Emergency stop when router circuit breaker trips?

[graphicmetals]

Has anyone setup their bot to trip the emergency stop as soon as the router ciruit breaker trips?

Regards,

Kevin Fitz-Gerald
Project Manager

Graphic Metals, Inc.
P.O. Box 31
Bryan, OH 43506
Voice 419-636-5757
Fax 419-636-6404

kfitzgerald@graphicmetalsinc.com (mailto:kfitzgerald@graphicmetalsinc.com)

[gerald_d]

We run the Bot and the router off the same circuit breaker, so everything will stop if the CB trips - but it hasn't happened yet.

[ron_cleaver]

I was having a similar problem with a circuit breaker tripping often. My solution was to install a dedicated 20 amp circuit for the ShopBot control box, computer, router and dust collector. So far, so good.

[graphicmetals]

In the setup directions, it specifically states that you should not run the router and the computer on the same circuit. So I didn't.

If you did that, when the breaker tripped, you would not know where to resume the program because the computer would die. Or am I thinking wrong?

-Kevin

[gerald_d]

A tripping breaker should not be regarded as a normal occurence. If a breaker trips, then there is a fault to be rectified before the breaker is reset. This makes tripping breakers an extremely rare event and it is not the end of the world when the program dies and loses its position. (You will get more "lost position" problems from other sources)

As for running on a "different" circuit, this is a bit of a vague recommendation because it is difficult to determine what is really "different". A different phase? A different power outlet? A different switchboard? Or a different utility company?
There is a conflicting requirement to keep the ground paths as short as possible, meaning that your circuits shouldn't be too different.

The different circuit recommendation has more to do with electrical interference (I think) and then it can help to have more cable/lead distance between components. (More copper to absorb interference?). My personal belief is to insert more copper by using thicker, shorter cables/leads. Two circuit breakers sitting side by side on a switchboard normally have less than 2" of wire between them and this gives a false impression of being on 2 "different" circuits as far as interference is concerned. If the 2 breakers are on different phases, only then can they really be considered to be on different circuits.

[kaaboom_99]

There is a quite simple approach to accomplish what you are trying to do. Get yourself a relay that has a coil rating of your router (probably 120 volts). This same relay should have at least one set of Normally Closed contacts. Wire up the coil of the relay to be on (energized) all the time. Wire up the one side of the normally closed contact to input #4 of the CNC control box and wire up the other side of the normally closed contact to ground. Should this circuit ever lose power, the relay will de-energize, closing the normally closed contact whereby sending input #4 to ground (which is how the estop button works)
Hope this helps.
Perry

[rgbrown@itexas.net]

Good and proper explaination Perry.

[ron_cleaver]

Kevin,

I don't recall the instructions calling for a different circuit for the router and computer when I installed my ShopBot (March 2001).

But suppose you do have the router and computer on a different circuit and power to the router is lost (more likely with a Porter-Cable 3.25 hp router since it has a 15 amp motor). Do you really want the computer to continue moving the router when it's not running? You will probably destroy your work at that point.

[rgbrown@itexas.net]

Ron,

My reading of Kevin's post is he wants to do just that. Shut the machine off if the router stops.

My Porter-Cable "3.25 HP" router pulls 7 amps normal load and up to 10 amps if I really bog it. If I do the math HP = watts/745.7 and stretch the Voltage to 130 V, my "3.25 Hp" router MIGHT produce 1.75 Hp "on a good day".

I know I run my "5 Hp" vacuum, my "15 Amp" router and 2- "8.4 Amp" vacuum clamp motors on one 20 Amp circuit breaker. I have never tripped the breaker except to test it and assure myself it is working.

An "AmProbe Type" tool is a valuable thing in figuring out what is and is not happening.

[ron_cleaver]

Ron,

I don't think Kevin wants to shut off the PC. I think he wants to simulate an emergency stop. The relay is one approach described above.

My approach doesn't cost anything. If my breaker ever trips, I can start the file again from the beginning if I don't move blank (and I can use my proximity switches to reset home if necessary). I've done it just to make sure it works. Since the tripped breaker is not likely to happen to me, I prefer the 0 cost solution. I can live with starting over if it ever does happen.

BTW, it's interesting to see the measured current draw of the router. But it makes me wonder why I used to have a problem tripping a 15 amp breaker regularly.

[dands50@hotmail.com]

Ok well my two cents The reason you run two circuits is to reduce the chance of line noise so that you dont glitch the program on the computer this is caused from 60 cycle buzz in the power side of the line: with proper grounding etc. you can help eliminate it but you should run two circuits: if you run only one then put in an inline noise filter to play it safe. also if a breaker keeps tripping has anyone thought of a weak breaker that trips at say 5 amps instead of the 15 or 20. just a thought. David In Wyoming