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Old Nov 19, 2007, 06:10 AM
Make something. Anything!
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Syracuse Hancock, New York, United States
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Quote:
Originally Posted by rosco
I keep poping back to have a look. Still lov'n it.
Looks like the good stuff is about to start...
cheers
roscop
Roscoe,

Thanks for you patience. I am hooking up limit switches next and then doing a brief description of my machine, followed by setting up Mach3 then moving right into Vcarve Pro, Cut3D and Photocarve.... Still a long way to go. I may break it into another thread or keep it all in one.... Haven't decided yet.

One thing is certain. The Hobbycnc Pro board has been flawless. What a great piece of engineering!

Bill
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Old Nov 22, 2007, 09:29 PM
Make something. Anything!
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Limit Switches

I am taking this a little bit out of order, and talking about limit switches now instead of the router they mount to. I am doing this so that all the electronics parts are in one place. I will cover the router next and then the software.

Homing and limit switches are added to CNC machines to prevent the machine from destroying itself by crashing the gantry into the endplates. Without some method of realtime feedback, the CNC software has no true idea of where the gantry is, so some other solution is needed. Limit switches are that other solution.

When the gantry reaches the end of travel on any axis, the gantry runs into a limit switch and depresses the switch lever. This circuit is then opened and the Proboard sends a signal to the software (Mach3 in this case) through a wire connected to a pin on the Proboard. Mach3 then notices the change of status of the pin, and stops the power to the stepper motor.

For the Proboard, we need to use Normally closed microswitches. If you used normally open switches you might never know if the wiring or the switches were bad because the machine would continue to function. When a Normally closed switch fails, the machine axis won't function so it is easier to track down the problem.
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Old Nov 22, 2007, 11:53 PM
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United States, AR, Little Rock
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Great thread!!
I need to switch projects right now like I need another hole in my head, but this is giving me the "I wanna CNC router" bug big time.

Just one quick question about the transformer though: I have a 500VA 120/240 input - 24V output txf. That is the same as saying it is a 24V 20A output right? It should be sufficient for this shouldn't it?

Thanks for all of your work presenting this.
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Old Nov 25, 2007, 07:35 PM
Make something. Anything!
bgriggs's Avatar
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Quote:
Originally Posted by PlaneCrazee
Subscribed!!!
Great thread!!
I need to switch projects right now like I need another hole in my head, but this is giving me the "I wanna CNC router" bug big time.

Just one quick question about the transformer though: I have a 500VA 120/240 input - 24V output txf. That is the same as saying it is a 24V 20A output right? It should be sufficient for this shouldn't it?

Thanks for all of your work presenting this.
If you calculation is correct then yes. I am not an electronics guru. Perhaps someone with more transformer experience will chime in? Having said that, 24V, 20A is plenty.
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Old Nov 25, 2007, 08:16 PM
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Difference between homing and limit switches

CNC machines can have many types of input devices including home and limit switches. These two types of switches serve different functions but are identical mechanically.

Limit switches - Prevent the linear axis from moving too far and in so doing, causing damage to the machine. Limit switches are generally place at the extreme end of travel of an axis.

Home/Homing switches - Consist of one switch per axis. The home switch may be mounted at any location on the machine. The motor driver software moves each axis individually until the home switch is reached. The axis is then set to ZERO and then the motor backs up a predetermined amount to reset the homing switch. This action is repeated until all axis have reached home.
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Old Nov 25, 2007, 10:26 PM
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Australia, NSW, Newcastle
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Quote:
Originally Posted by PlaneCrazee

Just one quick question about the transformer though: I have a 500VA 120/240 input - 24V output txf. That is the same as saying it is a 24V 20A output right? It should be sufficient for this shouldn't it?

Thanks for all of your work presenting this.
do remember that the DC output after it's rectified & smoothed will equal 1.414 times the AC voltage (in your case about 32.5V, after also taking the voltage drops across the diodes into consideration)
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Old Dec 03, 2007, 10:37 PM
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Quote:
Originally Posted by OzDragonFlyer
do remember that the DC output after it's rectified & smoothed will equal 1.414 times the AC voltage (in your case about 32.5V, after also taking the voltage drops across the diodes into consideration)
Hobby CNC boards can be used up to 42V safely. By the way, if anyone is interested I'm selling a 4-axis board in the For Sale section (non R/C since I didn't know where else to put it).

Best regards,
Mike
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Old Dec 07, 2007, 08:32 PM
Make something. Anything!
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Syracuse Hancock, New York, United States
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How do you heat your workshop?

I am still trying to get my limit switches and home switches sorted out. I have read the instructions and think I have a line on what I was doing wrong. The problem is we are in our first winter storm and it has been too cold to stay in the garage...... Which brings up the question, How do you heat your workshops? Any advice would be appreciated.


Bill
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Old Dec 07, 2007, 08:36 PM
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Quote:
Originally Posted by bgriggs
I am still trying to get my limit switches and home switches sorted out. I have read the instructions and think I have a line on what I was doing wrong. The problem is we are in our first winter storm and it has been too cold to stay in the garage...... Which brings up the question, How do you heat your workshops? Any advice would be appreciated.


