New Linear Z for my SO3 XXL - Long post with pictures

I have never been a huge fan of the Z on my SO3. This post is not meant to bash the design of the SO3 or anything like that. I read the forum all the time and know that plenty of people have no trouble getting their Z belt adjusted. I’m not one of those people. I have had issues with losing steps, especially when working with short bits toward the bottom of the rails. I also had issues with dust collector brushes being stiff enough to interfere and mess up my Z. My SO3 does bot have the screw tensioner like the newer ones come with, so getting tension meant prying of using wedges.

I saw several threads on the Inventables forum where people were installing linear Z slider kits from CNC4NWBIE on eBay and I could not find a negative review. So i decided to buy one of the XCarve Linear Z kits myself. I contacted Joe at CNC4NEWBIE via email and told him I had an SO3 XXL. He instructed me to purchase the XCarve version, and he would drill and tap holes for installation on the X carriage plate and drill/tap holes for the stock SO3 spindle mount.

A few days after I ordered the new Z arrived. I opened the box and was immediately impressed with the quality of the unit. The only thing I did not like was that the screws were loose in the box, and I managed to lose a washer somewhere in the packing material. No big deal. I let Joe know that bagging the hardware items would be a good idea.

Here is what came in the box. There were (4) M5 socket cap screws to attach the new slider to the X Plate. I found out later that 2 of these screws should have been flat heads instead of socket head. Joe said they must have acidentally sent me an XCarve hardware kit. No big deal, i picked up some M5 flat head screws at Home Depot and was able to complete the install. (4) M4 screws were included for attaching the Z Nema 23 to the top. A coupler to mate the motor and the fast pitch screw, and a couple of longer screws to attach the spindle mount.

On the back of the plate, Joe has milled out space to avoid the existing screw heads that would be in the way. this plate fits like a glove. I failed to take a picture of the back of the unit. I meant to do that before installing.

The first step was to remove everything off of the X carriage plate.

The current version of the SO3 kit uses existing holes in the X plate. You can get to the top holes, but in order to get to the bottom holes, you have to remove the bottom v-wheels and tilt the carriage assembly up in order to get the flat head screws in. i used a dab of blue loctite on each screw to attach the slide. Once the linear Z kit was installed i cleaned up the v-wheels and inspected them for damage. They looked good, so i reinstalled and adjusted the eccentric nuts to get things tightened back up. I am seriously considering trying the eccentric spacers. I just hate adjusting the eccentric nuts. Joe is looking at other options for the bottom screw holes to avoid disassembly of the carriage to make this a truly bolt-on kit with no disassembly required. He is going to test using the hole that was previously used for the Z belt tensioner.

In order to install the stock SO3 spindle mount, I had to remove 4 screws from the plate so I could remove it and install the screws from the back side. The fit is so precise using the holes that Joe drilled and tapped for me I had no issues installing the spindle mount.I used a dab of blue loctite on all of these screws as well.

Next was installing the motor. The kit comes with a coupler. the screw does not have a flat for the set screw, but I made sure to align the flat of the motor facing the set screw. Then I tightened down the set screws. I forgo to add a little loctite to the set screws, so i will probably go back and correct that.

Once the coupler was in place and the set screws tightened I installed the 4 M4 screws to hold the motor onto the mount. I had enough slack in my motor wiring that I did not have to disconnect anything. I had to cut off a couple of zip ties, but that was it. Motor is now attached.

Since the drag chain used to attach to the Z motor mount screws, and those screw holes are now almost covered by the new Z slider plate, I had to relocate my drag chain bracket. I ended up moving it over to use the holes on the outside of the plate, and everything seems fine.

The last thing I connected was the new Z limit switch that came pre-installed on the new unit. The spades were a little bit larger than my old limit switch, so I had the replace the connectors on my limit switch wires. But no other changes were required to get my limit switch working.

Time to test. I started everything up and attempted to jog the Z axis. I got movement, but it was in the wrong direction. The Z movements were backwards. So I changed $3=2. This corrected my z travel direction.

The next thing to fix was the Z travel steps/mm. I was using the stock 40mm per step. There are many ways to measure your Z steps, but I decided the easiest way for me was using my 3-2-1 blocks. I jogged my Z down to where the 3" block just slid under it. Then i sent the Z down 1". It only moved about 1/3", so I knew I needed quite a bit more steps. I kept incrementing the $102 setting up until I was getting 1" of travel when I told it to jog 1". I’m very close using a setting of $102=200.

Next was my Z acceleration. I was still using the stock setting, and since I now have a fast pitch screw I increased my acceleration $122=750.

