So much for plasma cutting...

[Anonymous-0]

Had a customer of where I work cut me some parts to make the 3 pt. hitch mounts for a scarifier I'm fabricating. I didn't want to drill 7/8" holes in 1/2" plate with a hand drill. I gave him a drawing and said I need the bottom holes 7/8" and the top link holes 3/4". He said his plasma table has true hole technology and could cut perfect holes at the same time as the plates. I guess he needs a better plasma set up than the one he has. It cost over $250,000.00! The cuts were smooth but I've seen better cuts from an oxy/fuel shape cutting machine. Like Puddles had mentioned, the cut edge isn't square top to bottom on several pieces and the true hole technology needs some improvement. The pins wouldn't go through any of the 6 holes. I can clean them up but they would have been a lot more accurate if they would have been punched with the ironworker in the shop. For a lot of stuff plasma is the cats meow but I still think oxy/fuel can do a nicer cut. For $250,000.00 I think a water jet machine would be the ticket.

 

[Puddles]

For $250,000.00 sounds like his software sucks, or he doesn't know how to use it. The software on my CNC machine you can add nodes to increase the accuracy for truly round holes. But you need to learn the math. By that I mean, how wide is the curf of the cut for each size nozzle. For small cuts I can cut with in .007, but the longer the cut, and more heat the plate absorbs the accuracy starts to fall off.

Agreed, for $250,000.00 why would anybody buy a CNC plasma when you can buy an entry level water jet! Water jets will out perform a plasma any day. But to cut any thickness you need major 3-phase power to run the pump. :shock:

 

[Flambeau one]

Hands down water jet for smaller holes no comparison. Like you said holes should've been punched. The table at work has been down all week. Lightning burnt something up during a storm last week. We haven't been able to get an Esab tech out.

 

[Anonymous-0]

I think they might have been in a hurry to get them
cut for me but slightly oversize would have been
better than under size. I'll have to grind the 2"
spacer for the uprights because it has a bevel cut
instead of a square cut. I just wasn't that
impressed considering he said he paid about
$275,000.00 for the machine.

 

[sflem849]

I could buy an excavator for that much money...that doesn't mean I know how to use it. :lol:

One of my neighbors has an excellent fab shop. He bought a brand new waterjet a while back. It was around 5 years old and he just replaced it last year because he couldn't get parts for it. The story is really irrelevant to this one, but I can't believe how fast that technology is growing.

Stickweld - I just saw a MM 210 that needed a new gun for $600. I figure by the time I bought a new gun and went to pick it up (LONG 2.5 hours) I would have about $800 in it. Good deal or better deal to come? IIRC the local places are selling the 212 for $1700.

 

[wh]

sounds like he needs to check his adjustments. i had a cheapie plasma control at school where i taught (cost less than $10,000). it would cut dead on. you just had to check and make sure 1) the torch was set correct 2) parts were placed correctly 3) plasma was set correctly 4)drawing was correct. get all that check/correct push "cut" and get out of the way.

 

[Lanse]

$250k and the holes dont come out right? Jeeeze, he woulda been better off with an $800 mag drill and $10 hole saw, he'd still have $249k to spend on something else

(Hope you get it all straightened out)

 

[Anonymous-0]

$600 is a good price. The MIG machines that size
usually hold their value really well. I wouldn't
put a Miller gun back on it though. I'd put a
Bernard/Tregaskiss on it and it would be trouble
free for years. The Miller guns are OK in a home
shop or garage but don't hold up in an industrial
setting. A better gun like a Bernard is only a
little more money but is way better quality. I
worked in a shop with 6 MM 252's. There were at
least 4 broken Miller M-25 guns hanging in the
tool crib. The Miller guns are made in Mexico.

 

[Anonymous-0]

He has a few mag drills and a big Scotchman ironworker. Other than having to mark the hole with a center punch, nothing is faster than an ironworker and punches make very accurate holes.

 

[AlinArk]

Lanse
you are going to do all right in life, good answer
al

 

[S.Crum]

Sounds to me like his system was not set up correctly or the operator didn't know what he was doing or both. I've cut holes in 3/4" plate that were true top to bottom. Most needed only a pass thru with a grinding bob the get a smooth tight pin fit. My CNC plasma system was only 15 grand.

 

[M. Doud]

I'd have a hard time paying for that work if you were clear the holes needed to be true and they aren't.

 

[MPK]

On a plasma cutter, if the consumables are worn too much, the cut will not be as straight as was when new.

 

[Anonymous-0]

I think they must have been in a hurry but why bother with the plasma when you have an ironworker that needs no touch up on the holes.

