Hello everyone and here we are again in the next thread about avoiding bevels.
Im using the Crossfire pro (with THC) for a couple of weeks now and first of all the machine works really great.
The Hypertherm XP45 is the Plasma cutter im using and for my undertstanding i get really good parts out of this setup based on cut quality, cutting speed and consumable lifetime. Also there is just a little dross on the backside of my parts so i think the amperage and speeds are fine ( picture)
The only thing that bothers me since my first cut is an noticeable bevel on all four sides of my parts (crosscut looks pretty much like a trapezoid )
The bevel is most noticeable in holes, because they always look like they were chamferd.
I searched the Forum and checked all the common parameters:
i used new consumables
checked squareness of torch
made sure the air is dry ( installed in line 3 stage air dryer)
Than i checked the actual cutting hight by running the test program and measuring with the feeler gauge. I noticed that my cutting hight was 1,8 mm (0,07) instead of the programed 1,5mm (0,06).
I changed the cutting hight in the post processor to 1.15 mm (0,045) to compensate the difference but the outcome was pretty much the same.
I than messed around with that number and went to the extremes like 0,3mm (0,01) but still there was no significant changes in cut quality and bevel establishment. The changes do get into the crossfire because i tested very high extremes as well and it was noticeable. So at this point im pretty much done with my competence and for further testing i think i need more general information from you guys so thats why im opening this thread.
I think i need to understand the mechanincs a little bit more to come to an conclusion on whats the issue and i hope that some of you are able to answer the following questions:
What is the straightest cut to achieve? Am i right that there always will be a slight bevel on the parts or could you really tune in the crossfire pro to achieve pretty damn straight cuts. Any experience here?
Is the postprocessor the right place to adjust cut hight?
Does the THC play a part here? Could adjusting the THC be the key ?
I got al lot more questions to this topic but i dont want to overflood this thread. Maybe some of you can share theire experience. Thanks to all of you in andvance!
Mainly because I had straight cuts all around; what you’re running into is the definition of incorrect cut height.
So why am I tagging along? I’m running a different torch with a different consumable set and running into beveling myself now even after utilizing what I know to get rid of the beveling. Still present ever so slightly.
If you are routinely having significant bottom side dross (on straight cuts) then your cut height is too high, amperage too low or cut speed is too fast. And this is really going to be an issue with holes because the plasma stream is lagging behind the torch. If you are not using “Feed Optimization” (Fusion 360) or whatever it is called in SheetCAM, you will forever have poor hole completion.
Do a practice straight cut and hit the space bar to interrupt the cut. That will stop FireControl and turn off the torch. Measure the stand off distance between the torch and the metal. If it measure okay then it is likely your nozzle. Perhaps not the electrode.
I had terrible dross on both sides and a much worse bevel than you are having. My cut height was way too high. Corrected the height by reducing my post processing from 0.06 to 0.022. Perfect cuts and bevel was gone.
Bevel recently returned but no significant dross. It was the nozzle. Nozzle had a perfect concentric orifice but it was enlarged. That was causing the bevel.
Replaced electrode and nozzle. I have been cutting all sorts of metal with those same consumables. Two days ago I used the same ones on 1/2 inch steel. None of these plates have had any attempt to remove dross whether by chipping, dropping or fingernail. Notice how they balance. No significant bevel.
I was so afraid she was going to bump those plates. The bottom one is 55 pounds and the upper one is about 22 pounds. I was quickly trying to get the pictures.
@ChelanJim great advice on chasing bevel. One thing I did to help improve my cutting. Instead of squaring my torch to the slats I leveled it with a level. When I do thicker metal I will shim the plate to make it level as well… mt thoughts is if you square up to the slates as you cut things the plate won’t be square to the torch.
I guess it could if it was getting some inconsistent readings in the first .25 inches of the cut. The default is that THC monitors for 0.25 inches and then averages the readings. That average is the target it tries to keep.
I am trying what @TinWhisperer said he does (paraphrasing):
When consumables are new/great shape then use Nominal voltage not SmartVoltage. When you get to the last 30% of the life of the consumables, let THC do its job.
Edited after Tin’s reminder which follows:
When I was cutting this 1/2 inch plate I used Nominal Voltage (not SmartVoltage) set at 141 volts as per Hypertherm’s cutting chart.
Side note: I have never used Nominal voltage before so it took me a bit to figure it out. Basically, you tell post-processor that you will be using THC but you go into the settings of THC in FireControl and manually input the Nominal Voltage value. If THC is turned off, you won’t be able to enter a value for Nominal Voltage (SmartVoltage is triggered by entering “0” volts in this area).
When the consumables are brand new I use nominal voltage from the cut charts. Once they have worn down those consumables some I’ll switch over to Smart voltage for the remaining life of that consumable.
For very small or short geometry I also like using nominal voltage. Because it takes a certain amount of time to initiate the smart voltage so some geometry is just too short to have enough time. So that short geometry will not have any THC height correction applied to it. If you were cutting a half inch long single line using smart voltage it takes about 3/8 of an inch of travel before smart voltage really starts coming into effect
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