View Full Version : PR Conversion photos

09-29-2007, 03:29 PM
I promised I'd post a couple pics of my gantry and rails for an upgrade I'm working on.


I have a PR shopbot with rack and pinion. I wrecked my PR gantry trying to weld it square, and decided to replace it with a vertical orientation gantry. The extrusions are from 8020, and are probably overkill, but allowed me to assemble without welding or machine shop expenses. I can also mount a spindle later without worries of deflection.

The rails are Bishop Wisecarver, and use the wheels from the PR gantry. The new Z axis in the foreground is an Ebay deal that has a badly galled ball screw. I'll replace it, and end up with 10" of Z travel.

I'll be using an Ascension controller and Mach 3 software.

I've spent more than I wanted to, but learned alot.

Is it still a shopbot? I think so.

Thanks for comments

Wayne from White Salmon

10-04-2007, 12:18 AM
I sure like the idea of the upright gantry.
How are you going to attach the gantry to the X rails? Just rollers with the motors with tension on an under mounted rack?
I have been thinking of retrofitting mine with linear bearings of some sort. I think long ones are a little too expensive for now. But I need to build what you have started first.
I can't have my machine down for long.

10-04-2007, 10:29 PM
I'll try to post another pic or two. I've got the gantry mounted now, so I can show you how I have the gantry mounted on the X axis.

Basically, I bolted a Bishop Wisecarver steel rail that matches the Shopbot Vwheels to the side of the unistrut X rails. The rails were about $250 as I recall, including rails for the Y axis that mount on the gantry.

I also used a couple of the old gantry wheels from the underside as hold down wheels for the gantry. One on each side seems to do the trick.

The gantry rolls nice and smooth, and doesn't seem to be to heavy as I initially feared. But I think if I were to do it over I'd copy the Shopbot PRS method and use a triangular end plate instead of my inverted T gantry ends. I think I'll end up putting triangular plates on the gantry ends to firm things up.

So far so good. Next comes mounting the Z and Y motors, and then wiring things to my Ascension controller.

Thanks for the interest.