Finecut Woes

[philb86]

Hello All,

I've read and searched through all of the fine cut threads I could find.

I have an LDR 4x4 with water table, PM65, 2 Stage Dewalt 5 hp 80 gallon compressor with dry air. I can not remember what CanDCNC system, but I believe it is the most recent. Table is only 3 1/2 months old.

I have went through tests with everyone, manufacturer of the table ( Dan who is super helpful and great to work with), and Hypertherm tech, and have run all the tests with them as well.

I have tried the varying cut heights, .06,.07, .075. Tuning the voltage with line tests for each, either way I do it, I can achieve great cuts with all the heights on my line tests, at book speeds.

I have verified that I am using the correct set of consumables, the right shield, nozzle ( tried 3 different sets of packages), regular electrodes and copper plus, changed o rings and different swirl rings.

I go to cut a sign, and voila, I have areas that do not cut through, randomly throughout the entire sign.

I moved to the next step, of slowing the speed down to 90, 85, 80, 75% of book speeds. I can once again at all cut heights achieve a good cut with my line tests and no dthc.

I have moved to trying to turn the tip saver off before a cut, with the same result of random areas not cutting through. I worked with changing settings for the dthc with Dan and that didnt help.

I have verified that the material I am cutting is the correct thickness for the settings I am using. Doesnt matter if its 16, 14, or 12 ga material, ther results are always the same, random areas not cutting through.

After tonight and trying to cut a roughly 28 inch round modified version of the tree of life for my parents 40th anniversary, i am considering just throwing the whole idea of using fine cuts out. I am at wits end with these things. The worst part of it is, i can cut with regular 45 and 65 amp consumables, and have no issues what so ever.

I guess this is my plea, who has went through this and figured it out. I do alot of art and am getting into smaller designs and much more detailed, that having the ability to confidently use finecuts would be great. I am wasting alot of material and its starting to wear on me.

I have attached a couple pictures of the most recent cuts of the tree of life.

Thanks for all your help, I know this site is an invaluable resource of information.

There are alot of little areas no circled that didnt cut as well.

Phil B.

[jimcolt]

You do not mention the thickness of the material, however with your symptoms (not cutting through all the way on the whole sign) I am going to guess you are cutting 14, 12 or 10 gauge steel.

Slowing the cut speed is the first instinct that everyone has with this issue, however it is not the fix, and causes other issues (dross, warpage, wider kerf).

You need to set cut height at .080", and then adjust arc voltage so that it maintains .080" (not the book setting of .060") throughout the cut. Everything else needs to stay at "book" specs (pierce delay, pierce height, amperage, cut speed). This problem is likely caused by plate chemistry variation combined with the fact that the Finecut consumables are touchy to any changes (in material or settings).

I am 99% sure this will solve your issue. I changed the configuration specs on my home shop machine to run at this higher height...and have not had the problem in over a year. Jim Colt Hypertherm

[motoguy]

Have you tried sheets from a different supplier, to see if it's a plate chemistry issue?

[philb86]

Jim,

I will give .080" cut height a try tonight when Im in my shop. Thats where I am confused, I can get a good cut with the test cuts, not always at book speed, since I was told by tech at hypertherm to slow it down to 75% of book speeds. Usually right around the 80-85% of book speed is where I can acheive the best straight line test cut.

I will try it tonight and let you know my results.

Motoguy,

I have tried two different suppliers. Sheet was supposed to come from different manufacturers from what I was told. Although I know fine cuts can be finicky of chemistry, my 45A and 65A have cut sheet from both suppliers with no issues.

Thanks for the reply guys!

[philb86]

Jim,

I did as you suggested and ran the cut height at .080" at book specs for everything else.

Below is a picture of 3 of the cuts that I did, furthest right is .080", all book specs. Middle is .080" cut height, adjusted voltage to from book spec of 82 volts, to 85 volts per what I saw during the test cut, furthest to the left is .080" cut height, with same voltage of 85 volts per second test leveling out at the same voltage again. Unfortunately, it still doesn't cut through in random areas. I also notice, in the areas that it did cut through, the angularity is awful, check with dross on bottom and with dross cleaned off, I can barely get a .015" feeler gauge through the cut. All this testing is currently on 14ga, as well as the sign that I originally posted pictures was 14ga as well.

I also did some testing back at book height going through the same process of line tests and adjusting the voltages to match. Although I got cuts that were about 90% of cutting through, the angularity is still roughly same, I can get depending on the cut a .020-.025" feeler guage through the bottom of the cut.

