Tool length touch probe

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Tool length touch probe

Postby Ollie78 » Thu Mar 21, 2019 11:35 pm

Hi everyone

I have a crocodile clip and aluminium plate type touch probe. It was working great the first few times I used it. Now it only works half the time.
The other times it says "the touch probe is active " or something like that. It is weird because it will start to move for a second, then stop and ping up the warning.

Wires are physically well connected, sometimes I can get it to work by removing it from the i/o setup menu and then re activate it.

Any explanation?

Ollie
Ollie78
 
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Re: Tool length touch probe

Postby ger21 » Fri Mar 22, 2019 2:02 am

Sounds like a noise issue, triggering the input.
Gerry
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Re: Tool length touch probe

Postby Ollie78 » Sat Mar 23, 2019 11:14 am

Hi Ger21

What is likely to be causing the noise ?

The BOB, power supplies and stepper drivers are in the same box but the VFD and UC300 are outside it.

Could a different type of wire help ?

Thanks

Ollie
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Re: Tool length touch probe

Postby Robertspark » Sat Mar 23, 2019 11:40 am

Do you have a schematic of how you wired everything up?
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Re: Tool length touch probe

Postby ger21 » Sat Mar 23, 2019 11:49 am

The wires from your plate and clip can pick up noise from almost anywhere.
Gerry
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Re: Tool length touch probe

Postby Robertspark » Sat Mar 23, 2019 12:50 pm

You can try adding ferrite cores and 0.1uF capacitors, but if the probe is intermittently lit, it suggests the current is sufficiently high to indicate a triggered input.... The ways to combat this are check yoxur ground wiring you can also use a resistor to bias the input to minimise the effect of noise, as the resistor is wired in parallel with the input to act as a drain for any induced current


A wiring schematic would be most useful to see what is the best method to resolve the issue
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Re: Tool length touch probe

Postby Ollie78 » Sat Mar 23, 2019 12:52 pm

Hi

I do not have a schematic as I did not wire it up myself. I bought the machine second hand.

This is a picture of when I got the machine so it is a bit cleaner and I have removed some stuff but it is mostly the same. I have this mounted under the cnc on a plywood shelf along with the uc300 and its 5v power supply and next to it the spindle VFD and nearby a barrel with a pond pump for the spindle coolant.

resized cnc pics 020.JPG


This was when I was testing the uc300

resized cnc pics 074.JPG


Now the case has its lid back on as well.

I know this is not ideal and it is on my ( long ) list to re-do all the wiring into a proper enclosure and mount the PC next to it under the router bed.
I just want the monitor arm mounted to the frame and the keyboard and mouse on a little shelf mounted to the side.

Ollie
Ollie78
 
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Re: Tool length touch probe

Postby Ollie78 » Sat Mar 23, 2019 12:58 pm

Robertspark

I posted last post before I saw your reply. I might try the resistors ( I wish Maplins had`t closed ) and I think I have some of those ferrite cores somewhere. Do I just solder the resistors in line with each wire?

Cheers

Ollie
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Re: Tool length touch probe

Postby Robertspark » Sat Mar 23, 2019 2:07 pm

Amazon ..... I use Amazon prime for next day delivery if I really need something.... It costs a premium though but if you want to finish something in a hurry and not want to wait for the slow boat from China (6 weeks) or a couple of days from someone like bright components on eBay (they have an online shop too.... But there is more in the eBay store).

No the resistor is wired in parallel from the probe input to the ground (vss supply voltage)

But before doing that what breakout board are you running and how is the probe wired .... What voltage is it wired up as (5v, 12v, 24v????)

1 220ohm resistor at 5v connected from the probe input to 0v will draw ~23ma when 5v is connected to the input And about 113mW so a 1/4 resistor will do fine

So.... Do you have a volt meter to measure the proving voltages

I am out at present but will do a sketch later to explain my waffle
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Re: Tool length touch probe

Postby Ollie78 » Sat Mar 23, 2019 9:47 pm

Thanks Robertspark

I do use amazon a bit actually, got some nice chinese endmills the other day.

The breakout board is a DIYCNC uniport V2, I think its 5v if i remember its wired to input 2 on the board.

I do have a multimeter, though I am not sure if I should be allowed to use it ! I find electronics a bit of a black art, Mechanical/ physical stuff is easier to visualise for me.

I will take a close up photo and check the voltage next time I am in the workshop.

Thanks

Ollie
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