In this installment, I will show you how to tune your KReduCNC. You will also load up some G-code and run a break-in test. These procedures ran a little log so I won’t be getting into the clamp table this month.

Before starting, make sure the PC you are using to control the CNC Is on and connected.  Verify it is connected properly by using the arrow keys to move each axis.

 

Y-carriage Tuning

Start the Y-carriage tuning process by moving the Y-carriage shown in Figure 1 back and forth several times. Move it back to the center, and using a Phillips screwdriver and 3/8” wrench, tighten the two screws (Figure 2) holding the Y drive nut in place. Tighten all the screws securing the carriage to the bearing trucks. Once tightened, move the carriage back and forth a few more times to make sure it does not bind.

Move the Y-carriage to the front, as shown in Figure 3. Using a 5/16” wrench and a Phillips screwdriver tighten all the screws on the front bearing block. Tighten the screws holding the front shaft supports.

Move the Y-carriage to the rear, as shown in Figure 4. Tighten all the screws on the rear motor mount. Tighten the screws holding the rear shaft supports.

Once all the screws indicated above have been tightened, move the Y-carriage back and forth to the full extent and make sure it does not bind.  Do this at top speed by holding down the shift key as you push the arrows.  If it does bind, you will have to loosen all the fasteners and start again. 

 

X-carriage Tuning

As on the Y-carriage, start by moving the X-carriage shown in Figure 5 back and forth several times. Move it back to the center, and using a 3/8” wrench, tighten the two screws (Figure 6) holding the X drive nut in place. You won’t have access to the head of the screws due to the Z-carriage, so hold the exposed portion of the screws while you tighten them. Tighten all the screws securing the carriage to the bearing trucks. Once tightened, move the carriage back and forth a few more times to make sure it does not bind.

 

Move the X-carriage to the left, as shown in Figure 7. Using a 5/16” wrench and a Phillips screwdriver tighten all the screws on the motor mount. Tighten the screws holding the left shaft supports.

Move the X-carriage to the right, as shown in Figure 8. Tighten all the screws on the bearing block. Tighten the screws holding the right shaft supports.

Once all the screws indicated above have been tightened, move the X-carriage back and forth to the full extent and make sure it does not bind.  Do this at top speed by holding down the shift key as you push the arrows.  If it does bind, you will have to loosen all the fasteners and start again. 

 

Z-carriage Tuning

Move the Z-carriage shown in Figure 9 up and down several times. Move it to the top, and using a Phillips screwdriver and 3/8” wrench, tighten the two screws (Figure 10) holding the Y drive nut in place. Tighten all the screws securing the carriage to the bearing trucks. Once tightened, move the carriage up and down a few more times to make sure it does not bind.

Tighten all the screws on the Z motor mount and run the Z-carriage up and down one more time.  If it binds, loosen the screws and repeat the process.

 

Break-in

It’s time to run some G-code and put your machine through its paces.  This will break-in the machine and show any failure points before you add more components to the machine. I do this procedure to all my CNC machines. From the smallest CNC router to the largest CNC plasma, they all are broken-in this way.

Before starting, you need to set the machines home position.  This is done by placing the X, Y, and Z in predetermined positions and Zeroing out each axis in Mach3. 

Zero X

To zero the X axis, jog (move) the X-carriage all the way to the left until it is near the left shaft supports, but not touching, as shown in Figure 11. Hit the Zero X button shown in Figure 12.  This effectively sets the X axis on the machine to the zero position.

 

Zero Y

To zero the Y axis, jog the Y-carriage all the way to the rear until it is near the rear shaft supports, but not touching, as shown in Figure 13. Hit the Zero Y button shown in Figure 14.  The Z axis is now zeroed.

 

Zero Z

To zero the Z axis, jog the Z-carriage all the way to the bottom until it is near the lower shaft supports, but not touching, as shown in Figure 15. Hit the Zero Z button shown in Figure 16.  Your machine is now set to position 0,0,0 and should look like the machine shown in Figure 17.

It is important that you understand how to zero your machine, as this is a common practice before running any job. A set of homing switches can make this task as easy as hitting a button.  There are also times when you will set the machine up on the corner or center of a work piece.

 

Loading the Code

If you have not done so, download the test file listed below. Using the File menu, load the G-code file labeled “KReduCNC slowtest 10x8.txt”.  Once loaded, your Mach3 screen should look like the one shown in Figure 18.

 

Test Files

KReduCNC Test Files

 

To run the G-code, hit the Cycle Start button shown in Figure 19. Your machine should start to move. This particular program is a very small program I wrote that uses the ability of the G-code interpreter to run subroutines. It simply moves to each corner of the machine, raises and lowers the Z axis, then does it all over again forever, until you stop the program, by hitting the stop button.

Let this program run for a couple of hours. If your machine is losing steps, eventually one of the axis will start banging against something.  If this happens, stop the program and go back to the appropriate tuning section and repeat the process.

If everything seems ok you can stop the program and load the G-code file labeled “KReduCNC fasttest 10x8.txt” and run it.  This program runs about four times faster.  Let it run for a couple of hours as well.

 

Important!

When running the tests, make sure the wires going to the stepper motors are clear to move without rubbing.  The X and Y axis motors are stationary so they don’t present much of an issue. The Z axis, however is another matter. It will have a tendency to rub against the upper frame brace.  Over time you could rub the insulation off the wire. There are a couple ways to prevent this from happening. You can support the wires from overhead, or you can put some sort of sleeve over the wire.  Split loom tubing works well for this and is available at most home centers in the electrical section.

 

Conclusion

This completes the KReduCNC tuning and break-in.  Your machine should be able to run smoothly and accurately. Next month, we will get the clamp table built and attached to the machine.