What do you suggest next to try? I am out of ideas of what to do at this point.

Thanks for your help.

Phil B.

[larrycameron44]

Hey Phil, something I and a few others have discovered (there is a thread somewhere) that when we change consumables and adjust volts for the new consumable back to the correct height, for some peculiar reason it won't cut through in certain cuts.
We discovered that after a consumable change, we up Amps by 3-5 and slow down to 75% or normal cut speed for minimum of 40-50 pierces.
I must say that during this 40-50 , I slowly increase speed back to 100% at 50 pierces.
I have been doing this for the last 2 years and never had the problem repeat..... until I forget to adjust speed and amps after a consumable change.
This is just my and a few others opinions.
But it works a treat!!!!!!!!!!!!

Larry Cameron
RusticMetalArt

[jimcolt]

Assuming that you are 100% sure the torch is at .08" (at the arc voltage you set), then I would next check the following:

- Be sure your air pressure is set in auto mode.
- Install a pressure gauge hardplumbed on the rear panel air inlet on your Powermax.
- Monitor this gauge when air is flowing at the torch, especially when your compressor is at it's lowest pressure (bottom of cycle). It must always be between 90 and 135 psi. Best to stay even at around 100 to 110 psi.
- Check the clear water separator bowl on the Powermax to see if any signs of water or oil are getting to the plasma.
- You can shut off the height control, set the torch height to ,080" with a thickness gauge, dry run through a long straight cut to ensure your plate is level and torch stays at .08". This eliminates the possibility of the THC diving, which can make you lose the cut.
- Change (one at a time) swirl ring, retaining cap, shield (using a perfect nozzle and electrode) and do test cuts.

As I stated earlier, you will not see this issue with the 45, 65 and 85 amp shielded consumables.....only Finecut. The book speeds listed in the manual are the best combination of minimal dross and acceptable edge bevel. Going slower will improve bevel, but expect more dross, wider kerf and higher probability of warpage.

I find this problem that occasionally occurs with Finecut consumables (as Larry Cameron also mentioned) goes away after you get 50 or more starts on an electrode.....this makes sense because a worn electrode creates a higher arc voltage....same thing I recommend for running a higher cut height, which also increases arc voltage. Jim Colt Hypertherm

[BTA Plasma]

I have an LDR 4x4 with water table, PM65, 2 Stage Dewalt 5 hp 80 gallon compressor with dry air. I can not remember what CanDCNC system, but I believe it is the most recent. Table is only 3 1/2 months old.

How do you know the air is dry? A water separator does not cut it with fine cut. You can actually see the water come through in the beam color and the tip volts will change, cut will suffer.

[tcaudle]

One last thing (just in case) You need excellent conduction so all of the heat goes into the actual cut. A weak or poor workclamp connection can cause bad cuts. Always clip direclty to the material The table gets worse over time as a conductor as slag builds up on the slats. If you do clip to the material disregard!.

Finecut cutting is always harder than conventional consumables. There is simply no room for error. its beautiful when it works and a PITA when it doesent. There are just a lot of factors in getting the perfect plasma cut and ALL of them have to be daad on for a Finecut. We cut 14G and up with 45A consumables and settings at book speeds and settings and get good cuts.

When we do cut with Finecut I make sure we use the special shield that covers the nozzle. it focuses the plasma stream better .

[steel 35]

Glad Tom jumped in because that's were I am at, 14 I like 45 anything less finecut! You may need to change a few areas in that tree, so you don't get extra starts and stops look for these areas closely in sheetcam.
Try using No cut rules that has gotten me in the past, The small holes rule is a great one if you are trying to cut small holes (none in that tree.)
Your test cut's show a significant amount of dross, don't jump past that and note all the changes you make and what difference it makes, don't rely on memory it will get you as well
I looked through at your notes you say book specs, Fast or slow? You have a quality machine I believe without ever seeing one, I try to run fast as I can but when cutting thinner metals then 14 I am nowhere close to book spec, yes (one) would say I am not getting the life out of the consumables, but it is dross free and the book spec, say not dross free so I prefer not to clean the dross off my projects and to through the consumables away rather then my project's and i can easily cut a full sheet or more with very nice cut's.
PS: I do cut the trees but its thinner then 14 G
Yep I am bad I don't cut book specs with the 14 G 45 either Best wishes and go burn up some more stuff!

[philb86]

Wow, Thanks for all the responses guys.

