Ok guys, ive decided to start another build. The large machine i built has now been dismantled due to leaving other job and premise.
This new one will be a 1000x1000, just big enough to cut the largest part my company offers at the moment (760 dia circle @ 25mm thick)
Look forward to adding my progress here and would very much apprecitae any help on the Z axis as this is the bit that always gets me. Or if anyone has one for sale that could be adapted i could be interested.
Ok here goes
80 x80 extrusion | 20mm aluminium gantry sides | 80 x 160 gantry 20mm aluminium front and back plates (This may change due to funding)
I assume at that size you are looking to cut wood, not metal?
I also guess this is an initial layout to see how it might work because there is clearly a lot to add. The bed I assume would also be aluminium box sections running between the 2 end plates? Even for wood you need a reasonable support to reduce vibration.
The raised legs and gantry sides dropped down look like you are considering a cross beam underneath for a single X drive in the centre? If this is the case then at this span it is not advised due to racking problems. 600mm width is considered the general switching point from single to twin.
If you are going twin X then I would extend the end plates to have additional material to allow you to mount steppers, bearing blocks etc. You can either go further out and run the ballscrews down the outside, or go up and run the ballscrews directly above the supported X rails (clearance hole required in gantry to clear ballscrew). Going above the rails is a bit stiffer and would be my preference (direct connection to gantry rather than bracket off the side), but would get more dust/swarf from cutting if no extraction used.
I think by 'Z axis' you also mean the 'Y' as that is not yet drawn also. Can you afford 1000mm profile rail for Y? Used sets go for £150-£200 on e-bay e.g. 'fa-system'. You can put the rails top and bottom and have a semi-wrap around Y axis leaving you to put the ballscrew on the top, or behind (although not favoured by some). This keeps the Y axis close to the gantry.
The standard Y/Z axis is usually a pair of 20mm plates, recessed to take bearing blocks, etc. The front plate can be tapped to take your spindle mount, and the rear plate then fixes to the Y bearings via small intermediate blocks bolted at either end perpendicular to the main plate.
Last edited by routercnc; 21-01-2014 at 08:28 PM.
Correct, additional extrusion will be running across the bed, and ali for the bed, which ive just noticed that will raise my bed so the gantry will need to be raised.
I am actually going for the double on the X as you can see i have to screws in there, however i was thinking one motor to drive the two on belts and pulleys. But saying as i ripped my large machine to pieces, and i have the parts I might as well do direct drives.
Im in two minds to use ali plates and might just go for some 160x40 extrusion, this way as you say i could extend the end plates and run the screws parallel with the rail.
Yeah good point with the X and Y, I did throw this on there to see what the distance was, and i hate it, as you say by the time the Z and rails are on, im possibly looking at 180mm to the centre of the router bit...
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