Home built machine, hypertherm, mach3, G540 cut quality issues...

I built my own cnc plasma table. Rack and pinion setup with steppers and other parts from cnc router parts. Mach3, Gecko G540 controller. I have tried cutting some 14ga with recommended settings and i feel like I should be able to achieve better accuracy and lines, or at least i would have hoped so? Most of all I dont know if my machine should be moving as jerky as it is or if its just the speeds/amps that I am running. The following example is 14ga at 40 amp and 280 ipm.

Link to video https://youtu.be/KtbvitklCds

https://www.cnczone.com/forums/attac...d=390798&stc=1https://www.cnczone.com/forums/attac...d=390800&stc=1https://www.cnczone.com/forums/attac...d=390802&stc=1https://www.cnczone.com/forums/attac...d=390804&stc=1https://www.cnczone.com/forums/attac...d=390806&stc=1https://www.cnczone.com/forums/attac...d=390808&stc=1

I have had to deviate quite a bit from the factory suggestions with both the 45 and the 45XP. Not as much difference with the 45XP, but still not on factory settings.
I would be cutting that at about 110 to 120 IPM.

I agree with Leeway, slow down to at least 150 IPM and work from there, is your voltage around 115,?
We use Fine Cut tips. Hard to tell from the video what your cut height is.
There are a lot of variables, trial and error helps decide the settings.
Do you use an air drier and filters?, also important.
Larry

that waffle cut is not from cutting at the wrong speed. Grab your gantry and the motors with them on and locked and try to move it. It should have no play. Same thing with the cross axis. The Z motion needs to be smooth. You made no mention of if its parallel port or external pulse card. if you have a THC , and Did you invest in the belt reduction units for CNCRP? Does your table shake back and forth when you are cutting at 225?

You can get really good cuts with 45A consumables at 200 to 225 IPM with a tight table and good THC. Some computers cause MACH to put out step signals with lots of jitter and it causes ragged motion. You need to place you hand lightly on the top of your Z, close you eyes and "feel" the motion as you make the cuts. Do the same (with your eyes open to keep from cutting over your hand) on the material. The material can move in the opposite direction from the gantry motion on tables with fles on the table structure.

One good thing about slowing up is it puts less stress on the mechanics and causes less flex in the table . Its not the best solution but its one that will help of you cannot address the mechanics.

I was using 30 AMP consumables on the 45 and now use fine cut on the 45XP. I added a water table when I upgraded the plasma.
My machine is also a home mede skate bearing version with the CRP carriages and belt drives on flat bar, so not the most rigid.
I do have it all tuned to get great cuts though and that is what counts.

I tried 125ipm and it seemed smoother on the curve. Not really any better on the small letters. Could this be moisture or more likely shakiness in the table/motor movement?

I am using a parellel port on an older dell tower. I do not have a thc. yes im using the belt reduction kits from CNCRP.
When cutting 14ga, it does kinda bow up a bit, maybe because its an old mishandled piece? I think that could be messing with my cut height a bit. (I know, more reason to get a THC.

Im guessing this picture is evidence of moissture? I have water trap on compressor and one on back of plasma. But no real dryer. Im guessing it would be advisable to add a motorguard from what ive read in the past?https://www.cnczone.com/forums/attac...d=390860&stc=1

Moisture will kill cut quality but has nothing to do with the mechanics of the machine as Tom mentioned.
Setting up a cnc plasma cutter requires a lot of fine tuning of everything and lots of trial and error.
Start by getting the machine operating smooth and accurately. Have you calibrated the machine?
Is it a tight machine or a little sloppy? Do some test trials cutting nothing and calibrate the steps if you haven't.
What CAM are you using?

Then fine tuning the Plasma cuts will be the last on the list. Some of the bowing in the sheet will go away when you have the cuts correct.

