Hi Eloid
I'm using Solidworks.
The table will be lifted by two large air rams I'll post a more detailed pic when I get home. Basically the table has 4 Thomson ball slides mounted to it near the 4 inner legs of the frame. The rails mount on these legs and on the other side of two of them (diagonally opposed) are the air rams. This is the setup that was used in the vacuum frame in the original plate making exposer that they were "saved" from. The idea is that I will lift the table then pin stops below it then allow the table to come down to rest on these stops.
The rails are mounted on angle extrusion with adjustment slots to allow for setting them up parallel etc and will be bolted to the sides of the legs which have tapped holes in them.
I plane on using the same style of air ram as a counter balance for the Z axis.
I hope to be able to level the table out easily at each set height.
Hopefully I'll have some real pics by next week that show this stuff in better detail and "in the flesh".
I would love to get input on my Y axis drive idea as these bits cost money and want to be confident of success.
The AT5 x 25 belt will be held stationary and under tension. It also will lay in a grooved support for its entire length. The belt is lifted outr of this groove around a large smooth idler pulley on the Y drive carriage, around 180 degrees a 15 tooth pulley the laid back down on the support by a second idler. The 15 tooth pulley is driven through a 3:1 belt drive by the stepper motor.
This arrangement should mean that 1 rev of the motor will result in 25mm travel ( 1 rev of 15 tooth AT5 pulley = 75mm, 3:1 = 1 rev of motor = 25mm) devide this by 200 and I have a resolution of 0.125mm per step or 0.0625mm per half step.
I will be using micro stepping however I only consider half step as being considered as a reliable resolution figure.
Accuracy however is going to depend on a lot of factors and at this stage I think only building it will show how good or bad that will end up.
The grooved belt support has two purposes:
stop the belt getting any bounce
help with tracking
I'm hoping that this will form a rack and pinion style drive with better tooth engagement as the belt (flexible rack) wraps the toothed pulley (pinion).
Cheers
Mark  |