Project 1 from EmptyNester. Category: Custom Shop Tools - CNC Table

[acourtjester]

That is a very ragged cut I asked before what size tip are you using. I use a 1.0mm (about a .040") Also you may be too high still the top of the metal shoudlbe much cleaner then that in the picture. IMO
my cut height is about .060 ” Pierce height of about .080” to .090” i'm no expert but that works for me.

[sportbike]

I tried my first cut of a shape other than a circle. I made a name plate for my wife that I could mount in a wood base.

Everything worked great, but the cut wasn't very clean. I'm guessing that I had the torch too high. Any thoughts would be appreciated.

Attachment 8354

What was your travel speed? Looks like you could bump it p quite a bit.

[Rambozo]

I tried my first cut of a shape other than a circle. I made a name plate for my wife that I could mount in a wood base.

Everything worked great, but the cut wasn't very clean. I'm guessing that I had the torch too high. Any thoughts would be appreciated.

Attachment 8354

What were the following:
Torch height?
Travel speed?
Amps?
Air pressure?
Tip size?

[EmptyNester]

I'm embarassed to say - I don't know what size the tip is. They weren't marked. My eyes aren't great at that small a measurement, but the one I used for that cut appeared to be about 0.06" (I have others that I think are 0.04"). Does that sound right?

Pressure: 65 PSI
Amps: I think it was 30
Speed: 60 IPM
Pierce height: 0.2 in
Cut height 0.04 in (though, there could be some slop in my touch and go switch offset because it looked higher than than when doing a "dry run")

What difference does the tip size make other than the kerf width?

[acourtjester]

yes that does I have 2 sizes 60 amp and 80 amp the 60's are the .040 (1mm). If you have tip cleaners for a OA torch try to get close with one of those and then mic it for the size. But most likely you should just go with the smaller one and see how it works. there is not a great supply of different sizes for t e torches. I buy 1mm for a P-80 torch & WSD-60 torch, I have and the everlast unit I have is rated at 60 amp plasma (PM256 multi) and I have not tried to cut thicker then 1/4" steel on the table.
I'm sure there are guys with much more experience then I have with plasma tables.

[EmptyNester]

I've spent a while working on the THC and its finally at the point of letting me cut something real.

I did my first cut of any complexity. I was hoping for:



What I got was this:



It looks like everything but the top of the circle was okay.

Any suggestions on what to look at?

[Rambozo]

Did anything move between the inside and outside cuts? That's the first thing that comes to mind. You can run the G-code through a backplot simulator to see if there is something wrong in the code. Any calibration errors in the machine axis would have affected the ID and OD the same, so it might not come out round, but it would not be what you are seeing.
Did you check to make sure you haven't lost any steps?
Loose gear on a shaft?

[sportbike]

It looks to me like something is up with the travel to step ratios. I'd try cutting a series of concentric circles with a consistent increment in diameter increase. Then see if each circle is in fact round and be sure the thickness remaining is consistent and accurate.

Did the plot in sheetcam or whatever you are using look ok?

[Rambozo]

It looks to me like something is up with the travel to step ratios.

Except that would also effect the outside cut.

[acourtjester]

HI Empty
One of the things I see is some of the finer (sharp cuts) are not as the image looks that could be the kerf width you have set in the cam program. But that does not explain the top inside cut. What are you using to convert the image (.jpg) to G-code. I use a program called CR8trace (free) it converts .bmp to .svg then sheetcam to g-code. Very simple to run just load a bmp you see nothing on the screen then you just save as .svg and its done. I copied your image and did the convert and simulated a cut and the mouth and top of the moon pointed areas were not sharp as yours are too. But the top of the circle was thin as the image was.
I was going to attach the .tap file but cannot using this downloader in the manage attachments.
You may want to make a pen adapter for the torch holder so you can draw out a g-code cut path here what I made to do that saves metal.

[EmptyNester]

Thanks all.

I tried the cut as the last thing for the night. I hadn't realized but the saved Mach config had the THC off. I realized when it was giving constant torch up commands. I guess the torch could have pushed it, but it was a 2 by 4 piece of 16 gauge so I didn't think the torch would be able to push it that much.

I haven't had a chance to try again yet. I was trying to figure out how to spring load a pen. I'll have to see if I can piece something together likes your setup Jester.

I drew the original image in Corel and exported to DXF. It looked fine in sheetcam and in the Mach window, but I wasn't paying close attention.

The distortion seemed odd because it appeared random.

I didn't get a chance to do anything tonight. Hopefully I'll get a chance tomorrow night.

BTW - when I put a new electrode and tip on, the quality of cut really improved.

[EmptyNester]

Taking all the advice, I checked all the motor settings. It turns out that the Y axis had a different acceleration that the X/A. I didn't think that would make a difference, but I set the Y to match the X/A anyway. They are all set the same except the max speed on the Z is much lower.

I then taped a 1:1 image down and manually positioned the torchhead at multiple points on it. That all seemed to line up properly.

I tried to cut again, and I remembered to turn the THC on in Mach before I started. I also up'ed the cutting voltage by about 3/4 volt. This is what I got:



It's a perfect match to the pattern. My best guess is that the torch did move the metal because it was too low before the THC was turned on. I guess that was a lesson in the value of the THC.

My wife is happy with the result, so I can be assured of continued "enabling"

One other thing that is interesting is that having up'ed the voltage 3/4 volt, it seemed I had more spatter on the top at pierce points. So, I'm impressed with the precision of the control. It makes an argument for setting cutting voltage in "counts" instead of volts since it has seven times the resolution.

I did have an interesting though on the THC. All I've used it on is 16 ga. I'm wondering if any aspect of the voltage behavior (other than being at a different voltage) will change on thicker metal.

Thanks all for the help.

[sportbike]

Looks good. Congrats on your first "Real" part.

Best part of the whole thing is that your wife likes it. Time to call Alro and have them drop off a truckload of sheet materials...

[sportbike]

My wife is happy with the result, so I can be assured of continued "enabling"

My wife was discussing finding a new hobby the other day....up pops a plasmacam and she was like "that's neat". I talked to her a bit about a plasma table and she was actually into it. She is an accountant, so this is totally different than her "normal" day, which is why I think she is sort f into it.
I told her that if she wants to get into Metal Art, I fully support her and will do what I can to enable her to get started.

If this takes off, I may be building a plasma table and hell, even breaking ground on a new garage by the fall... wouldn't want my wife to have to work out in an old drafty garage would I?

[ShaneJackson]

You have mastered the force young Jedi. You have demonstrated mind control... making her want a new shop and a plasma table.

[travis]

took my wife to see a plasma cutter demo at a car show shes like you "need' one of them then i show her the price on a blue boxed and the price on a powerultra half the price 3 in 1 shes like save for it lol

[EmptyNester]

My wife was discussing finding a new hobby the other day....up pops a plasmacam and she was like "that's neat". I talked to her a bit about a plasma table and she was actually into it. She is an accountant, so this is totally different than her "normal" day, which is why I think she is sort f into it.
I told her that if she wants to get into Metal Art, I fully support her and will do what I can to enable her to get started.

If this takes off, I may be building a plasma table and hell, even breaking ground on a new garage by the fall... wouldn't want my wife to have to work out in an old drafty garage would I?

Excellent work! All I can say is "keep working it"

Today my wife had said she wants a new railing on the front porch. The existing one is wood and she wants to stick woth wood. I said that I can leave a framed opening in it for a laser cut design. Now she's really excited and trying to think what she wants.