Ill start clear back with Larry. I have tried the method of going through so many pierces at 75-80% of book speed, and both slowly increasing the speed as I get more pierces on the consumables. Have not had much luck trying it that way, pretty much the same results. Im going to pull out an older set that I have and give it shot through the same process and see if it changes anything. But, we will have to see if that changes.

Jim, i have checked and verified I am in auto mode and that I am at my cut height that I have set in my tooling in sheetcam at the various heights that i have tried. I have checked all of my water separators, desiccant dryers and also drain my compressor every night as well as each day before I start running my table. I will try another dry run checking my height on a long cut and see what I find this evening, but from prior experiences it is where it should be. When I was working through this issue initially with Hypertherm tech, I went through the process of slowly changing each consumable out one at a time, and then complete new set as well, both various times and have went through a lot of consumables. I did not come to any conclusions that one or the other was at fault for my issues. The one that I have no tried is to put on a seperate pressure gauge right at the back of my Powermax, and I do believe that I have a spare one in my shop that I could do that with. I know at my pressure regulator that goes to my power max never drops below 110psi while cutting, but there is 25 feet of line between the regulator and Powermax.

BTA, I have run through a few different tests to verify that my air is dry, including using a mirror and allowing the Powermax to run air through the system in manual mode for 10-15 minutes, with no moisture showing on the mirror. I have a water/oil seperator, a coelescing unit, running to a cutom built rather large desiccant dryer. Before that I have a cooler with two drip loops that is inbetween the compressor pump and tank. I also run a smaller inline filter shortly before my Powermax. Maybe that is not enough and I need to put a refrigerated air dryer in.

Tcaudle, always clamp directly to the work piece. There are times when I use scrap pieces to cut smaller items that I will clip to the slats, but I have always been clamped to the work piece while using FineCut consumables. I do use the shield that you are talking about, I believe the part number is 220948, unless there is a different one that I dont know about. It may come down to using 45 amp consumables with 14ga and thicker and starting to retest with any thinner gauge than that with the FineCuts.

Steel 35, I am going to do pretty much what you said. I am going to rework the tree and cut with the 45 amp consumables. I have really good results using those and pretty much use that for most of the things that I cut, but I was seeing alot of raving about how nice the cut is with the Fine cuts. So, I decided it may be time to dive into them and get them worked out.

Thanks for the replies guys, it is great to have this community, who all are so willing to help. I am going to try a few cuts this evening and some of the stuff you guys talked about, and even retry some of the others you have all suggested. If theres one thing I have learned being a mechanical engineer for a titanium company, data speaks volumes, so I may need to do more tests than I already have to rule out as many things as possible.

But for now, Im going to go and enjoy some time with wife and my daughter, have a nice jack on the rocks, and enjoy the rest of my birthday.

Thank you again.

Phil B

[Old Iron]

Just my 2 cents.
I've had so much trouble with fine cut that I refuse to use them period.

[motoguy]

I use fine cut for 95% of my work. On 14ga, I run 200ipm, 88v, .076 pierce height, .075 cut height. I use finecut for 1/8" and below.

[jimcolt]

So....by chance are your " water/oil seperator, a coelescing unit, running to a cutom built rather large desiccant dryer. Before that I have a cooler with two drip loops that is in between the compressor pump and tank" all in between the "pressure regulator" and the inlet to the powermax? It is impossible for me to tell from your statements.

If your regulator and gauge read 110 psi when cutting.....and all of your moisture removal components and filters are between that and the plasma, then I can imagine a relatively big pressure drop through all of the equipment you have on the air system. This is what you may find when you install a pressure gauge at the Powermax inlet. The gauge at your regulator and the gauge at your powermax will be the same (unless the gauges are not in perfect calibration), but as soon as the air flows at your plasma torch, you will see the Powermax regulator drop, and usually when the compressor is at the bottom of its cycle the gauge will drop some more.

I have 50' of 3/8" ID hose between my compressor gauge and my Powermax85. No air filters, no anything but hose and hose fittings, and I see the gauge at the Powermax drop about 8 to 9 psi (below that of the gage at the compressor) as soon as air flows at the torch. I readjusted the "bottom" of my compressors cycle so that the gauge at the plasma never gets below about 95 psi, and solved a few cutting issues when I first connected the 85 6 years ago.

Every filter, every fitting, everything in the airline creates a restriction....the only way to read it is with a gauge at the source and another at the load (plasma cutter). Sounds like everything else is perfect, so we are running out of tests for you! Best regards, Jim

Wow, Thanks for all the responses guys.



