You Big Dummy! (Fred G. Sanford)

[RunsWithScissors]

So there I am, in the shop playing with my new CNC Plasma cutter.

Until now, I have had very good luck with it. Most of my problems are “CAD” related. I am currently using Fusion 360 and it has been kicking my a$$ for about 6 month’s, but I am getting “better”.

So I decide to make a sign for the annual “take the girls ice fishing” trip this year.

I have only made a few parts and one sign so far, but I have never had any problems…yet.

I decide to use 16 gauge mild steel, just because I have used it in the past with good success and so far it has “resisted” warping pretty well.

So I toss a chunk of it onto the machine and do a “dry run” to get it lined up…so far so good…

Then I hit “run” and it starts off fine.

Well about 10 seconds into the cut I notice something is off…

The cuts are not going “through the material”, they are just going about 1/2 way through.

The cuts look like total crap, so I abort the mission and start troubleshooting.

To me it appears as if there is not enough “current” to make a proper cut, or possibly the machine is going too fast?

So I “up” the current setting on the machine and hit “go” again…

Not wanting to waste material and since I have already screwed up this section, I decide to “cut over” the already screwed up section to “test it out”.

Nope…still jacked up.

WTF???

So then I start changing cut speeds and messing with the plasma machine…This all takes about an hour.

Still sh!t!!!

So I decide/conclude that the the drawing is “too detailed” for my machine and I decide that I need to “redo” the design to something simpler…

I also need a “Tool Rack” for my Lathe, so I go upstairs and embarrassingly enough, about 1.5 hours later, I have a simple “tool holder” designed.

So its off to the Langmuir to cut it out.

Nope!!! Same jacked up cuts…Now I am pissed, and begin my usual “cussing temper tantrum”…I dont even have the witts to take a picture of it I am so damn mad…

Then I look over, and it hits me like a sack of hammers…

The ground clamp was off…

I felt both 'relieved" and “stupid” simultaneously…

After grounding it properly, I get this…

Now it’s time to see if my "original sign design will work…

Yep…all good now.

Amazing how a proper grounding clamp can change things…hahahah

Just one small "snafu’ is that piece in the center must have been a little too “tight” for my machine.

So a few minutes on the “TIG” machine and a little “body work” it should paint up nice.

[Knick]

Trust me everyone has done this at one point!

[Wsidr1]

RWS, as stated, we’ve all done it.

I have implemented a pre-start checklist based on the Toyota “point and call method” I learned working there and riding the trains in Japan (operators use the method). I point and say “on” at: work clamp to confirm on the material; the air valve open exiting compressor tank; amperage set on cutter; axis zeroed over start point; orientation corner selected on the sketch.

Why Japanese Train Drivers Pointing and Calling

[Knick]

That’s a great idea, how do you remember where the check list is?

[PC-PlasmaCut]

That would be my problem! It’s a good process to have. Maybe laminating a card with the process and mount near the machine. I did missed the work clamp item couple weeks ago, there goes a $40 sheet of steel.

[ChelanJim]

@RunsWithScissors

Amazing how a proper grounding clamp can change things…hahahah

As most of us were reading your description of the problem and seeing the picture we were wondering about your “work” clamp. Why? Because we have all done it. For me it was probably 6 times. For others, it was probably only twice.

I can see why some like to clamp to the table vs the work piece because they don’t need to remember. Always a good habit to try to be in direct contact/clamping with the workpiece. It will give you the consistent best results.

[RunsWithScissors]

@ChelanJim

As most of us were reading your description of the problem and seeing the picture we were wondering about your “work” clamp. Why? Because we have all done it. For me it was probably 6 times. For others, it was probably only twice.

I can see why some like to clamp to the table vs the work piece because they don’t need to remember. Always a good habit to try to be in direct contact/clamping with the workpiece. It will give you the consistent best results.

I can see the wisdom in grounding to the table all the time.

But, for now at least, I am going to keep grounding to the piece I think.

As per normal, things evolve, so maybe I will change it up one day and use the table.

[RunsWithScissors]

If I have one complaint about this machine, it would be that the small’ish holes tend to not come out well. (It’s not really a complaint per se, its more of a consequence/result of the “kerf”)

so I have to usually “chase them” with a drill bit.

But the bigger holes come out very well.

Man this sure beats the hell out of actual “drilling” old school style.

Now to bend her up on the homemade brake…

But wait!!!

