I've been running the Lead1515 for a few years and love the machine. I'm wondering if I could expand this set-up from x60" x y60" to x60" x y120".
I asked about that myself, the response wasn't encouraging. Since they don't stock parts that long you'd need to find a different supplier for lead screws or switch it a belt drive which has it's own issues. Then you'd need to use plates to join the C-Beams together, which wouldn't be as rigid as a single piece (unless you TIG weld them together). Unfortunately as you get into those machine sizes, the price tag climbs on a rocket and takes on heck of a ride. If your research differs please share, I'd love a cut area capable of holding standard plywood.
The free-spanning side rails of the Lead 1515 make it less than ideal to extend by any significant amount. The longer the span, the greater the flex in the rails and flex is the enemy of cnc. And it's not a minor amount of flex. Doubling the length results in 8 times the deflection of the member. That's not to say a 4x8 system can't be done though. There are several examples of extended beds here on the forum. You will need to overcome propulsion issues though. If you go belts, I would suggest a dual belt system with 15mm belts on the longer axes. Rack and pinion is also an option you'll just need to figure out how to integrate it. There are also examples of this on the forum. Ball screws are also an option but they get fairly substantial in size when spanning a 3 meter distance. Like I say, a 4x8 system is possible. You're just going to have to do a fair amount of legwork to make it happen. Let us know what you come up with.
But... One doesn't necessarily need a 4x8 machine to do 4x8 work - you can process a full sheet half-at-a-time using Vectric Tiling: LEAD1515 can slide through a full sheet (Feed Through in Y) : Cut half, move sheet, cut other half. Precise Indexing is easy with dowel pins, fence on the side and other clever workholding tricks. Checkout other discussions on the forum: Search Results for Query: tiling | OpenBuilds
From what I've seen so far, one approach (that I like most) is rack and pinion rails for the Y-axis. You can get them in shorter lengths and bolt or weld them together to make longer runs. I was talking to a guy local to me that is building his own 5'x10' machine. He fell bass ackward into stash of free lead screws that support both X and Y for his build. If he hadn't though, he said he would have looked at R&P as well.