The last thing I adjusted was the amount of Z travel I have. The Linear Slider has 5-6" of travel available. since I do not have lift plates on my machine (yet), I only have about 3.5" under the gantry to work with. So I decided to take advantage of as much of the travel as I can. I set my DeWault router so it is sitting about halfway in the mount. I had to be careful to keep the top of the router low enough so it does not hit the motor mount when homing the machine. Once the router was in place, I homed the machine, then set UGS to mm and jogged Z down as low as I could. I dd not have a bit in at this time. so rather than going all the way to the bottom where I could hit the plate I left about a half inch. So my total Z travel is now set to $132=120. So I gained 40mm of Z travel from stock. Even though I do not have any more room under the gantry than I did before, I can now use a short bit and go as low as I need to without worrying about falling out of the rails or losing steps as I often did before.

First cut. After getting everything adjusted I was ready for my first cut. I did a simple 4" square pocket .26" deep in MDF. I cut shallow the first time since I had just readjusted the v-wheel eccentrics. I will be pushing it more.The first cut ran perfectly. I have a video, but it is too large to send from my phone at the moment. I’ll update the post with the video later.

Once I installed the kit it was apparent that my Suckit dust shoe was no longer going to fit. I was expecting this, so it was no surprise. I new I would need to modify it to make it fit.

I found that I had a set of holes available that were about an inch outside of the original mounting holes.

I held the Suckit bracket up trying to align it as close as possible to the old mounting holes. Then I used an awl from the back side to mark the location of the new mounting holes. I drilled out the holes and did a test fit. It seemed to work.

Next I taped both of the Suckit arms together and drilled through to transfer the hole locations to the other side. I had to find some more spacers to get the Suckit to be out far enough.

Then I was still about 1/2" shy of the hole where the end mill goes through. I could see that I did not have enough room to just loosen the set screws and adjust it. What I ended up doing was removing both screws, then moving the piece out past the end, then installing one of the screws. This meant I can no loner use both screws on each side. To compensate for losing a screw, I ended up putting it back on the mounting arms, then adjusting the slides do the end mill travels through, then I marked the little slides. Took the bottom back off and used CA glue to fix the position. Sprayed a shot of accelerator on each side and the glue set up.

And that brings my story to the end. I plan on doing some more testing and cutting as soon as I have some free time, but I could not be happier with the quality of the CNC4NEWBIE Linear Z Slider. And Joe is really easy to work with. He returned all of my emails promptly and was receptive to all of my input. If you are ever in the market for a linear Z, make sure you give Joe at CNC4NEWBIE a shout.

EDIT - One thing i forgot to mention. Mounting the Dewault into the spindle mount is a little difficult because it is a very tight fit. The top of the Dewault rubs against the motor mount. I ended up putting a piece of scrap wood on top of the router and giving it a few taps with a hammer to get past the motor mount. I let Joe know that they need to include a spacer to go between the spindle mount and the plate to make installing the router easier.


Awesome write up. Can you put a link to the exact product you purchased. There are several there.

Here it the exact link.

I recommend emailing Joe ( prior to ordering to make sure he understands that you have an SO3, not an XCarve. He will make sure all the mounting holes are correct. You can ask him about drilling and tapping a hole to align with the hole where the Z belt set pully was at the bottom. That will eliminate the need to remove the v-wheels and reset your eccentric nuts. The downside is you would only have one screw in the bottom instead of 2, but it could be a fatter screw. And something I forgot to mention was that the Dewault is a pretty tight fit getting in to the mount due to the top of the router housing hitting the motor mount area. I think Joe needs to provide a spacer that will go between the mount and the plate.Mine did not have a spacer, and I had o put a piece of scrap on top or the router and give it a few taps with a hammer to get it to go past the motor mount.

Wow, this is an awesome update…and you got me thinking…hmmmm. Thanks for the info.

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Very well done!!!

I’ve actually been following this on the XCarve forum as well and waiting till I saw one adapted to the SO3. I’m really close to pulling the trigger, but I have a few thoughts holding me back. Current config the Z axis assembly looks to be about 1" thick. From the website I’m reading this version is 1.75" thick. I’ve always considered the X axis V wheels as a weak link in the puzzle. I see heavy spindle upgrades and I usually read that the extrusions can handle the weight, which I have no doubt, but the V wheels I’m not so sure about, and with the router cantilevered out an extra 3/4" I wonder what the strain on those will be. As an engineer (day job), I’ve watched other engineers test stuff, see it break, make it stronger, just to watch something else break, and chase the stress all over our products till they’ve built boat anchors. I’m not at all beating this upgrade up, in fact I’d like to do it on my machine, just looking at what the next upgrade will have to be to handle this upgrade, and where the next upgrade would go after that? Double V wheels? Fatter belts on X/Y? Screws on X/Y? Then heavier end plates? Pretty soon I’ve got something that is so far out of the original design approach I should have bought a Mori Seiki?

Seriously though, it’s a really sweet upgrade, and I’m not fond of the belt drive Z either. I may give this a go just to see for myself if my fears are unfounded and I’m just a couple hundred $'s away from CNC bliss!!! Haha!!



