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« on: June 07, 2013, 08:11:43 PM »
Hello to anyone interested;
In my quest to perfection my objective was to be able to do wood routing, plasma cutting, lathe work, milling and later add a sawmill bandsaw to mill trees into lumber. I original was going with a 5' X5' table but traded into and old shopbot (I think it was a PR95 5X10) so it became 5'X10'. From my past experience I learned that plasma cutters and extruded aluminum do not play well together. Also that a router table that the gantry just sets on top the Y axis will not stay there past the first Z axis plunge. So make design requirements became this:
1. All steel construction.
2. All rack gear axis.
3. V-wheel bearing sliders.
4. Stepper motors.
5. As close to all open source software as possible.
The only tools I had on hand where a chop saw, drill, torch, hand grinder, cracker box stick welder and some wrenches.
With this in mind and the above mentioned shopbot in hand I started by dismantling the old shopbot (someday I my write about all the crazy things they did.) I was able to salvage the lower table and 3 motors the rest was junk. I then decided to try a cheap TB6550 4 axis motor controller. Within 3 minutes one of the IC chips was actual on fire. Not just smoking hot but burning. I ordered a Gekco G540 that day from Ebay. That was the best thing I had done so far. I had bought a Mach license about 10 years ago and played around with it with no hardware hooked up. So i dusted it off and fired up the computer, software, motor controller and motors.
It was now time to build the all steel gantry. I had been making some receiver hitch for trailers so I had a large supply of 2"X2"X1/4" square tubing so this became my base for a 6' gantry. I welded a 1/4" rack gear to one side of the square tubing. I then used 2 1/2"X3/16" flat steel on two sides for the slide rails for the v-bearings. (all v-bearings are not created equal) I then used some 3/16"X6"X71/2" flat steel to make motor plates and back plates. I drilled out the holes for the V-bearings and bolts to hold the motor plate and the back plate together. I used 11 1800lbs.V-wheels per slide. This gave me 3 on the bottom and 3 on the top of the back plate and 3 on the bottom and 2 on the top of the motor plate with the rack gear in the top center potion instead of a v-wheel. OK for a router and a plasma cutter I could have gotten away with just a motor plate. But the force to do mill and lathe I used the extra plate and wheels. I added motor and wiring and this gave me my X-axis gantry. I repeated the build but only used 32" instead of 6' for my Z-axis. This gave me 17 1/2" of travel on the Z-axis. I am using a 3 1/2 hp cable porter router that I got in the trade for the shopbot to power my z-axis. Instead of placing the router down by the work piece I built an arbor shaft and mounted the router up even with the x-axis gantry. This has several advantages. One is that the arbor shaft bearings catch all the side was pressure from the cutting tool saving the router bearings. The only force on the router is the motor turning the cutting tool. Another is that the router is up out of the dust. The other reason to add the arbor shaft was so when I mill or do lathe work I can add in a 10 to 1 reduction gear which reduces the router speeds from 21000 to 2100 rpm. and increase power to the cutting tool.
Now you ask what kind of speeds can this monster produce. In router or plasma mode 500 to 600 inches per minute all axis.
In milling or lathe mode 150 inches per minute on the z-axis and 350 inches per minute on the x and y axis. The difference is the weight of the reduction gear plus for these operations I do not see the need for speed.
Now with all that said I have ran into some quirks in Mach3 maybe someone can enlighten me about. when in the jog mode I can run the motors a lot faster without stalling than when I use a gcode command. Is this normal? I am using a parrelle port. Would maybe a smooth stepper fix this?
Anyway thanks for your time to read this I plan to add some pictures when I find m camera. Would use cell phone but they do not work down in my valley.
Thanks
Larry
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