SO2 Upgrade Instructions

My Upgrade kit arrived today (according to UPS), is there an instruction set/video for the upgrade, or should I just pick out the portions of the standard assembly instructions I need?

Allen I am in the middle of upgrading mine and thought at first I’d be able to just swap out a couple parts… but what I’ve found is that I pretty much had to disassemble my SO2 and then build the X-Carve using the instructions that Inventables has. If you find a better way I’d love to hear about it.

Mike, I am finding the same thing, my SO2 is completely disassembled now. My biggest issue is knowing what washers, nuts and screws to reuse and which should be replaced with the ones included in the upgrade kit. For example the instructions for the spindle assembly says to use nylon lock nuts to secure the v-wheels, but the my SO2 used regular nuts and I don’t see enough nylon lock nuts in the upgrade kit so should I just reuse the old nuts?

I also had a few minutes of panic last night when I started the Z -axis and the first step was to install the top bearing. I could not find a new bearing in the upgrade kit and I thought it had been left out. After I settled down, I realized I was supposed to reuse the existing bearing. A step in the instructions saying to reuse the old bearing would have saved me a few bad moments.

A related question - Why is there no lower bearing on the ACME rod? It seems like a bearing at each end would be very beneficial to the overall accuracy (and help protect the ACME rod).

You do need to disassemble it. We changed over from standard nuts to nylon lock nuts because if people did not use Loctite then nuts can loosen from the vibration over time with heavy use. Since the SO2 doesn’t have those you’ll want to use some sort of thread lock fluid like Loctite.

Zach. Quick question - the assembly instruction for the ACME rod with the standard thread at the top seem confusing to me, do I still need a nut above and below the bearing (like on the threaded rod of the SO2)? It seems like I do, but the instructions did not seem clear to me. Also the nuts from the old threaded rod do not seem to fit the new top thread on the ACME rod.

@JohnHayes just worked on this in our office. He has the converted SO2-> X-Carve next to his desk. @johnHayes can you answer @allenmassey I’m not in the office and don’t want to answer without checking to be sure.

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Hi @AllenMassey, sorry for the confusion. The ACME lead screw kit only requires the one M6 nylon lock nut to attach the ACME rod to the z axis motor mount plate, and shouldn’t need a nut on the underside of the z axis plate. Here’s a better picture of one of our test machines that might do a better job of clarifying this:

If you didn’t receive the M6 nylon lock nut in your lead screw kit, please email us at with your order number and I’ll have a replacement sent out right way.

The Shapeoko 2 Upgrade kit assumes that you are starting with the M8 threaded rod and uses the two M8 nuts to secure the rod to the z axis motor mount plate. Here’s a picture of that as well for clarification:

Hope this helps!

Thank you John, the picture of the ACME rod and the nut at the top cleared up my confusion.

Is there a reason why there’s no lower bearing on the ACME rod, or is it just to keep cost down.

None of them have lower bearings at least these machines. They really don’t need it to stay in good alignment. the delrin nut and top bearing keep it nice and straight that and its riding on 4 v wheels. They keep the whole z aligned.

Allen, I purchased some additional nylon nuts once I realized the X-Carve was using those instead of the standard nut used on the SO2.

As far as the lower bearing, the only ACME rod upgrade that used a lower bearing was the one that was previously sold at Although it fit for the SO2, it will not fit with the X-Carve without some additional spacers to make sure everything is aligned. I did make it work since I had already purchased that kit and was using it with my SO2. If I had to do it over again I would not have spent the money. That “other” maker of desktop CNCs charges twice what inventables does for the Acme upgrade. I didn’t even realize at the time that they were two separate companies. I was able to make the Z access knob and crank work with the X-Carve because of it but I’m not sold that the additional bearing makes any effect on the accuracy of the machine. After all there is zero play because of the four V wheels riding up and down the makerslide.

But I think this brings up a good point that should be addressed with open source machines like this. There is literally no limits to the possibilities of where and what you use to upgrade or modify your machine… BUT I think we all need to keep in mind that it in most cases will not be plug and play.

I’m sure there will be more to come as I continue to build “my” X-Carve! I’m already regretting not buying the drag chain.

Mike, I went to Lowes to purchase some thread lock and found that Lowes sells the M5 lock nuts for less than what the thread lock costs so I bought 20 lock nuts. The lock nuts are much easier to use than messing with the thread lock.

I think you are correct about the bottom bearing, now that I consider how the whole z-axis assembly works together there is really no need for the lower bearing.

I also installed the Z crank on my SO2 and now I can’t get the thing off the motor shaft. I have removed the set screw and the crank feels like it is welded to the shaft. I am reluctant to use much force for fear of damaging the stepper motor. Did you have any difficultly removing yours?

Now my last bit of confusion is about the GT2 pulley’s. There seems to be an extra one in the upgrade kit. I know I need two for the Z-axis (motor and rod), But there were three pulleys in my kit, do I need to replace the existing pulley on the X motor? The X and Y motors already have GT2 20 T pulley’s on them so I am not clear why I would need to replace one.

I would also like to thank the person that designed the new x carriage for having the excellent forethought to install the two access holes for reaching the motor mount screws! Without those two holes installing the motor would have been crazy hard.

I don’t have one, so correct me if I’m wrong, but I’m pretty sure the Z crank is aluminum . If so, you can try heating it up, and see if it expands enough to loosen up on the shaft.

Allen, I had a little trouble myself removing the knob. I removed the set screw completely and then gently pulled and it eventually came off. Yeah, these parts are definitely well thought out. I am really contemplating getting on and ordering the drag chain and new wires.

Hi @AllenMassey,

I think that the extra GT2 pulleys are a result of Inventables covering all the bases and including one set for NEMA23 and NEMA17 stepper motors.

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@AllenMassey turns out @sketch42 is correct. We included both GT2 pulleys because some people have NEMA17s and others have NEMA23’s. Also some people might upgrade from 17’s to 23’s.

We included both so no matter what set up you have the pulley is included.


Well that explains the extra pulley, thanks Zach! I will store it away for when I do my next upgrade.

You might want to put a note in the instructions about the extra pulley, it just feels wrong to have an important part left over when it is all put together.

Steven, Heating the Z crank was a good idea, I applied a little heat and it came right off. Thanks for the help.

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Awesome!! Glad I could help.

Heat and cold are one of the secrets of tight tolerant machining that few talk about.

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