Archive for August, 2008

My CNC Engraver (Part 1)

The goal of this project is to design and build a CNC wood router/engraver.This turned out to be a much larger project than I had anticipated.  Bigger both in terms of dollars and hours I spent on it.  It took me about 50 hours to build the mechanical portion of my CNC machine and I still have to do the electrical and software work.  This posting will focus on the parts list and the mechanical systems.

I have done a lot with electronics and with software, but never have I build such a complicated mechanical machine before so I needed to do a lot of research before I started my build.  The best tools I found for this research phase where cnczone and google.  Eventually I decided on a gantry style table because the were the most common and simplest form of table. This thread in particular on cnczone influenced my final build. I didn’t do a very good job at recording the time I spent during this research phase, but it was probably something like 30 hours.

There is no way I’m going to take the time to explain every step of this build procedure, but here is a part list and the price I paid for each one.  I wish this list had existed before I started my build so I would have had an example of the different components you need to build a full CNC router and the approximate cost.

8020 Garage Sale Series 15 Aluminum Frame, connecting plates, bolts, nuts, … $581.80
CNC Router Parts (6) Linear Carriage with ABEC 7 Bearings $141.00
CNC Router Parts (2) Extended Linear Carriage with ABEC 7 Bearings $67.00
Speedy Metals Cold Rolled steel (2) 0.25x4x36, 0.25x6x32, 0.25x4x16 $89.26
K2 CNC RM-PC892 Porter Cable 690 & 892 Mount $57.95
Local Hardware Store Bolts, angle iron, washers, screws, … $50.00
HobbyCNC HobbyCNC PRO Driver Board Packages with 305 oz-in motors $240.00
Mouser Pactec case #DM-4 $37.21
Allied Electronics 24VAC 10A Triad Transformer $52.00
Amazon Porter-Cable 690 LR Router $125.85
XYZ Threaded Axises Go to CNC Router Part List to see how these axises are assembled (note: I did not use the drill that he listed as optional).
CNC Router Parts (6) Bearing Block and Cover for 1/2″ ACME $75.00
CNC Router Parts (3) NEMA 23 Motor Mount $37.50
McMaster (3)5 Start 10 thread/inch 1/2″ Acme Threaded Rods – 3ft $117.51
VXB 10 R8ZZ Bearings (only use 6) $31.34
DumpsterCNC (3)1/2″-10 ACME 5 Start Anti-backlash Nut $73.50
MSC (12)Thrust Washer $10.08
MSC (6)Clamping Collar $9.06
MSC (6)Thrust Bearing $17.52
MSC (3)Spider Lovejoy Connector $5.31
MSC (3)1/4′ Lovejoy Connector $9.90
MSC (3)1/2′ Lovejoy Connector $9.90
Total 1838.69

Some other parts you’ll need are an old PC and the CNC software, but I’ll discuss these in a future post.

The main tools I used were hammer, table saw with aluminum blade, hacksaw, screw drivers, wrenches, hand drill, drill press, threading die (5/16th-18 male), center punch, Allen wrenches, Dremel, and a measuring ruler.

The best way to describe the my machine is with pictures so here we go.

Images of my engraver from different angles.

Images of the threaded axis assembly.

The plate used to attach frame to threads.

Image of the moutned motor.

Image of the rollers on the y-axis.

Image of the y-axis (it’s upside down so you can see the bottom).

Image of the z-axis.

I’ll also haven’t tested it yet, but it feels extremely smooth and sturdy so I’m quite confident that the machine will work great, but complete confidence won’t exist until I’ve used the machine for awhile.  In future posts I’ll cover the electrical systems, software, possibly other add-ons, and the reliability of the machine (after I’ve used it for awhile).

Update: I’ve made some improvements to the engraver here.

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