I'll apologize for this question now, but

LowRider CNC Advice
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I know I should just really finish building the parts and then worry about this stuff later, however I have a question regarding the ease of removing the gantry and size of the table.

basic question is if I had two tables, one for cutting 48 x 48 and the other for cutting 48 x 96 inch material, it would seem easy enough to simply move the “machine” from one table to the other, using same belt, just minding the excess belt when on the smaller table top?

I have my reason for wanting to do this LOL

i would mostly be using the smaller table, like 90% but there will be times I will need to cut a full sheet of plywood, mdf, etc. on those rarer occasions, I’d like to have the ability even if it meant making a temp full-size area (emt is cheap) on the ground like I will when I cut the strut plates.

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Shouldn’t be too hard but squaring it up will be a bit of a chore each time you move it. Clearly would need to remove the Y belts as they will be a different size but aside from that I don’t see why not since the X axis is the same length

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I bet it would work. You may need a new belt clamp so you can shorten it for the smaller table. Or just have two sets of belts. But you would have to still swap them and I’m not sure how well the calibration would survive that.

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You would have to square it for each table. I would think as long as the belt holders never moved you would be ok writing down the different pull off amounts for each table and just swapping it in the config. Or I think you can have 2 different configs on the Jackpot so you could just switch to the one for the table you are on. Assuming you are running a jackpot and not a SKR board. Either way I would still check square the first few times you move it to be sure all is the same. Oh and your X beam level as well.

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Here’s a fun idea (and it’s an idea only…) Take a full sheet sized bed and cut it in half (2 4x4 squares). Connect the 2 pieces with a hinge so half the bed can swing vertically down. Install a split Y rail the full length, joining at the swing away location. Use full length Y belt with a middle length connector.

When you’re going day to day, he 2nd half of the bed is folded down and out of the way. When you need full length, raise it up and extend out the belts. 1 table, 1 CNC, 2 sizes. Use the fixed half for detail and fine work, use the full size when you want to do cabinet type cuts where the little extra wiggle when the move from rail to rail happens doesn’t matter.

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Interesting idea. My first thought is of critique and how it could go wrong, but I really want to believe this could be a viable option. How could one make the belt situation work and maintain a square and uniformly flat work area?

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i had considered something like this, only concern is would the bearings skip/ bounce as they hit the join , as nothing ever lines up perfectly

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having only experience with the primo, I don’t even know how this LR4 gantry really attaches to the table. is it fastened to the y rail so it does not fall off or is it floating on the y rail? I was under impression that the gantry was easily removed/repalced so that prompted me for two size tables.

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It just sits on the y rail on the X max side. And sits on 2 bearings on the X min side

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it will be interesting at least for me to see how this works (i know it will) if it is just sitting on rail and max X bearings. I would think it would be prone to bounce all over the place, get out of square, etc., but guess that is due to lack of experience with running the LR :slight_smile:

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I am with you on this one. While it MAY be possible to connect the two sections of Y rail together to minimize the bump, and it MAY be possible to build a hinged table so that the two sections are close enough together and at the exact same height at the non-rail side so as not to have an uneven transition, it seems challenging in my mind as to how to do that.

To me the biggest issue, however, would be the belts. I don’t see any way of “hinging” the belts, so you would have to remove them each time you go from one table to the next, and getting the exact same position each time you re-install then in order to maintain square would again be somewhat challenging. (by this I mean inserting and re-installing the belts within the holding blocks at the same teeth each time)

Quite honestly, if you are using the smaller build 90% of the time, just buy a set of longer belts, a longer section of EMT, and then re-level and re-square every time you infrequently change tables.

Or build a second machine. :upside_down_face:

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so i think it is better to build a second table with longer belts. the table could be just a frame that the Y rail sits on and the end-stop for the X max belt, hang it on the wall until needed (sort of in line with the temp on the floor frame to cut the strut plates). Build the 4x4 more permanent table, then I think I could just move the gantry to the larger frame, install the belts, square it up for those infrequent cabinet cuts and put it back on the 4x4 table when finished. I guess I will know how hard (PITA) it will be to swap the gantry between tables in due time LOL

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There are absolutely indexing techniques that could allow for cutting pieces longer than the Y axis. It depends on how often you’d do it, and how much imperfection where the cuts meet that your project could tolerate.

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Or use your hinged table like an outfeed and cut in sections with registration dowels.

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Bearing in mind that I have given this easily 35-45 seconds of exhaustive thought and planning… :slight_smile:

I haven’t built the 4 yet as I’m redoing a ton of things in my shop and haven’t gotten to the breaking down my 3 for parts yet. But I’d start with building the 4x4 bed area with the extension in place so I can more or less level the bed using swing away or otherwise moveable/temporary supports/legs. Install the Y rail(s) so they are completely in line with each other so there is no sway, and with the ends butted up against each other so any little bump would be minimized as the machine transitions across.

The 3 used a 2 part piece for the belts so you had a base that never moved and a removeable belt holder. I’m guessing but don’t know for sure on if the 4 does as well. So from conjecture alone that it is the same…
Install the max Y belt base positions firmly, install the Mins as well. Find a half way point and install a 2nd set of bases in line with the outer points.

Put the belts through the holders as normal on the MAX positions but feed the belt through without the double-back to lock the mins, so the piece can slide along the belt. Make a clip to lock the belt once you have it in the position you want.

So in practice, you have the bed full extended, move the machine to the main table, remove belt MINS and slide the holder to the mid table position, tension belt and install locking clips, Lower table extension out of the way entirely, and you are at your 4x4 bed.

You’ll likely need 2 different pullbacks for squaring, but once you square both table sizes you’ll just jump into fluid and put in the right ones for that table and you should be set. You can probably macro that so you just push 1 button actually but I’m not a fluid guy so don’t take that as gospel.

The main bed would be more solid than the extension, so all carving and real detail oriented work should take place there. But for cutouts, doing cabinet style work where fine detail isn’t needed, the full table should be useable.

That took 10x longer to type than I’ve actually put into it. But I can see it working in my head, and I’ve done a TON of reverse engineering on items. If I can see it work, it usually does :slight_smile:

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I really like the idea of building in a drop leaf support for longer workpieces. Assuming the LR is no more than 30" off the ground, You’d probably be adding a leaf on each side to get to a full 96" of support.

But with a built in indexing system, the machine would be really capable, but more compact.

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I wouldn’t expect more of an issue than when it runs over a wood chip. I wouldn’t think this would be an acceptable error range if I was doing LASIK on peoples eyeballs, but for carving wood… probably ok :slight_smile:

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just remembered this can be done using lightburn for laser cutters, so prob most cnc programs will have similiar functions which woud mean you would only need a support
https://www.youtube.com/watch?v=n__saOKVupA&list=PLE_Be8N7zXVi8qTV5XB4hYQgTVc40Zse2&index=8