Cut quality tuning - Pirate4x4.Com : 4x4 and Off-Road Forum

MQYJ · 03-18-2010, 07:24 PM

I was cutting some 3/8 plate today and found that two sides of a four sided part were coming out nearly perfectly square and the other two sides had a slight bevel to the cuts. Not horrible, but I know the machine can do better. I tried to cut at a couple different speeds and got pretty close to the same result at both speeds.

80amps on an A120 at 40-50ipm. pierce height and working height per manufacturers specs. .20 pierce height and .19 cut height

bigS-dime · 03-18-2010, 07:36 PM

Quote:

Originally Posted by MQYJ

I was cutting some 3/8 plate today and found that two sides of a four sided part were coming out nearly perfectly square and the other two sides had a slight bevel to the cuts. Not horrible, but I know the machine can do better. I tried to cut at a couple different speeds and got pretty close to the same result at both speeds.

80amps on an A120 at 40-50ipm. pierce height and working height per manufacturers specs. .20 pierce height and .19 cut height

having exactly same issues. my cutting specs are a little differnet since I have a TD A80, but exact issue. Curious as to the input you get here

waynehartwig · 03-19-2010, 08:08 AM

which two sides? Same axis?

HardcorewannabeXJ · 03-19-2010, 08:10 AM

It could be the torch is not perpendicular to the material in both axis, this would result in even cuts on one side and on the other, unequal.

Check to make sure that your torch is perpendicular to the material you are cutting. If the tip has started to elongate out to one side you can get the same issue.

Beyond that, to get as best of a square as possible you need to program a sort of, four leaf clover toolpath. When the Plasma torch makes a 90 degree direction change, since the plasma stream is trailing behind, it usually undercuts the corner. If you were to ask the Plasma Cutter Manufactures they would tell you to cut past the corner, radius around and line up straight to come into the cut again. Look at the attached picture below to see the procedure.

Beyond that you are still dealing with a Plasma Cutter, you should expect 3-8 degrees of bevel, and the thicker the material you go the more noticeable it becomes!

jimcolt · 03-19-2010, 03:29 PM

My Powermax 45 cuts 3/8 plate with a very consistent taper on all four sides. I have a sample next to me that the edge bevel was measured with a precision protractor...3 sides are 2.6 degrees and the last side is 2.2 degrees from square. The part was cut at book speed, at 45 amps.
Assuming that the torch is perpendicular to the plate....most likely there is a damaged nozzle or shield on the torch.....the nozzle and shield orifice control the shape of the arc, any little notch (caused by pierce blowback) will change the shape of the arc and usually shows only on the same axis (2 sides). Inspect the consumables carefully with a magnifier....you likely will see an out of round orifice.

Also....the thicker you cut with plasma...the LESS bevel. The material acts as a virtual nozzle helping to stabilize the arc, improving squareness. This of course assumes that the nozzle orifice is not damaged! When I cut 1/2" and 5/8" the bevel is less than 2 degrees, when I cut 1/8" the bevel is in the 5 to 6 degree range.

Jim Colt

HardcorewannabeXJ · 03-19-2010, 04:00 PM

Quote:

Originally Posted by HardcorewannabeXJ

Beyond that you are still dealing with a Plasma Cutter, you should expect 3-8 degrees of bevel, and the thicker the material you go the more noticeable it becomes!

Quote:

Originally Posted by jimcolt

Also....the thicker you cut with plasma...the LESS bevel.

Jim Colt

Simply stating it becomes more noticeable to the naked eye that you are getting bevel, versus the thinner material where it is not as easy to tell.

MQYJ · 03-19-2010, 05:12 PM

Ok, the torch was and is perpendicular to the plate. I think the tip may have been a little out of wack as I had used it before and I really don't know how much. The bevel I had was on one end and a side of a rectangular part. The clover leaf type corner seems like a good way to go about cutting perfectly square corners but how exactly does one go about setting up a cut path to loop back around and cross itself?

My part was radiused on the corners so it wouldn't have worked this time anyway, but for future it would be good info to know.

Also, the good side was measured at 1-2 degrees or less and the noticeable side was right around 5 as I remember.

