PRT to PRS Retro-Z gantry upgrade reviews?

[Stagecraft]

I have a 4x8 PRT Alpha with the older bolt-together Y carriage running a 5hp Colombo spindle. Just wondering who here has done the upgrade to the PRS Retro-Z gantry and was it worth the cost and effort? - Boyd

[beacon14]

I put a retro Z axis on my 2004 PRTAlpha and am very happy with it. It's much more robust than the original Z axis, and it's easier to obtain and maintain proper Z alignment to the table as it bolts both above and below the support beam instead of just into the side.

Installation was easier than I expected. The hardest part was getting them to ship all the parts (spindle adapter plate) and bolts (dozens of extra bolts in the bag, but still had to make a trip to the hardware store for the ones they left out). Other than that the whole thing is pretty much pre-assembled, it just slides in and gets bolted with 8 bolts, attach adapter plate and spindle, adjust using trammel, ready to go.

Only downside (besides cost) is losing an inch or more of Z clearance above the table. I rarely cut thick material so it's not an issue for me. I could raise the whole thing one hole but then I'd only have one of the two holes in the bottom mounting brackets engaged and to me the rigidity is more important than extra Z clearance.

Whether it's worth the cost depends on your situation. It doesn't actually do anything that the old one didn't do. In my case I mounted the old Z axis as a second Z to replace the air drill, and it was well worth it.

[davidp]

HI Boyd,

We upgraded our PRTAlpha to a 5 hp HSD Spindle with tool changer last year. This involved upgrading the Z to the new Z. There were several gotchas but in the end it was worth the effort. At the same time we upgraded our rails to BWC rails and new rollers.

The new Z did not bolt directly onto the old carriage. We had to drill new holes and move the Z back as far into the carriage as possible to allow for clearance. But if we moved it too far it hung up on the Air assist ram holding plate. It involved a bit of trial and error.

Was it worth it? Definitely!

Would I do the whole upgrade from a 3hp Columbo to a 5hp HSD including ATC and retro Z on a PRT, again? Possibly.


FWIW

David

[Stagecraft]

Thanks guys!
Hadn't thought about retaining the original Z as a drill carrier - brilliant! Would like to see how you've set it up though as I'm surprized there's enough room on the carriage for all that hardware.
The ATC is a bit rich for my budget at the moment but something I've drooled over ever since seeing my friend's Haas CNC with tool changer in action.