Shortening a PRO4896 to PRO4848 – Do the Linear Rails Need to Be Cut?

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Hi all,

I recently picked up a nearly new PRO4896 at a great price, but unfortunately my shop space won’t accommodate the full length. I’d like to shorten it down to a PRO4848 footprint and was hoping to get some guidance from folks who may have done something similar or know the machine well.

I did come across a post somewhere here on the forum suggesting the linear rails need to be cut down — but I’m not sure that’s actually necessary, and I’d rather avoid it if possible. From what I can tell, the Y-axis linear rails appear to come in two pieces: one roughly 65" and a second around 48". If that’s correct, it seems like the rails themselves might already be the right lengths and wouldn’t need to be modified.

One thing I’m trying to wrap my head around is the structural difference between the two machines. The PRO4848 has legs at all four corners, while the PRO4896 has a cantilevered section extending beyond the rear legs. My question is: do I need to eliminate that cantilever entirely to end up with a proper PRO4848-style setup? Or can it be left in place in some form?

On the surface, it seems like this conversion could be relatively straightforward — just a matter of relocating the longer (~65") linear rail to sit over the longer extrusion section, effectively shifting the working envelope without cutting anything. But I want to make sure I’m not missing something that would affect rigidity, squareness, or the machine’s ability to home and travel correctly.

Specifically, I’m hoping someone can help me understand:

  1. Do the linear rails actually need to be cut, or can they be repositioned as-is?
  2. Is eliminating the cantilevered section necessary, or can the machine function properly with it retained?
  3. Are there any gotchas with the gantry, or wiring that I should plan for?

Any advice, photos, or links to prior threads would be hugely appreciated. Thanks in advance!

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You might find some useful information in the instruction on how to upgrade a pro4848 to a pro4896.

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  1. No, they do not have to be cut, at least on a modern PRO frame. The 4896 has the same basic parts as a 4848, just with additional pieces the 4848 doesn’t use (because of the extra length). If built to factory spec, the short rails at the front of a 4896 have to be removed (slid out), and the long rails at the back repositioned flush with the longer side frame extrusions at the front. The front gear rack does not even need to be moved, but the second one (and the extrusion it’s mounted to) will be removed entirely.
  2. I have a 4848, I would not personally run that overhang without the additional weight of the second four feet of structure. Moving legs is pretty simple, however, you’ll have a shorter electronics bar that determines your leg rows distance apart. And the back legs would only be half under the frame extrusion without adjustment. You could order a longer elec bar meant for a 4848 to set the correct spacing. You could shift the legs with the existing elec bar to roughly center of mass and omit the front gussets (that used to support the overhang). You could omit the elec bar entirely and replace it with lumber, plywood, or whatever else you have on hand for the time it lives as a 4848. You’ll have some extra legs and fasteners leftover from the disassembly, get creative.
  3. Personally I would look at removing the gantry at the very start, except leave the linear rail bearing blocks on the linear rail sections you won’t be removing (the longer pair). If you slide the bearing blocks off without the little plastic ‘keepers’, all the stupid ball bearings will fall out and you’ll curse your roof off. So - slide it onto the longer linear rails, support its weight somehow (get creative), move aside any cabling and brackets and so on, unbolt it from the bearing blocks, and get someone to help you lift it and set it down off the machine frame. Then you’ll have lots more freedom to mess with the structure without the extra weight and complexity of a moving hunk of metal.