If I only had a “air over” press brake…Oh wait… I do!!!

So a few minutes at the brake and whaaalaa.

I “over bent” it a little, but a little work, and I get it “good nuff”

A few minutes with the TIG machine.

Now its ready for “paint”

[ChelanJim]

I can tell you are feeling better in this post: You are back to story telling mode with lots of pictures for us 50 and over “kids with toys.”

[mechanic416]

Work clamp on the metal is the best. If its hooked to the table when cutting aluminum or stainless you can get arc marks on the back side of your project.

[RunsWithScissors]

@mechanic416 Thanks for that info.

I am going to take the “if a little is good, then more must be better” approach.

Tomorrow I will run a grounding wire to the table and then to the “house ground” that already exists. However I will continue the practice of ground directly to the piece as well.

[Wsidr1]

@RunsWithScissors

small’ish holes tend to not come out well.

Small holes are a challenge for most of us. If you search you’ll see a lot of others have struggled too. Often changes to CAM settings can help. You may want to start a new thread and post images of your CAM settings from your Linking tab, and some results with those settings, along with the consumable type, metal thickness, amperage, etc.

[TinWhisperer]

@RunsWithScissors

Tomorrow I will run a grounding wire to the table and then to the “house ground” that already exists.

Running a separate grounding plate for the table and equipment is a good idea.

"GROUND" what is it?

“Ground”, I hear this term a lot on all the forums welding, automotive, etc. and a lot of the time its not used in the proper context. I am not going into all the technical terms of what, when and why but this should help people understand. Electric systems AC uses a ground you have power wires and ground wires. If for some reason you lose your ground you lose your power. DC power systems use positive and negative there is no ground. Like the battery in your car or truck lose the positive or …

Here’s some PDFs on grounding advice from Hypertherm.

https://www.hypertherm.com/Download?fileId=HYP103900&zip=False

And @Bigdaddy2166 has quite a long running topic on this somewhere if someone could kindly post it.

[Bigdaddy2166]

Do not ground the table to the service ground in your shop… It needs an independent ground system. I am out in the marina right now. I will check back later.

[ChelanJim]

Here are two solutions for grounding/isolation of the table:

Solving Crossfire Pro CUT60 EMI and Ground Loop issues once and for all

I have been chasing EMI and ground loop issues on my Crossfire Pro with Primeweld CUT60 for years. To be clear, I do not believe this is a Langmuir problem, the Primeweld CUT60 is known to be a noisy girl and was removed from their recommendations list. But that said, the Crossfire Pro electronics were not designed to have robust protection against such cutters that throw off a lot of noise. What were my symptoms? The most common was simply disconnections to the electronics during a cut. But it…

Grounding interference solved!.....I wish

Drive a 8ft copper ground rod into the earth. Connect all motors with 12Gauge wire or copper braided wire to ground bar. Connect positive work piece lead to ground bar. Every thing BUT the Langmuir box and your computer. ENSURE YOUR COMPUTER AND LANGMUIR CONTROL BOX HAVE NO CONTINUITY AT ALL TO THE TABLE FRAME AND MOTORS. Take multi meter from table to outside shield on printer cable from laptop. EMAIL ME IF YOU NEED HELP. YOUR PROBLEM WILL BE GONE FOREVER… Do not try to use grounding sys…

[RunsWithScissors]

@Bigdaddy2166

Do not ground the table to the service ground in your shop… It needs an independent ground system. I am out in the marina right now. I will check back later.

Alrighty then, I will take your word for it sir!

[Bigdaddy2166]

Why do you want to ground the table? Are you having EMI issues. If your not it is a total waste of money. Now if there is a problem then we will move forward.

[RunsWithScissors]

I am not having any problems other than my memory…LOL

I was going to ground the table just to have a "back up ground "in case I forgot to ground the piece (like I normally do).

Grounding it to the “house ground” would be no more work than grabbing a scrap piece of wire and making the connection. (short, unobstructed run…maybe 3 feet or so)

But if it might cause problems, then I will just forget about it and move along…

[Phillipw]

The "ground clamps"is actually the positive DC on the plasma.

Current runs from negative to positive. That’s why the clamp is positive and torch is negative

[RunsWithScissors]

@Phillipw

The "ground clamps"is actually the positive DC on the plasma.

Oh wow, I did not know that.

I just “assumed” that “ground” meant negative.

Well theres that old saying about “assume” coming around to bite me.

Thanks for the “heads up” on that.