# We Have Movement



## papermaker (Jun 24, 2013)

Well after mailing breakout boards back and forth from Bucksport to Peoria finally went to Plan B. I gave up on the PBX-USB breakout board and got my original parallel port breakout board back. I swapped two "dead" PC's for a good PC that is dedicated to just the CNC mill.
I got everything connected and working although there were a couple issues that have to be resolved. The biggest issue right now is that the X and Z axis are working backwards from what the buttons are pushed. Oh yeah I'm using Mach 3 demo software. If you push the left arrow key the X travels to the right and vice versa. The Z is the same...Push page up the spindle lowers . There are about 4 chances on each axis to get wires crossed. The drivers are all wired the same so I'm guessing that the plugs may be wire wrong . 
So looking for ideas!


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## Hawkeye (Jun 24, 2013)

Seems to me I tried to reverse steppers by swapping wires. It worked for a couple of seconds, then the board 'corrected' for me and the motors went back to the original directions. It takes changing a setting in Mach3 to set your desired direction for each axis. I just don't remember off the top of my head where to find the settings.


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## DMS (Jun 25, 2013)

EXCELLENT!!!!

Swapping the the direction should be easy, I know how to do it in LinuxCNC. Not familiar with Mach, but there has got to be a similar setting.

You can also do it via wiring. Swap any single pair of wires on the motor. If you swap both pairs, you are back where you started . 

Once you get that sorted, you can start tuning things, you'll be slicing through aluminum in no time now


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## papermaker (Jun 25, 2013)

I think you're both right. Somewhere in the settings you  can invert ( I think that's what they call it ) the direction. I too am not sure where!


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## papermaker (Jun 25, 2013)

I got that figured out. Under configuration, homing and limits you can set the motors to reverse. That did the trick. We're getting closer. Now I waiting for some new fans to cool the drivers. I have a heat shrink connected to the drivers but they sure do get quite warm. I'm still trying to figure out how I'm going to power these. I had  two fans installed and powered from a 12v power supply. I wanted to clean thing up a bit and bought a stepper board to reduce 40v down to 12v dc. That didn't work out so well as it burned out both fans within about 30 seconds.
Now I'm going with 4 fans and would just as soon not burn up for more so any suggestions would be appreciated.


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## awander (Jun 25, 2013)

Ummm-well, I am glad you figured out how to reverse the motors.

But assuming your mill is a regular moving-table vertical mill, pushing the Left Arrow key SHOULD move the X-axis table to the Right.

Movement on a CNC mill is from the point of view of the cutting tool-so moving the table to the Right "moves" the tool to the Left.

Now that you know how to reverse axes, I suspect you will need to re-reverse your X axis to get it working correctly. And you will also need to reverse your Y axis so that pushing the Up Arrow moves the table toward you.

Hope this helps,

Andy Wander


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## papermaker (Jun 26, 2013)

I think your right in what you're saying. I'm posting this graphic just so I can compare the graphic of the Mach 3 MPG


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## awander (Jun 26, 2013)

papermaker said:


> I think your right in what you're saying. I'm posting this graphic just so I can compare the graphic of the Mach 3 MPG



So if you are standing in front of the mill, with the X axis parallel to your shoulders, and the Y- arrow poking you in the belly, then pressing the UP arrow should move the table toward you. Pressing the LEFT arrow should move the table to the right.

Takes a while to get used to at first-just visualize all movement from the point of view of the tool.


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## DMS (Jun 27, 2013)

I had some "mental" issues along the same lines Andy is describing. X and Y seem backwards at first. It helps if you tape a piece of cardboard to the table, and chuck a magic marker in the spindle. Then, draw a line from left to right on the cardboard. This should be done by pressing the "right" arrow. The spindle is stationary, the bed moves under it, and that means the bed is always going the opposite direction.

Took me a while, but it finally clicked, I rarely even think about it anymore. I will tell you though, with the feed speed turned up high, forgetting which direction you're going is a great way to break endmills


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## brucer (Jun 27, 2013)

picture the spindle or the torch as moving..


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## jimemack (Jun 27, 2013)

papermaker said:


> Now I waiting for some new fans to cool the drivers. I have a heat shrink connected to the drivers but they sure do get quite warm. I'm still trying to figure out how I'm going to power these. I had  two fans installed and powered from a 12v power supply.



Congrats!

