Revnull LR3 Build, my 1st CNC

Let the build begin!

I’m planning on printing my parts out of ABS since I built a Voron v2 last year. This should provide similar (possibly better) rigidity to PLA but with higher heat deflection. Here is the first batch of parts from this last weekend. I didn’t really have a color scheme in mind, but orange was already on the printer, so orange it is.

This will be my first CNC, so looking forward to learning along the way. Thanks in advance for any help and advice the kind members of this forum can offer along the way. If there are any kind souls in the Bay Area of Northern California that would like to cut my strut plates for me, I would be forever grateful. :wink:


I’m in Tracy…

Wow, nice to have a project were the primary dev is somewhat local. I’m in the south bay, about an hour away in Morgan Hill.

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Today’s print, the Core.

I’m still deciding what my contrasting color should be. Thinking either a dark gray or matte black. In the long run, all color combos get thrown off by the color of the router/spindle. I have both the Makita (blue) and HF Bauer (red) routers. Maybe if I’m feeling ambitious, I’ll try to model a printable top cap to color match the rest of the printer. :laughing:


Wow, it’s like pulling a tri-tip off of the print bed. :laughing: The edges are surprisingly sharp.

I’ve got about 200g of filament on the roll. What should I print next?


A few more parts done. I think it’s time to start shopping for hardware.

Looking at the Amazon links in the documentation, it calls for 110mm lead screws, but links to 300mm versions. I assume this need to be cut to length. Would 100mm lead screws be too short? I found these:


I don’t think it’s going to make it. Luckily I was around for a manual change. A runout sensor is definitely in my near future.


Yeah cut to length or leave them sticking up. I have 110’s here. 110mm T8 LeadScrew and Nut – V1 Engineering Inc


I think I squeezed that last little bit out of my orange remnant spools. Time to move on to black.

I also found a stash of skate bearings in my parts bin, so a quick trip to Ace and I now have metal installed. It’s practically a CNC already. :wink:


You’re off to a great start!!

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Has anyone used these type of flex couplers before? I have a couple in my parts bin that I can use for my build, but haven’t seen them in the build pictures that I’ve come across so far.


Never seen before, looks interesting. Does anyone know how this approach compares regarding ease of reliably snugging grub screws?

Am relatively new here, but I’m guessing a LR3 troubleshooting guide, at the very top, would have a PSA stating “1) Ensure grubs screws in your Z axis couplers are snug. 2) Seriously, double check your grub screws are loctite/thread-locked”

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No problem they should work great, we don’t typically use them because they cost a bunch more. They are not good at pulling but we have gravity for that.

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Just a PSA for those using “no name” filament. Not all spool cores are the same size. My no name black filament on an oddly wide spool looked to have about 500g left (I should have weighed it), when in reality it had much less.

The result…

and a very late night Amazon order of more black filament. :laughing:

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I have those on my build. I put them on the LR2, and transferred them to the LR3 after stretching the springy ones one time too many. (Not a problem on the LR3.) If you bottom out an LR2, they will just pull apart, and then you just set them back together afterwards.

The Amazon basics spools get me every time. The core is huuuuuuge. I always estimate 3 plus hours left on it and boom, it runs out compared to every other spool I have.

Yeah, it’s the worst. Just before I was heading to bed, I checked on the spool and saw the exposed core. :frowning: I stayed up way too late waiting for it to run down so I could pause and swap it out. The other spool of black that I had was PETG so no dice there. My last available spool of ABS was the inland “sliver” I’ve been trying to burn through for a while.

I think by-weight is the best way to go moving forward. Most slicers give a filament usage estimate in either weight or length (I use Prusaslicer). If I find the average weight of all of my empties and pad it by a few grams, it should give me a good baseline to estimate the remainder of a spool. It would at least give me a higher confidence level before starting my next print.

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Slicer’s most precise measurement is distance. Since they control the extruder. Volume is then computed based on the diameter setting and mass is based on the density (which can vary between plastics).

If you have a way to weigh the spool without disconnecting it, then that should be pretty accurate. But accumulating the weights over the while kg is going to add up error.

I like to count the number of loops near the end. Then I can compute the length left by multiplying by the circumference of the spool. It only works right at the end though.


All true, but for the most part I’m just looking for a decent swag number so I can better plan the usage of remnant rolls. In the end, a runout sensor should negate the need for any of this. I have it on my desk, I’m just being lazy to install it. I’d rather be working on my lowrider. :smiley:


Amazon stopped by. :slight_smile:

Not the haul I was hopping for but who couldn’t use more filament? The emergency stop button came in a 2 pack so I guess I have 2 build a 2nd CNC after this. :wink: