Pebble's Low Rider 3 Full Sheet Build

I figured rather than making multiple topics to ask questions throughout the build I may as well just start my own build thread.

I’ve been making a “short” term table to use for the first year or so of use and I ended up going with a 2x4 construction with Unistruts. My question is I think straight forward enough. Does the run surface of the CNC have to be level with the spoil board surface? Said another way, is it ok if the Unistruts that the CNC rides on are lower than the spoil board surface? Essentially I have 2x4’s with a 3/8" sheet of particle board and then a 1/2" sheet on MDF will go on top as a spoil board, but my Unistruts will be at the level of the bottom 2x4s. I’m guessing it’s ok, but I may lose a little Z height?

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Yes, you are correct. If I understand you correctly at least, and yes it is just a lost of a bit of z height. Just note that the lower the Z height is the more rigid the machine. With what you are doing this way you are setting your zero height to be higher than “normal” and thus not as rigid. Not sure how much you will notice this as it is most likely not that much.

Philip

You also lose a little machine rigidity.

The LowRider is most stable closest to the table. By lifting the spoilboard, you lose thst space where the machine is most stable, as jt always needs to run that much higher than it otherwise would.

Eemember also that you get 80mm of Z or so (unless you are using taller plates like mine) so losing 18mm of Z for the spoilboard is nearly 1/4 of the Z capacity.

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Is that frame pinewood ? I run mine lr3 on top of pine and I can’t recommend that. Mine (14kg) lr has made grooves on the pine.

Yes, I am using pine for the frame, however the running surface, which is a metal unistrut, is not yet mounted. I agree that pine for the running surface is a poor option.

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Sounds like the best option is to probably rip a 7/8" board and glue that to the top of the pine rails and then mount the unistrut on the side to be at the same level as the spoil board. This way the strut has plenty of surface to screw to and support it.

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Well I got the boards ripped and glued on. Then mounted up the Unistruts. It was probably a bit overkill to drill and tap the rail blocks for the Y rail but now they’re nice and secure.

I was having some issues with the x belt tensioner nut spinning so I may have to reprint that piece. Not sure why it was spinning though, so hopefully that fixes it.

I also realized I don’t have enough belt material as I originally planned for only ~8ft on the Y. I didn’t want to trim the 10ft Unistruts so I had to order belt that should be here Sunday.

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Congrats! Nice!

I reprinted the part and the nut still spins. Printer is pretty dialed in so I’m not sure what else it could be. Another person in the forum posted about the same thing but never saw a resolution in the thread. I suppose I could try super gluing it like the other guy did, but he said that didn’t really help either. Maybe it was designed for a slightly bigger nut?

I did also glued that and it is working.

Glue is working so far. I found I needed more m5x30mm screws and nuts and for some reason it’s nearly impossible to find them in anything other than stainless steel on Amazon. Not sure why that is. So I ordered some and now I have to try and make sure I don’t mix my metals. Otherwise things are going alright.

For the wiring, I couldn’t exactly find which side is Y1/Z1 so I’m assuming that is the side closer to the control box which would be the left side when facing the router side. If that’s wrong please let me know.

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Whichever side you choose. They don’t even have to be both on the same side. But for simplicity, I went with 1 on the near (non-rail) side and 2 on the far (rail) side.

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Regarding the nut spinning on the X axis tensioner, I had the exact same problem and had to reprint a couple extras after breaking previous ones. The best solution i came up with was to melt out the nylon inside the M5 nut, making it essentially a normal M5 nut. In turn this made it so less force was required to spin the bolt into the nut, and it does not strip out the plastic the holds it. I think that the near side wall of the nut holding portion is much too thin, and after about 1 use it breaks and gives the nut a little more wiggle room that makes it able to spin freely.

So close to getting it started up for the first time. I’m not sure how to manage the cables for the X stepper and limit switch (and router power cord eventually). I tried putting them in a plastic wire loom but it flops all over. I almost wish I had a stiff plastic/fiberglass piece to put in there to give it some form. Kind of like the cable management system on the Prusa XL. I tried looking around for a chain system but haven’t found anything yet that works with the V1 Engineering Jackpot case.

I also realized I installed the control board the wrong way with the stepper drivers on the bottom so I’ll have to flip that around and reconnect the wires at some point.

Edit1: Just realized, I could just add the vacuum hose and that would almost perfectly solve the problem. Not sure how I missed that obvious feature.

Edit2: I found this post from Doug. Went ahead and ordered the suggested cable chain and will print the parts in the coming days. Looking to build a low rider - #66 by DougJoseph

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I used a length of 6mm OD air line tubing, with a short piece of fencing wire inside at each end for additional stiffness. Ran the X motor and X endstop wiring and the tubing inside some mesh loom, and connected each end using a zip tie on the core and on the top of the center strut brace (rear side).

Then I ran my Air Mist tubing and router power cable inside a plastic split loom, and strapped that and the vacuum hose to the previously mentioned tubing/wiring section using velcro straps. This lets me remove the router and/or the Air Mist system and/or the vacuum hose without disturbing the LR3 motor/endstop wiring,.



Works pretty good, looks okay.

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Alcohol mist?

Yup! I said Air Mist above for simplicity sake, but is actually IPA and air

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Well… I went to power it on for the first time, plugged it in and… nothing. No green light on the power supply, no 24vdc out. Measured 120VAC at the plug to the brick. Maybe it’s just a dud power supply that I got from the V1E shop?

The only thing I noticed before plugging it in was I manually moved the unit back on the Y axis which back fed voltage enough to light up the board LEDs and the LED on the power supply. My Ender 3 would do that but it never caused a problem.

How fast did you move it?
Fast hand moves of the CNCs or bed drops of the flying printer beds does, in fact, blow the voltage regulator and/or stepper drivers on SKRs or Jackpots.

Pull the power supply wires out of your control board and measure the DC voltage at those wires. If you have the right voltage, then there is a good chance you blew up the controller.

Honestly not very fast, but I’ll certainly be more careful now. I did measure the power supply without anything connected and got nearly 0v. I just hooked up my bench top variable power supply and was able to power up and move all axis so I think we’re ok from a control board perspective thankfully.

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