The two main things to remember about cooling are:

1. Drivers are going to get hot - let them
2. Orient the fins for the most efficient convection cooling

You probably don't need cooling fans - not that there's anything wrong with that. I build power amplifiers for radio that get extremely hot. Most folks would think that this amount of heat will destroy the devices. Not so. Just stay below 100°C (212°F) and you should be fine. Some devices can even operate up to 450-500°C.

The most effective thing you can do is provide the proper ventilation for the cooling fins. If you orient the drivers properly, the heat will dissipate. The only time you'll need fans for cooling is if you run the drivers very close to or at their maximum rated power, which is a bad idea to begin with.

The drivers should be mounted such that the fins and the spaces between the fins are oriented vertically so that the airflow is from bottom to top, since heat tends to rise. Also, they should be mounted so they are outside of the enclosure you're using. That way, convection will take over and you should be good to go without the need for fans. Again, that assumes you did not pick out drivers that are going to be stressed near their design limits. Convection works by heat rising and creating a slight vacuum under it, which will pull in cooler air from underneath. It actually creates a moving airflow, similar to a fan.

If you're going to block the airflow in any way, such as mounting the drivers internally or pushing the assembly against a wall or other obstruction, then you should consider extra cooling techniques.Another thing to consider is, if you've mounted the drivers  internally, you might just be blowing hot air right back onto them,  severely diminishing cooling efficiency, if you haven't created a  reliable way to circulate outside, cooler air throughout the enclosure.  So make an effort to mount them - the fins, that is - externally to the  enclosure, in open air, or punch many holes in the enclosure, bottom and  top, in line with the fan(s), to create the necessary ventilation for  proper airflow.

None of this is to discourage you from cooling things the way that feels most comfortable to you, rather, just some info to set your mind at ease. Also, keep in mind that powering fans is going to put stress elsewhere in the system, so understand _all_ of the parameters before you start buying and building.


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## jimemack (Jun 27, 2013)

Good luck.

Jim


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## papermaker (Jun 27, 2013)

I'm trying to get the gibs adjusted on the mini mill and there seems to be a fine line too tight and binding and too loose and getting a choppy cut. If I snug them up the stepper motor doesn't have enough power to overcome the friction. I'm running about .25 Vref. Will adjusting this up apply more power to the stepper.
I should have waited until I was smarter before I started this project but at 55 I doubt that will happen!!


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## DMS (Jun 27, 2013)

Don't wait, stuff like this is how you _get_ smarter. Before you start thinking you don't have enough torque, play around with your acceleration. More often than not that is the issue. Steppers don't like rapid acceleration (it takes a lot more torque than "cruising"). If you push them too hard, they can lose step, and that's no good. It is always possible that you are setting your gibs too tight, but I would check your acceleration first.

The practice I used to adjust my jibs was this

1) Loosen all the set screws
2) Tighten just the middle one _slowly_ while moving the axis back and forth until you just feel some drag
3) Do the set screw in front of the middle in the same manner, then the back.
4) Lock them all down, and check your drag again. There should be some drag, but it shouldn't be "hard". Run it the full length of travel, just to make sure you're not binding somewhere.

This worked well for me. Also make sure things are oiled. IIRC you purchased a ballscrew kit; did it come with ball-bearing mounts? The stock mounts are pretty high friction, if you are still running those, that may be part of the issue.


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## papermaker (Jun 27, 2013)

I know its a matter of tinkering to get it "zeroed in". I bought the CNCFusion ballscrew kit and have had some issues with binding but I seem to have that under control. I will try some tuning of the acceleration rate and see what that does for it.


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## papermaker (Jun 28, 2013)

This afternoon I ran the Mach 3 test G-code and everything went through the motions fine. It wasn't set to cut anything but I guess it is to test each axis. I'm getting braver and hopefully I will I can start cutting something soon.


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## DMS (Jun 28, 2013)

MDF makes mills pretty well, and is not too hard on cutters if you crash. Good starting material, and relatively cheap. Only problem is, it generates a lot of dust. I also recommend turning your feed rate _WAY_ down (like, 50%), and keeping your hand poised over the ESTOP button as you get started. Things get exciting fast .


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## papermaker (Jun 28, 2013)

MDF sure is cheaper than aluminum. I think that there are wizards in Mach 3 Demo that can be used until I get the license activated. I hope.


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## Dr.Fiero (Jun 29, 2013)

You can't use the NFS wizards without a license.  And you're limited to 500 lines of gcode without Mach itself being licensed.

But that's more than enough to test your machine, then decide to get it.


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