limit switch

[Tim Lucas]

I am trying to hook up some limit switches on my X & Y, not sure if the ones I have will work. They came with the machine but I bought it used. The only thing I see that may be a problem is the voltage. please tell me what you think, and thanks for the help.

[steve_g]

Tim…
10 – 30 volts DC … not sure which unit you have but likely voltage in that range is available on your board… if not it’s easily obtained from a wall wart or other power supply
SG

[Tim Lucas]

Hi Steve, I now have it hooked up but on the 5v pin input block - when I set the input to normal closed limit switch, I get a green lite with yellow around it. but when I move over the limit bolt there is no change. I am thinking not enough volts.

Do you think it would hurt to pick up 10v - I don't want to burn up the input

94 PRT with PRT V4.17 board with geckodrives

[steve_g]

Tim…
It’s a good chance that there’s not enough voltage to operate the switch. Before you try anything else, see if touching the prox with something metal, like a screwdriver triggers it. Possibly the gap is too large for the 5V to work. I wouldn’t be afraid to pick up the 10V as the current draw is going to be in the transistor level.
SG

[jerry_stanek]

the switch should be lit up and when you ass over it it should shut off. in your values what do you have showing for your switches. On mine the switch light on the screen are not lit till I trigger the limit

[Tim Lucas]

the switch should be lit up and when you ass over it it should shut off. in your values what do you have showing for your switches. On mine the switch light on the screen are not lit till I trigger the limit


Hi Steve, I now have it hooked up but on the 5v pin input block - when I set the input to normal closed limit switch, I get a green lite with yellow around it. but when I move over the limit bolt there is no change. I am thinking not enough volts.

Do you think it would hurt to pick up 10v - I don't want to burn up the input

94 PRT with PRT V4.17 board with geckodrives

Good morning Jerry,
paper with switch says normal closed so I set the input to normal closed limit switch.
According to what I see on Shopbots web site the switch I have is the currant accessory and my bot is a 94 so I think I will call them this morning and see what they say.

Thanks
Tim

[tlempicke]

Calling them is a great idea. At one time in the past I talked to one of the techs and he told me that the switches they use will give .002 repeatability.

This give an easy way to get the carriage to a known position each and every time.

Over the course of time that is going to save a tremendous amount of time.

[Tim Lucas]

just walked out into the shop and looked at the schematic again noticed that the output has a 12 volt so I will try that next

[Brady Watson]

There is no such animal as a 94 PRT 4G. It is at least a 2005.

PRTs used 5v proxy switches, normally open. PRS tools used the barrel type that you show here @ 24v in normally closed configuration. I cannot recall, but there could have been a short time where 12v prox switches were used on the non-Alpha tools. The move was made from 5v to 24v to reduce false triggering via static electricity and other shop noise.

You can use these on your tool, but they should be run at 12 or 24v. You should be able to run these at 12v, which you can use on the output terminal section. There is a 12v tap next to output 4.

Check the wires to be sure...if these are from SB, the wiring *should be* black to the input for that axis (2 for X, 3 for Y); blue is ground and brown is 12 or 24v. You will need to make custom mounts and targets for these on a PRT.

You can check out the assembly manuals for the PRTs and PRS tools on the SB Support/Documentation page on the main site to give you some pointers for mounting and adjusting.

-B

[Tim Lucas]

thank you Brady, you give me information the book doesn't even have. (book shows old style sensors)

i have the Y sensor hooked up an have a yellow circle with green center until it passes the bolt then solid yellow. does that sound correct?

[Brady Watson]

Yes. You can also test triggering with anything metal, like a flat blade screwdriver or coin to test without moving the gantry.

-B

[Tim Lucas]

Have sensors installed and operational now, hade to create a bracket to hold sensor for X.
Thanks for the help!
Tim