Sunday, January 8, 2017

Shapeoko2 X-axis beam upgrade & Dinosaur Bookends

The stock Shapeoko2 used two standard makerslide extrusions, separated by a small air gap, for the X-axis linear rail. This worked OK, but the assembly tended to twist and cause inaccuracy or cutting problems when driving the machine too hard. Some people stiffened their machines by bolting the two extrusions together or otherwise tying the two beams together and approximating a single beam.

Inventables recently released a new "Wide Makerslide" for their X-Carve CNC router. This new extrusion replaces both X-axis makerslides in their X-Carve product, and yields a much stiffer X-axis. This new part is a very easy and fast upgrade for older Shapeoko2 machines. They sell it in 500mm, 750mm, and 1000mm to fit most machines. My machine has the narrow X-axis so I needed the 500mm part.

Stock setup on the left, still assembled. New extrusion on the right.
Pay close attention to stepper motor wiring order when disconnecting Y axis steppers to disassemble unit
Together and ready for testing!
Cutting out parts for Dinosaur Bookend for Christmas present
The first project built with the upgraded Shapeoko2 were a set of these cool dinosaur bookends. They turned out great and were a hit at Christmas. The ~0.5" plywood was sourced from Menards- they had a super sale on Christmas Tree bases- pretty nice quality pseudo baltic birch 2' x 2' squares for $1.90. The bookend bases were cut from Ikea bamboo cutting boards.

Finished bookends

Shapeoko 2 Upgrades using XCarve parts

This post is actually a little out of order- I actually did this before rebuilding the Z-axis.

After doing some initial aluminum cutting and also running into some size limitations with the stock Shapeoko2, I decided I need to upgrade the machine to make it both a) larger and b) stiffer.

Inventable's X-Carve has a number of parts that are bolt-on upgrades that are compatible with the Shapeoko 2. The first I purchased was the improved DC Spindle mount. This provided a much-improved interface between the DC spindle and the Z-axis slide- both improved rigidity and alignment. It's machined from a single aluminum extrusion and black anodized.
Spindle Carriage
DC Spindle Mount
The second upgrade I purchased was the X-Carriage Extrusion. This was definitely a huge upgrade over the stock Shapeoko2 X-Carriage. The stock x-carriage is an assembly of plates bolted together with a ton of spacers and washers- it works, but the improved part is one massive extrusion. It should prove to be much stiffer in actual use.
X Carriage Extrusion
X-Carriage Extrusion

Installation of the upgrades was pretty straightforward. The entire Shapeoko2 X axis needs to be disassembled. The wheels and stepper motor can be attached to the X-Carriage. Then, the X-carriage extrusion is slid over the X-axis Makerslide extrusions. 
X-Carriage assembly in process.
Once the X-axis is re-assembled, the Z-axis with the new, improved DC Spindle mount can be bolted on and everything aligned.

I also took the opportunity to expand the stock build surface using new makerslide and some 8020 extrusions I purchased from an industrial salvage place.
Installing electrics on a board attached to the bottom of the frame

New, Super Beefy 8020 Frame, laid out but not yet squared
Just about ready to bolt together
Squared up and bolted together.

I used the stock 500mm x 500mm wasteboard, then added a new wasteboard I cut from 1/2" MDF. I did buy a set of 5mm threaded inserts to add hold downs to the new section.

New wasteboard cut from 1/2" MDF and hole locations marked
Holes cut and M5 threaded inserts added
New Wasteboard & Y axis makerslide braces in place
Assembled and ready for first part- a new faceplate from 1/8" MDF:

Cutting faceplate for E-stop and spindle RPM control
Faceplate cut & spray painted silver
Finished, assembled and ready to go

Shapeoko 2 Z-Axis upgrade to ACME screw thread

After having my Shapeoko 2 for a few years, I decided it was time to give the Z-axis an upgrade to the ACME screw threaded rod, vs. the standard threaded rod it came with. This upgrade should improve Z-axis precision and speed, as well as clean up the mechanical "look" of the system.

