First cuts today, random disconnects from static.

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tahlstrom
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Joined: Mon Nov 09, 2015 11:02 pm
Location: Lehi, Utah.

First cuts today, random disconnects from static.

Post by tahlstrom » Mon Nov 09, 2015 11:28 pm

I ran the logo test with a pen a few days ago with good results. I finally had time to setup the Dewalt today and try some real cuts. I was using Chilipeppr to send the code I generated with estlcam. The first cut seemed to go okay until I started following the bit with my shopvac to catch the dust as it was created. Once I started doing that I began to have random shutdowns. Sometimes the controller would lose connection other times it would simply stop but stay connected. It took me a frustrating hour to figure out it was static. If I had read this board sooner I would have known. I finally realized when I noticed it shut down when my arm just grazed the metal frame while it was cutting. The steppers stopped immediately and the z axis went free so the router rested on the bit. The shopvac creates massive static so I tried another cut without it. I think there must have been a buildup or something because I could not get the tool to run for more than maybe a minute without stopping. I finally moved the computer right next to the SO3 and connected a wire from the metal case of the computer to the metal frame of the SO3. I wasn't sure if the power supply on the SO3 was grounding the unit or not so I figured connecting it to the computer case would effectively ground it. I then clipped an anti static bracelet to the computer case and put it around my wrist. With this setup I could finish cuts while following the bit with the shopvac. The only time connection would be lost was when I would turn the router off when it homed after finishing the cut. The router was connected on the same circuit as the S03 and computer so maybe I'll try an extension cord to another circuit. I was a little surprised how static sensitive everything is. The USB cable and power cords are the ones that came with the unit. I looked at the USB and it has a choke on it. Hopefully the problem is cured.
Shapeoko 3 #0564

cvoinescu
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Re: First cuts today, random disconnects from static.

Post by cvoinescu » Mon Nov 09, 2015 11:47 pm

Note that, electrically, the Shapeoko 3 has four components that are insulated by the V-wheels: the frame (including the Y rails), the gantry (Y carriages and X rail), the X carriage, and the Z axis. Ideally, if static electricity is a problem -- as it tends to be during the cold season and near vacuum cleaners --, you'd connect all these four parts together.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

tahlstrom
Posts: 2
Joined: Mon Nov 09, 2015 11:02 pm
Location: Lehi, Utah.

Re: First cuts today, random disconnects from static.

Post by tahlstrom » Tue Nov 10, 2015 12:11 am

Yes, that is my plan. I'm going to hit up Home Depot tomorrow for some flexible grounding wire and some ring lugs. Right now my ghetto solution is some lamp cord mashed under a screw on the SO3 and the computer case. It worked but I'd prefer a more permanent solution.
Shapeoko 3 #0564

MidCitySlim
Posts: 39
Joined: Sun Nov 01, 2015 9:49 pm

Re: First cuts today, random disconnects from static.

Post by MidCitySlim » Wed Dec 02, 2015 8:02 pm

I second your experience (static shutting down the SO3). Isn't there a real fix here? It seems the SO3 is entirely too sensitive to static.

Seems like a design flaw.

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: First cuts today, random disconnects from static.

Post by RobCee » Thu Dec 03, 2015 10:00 am

I believe that there are a few different issues here:

1. From experience, the use of a shopvac generates a huge amount of static electricity. Just look at suggestions on grounding any fixed system and the lengths gone to by manufacturers in fitting conductive hoses, etc.

2. The electronics in USB connections are not as robust as those in an RS232 connection and are easily upset/disrupted by surges of different types. Think about everything else you have that uses USB, they are normally a long way away from nasty 'electrically noisy' devices like shopvacs or routers. They are typically not transferring lots of data, either.

3. The voltages used by the Arduino/TinyG/CarbideMotion based controllers are usually low (not the stepper control, but the general communication). Everything I have read about control circuits suggests that lower the voltage used, the more likely it is to be susceptible to noise interference. Most industrial guidelines suggest that 24V is the ideal for control circuitry in order to minimise the chance of interference.

My setup is not perfect, but I now rarely have problems with my SO2 losing it's connection randomly (which I did have originally). I have had a few recently, but found that I was transmitting a large static 'zap' to the machine when I used my shopvac to clean up. Holding the frame of the machine before using the shopvac resolved that one.
The biggest change to my system was to add a prototype of Cvoinescu's USB isolator (GIPSS), which really made a huge difference to my setup.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

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