Bill
Hi Bill,

What's your problem with the limit and home switches? I might be able to offer some help. And my only advice for heating your workshop is to have it in a warm place like Houston !

Are you using Mach3?

Mike
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Old Dec 07, 2007, 08:44 PM
Make something. Anything!
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Syracuse Hancock, New York, United States
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Quote:
Originally Posted by chem1
Hi Bill,

What's your problem with the limit and home switches? I might be able to offer some help. And my only advice for heating your workshop is to have it in a warm place like Houston !

Are you using Mach3?

Mike
Hi Mike,

Houston is not an option ;-).

I am using Mach3, a fantastic program with tons of features.... I have 5 switches, one at each end of the X and Y axis and one at the top of the Z axis. The switches are all wired in series and are NC switches. All the switches are wired into Ground and pin 11.

I can get the switches to act as Homing switches but have not figured out how to set then up as limit switches also. I have heard it can be done but I think I am missing something basic. I may have to split them up into two groups and use an additional pin???

Thoughts? Suggestions?

Bill
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Old Dec 07, 2007, 09:05 PM
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Quote:
Originally Posted by bgriggs
Hi Mike,

Houston is not an option ;-).

I am using Mach3, a fantastic program with tons of features.... I have 5 switches, one at each end of the X and Y axis and one at the top of the Z axis. The switches are all wired in series and are NC switches. All the switches are wired into Ground and pin 11.

I can get the switches to act as Homing switches but have not figured out how to set then up as limit switches also. I have heard it can be done but I think I am missing something basic. I may have to split them up into two groups and use an additional pin???

Thoughts? Suggestions?



Bill
Exactly the same set up I have. Have you seen if an LED light comes on (on the diagnostics page) when any switch is depressed? It should turn off when released. All the switches should do this. If they don't then you have a wiring problem. If they work correctly try using the automated setup of inputs feature. If you go to Config>Ports and Pins>Input Signals you'll see it at the bottom right. When the new screen comes up select whichever home/limit switch (i.e., X-Limit ++, X-Limit --, etc) you wish to configure and hit the Autoset button. The computer will then wait until you push the button you are configuring. The text box should change from "Searching for signal activation. Press switch or cancel" to the actual pin#, port#, enabled, etc. If it all goes well all five of your switches will have exactly the same configuration.

I agree, Mach3 is the best value for this "hobby" and is loaded with features.

Mike
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Old Dec 07, 2007, 09:38 PM
Make something. Anything!
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Syracuse Hancock, New York, United States
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Quote:
Originally Posted by chem1
Exactly the same set up I have. Have you seen if an LED light comes on (on the diagnostics page) when any switch is depressed? It should turn off when released. All the switches should do this. If they don't then you have a wiring problem. If they work correctly try using the automated setup of inputs feature. If you go to Config>Ports and Pins>Input Signals you'll see it at the bottom right. When the new screen comes up select whichever home/limit switch (i.e., X-Limit ++, X-Limit --, etc) you wish to configure and hit the Autoset button. The computer will then wait until you push the button you are configuring. The text box should change from "Searching for signal activation. Press switch or cancel" to the actual pin#, port#, enabled, etc. If it all goes well all five of your switches will have exactly the same configuration.

I agree, Mach3 is the best value for this "hobby" and is loaded with features.

Mike

Thanks for the help Mike. I sould be able to try this Tomorrow afternoon.


Bill
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Old Dec 08, 2007, 03:08 PM
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USA, WA, Spokane
Joined Nov 2003
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Quote:
Originally Posted by bgriggs
I am still trying to get my limit switches and home switches sorted out. I have read the instructions and think I have a line on what I was doing wrong. The problem is we are in our first winter storm and it has been too cold to stay in the garage...... Which brings up the question, How do you heat your workshops? Any advice would be appreciated.


Bill
Hello Bill,

Check this out: http://www.lowes.com/lowes/lkn?actio...0NT&lpage=none

You can use Propane or LP gas. I plan on using one in my shop/garage.

Jim
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Old Dec 10, 2007, 09:49 PM
Make something. Anything!
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Originally Posted by Catch-Air
Hello Bill,

Check this out: http://www.lowes.com/lowes/lkn?actio...0NT&lpage=none

You can use Propane or LP gas. I plan on using one in my shop/garage.

Jim
Thanks Jim,

I had seen those but wasn't sure how much venting they require. I know they use this type heater quite a bit in the south.

Bill
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Old Dec 14, 2007, 05:27 PM
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Syracuse Hancock, New York, United States
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Homing switches HELP!!!

I had planned to explain all about homing and limit switches but it would appear I don't know a darn thing about them. I have spent several nights trying to get the setup working right and I have not been successful. I will document what I did and hopefully someone will spot my error.

Jaime is helping me build my router. He is supplying some of the parts because after this router is finished, we will use the router to build a bigger machine. Jaime will get to keep this router.... Nice deal for both of us.

Jaime picked up 6 NC micro switches for me and also some 1" wide strips of plexiglass. The plexiglass allowed the switches to stick out far enough so the axes wouldn't crash. We basically drove the axis over as far as it could go (with a small margin for error) and placed the switch so that it would be depressed by some part of the moving trolley.
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