 

[orionsrx]

Any tool is only as good as the set up. I use a plasma at work all the time and can cut almost perfect holes by hand. My machine only cost $1800, I guess money can't buy everything.

 

[CHRISCO]

1 you asked for a 3/4 and 7/8 holes and you got them!

You were forgetting about a slip fit it sounds that the machine which has the accurcy of 1/32 did what you told it to do. maybe you should of asked for holes 1/32-1/16 bigger for a slip fit because sooner or later those pins rust up and get stuck in the holes. Just my thoughts.

 

[Anonymous-0]

When I drilled the holes for a similar project they fit the pins.

 

[eastexan]

Dave, a person assumes that a shop with the proper equipment will do a professional job. But as an afterthought, it probably would have been better to have given him the pins and told him to make the holes to fit.

 

[Puddles]

Everybody does things differently, also depends on the task. I would never trust a CNC plasma machine to cut very accurate placement of holes in a plate that was moving all the time the more heat that was added. On very elaborate / extensive cuts the plate moves all over the place. I'd say expecting to get within 1/16 of an inch would be dreaming! I always laid out and drilled the holes after the plate was cut when using my CNC plasma machine.

 

[sflem849]

Could part of it have to do with drill bits never cutting a true to size hole?

 

[bison]

(quoted from post at 10:49:38 07/18/12) Could part of it have to do with drill bits never cutting a true to size hole?

hey will when you drill in stages

 

[bison]

I think i stick with the oxy/acy torch and the drill press.
they're both paid for a long time ago.
250 K buys me a lot of hrs to watch he grass grow :wink:

 

[Anonymous-0]

You don't say who your supplier was that cut the parts for you, but if he had the Patented TrueHole technology on his cnc plasma machine and was using it as designed...your holes would have tolerances that would rival water jet, laser, and even drilled holes. I suspect that the process used was not the Hypertherm True Hole process....or the machine operator was not following protocol, procedure.

The holes should have had virtually no taper, and should have been accurate in the plus or minus about .005 to .008" range.

I would be interested to know who your supplier was. (you can direct email me at [email protected]) and I will make sure they are contacted)

There are many plasma system manuafcturers as well as software manufacturers that are claiming the TrueHole capability...however you must have the correct equipment to make it work.

I noticed some other comments regarding hole to hole dimensions and repeatability. Most high end industrial cnc machines with a high definition class plasma will hole extremely tight tolerances....with repeatability between holes in the .003" range. Theremal expansion and movement of plate is rarely a problem with plasma...as plasma puts very little heat input into the plate....due to its extremely fast cut speeds.

best regards, Jim Colt hypertherm

 

[Anonymous-0]

Water jets have their niche, as do cnc plasmas and lasers.

An abrasive water jet machine will make nice holes in steel...if you are patient. A typical industrial AWJ (abrasive water jet) uses a 60 to 70 hp pump, produces over 55,000 psi water pressure and injects garnet into the stream. Cutting 1/2" steel is accomplished at around 15 to 25 inches per minute. Purchase price of one of these machines with a 5 x 10 cutting bed is in the $350,000 range. Cut part accuracy is in the .010" range.

To cut 1/2" steel with a C02 laser system requires a system that produces about 3 kilowatts of power, expect cut speeds of about 30 to 40 inches per minute, and a purchase price for a 5 x 10 machine near $400K. Parts are generally accurate to about .010".

There are a few choices with plasma. An entry level cnc plasma with a 65 amp air plasma can cut 1/2" steel at 50 inches per minute, can hold cut part accuracy in the pls or minus .025" range, and can be purchased with a 5 x 10 cutting bed for under $20k

An industrial precision high definition plasma cnc machine will cut 1/2" steel at up to 185 inches per minute with cut part accuracies in the .010" range. A 5 x 10 machine with this capability is priced in the $120k range.

This kind of gives you a picture of how the processes stack up. Plasma is typically used for high production needs and steel from gauge to 2" thick, stainless and aluminum to 6". Often oxyfuel torches are mounted on the same cnc machine for heavier than 2" steel.

Virtually all parts over 3/16" thick on John Deere and Caterpillar equipment are cut with plasma...and have been for over 30 years. This is true of most tractor and equipment manufacturers.

Jim Colt Hypertherm

 

[Puddles]

There must be something wrong with my Hypertherm 1250! Because when it cuts, the plate gets so hot I have to use pliers to pick it off the bed to dunk in water.
One thing I'm very good at is heat shrinking, in my experience when the object / material is hot to the touch, it is still moving. :wink: