Sunday, January 22, 2017

X-Carve Upgrade - C-beam Z-axis

While trying to push the feed rates of my X-carve through some tougher materials, I began to notice some chatter in the Z-axis. This chatter was not up and down, but rather side to side. While the spindle was moving around (most notible in the Y-direction), the bit would chatter side to side (in X-direction) and could be stopped by holding the spindle with my hand. After some investigation, I found the spindle could be rocked side to side because the v-wheels on the Z-axis did contact the makerslide with equal pressure. After adjusting the eccentric nuts, the problem was reduced, but still noticable; therefore, I decided to replace the Z-axis assembly.

C-Beam Assembly

Image 1
C-Beam Bundle Pack
To start off this upgrade, I purchased the 250mm C-Beam™ Linear Actuator Bundle without motor. It came nicely pacakged with all the parts to build it as pictured. After digging through many resources, I found these two videos that explain the assembly in depth.
  1. Start this video at ~30 mins
  2. Watch this video from the start
C-beam Z-Axis next to Stock Z-axis for X-carve
Additionally, I purchased the following items to make this build.
Optional items purchased for belt reduction / install motor behind C-beam

Note: while building this, be sure to insert any t-slot nuts before placing both of the end plates on. I added 2 t-slot nuts to the two middle slots on the back side to install on the X-carriage. I also added 1 t-slot nut on each of the 4 side slots for installation of a dust shield at a later time.

T-nuts in two center slots of C-beam (view from back)

Installation onto X-carve

This was really easy. First, remove your spindle from the X-carve.

Stock Z-Axis with Spindle removed

Then remove the stock Z-Axis. Next, to install the C-beam, line up the TOP SET of t-nuts you dropped into the middle two slots on the back of the C-beam with the top holes on the X-carriage. Add screws loosely so you can still slide the C-beam up and down. 

TOP SET of t-nuts attached to X-Carriage

Next slide the C-beam down, and align the BOTTOM SET of t-nuts with the bottom holes on the X-carriage. Add screws loosely, then slide the C-beam all the way up before tightening all the screws. 

BOTTOM SET of t-nuts attached to X-Carriage
Finally, install the Spindle and tighten down the spindle mount.

Spindle and C-Beam on X-carve (no Z-Motor)

Belt Reduction Fun

Instead of mounting the motor over top of the C-beam, I opted to mount it behind the C-beam similar to how the X-carve does it. The only issue is that the 140mm belt that comes standard with the X-carve is too short. 

For a temporary solution, I purchased qty:10-200mm belts from amazon utilizing a 8mm bore and a 6.35mm bore GT2 pulley (12mm diameter). Well the 200mm belts were too long, so I rigged up a few bearings to give a 200mm path so I could start carving. It's not pretty but it will work for now.

Since the standard belts didn't work I figured I would improve on the belt drive by adding in some belt reduction gears to improve my Z-accuracy and increase the torque. After much reading from here and here and here and here, I found my solution. I purchased this gear reduction from ebay with the 8mm bore 50T pulley (diameter ~ 51mm) and the 6.35mm bore 25T pulley (diameter ~ 26mm) and sent a message to the seller to get a wheelbase of 70.2 (length of belt ~270mm).

[Insert picture - once installed by 02/10/2017]


With the stock Z-axis on the X-carve, I was experiencing lots of side to side chatter in the Z-axis. This was due to the eccentric spacers and v-wheels not being tight enough no matter what I did. Many other people have upgraded their Z-axis to a linear slide like this, but I did not want to drill into my X-carriage or make any adapter plates. The C-beam linear rail is a bolt-on, un-doable and upgrade-able option that costs around the same as the linear slide. Overall, it has removed any Z-axis chatter I was seeing; now the weakest point is my X-axis (which I will upgrade to the new wide makerslide extrusion once it arrives). After about 3 hours of run time, I can already see the improvement! I am able to run slightly faster that I was with no signs of chatter! 

Now its time to make a new dust shoe...

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