I had an entire week off from work and decide to start on my 80/20 extrusion gantry build. All the major parts were purchased from ebay. It consists of:
The long X axis are 10 series 2040 38" length.
The Y-axis uprights are 15 series 1545 18" length.
The horizontal Y-axis is 15 series 1545 36" length.
The router top surface is made up of 10 series 1030 29" length.
Thk linear rails
The X-axis are 32" SR15.
The Y-axis is a 30" SHS30.
The Z-axis is a heavy duty NSK linear slide, 9" of travel, with servo motor and NSK ground ballscrew.
Three Gecko 202 stepper drivers to move the 276oz-in stepper motors.
Gecko 320 servo driver for the Z-axis.
The dual X-axis and Y-axis ground ballscrews are NSK brand. There is very little, if any backlash that I can detect with my dial indicator.
The actual cutting area is 25"x28". I would of like to have made a bigger gantry router but finding longer extrusion, linear rails and ballscrews would of increase the cost tremendously. The cost of the build was $1400, not including spindle. This includes the electronics, nuts, bolts and aluminum plates that hold everything together. To purchase a similar sized commercial gantry router is atleast twice that and I believe this gantry is much stiffer and more precise due to the use of high end linear components.
The gantry is able to move over 400IPM but I have that dialed down to 250IPM for now. The table that the gantry rests on starts to shake when the gantry moves at high speed. The table is on a base with 4 rolling wheels. Once I finish building the gantry, I will put the table on blocks and maybe bolt it down to the cement floor.
My CNC Gantry got posted to Hackaday.com!!!!
Now on to the build pictures, it took me 2 weeks to build this.......
The NSK ground ballscrews from ebay. Nice find for $180. One looked like it was never used. They all looked good once I cleaned off the grease. No detectable backlash with dial indicator.
I machined two mounting plates for the X-axis THK SR15 linear rails. Alot of holes drilled and tapped.
Test fit the X-axis mounting plates and linear rails. I then machined two L brackets to hold the extrusion uprights.
Test fit of the NSK ballscrews.
1545 extrusion uprights
Machined another plate for the Y-axis SHS30 linear rail
Lets see what the Z axis looks like on the linear rail
Test fit and see how big the gantry will be.
I cleared my work table and moved the gantry from my movie room table to the shop.
Milled out two ballscrew bearing end mounting plates.
Test fit X-axis stepper motor standoffs
Machined a plate to mount the Z-axis linear stage.
Machined a chunk of aluminum for the Y-axis ballscrew mount
Y-axis stepper mounting plate.
Installing the NSK linear stage. It's made from cast iron/steel and probably weights close to 35lbs.
Just a image of the gecko drivers before I mounted them to the heatsink.
Gantry Y-axis stepper movement test at 300IPM
3-axis movement test
Test cut using a temporary spindle mount made out of plywood
Cutting hackaday.com logo
Gantry accuracy test
Gantry accuracy test #2
Big piece of 24"x7"x1" thick cast aluminum plate I found at the metal recycle placed for around $25. This will be used to make the Z-axis spindle mounting plate.
Finally installed the 2.2KW water cooled spindle.
Test cut 6061 aluminum
30ipm feed rate
12,000 rpm spindle speed
3/16" hss endmill
The original direct drive Z-axis servo motor died, the motor over heated and burned out. The Gecko320x servo driver survived the ordeal with no issues, they make good stuff. It was replaced by a 250oz-in minertia servo motor with 1:5 gearing. 2mm gt2 belt and pulleys. Plenty of torque now. A side benefit with the pulley reduction, there is enough belt tension/friction that the Z axis doesn't drop down when power is shutoff.
Was doing a wood carving and the gantry x-axis lost position/steps. Took me a few minutes to figure out the stepper coupler had snapped. I bought these helical couplers on eBay for about $7 each. That's what you get for buying low quality. I had a spare in stock so a few minutes to remove the stepper motor and install replacement coupler. Time to find better motor couplers before it happens again.
Installed larger spoil board and T-track hold downs bought from Rockler. I cut the grooves using a table saw and dado blade set.
My shop vac finally died so went to Lowes to pick up a new one. Woodcraft was having a sale so I bought 25feet of 2.5" hose and another Dust Deputy. The Dust Deputy works better than the Thein collector that I used before. The 2.5" diameter hose has much more air flow than the original 1" hose. I made some speaker baffle cut outs out of MDF today and it sucked all the dust away.
I purchased a 12volt Flojet water pump from Electronic Goldmine. This is a high quality 1.35 gallon per minute pump but instead of running it at 12volts, I used a 6 volt phone charger. There is plenty of water flow at 6 volts and the pump does run much quieter. The tubing I used was purchased from Lowes. I had to heat up one end of the tubing so it can get soft enough to fit in the supplied water connectors that came with the spindle. The coolant in a 5 gallon bucket is a 50/50 mix of Prestone antifreeze and water.
The VFD is controlled by a Mach3 plugin using a USB RS485 serial adapter that I puchased off eBay for $3.50. The plugin works great, you can turn on/off and vary the spindle RPM with Mach3.
I have a Radio Shack Car temperature gauge monitoring the spindle temperature. The sensor is just taped to the spindle. After running for over an hour, the spindle temperature is about 75 degreeF.
I highly recommend anyone still using a woodworking router as a spindle to upgrade to a water cooled version. Less runout, more power and best thing is that you don't have to yell when talking to someone when the spindle is running.
The Z-axis servo motor was running a little warm so I placed a 12volt computer fan next to it. Servo motors don't like to be run hot unlike stepper motors.
Things still todo:
Make ballscrew end bearing plates. Update: made and installed the end bearing plate for Y-axis
Order more 1030 extrusion for the gantry top surface. Update: I purchase the extrusion but haven't cut and installed them yet.
Wire up home and limit switches
If anyone needs a carved wooden sign or aluminum cut, please contact me. I am located in southeast Michigan. fong.jim@gmail dot com