CNC Router Construction

Over a few days, I (with the help of my father) managed to complete the mechanical structure of the CNC router.  I purchase 4' x 8' x 3/4" MDF (Medium Density Fiberboard) at Home Depot for about $32.00.  I tried Lowels first... but apparently they do not cut that material in the store (their loss).

Day 1:
Today started at 8am and finished at 7pm.... a long day.  The wood cutting part was easy. The picture below  shows our progress after a few hours.

Main Structure Assembly

The difficult and time consuming part was aligning the precision rod such that the X table can slide freely.  I had a feeling this would be difficult, but it ended up being harder than expected.  The precision rod has a tolerance of +.000 / -.0005 (yes, thats 1/2 of one thow) and the bearings have a tolerance of +.001 / +.002.  This means the rods have to be parallel within about .001".  We 'fixed' the problem by opening up the inside diameter of the bearing with a Dremel (not recommended but effective).

The below image shows the progress at the end of day 1.

Assembly after day one

Day 2:
Today, I spent about two hours making the Z-table (up-down direction).  Using the lessons I learned from the X-table difficulties, I managed to make the bearings slide by taking everything slow and match-drilling when possible.

Full Assembly - Awaiting Rod Engs

YZ Carriage - Y is left and right, Z is up and down

Day 3:
Today, I spent another 2 hours finishing the remaining parts. mostly the rod end holders.  These rod end holders allow me to adjust the rods to align the table.  There are clearance holes in the main structure and tight fitting holes (drilled using Forstner Bits from Harbor Freight ~$10) which hold the rods in place and secure them to the main structure (shown in the image below, the block of wood at the very front of the structure with the four bolts).

Finished XYZ Table

Next, I have to adjust the axes to allow them to move more freely and order the motors and drivers.

Parts on Order!

As of late last night, I placed a $100 order from McMaster Carr.

My McMaster Carr Order

Overall, the cost is not bad given the fact that this is ALL the mechanical components to create the structure of the CNC router (excluding the wood and wood fasteners).

One thing I want to point out.  When shopping on McMaster, don't be too specific.  Although I only need two foot segments of 3/4" rod, look for four or six foot segments and compare the cost.  Check out line item 6.  I was able to find precision rod, with a tolerance of +.0000" / -.0005", which was six feet long but only costs $33!!!  This is a fantastic deal.

Soldering of the Joystick and Power Plug

Before I placed the order of the joystick and power plug, I spent a little time looking at the power plug foot print.  To my horror, I noticed I used the wrong foot print.  Instead of a typical power plug, I added an audio RGA plug.  It was not totally my fault, the library was rather confusing and had the part number I wanted for the wrong part... but either way, I still have the problem.  I decided to buy the RGA plug and wire up the power from a hacked apart RGA wire (not shown).

Top of board with RGA plug as my power port

Bottom of board with mini nuts holding the joystick in place.

My first attempt of soldering the surface mount joystick in place went quite well.  Afterwards, I ohm'ed everything out and everything was working as it should.  The mounting holes were a little off so I decided to remount the component.  Bad idea!  I ended up ripping a pad off of the joystick.  But luckily I have one spare, and now I get to take the broken one apart!

Exploded SparkFun Joystick (PN COM-09426)

The sliding part of the joystick consists of two pieces of plastic, one for X and the other for Y.  These pieces of plastic have the contact on it to touch against the the center PWB.  Simply put, there are two linear potentiometers that make up this joystick.

Here is the link to the joystick on SparkFun's site. Joystick COM-09426