Stefan,
I have two separate servos driving the two X-axis screws through two step and direction input servo drives driven by the same step and direction pulses from the controller. The Y axis is a single servo drive. Both X and Y axes are driven through timing belts of 1.5 : 1 reduction.
The reason for using hexagon rod in the wheel carriers is the all the angles are automatically true. If bolt and axel holes are drilled on the centre-line of the long axis then everything will line up truly.
I have uploaded two more diagrams of the Y-axis setup in files/JLC/ for you to have a look at. I believe that my setup is about the cheapest way to get a reasonably accurate XYZ table.
HTH
Regards
John C
-----Original Message-----
From: Stefan Trethan [mailto:
stefan_trethan@...]
Sent: Monday, 4 August 2003 4:52 PM
To:
homebrew_pcbs@yahoogroups.comSubject: Re: [Homebrew_PCBs] Re: re : sqare steel "pipes" as rails?
hi john
i see the importance of bearing size comes (at least as a big part) from
using another hexagonal rod
for screwing the bearings onto it.
how have you coupled your 2 screws?
timing belt? (i even saw chain on the web.....)
your second axis (the one riding on the main axis), this uses also two
rails normally and one screw.
but i wondered if it would be preferable to mount this two rails
horizontally or vertically...
(lie them flat down on the first axis carriage or put them on a 90 degree
mounting in relation to the first axis)
regards
stefan
> Hello Stefan,
> I use 2 screws.
> As for the bearing size, If the bearings are too large for the size of
> the hexagon: -
> the screws and ID will be too large for the hexagon bar carrier;
> the bearings might interfere with each other and will not ride on the
> rail properly; and
> will set the carrier and the rail too far apart.
> If the bearings are too small there will be no clearance between the rail
> and the carrier.
> HTH
> Regards
> John C
>
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