Well, I guess my measurements and my surface spoil board really worked. The laser is still there, yet I cut all the way through.
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Now that’s perfection!
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I got 2 of these as well to set up my table! Now I just need to find the time to……set up my table!! Doh!!!
A complete newbie here, and to CNC in general. The whole point in my interest in CNC besides the obvious labor savings and exacting repetition, is I’m now a disabled Veteran and can’t stand over a workbench for hours on end carving or cutting hand joinery like I did 40 years ago when I was a Cabinetmaker/Furniture maker. CNC would allow me to replicate many of the things like carving and inlays I used to do entirely by hand. Watching the discussion I like the idea of a drop table. Still, other than removing an entire section of the table, I am wondering if anyone has come up with other ideas, a scissor lift table height adjustment perhaps? Also, this removable center might allow for adding a fourth rotary axis but the stepper-driven ones I’ve seen so far are too small to turn pieces up to 6" in diameter which was on some classic furniture designs. I realize this is usually far beyond the “hobbyist” but if driven slowly, I still believe it doable. 4" would be the norm however. V1 and LRv3 is the most brilliant designs I’ve seen all across the introductory CNC universe, and by FAR the most inexpensive, not cheap, for that would be derogatory, just everything you need and nothing you don’t and giving it out to the community is to be applauded for sure, and I’m sure I echo the thanks of so many you’ve allowed to enter this world of wood/maker technology without selling a child - although I have considered it of my four kids on more than one occasion…grin.
So one of the most clever approaches to this that I have seen, is the one done by Steve, @steved, in which he used the approach of having metal struts for the LowRider to ride on (that are normally used for construction and garage projects, sold in 10 foot sections at Lowe’s or Home Depot, under several brand names, including Unistrut and Superstrut), and instead of cutting off the excess part of the metal struts, the left them sticking out on one end so his LowRider can actually travel right off the end of his table and operate out over mid air, and then he used a couple of (12”?) press screws to add a great Moxon Vise clamp that was made from some extra copies of the torsion box ribs, that he cut and couldn’t use for whatever reason. I think there was some mistake made in how they were cut, and so he didn’t use them for ribs on the table, but rather glued a stack of them together, and use them for this clamping piece. If you check out his build log there are pictures of it. I love the idea.
Here is the post of that LR3 that @DougJoseph mentioned. I‘m thinking about doing just the same 
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Maybe a dumb question, but if I want 4x8 cuts the calculator says 9.25 table for this, are you just gluing boards together to get over 8ft or am I missing an option to purchase a 10ft MDF board?
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I used flat MDF trim boards from Lowe’s for the rails. They come really long, beyond 10’ for sure.
The rest was a bunch of small pieces, I made Ryan’s table design.
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The key is that the whole table does not need to be that long, only the edges, which I sometimes call “riding plates.” Those can be made by either buying long MDF trim boards like @coinbird mentioned, or by gluing together two shorter pieces, or by using metal struts like in my design.
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Gonna go the metal strut option, should I be concerned about it riding off the metal rail?
I’ve never had it happen. Remember there is a long EMT tube referred to as “the Y rail” and the LowRider is guided by it in the long axis down the table’s length.
With this option, you have the added possibility of doing my mod that hides the long Y belts inside the struts. This can be done for one or both.
My video on this mod:
My Printables listings on this mod:
https://www.printables.com/model/422468-lowrider-3-cnc-hidden-belts-mod-hideprotect-either
https://www.printables.com/model/670446-lowrider-3-cnc-printed-holder-for-kobalt-routers-w
If your LowRider’s riding line on the non-rail side is different from mine, the “coupling nut spacer” part can be remixed to change its length as needed. If you run into this, I can help with the remix.
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Hi! Awesome thread. I’m going to build my first lowrider, and I’m going to put it on top of @DougJoseph 's table since I need full sheet cutting area.
A question regarding materials: why MDF over plywood? I would assume the latter is more solid.
Also, beyond the preference ranking, how much better are any of these compared to others? i.e. if MDF is preferable to plywood, is it WAY better, or just slightly better and plywood and plywood will work just fine as well?
Thanks!
Ryan has formal training in engineering, while I do not. The order of preference was quoting his advice. My understanding is that preference is because, for what is needed here (resistance to warping, cupping, twisting, bowing, stretching, etc) the more homogenous an engineered wood product is, the better. Plywood, compared to MDF, has strengths and weaknesses. Among its strong points are high tensile strength. However, the wood fiber that causes that, i.e. the grain of the laminate layers, means it’s also not as resistant to warping, bowing, etc, as MDF is.
I don’t know the degree to which one is better than the other. I know plywood can work, but I also know it can bend (flex) over distance. Technically MDF can bend too, but apparently not quite as much.
My understanding of the situation is that it’s much easier to add stiffness than it is to add flatness and much much easier than it is to add dimensional stability.