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Great write up!its on my list of upgrades now

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I share the same concerns. The new assembly is actually closer to 2" thick when you add the plate that connects the spindle mount. It is about 1.25" thick at the bottom. So it is adding some cantilevered weight out front. And it weighs 4 pounds. I did not weight the old, but I doubt everything I removed adds up to 4 pounds. So I will be watching it pretty closely. I already ordered some eccentric spacers. I’m going to give those a go with a socket cap bolt and a lock nut to see if that makes adjusting the v-wheels easier/better. Since the SO3 extrusions only have a lip on the bottom front side, I guess if you added a rear plate it would only be able to roll along the flat of the extrusion. But that would still provide a little support for the weight by transferring some weight to the rear. You are correct in that this could be the start of a slippery slope. I’m already thinking of lifting the Y extrusions to gain more clearance and space under the gantry. But luckily this machine is a hobby in and of itself for me. I sell a few pieces here and there, so the machine has paid for itself, but I don’t rely on it for steady income. So if I manage to break something I am just down until I fix it.

The top pic show the measurement from the original X plate to the edge of the new spindle plate. Just under 2".

The lower pic shows the bottom measurement from the X plate out. It is 1.25".

THe Makita is smaller, (and the hp) so I think it should be a great alternative.

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It’s partially the weight, but also all of the forces generated by the router itself when cutting. Everyone gets the idea if you can’t break a bolt loose you add a cheater bar for more leverage, with this mod you’ve essentially doubled your wrench length prying against the V wheels. I have no idea what kind of loads they’ve been designed to handle, so it may not matter in the end? I really hope I’m wrong as I’m really interested in making this change, more so because I’d like to increase Z a little.


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Oh yea, forgot to ask, did you use your stock Z stepper motor or something bigger?



Stock Z stepper. Time will tell…

Parts to do the z axis here :

And G - Code

(Grbl 1.1f)

$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask)
$3=6 (dir port invert mask)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=255 ($status report mask)
$11=0.020 (junction deviation, mm)
$12=0.010 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=1 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=0 (homing dir invert mask)
$24=100.000 (homing feed, mm/min)
$25=1000.000 (homing seek, mm/min)
$26=25 (homing debounce, msec)
$27=4.000 (homing pull-off, mm)
$30=1000 (max spindle speed, RPM)
$31=0 (min spindle speed, RPM)
$32=0 (laser mode, Boolean)
$100=39.905 (x, step/mm)
$101=40.000 (y, step/mm)
$102=1012.500 (z, step/mm)
$110=3000.000 (x max rate, mm/min)
$111=3000.000 (y max rate, mm/min)
(note: $112 z max rate much slower than x and y rate)
$112=500.000 (z max rate, mm/min)
$120=400.000 (x accel, mm/sec^2)
$121=400.000 (y accel, mm/sec^2)
$122=400.000 (z accel, mm/sec^2)
$130=386.000 (x max travel, mm)
$131=425.000 (y max travel, mm)
$132=119.000 (z max travel, mm)


Valid point. Another upgrade I want to try is making pillow block bearings for the X&Y rails out of Teflon blocks. There are some linear rail systems which use this design.

Yep, there’s a bunch of ways to go at it. I think the Y rails are pretty sound though as they have double the wheels between left and right and there’s nothing big twisting at them like the X…it’s like the difference between standing on two feet versus balancing on one foot while holding a heavy box out in front of you. Technically you could double and double and double even more, but at some point you could have doubled into a more robust machine. Currently my XXL is performing really well, so I’m not in a huge hurry to change stuff around, the only thing I’m really after is more Z travel. I’ve doubled up on waste board, and my latest project was 2 1/2" thick, which I two sided machined, but I had my hand on the kill switch nearly the whole time because everything was so tight. I’d like to do some even thicker stuff, and I could remove some waste board to do that, but I’d rather not have to. I’ve also been pining over the idea of putting a lift kit on this thing to raise the Y rails up an inch or so…you can always add more waste board, but with the low Z you can only remove so much waste board before you’ve dug a whole to China, haha!!!


I don’t see this giving us any extra Z height - you still have the wheels and bottom rungs of the X carriage to contest with?

I also can’t see it’s weight being an issue - I doubled my router weight and it handles it like a champ.

Worth noting the guy selling them now has a dedicated listing for the S3 - and its $200

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There are a lot of items that are tall and narrow that could be machined with the added Z. Meaning not every part needs to pass under the rails to be machined.

Example: Facing, drilling and threading the end of a 2"x2"x5" long piece of stock.

Here is the link for the Shapeoko Model Linear Z:

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Fair point, I’d not have thought to do that, I’d be worried I’d screw up clamping or edge finding it but many others might.

Correct, no more room under the carriage after the Z upgrade. That will involve a lift kit of some sort. I’m kicking around some ideas in my head about how to go about this, how much to raise the X, etc. Also to consider - do you lift it by making taller X plates or do you make taller Y brackets? Taller Y brackets would raise the X and give you more room under the Y rails if you like to tile and need stock to stick through there.

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That is my machine in the photo!