I used parts from Inventables- I've always found them to be high quality with good service and speed. components used: (with P/N)
  • ACME Lead Screw Kit 30658-01 (includes M6 locknut)
  • Z-axis motor plate 30534-01
  • GT2 Belting 2" x 3" x 1/4" 30547-01
  • 20T GT2 Pulley, 8mm Bore 26054-04
  • 20T GT2 Pulley, 5mm Bore 26054-01
Additional hardware used:
  • 2x M5 x 8mm button head screws
  • 1x M3 x 12mm socket head cap screw (SHCS)
  • 1x M3 washer
Inventables has a great step-by-step illustrated set of instructions for the newer X-Carve CNC. Their instructions are mostly appropriate for upgrading their older Shapeoko 2 as well. 

Before I could start assembling the new Z-axis, I had to take apart the existing, stock Shapeoko2, Z-axis.
Stock ShapeOko 2 Z Axis - before disassembly
Z-axis apart and on the table

1) Use 2x M5 x 8mm button head screws (new screws to assembly) to retain the stock thrust bearing in the new Z-axis plate. I didn't have M5 x 8mm button head screws in my hardware collection, so I used the screws from the belt clips on the Shapeoko and used some M5 x 8mm SHCS on the belt clips.

Thrust bearing in Z-axis plate

Screws in place to retain the bearing

2) Use 2x M5 x 20mm button head screws to attach the Z-axis plate to the Z-axis makerslide. These screws were part of the original Z-axis assembly. I left the screws a little loose to allow for adjustment once everything was assembled.

3) Attach Z-axis makerslide to X-axis rail using original hardware. At this point it pays to take some time to get the Z-axis makerslide as square as possible with the rest of the machine. The recommended  height is to leave just enough makerslide exposed below the X-axis slide to not expose any of the T-slot clips. Depending upon how you want to complete your assembly, you might also consider loading the Z-axis plate to the Z-axis makerslide before bolting it onto the machine.
Squaring Z-axis slide with the machine
Adjusted height to not expose the T-slot clips. 

4) Took off Z-axis plate assembly, dropped Z-axis slide with ACME screw and block onto makerslide, then re-attached Z-axis plate assembly
Z-axis slide attached

5) Attach 20T GT2 Pulley (8mm bore) to top of ACME screw with setscrews, then tighten down M6 locknut)
ACME Screw 20T GT2 Pulley and locknut installed

6) Using 3x existing M3 x 12 SHCS & M3 washers, plus a new M3 x 12 SHCS & washer, attach stepper motor to Z-axis plate. Do not tighten screws though- you'll need the slop soon to tighten the belt.

Z-Axis motor installed

7) Attach the second GT2 pulley to the stepper motor shaft. 

8) Load the GT2 Belt across the pulleys. You might have to loosen and remove the motor to get the belt in place. I actually had to completely detach the stepper motor to get the belt across the pulleys. 
Belt in place, ready to test
9) check that everything is square and all screws are tight.

10) Use Universal G-Code sender or another G-code sender to update the Z-axis steps per mm:

Update Z-Axis setting to:
188.976 Steps/mm (for 12 threads per inch ACME screw thread)

with the following command in Universal G-Code Sender: $2=188.976

Enter $$ in the Universal G-Code sender command prompt to get a list of current GRBL settings. Take a look at the $6 setting- I had to subtract 128 from my current $6 value.

After getting everything set up, it was time to test by manually driving the tool head around using the Universal G-Code Sender's manual controls. Initially I had some binding and stepper motor skipping steps. I ended up having to do a few things to fix the step skipping:
  • loosened the screws attaching the Z-axis plate to the Z-axis makerslide, re-aligned the parts
  • added a little silicone grease to the ACME screw
  • increased the current to the Z-axis stepper by 1 increment on the adjustment pot
No test parts yet....