03-18-2010, 07:24 PM	#1 (permalink)
MQYJ Rock God Join Date: Nov 2002 Member # 15076 Location: Indianapolis Posts: 1,677	Cut quality tuning I was cutting some 3/8 plate today and found that two sides of a four sided part were coming out nearly perfectly square and the other two sides had a slight bevel to the cuts. Not horrible, but I know the machine can do better. I tried to cut at a couple different speeds and got pretty close to the same result at both speeds. 80amps on an A120 at 40-50ipm. pierce height and working height per manufacturers specs. .20 pierce height and .19 cut height

03-19-2010, 08:08 AM	#3 (permalink)
waynehartwig Yukon Gear and Axle Join Date: Sep 2004 Member # 35700 Location: Mead, WA Posts: 6,887	which two sides? Same axis? __________________ #4502 "The Rental", Team Yukon Gear and Axle Good Seller/Buyer List! www.150Tunes.com www.DiffsOnly.com www.Jeeperman.com 10% PIRATE COUPON CODE: pirate4x4 Special thanks to: Yukon Gear and Axle, Pace Oil Field Hauling, AllTech Motorsports, A1 Performance Transmissions and Converters, Randy's Racing Transmissions, Fountain Tire/Goodyear, Warn, Reid Racing, RuffStuff Specialties, BearTrax 4x4 OutFitters, Skinny Pedal Products, DiffsOnly.com, and 150Tunes.com

03-19-2010, 08:10 AM	#4 (permalink)
HardcorewannabeXJ Registered User Join Date: Jan 2007 Member # 84593 Location: Reno, NV Posts: 3,004	It could be the torch is not perpendicular to the material in both axis, this would result in even cuts on one side and on the other, unequal. Check to make sure that your torch is perpendicular to the material you are cutting. If the tip has started to elongate out to one side you can get the same issue. Beyond that, to get as best of a square as possible you need to program a sort of, four leaf clover toolpath. When the Plasma torch makes a 90 degree direction change, since the plasma stream is trailing behind, it usually undercuts the corner. If you were to ask the Plasma Cutter Manufactures they would tell you to cut past the corner, radius around and line up straight to come into the cut again. Look at the attached picture below to see the procedure. Beyond that you are still dealing with a Plasma Cutter, you should expect 3-8 degrees of bevel, and the thicker the material you go the more noticeable it becomes! Attached Images Last edited by HardcorewannabeXJ; 03-19-2010 at 08:10 AM.

03-19-2010, 03:29 PM	#5 (permalink)
jimcolt Rock God Join Date: Nov 2009 Member # 145912 Location: New Hampshire Posts: 1,251	My Powermax 45 cuts 3/8 plate with a very consistent taper on all four sides. I have a sample next to me that the edge bevel was measured with a precision protractor...3 sides are 2.6 degrees and the last side is 2.2 degrees from square. The part was cut at book speed, at 45 amps. Assuming that the torch is perpendicular to the plate....most likely there is a damaged nozzle or shield on the torch.....the nozzle and shield orifice control the shape of the arc, any little notch (caused by pierce blowback) will change the shape of the arc and usually shows only on the same axis (2 sides). Inspect the consumables carefully with a magnifier....you likely will see an out of round orifice. Also....the thicker you cut with plasma...the LESS bevel. The material acts as a virtual nozzle helping to stabilize the arc, improving squareness. This of course assumes that the nozzle orifice is not damaged! When I cut 1/2" and 5/8" the bevel is less than 2 degrees, when I cut 1/8" the bevel is in the 5 to 6 degree range. Jim Colt Last edited by jimcolt; 03-19-2010 at 03:32 PM.

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03-19-2010, 05:12 PM	#7 (permalink)
MQYJ Rock God Join Date: Nov 2002 Member # 15076 Location: Indianapolis Posts: 1,677	Ok, the torch was and is perpendicular to the plate. I think the tip may have been a little out of wack as I had used it before and I really don't know how much. The bevel I had was on one end and a side of a rectangular part. The clover leaf type corner seems like a good way to go about cutting perfectly square corners but how exactly does one go about setting up a cut path to loop back around and cross itself? My part was radiused on the corners so it wouldn't have worked this time anyway, but for future it would be good info to know. Also, the good side was measured at 1-2 degrees or less and the noticeable side was right around 5 as I remember.