasionally having a full sheet table, though.

All of this distilled into the idea of a frame that could support a MechMate gantry and a table that moves in just the X axis. The frame could be designed to sit flush with the end of a full size mechmate table so that gantry could be rolled right off the end of the table and onto the frame.

The frame would be the full Y dimension, but only 2 to 2 1/2' in the X dimension. It would have rails, but no racks, and a mechanism for locking
the gantry in place at the center of the table. The MechMate X driver pinions could engage short shafts passing on bearings through the X support beams to provide a pinion on the inside of the X beams that drove a rail on the top side of a movable table. The bottom side of the table would ride on standard industrial ball transfer casters, and the sides would use bearings against the insides of the X beams.

Take away the original MechMate table, and you have a small footprint machine (5' deep in use, 2 1/2' in storage). Extend the vertical legs on the rear side above gantry height, and you could place overhead shelving to support the electronics. The entire frame, including the X beams, could likely be built out of 1"x3" channel.

If you make the X cable bundle long enough for a full size table - or slightly longer, you have a starter module that can be used with a future
full table by unlocking the gantry, rolling it onto the table, restoring the rear X stops, and off you go.

Does any of that make sense? Should I draft up some pictures to send, or have I already left the boundaries of sanity?
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  #2  
Old Mon 21 July 2008, 20:33
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Brad,
Think of the MM as a Wagon that can store upstage in the garage.
I have gone down this path and I think I might have a solution for you.
Sean
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  #3  
Old Tue 22 July 2008, 00:52
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Welcome Brad, no, I don't think you are insane . . .

Draft up some pics. I look forward to some sane lateral thinking.
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  #4  
Old Sun 02 November 2008, 15:30
servant74
Just call me: Jack
 
Nashville (Tennessee)
United States of America
I went to a ShopBot Jamboree a couple of weeks ago. They had a full size SB there, and several 'ShopBot Buddy'. I too like the concept, of using less space taken up in my small area, where I can see using a smaller working area for 'daily task' and clearing things out when I want to work on a 'full size' piece of MDF or plywood. The SB Buddy moves the work area underneath a fixed gantry.

So working with a 2'x4' really takes up 4'x4' or work area (roughly) but if you want to work on a 4x8' sheet, it takes up 4'x16', about. The buddy is really about 5'6"wide to make room for rails, etc on the side. When stored, the SB Buddy is about 5'6"wide and a bit over 2' deep, and with associated 'stuff' about 5' tall. The moving table is mounted on a 8020 extrusion, with a rack and 2 hardened V-rails attached on each side of the extrusion, that has a 'spoil board' attached. It sounds like most SB Buddy users attach a 2nd spoil board or thin vacuum hold down on top of the one that is attached to the extrusion.

I like the idea of a 'fold out' bed extension with a movable gantry if it could be done. The SB Buddy seems to have some issue with tolerances related to the moving table, or so some people were saying. It could be in the use rather than the equipment too.

Last edited by servant74; Sun 02 November 2008 at 15:32.. Reason: wording was not appropriate.
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  #5  
Old Sun 02 November 2008, 22:58
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The fixed gantry / moving bed style of machines go back probably a century to the heavy metal working industries. Heavy router guys also use it today, eg. Komo. It is nice to use with automatic tool changers, because the tool magazine is stationary and not far away from the collet.
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  #6  
Old Wed 11 August 2010, 06:41
qroger
Just call me: Roger
 
Matthews (North Carolina)
United States of America
Here I am bringing a zombie thread back to life. This moving x table is the way large scale pen plotters worked for years. The pens moved back and forth in one direction and the precut paper sheet moved in the other direction. At first glance, the inertia of an OSB sheet would eventually limit the speed, but on second glance, the gantry assembly must weigh close to what a sheet of OSB weighs. At first glance, you would be limited to standard sheet sizes, but using a moving platen that would be engaged in the stationary machine would fix that. If the problem for consideration is floor space though, It would be much closer to the original MM design to just tilt it up so the y direction was verticle, like a panel saw.
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