Our 5' X 10' machine actually has 8020 wheels running in the grooves of the 8020 extrusion, and a plate with small v-rollers on
the lower side to help guide the gantry.
We started out with the MP-1000 with THC, and upgraded to the MP-3000 with THC, and everything works great, but because
of our not so rigid gantry, we run at 150 to 185 IPM on 14-16 gage galvanized sheet metal.
It works for us, trial and error, we tried running faster, but it just doesn't work.
Larry

14 ga WILL bow from both heat and stress relief....fact of life. I have seen 14ga popup 1/2" on the sides. The slower you cut the worse the heat warping will be. there is no way with ragged motion you will ever get good cuts. While there are numerous factors in cutting with plasma (such as dry air, good air pressure, good workclamp connection, etc) you cannot ignore the basics. A smooth cut starts with smooth mechanical motion. The cut gap on most torches is about .063. A variation of over .010 effects the kerf width. the slag level and the angular "flare". Slower speeds mean more slag and higher torch volts and that causes torch diving with a THC involved. The MP3000 was a second generation THC that relied on the internal MACH3 feedback loop and was constrained as to speed by that loop delay. Later technologies had moved outside that model and THC speeds have increased almost 10 fold. In turn its allowed better response and high cut speeds.. Its all a delicate dance that looks deceptively easy to start with and proves to be a lot harder in the end.

Im using HIWIN bearing rails(used rails with new bearings). I cant swear that everything is as rigid as it should be. How do I tell other than "feeling" it?

LeeWay - I am using sheetcam.

I will re-visit the ridgidity of my table and see if there is anything I can improve. In the mean time I also ordered a motor guard filter to help with moisture being a factor.

I have my gap set at .06 I believe, but my concern is that it is pushing the metal down when it sets the gap and then comes up to leave less of a gap when the metal pushes back up a bit. The main thing I am worried about right now is the jagged edged on the letters, smoother lines. If I have slag issues or kerf width, I can certainly work through that stuff.

For thin sheets, I use sheet metal clamps on two corners of the sheet.
This certainly helps to maintain the flatness. I clamp 4 corners on particularly bad stuff.
I face the bow downward and when I clamp the corners, it pulls the sheet flat.
I do this because I also scribe my parts and I need accurate holes in the parts.
Clamping them down is the only way to do everything accurately for a whole sheet.

The water table has almost eliminated the warping I used to get without it. Virtually eliminated any slag too.

Maybe there is an upgrade in your future? ;)

If you have a moisture problem, A motoguard filter will not solve it for long. I do a lot of cutting in the summer and the moto guard gets soaked in a few minutes.
I run 2 large compressors that generate a lot of moisture because they run constantly. I have a motoguard as the first filter in line and then a refrigerated air dryer as the final. I also have a large desiccant filter in a branch line after the motoguard for a special application where I need really dry air. The moto guard is there to remove oil in the air before it hits the desiccant. I don't know if it makes any difference to the refrigerated dryer.

I don't think moisture would cause the problem you are having but it will use up your consumables much faster than normal. One thing I noticed in your pics is that the middle of the torch cable is dragging on the table. You should have it supported above the table where it doesn't hit on anything. It doesn't take much to give you a ripple in the cut.

Good Luck.

Willy

Thanks for the Info flyinwilly! I do have a couple water sep/filters inline and a inner cooler on the compressor. And yes I have been holding the torch cable, I know i need to make something to hold it up.... messed with it tonight and I am getting noticeable jittery steps when jogging. running parallel port so maybe pc issues? Probably could benefit from a ESS but Idk if that will cure all my issues....

An easy way to see if you are getting interference issues from the cutter is to remove the torch from your holder and put a pen / sharpie in its place. Run a program ( with the 45 turned off) and see what you get. If you are still getting wavy cuts, the problem is mechanical and /or software.

If you don't get your wavy lines, then get a long (15-25 foot) parallel port cable and move the pc away from the table. This was the solution I used when I was using a chinese cutter. Also, if this does turn out to be the problem, you may have to sink a ground rod to ground the table (if you don't have it already). One other thing to check is the kernal speed (under ports&pins config). Make sure it is not set too high for your PC.

Good Luck,

Willy

The picture of your consumables is indicating that you have moisture or oil contamination issues. My consumables use to look identical to this and I tried quite a few different types of filters without any real success. I eventually went to a refrigerated air dryer and about 95% of the problem went away. The consumable life went up and the stuck consumable error message (code 30 I believe) I was getting on a regular basis was drastically reduced.