MDF is the flattest and most stable option, not the stiffest nor most durable. That covers the 2 hardest problems to solve. We can make it stiffer by adding support underneath such as a torsion box structure or really any other form of simple supporting trusses etc. We can manage the durability by just taking steps to avoid/minimize any damage, making it easy to replace, coating it or skinning it with something etc.
Whether a given material is slightly better or way better probably depends on your goals. A warped table will eat some Z height, but if you’re only cutting 1/2" to 3/4" plywood then I doubt even 1/2" of warp actually matters. A warped table will take longer to cut because you’ll need to start the cut higher to clear the high spots and cut deeper to get through the material sitting in the low spots. A warped table will make mechanical engraving less consistent in small areas and potentially impossible over large areas. A warped table will make it difficult to accurate cut pockets to a specific depth.
Based on that, if you’re making a smaller design and only doing through-cuts, you could probably get away with damn near anything, and it looks like many people have. Chuck it on a sheet of whatever is laying around and replace later as necessary.
If you’re trying to make a full sheet machine then minimizing warp is probably a good approach even if you’re only planning through-cuts because having to do an extra pass to make sure you’ve got through the material could be a significant increase in total time.
If you’re trying to do engraving with a v-bit then flatness is super important so you’d probably want to prioritize that.
Of course, with all of this there are ways around it. Even if your table isn’t flat, you can surface your spoilboard which will then give you a flat surface, relative to the machine. Even if that isn’t actually flat, as such, as long as your material is flexible enough that it will follow the table then you’re fine. For example if you made a full sheet machine that had one rail level and one that rose 5mm over the length, that z=0 plane would have a twist in it, but that twist is low enough that even 1" plywood would follow that contour.
If you would only seldom do engraving then you can always either surface the piece with the machine before engraving or surface a small section of sacrificial spoilboard big enough for the job.
Also, the thing that helped me the most was to just do the easy thing to start with, get to know the machine (an MPCNC in my case) and then make changes as you go. The parametric tables are cool, but I could easily see a scenario where I’d never actually build/run the machine because I’d still be trying to design and build the table. Other people who have just bought an old solid-core door and gotten started on that have it figured out. I bought a scrap of 40mm tri-board and mounted the MPCNC to that thinking I’d make a fancy cart type thing with space for tooling etc. It’s still on the tri-board ~6 years later?
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@DougJoseph i think there might be a slight issue with the files of the 49x97 cutting area, 3.625 inches tall torsion box here: your site + /for-lowrider-v3-cnc-cut-table-dxfs-for-cutting-f360-archives/
The F360 file lists 4 long cuts and 7 short ones (all in 23/32’‘). Plus, the riding plates are half inch cuts. The thing is that the pre-arranged DXF files include one extra long cut, which takes the 7th short cut to the other plate, making it appear as if that cut should also be 23/32’’ and it says so in the file. Anyways, it just makes it a bit confusing.
Good catch. Here’s how that happened. At the start, I had all the ribs (short) and spars (long) on the first sheet, and only the riding plate parts on the second sheet. However, to get that done, I had the ribs and spars close, only 1/4" between them. For use of a 1/4" bit, this closeness is what I have termed as “common cut” — where each rib or spar mutually shared a profile cut edge or two with its neighbor(s). However, I later realized that cutting it that close can possibly lead to issues with cut quality. So, I moved them apart a little and that required moving one of the ribs onto the other sheet.
There are three possible workarounds to consider. One is that the riding plates could be cut in 23/32’‘ material. Another is to manually drop the last rib onto a cut of its own, and when prepping the Gcode for the riding plate cuts, ignore the rib that’s shown there. Finally, one option is to move the ribs and spars back to 1/4" from each other, so they can fit on only one sheet, and either risk the close cut with a 1/4" bit, or use a 1/8" bit, in which case they would not be common cut. Sorry about the confusion.
I may be wrong but there might be a simpler option? I think ther’s an extra spar in the first DXF. The full table only uses 4 but there are 5 spars to be cut. If you remove that spar, it leaves enough room for the extra rib which currently sits in the second DXF.
On another note, how would you recommend aligning the top and bottom sheets to the torsion box? Since the full sheet is a bit longer than the table and there’s some extra coming out of both sides.
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Wow. Sorry if I missed a mistake like that. Will correct
Thanks again for this sharp-eyed catch. Don’t know how I missed it. I have created a new cut plan file, and replaced the zip file on my website with the new one. As a convenience, here is a link to the new one:
If you think you might ever want to add a vice type clamping section to one end for doing vertical CNC cuts on taller items, like @steved did by using press screws and extra ribs he cut, which is a great idea, then I suggest aligning the tops so one edge is flush with the torsion box edge.
Otherwise, maybe just center the tops on the torsion box, with the lip on each side being about equal.