The one that I have no tried is to put on a seperate pressure gauge right at the back of my Powermax, and I do believe that I have a spare one in my shop that I could do that with. I know at my pressure regulator that goes to my power max never drops below 110psi while cutting, but there is 25 feet of line between the regulator and Powermax.

I have a water/oil seperator, a coelescing unit, running to a cutom built rather large desiccant dryer. Before that I have a cooler with two drip loops that is inbetween the compressor pump and tank. I also run a smaller inline filter shortly before my Powermax. Maybe that is not enough







Phil B

[Tautog13]

Philb86,
Great group of contributors here, I know because I have been lurking for nearly a year now, and I'm sure they will get your fine cut issue sorted out.

I am not yet an owner of a table, but I do have a question that may help you, and satisfy one of my own questions at the same time, as to importance/requirement of an "earth ground rod". (Jim Colt: "99.9% have one earth ground...hope I have that right Jim)

Do you have an earth ground rod connected to your table? (I ask because ground clamp to work material was asked about)

Best regards,
Charlie

[jimcolt]

The plasma cutter itself does not need a ground rod, however the computer and the machine electronics may. The idea of an earth ground is to route stray electrical energy (aka: noise, RF, EMI, etc.) back to a good earth ground instead of having it inductively or capacitively couple with wires and cables that carry low voltage signals for the machine. Computers use a lot of low (less that 12 volts) logic levels as do most modern electronics (used for height controls, drive motor electronics, etc.). If electrical noise gets into these circuits you can have runaway issues, computer fault issues, even circuit board failures on the cnc machine.

I have 3 cnc tables, two get transported around a bit, and those two run fine and have never been connected to a ground rod. The older table has been in my shop for over 12 years, it has a ground rod, not because it needed it, but because I have installed CNC machines for the last 39.5 years, and that is the way I have always done it.

The work cable goes directly from plasma to ground rod (bolted, not clamped), it is the right length (not coiled up), then a short cable goes from ground rod to the cnc table frame (bolted to clean metal), and I have a short length of cable bolted to that same location on the frame with a clamp on the loose end....in case I feel the need to directly connect to the metal (aluminum or small pieces that may not get a good connection). The cable must be a multistranded welding style cable sized for the amperage of the plasma you are using. Why multistranded? Because RF (radio frequency) energy travels on the outside of conductors....with multistrand cable you have more conductor surface area to conduct this "noise" away from sensitive components.

Any plasma that uses a high frequency starting system absolutely must be installed with a ground rod, and done properly...or you are asking for trouble. Air plasma systems today use blowback starting (except for older technology and low cost imports), producing very little "noise", and in most cases have no real need for a ground rod.

Listen to the recommendations from the manufacturer of your cnc and height control electronics....some strongly recommend proper earth grounding, some suggest it only if you have issues after installation, some say you do not need a ground rod.

Jim Colt Hypertherm

[philb86]

Jim,

I will be getting to trying the pressure gauge at the Powermax tomorrow. Had a busy weekend and end of week getting ready for my daughters birthday party and it occupying the shop space since it was raining the day of her party. It was clean up time today and tomorrow I will get back to testing. As always, everyone here is a huge help and this community is just great with everyone and their willingness to help.

Thanks.

Phil B.

[philb86]

Jim,

I sure could have stated that a bit more clearly. From my pump on the compressor, I have roughly 20 feet of vertical looping with two drip legs and a ball valve at the end of each to drain any accumulated water. The outlet of that runs into my tank. From the outlet of my tank, I havemy regulator, with an oil water separator, a coalescing unit then my home built desiccant dryer. (I may be switching those around from what I'm seeing that others run). From my regulator which is set at 120psi, I split into a dedicated plasma 3/8" Id hose, and a 3/8" Id 50 ft hose reel. The dedicated hose has an extra filter before it goes into the powermax.

Tonight I put a gauge at the inlet of the powermax to monitor pressure there. My drop in pressure I am seeing from the initial 120 psi, is 118 psi while static, while the plasma is running, the pressure drops to 113 psi. When the compressor kicks on at the bottom of its cycle, 145 psi, it never budges off of 113 psi as the compressor builds back up to 175psi.

I also ran a mirror under neath of the plasma for 5 minutes straight again this evening in the powermax diagnostic screen. I saw no presence of water or oil on the mirror after those 5 minutes.

At this point, the circles that I am running in, I decided to recut the tree of life that started the original post, with regular 45 amp consumables. It cut beautifully, minimal dross other than at extreme corners and where I had it set for inside corner slowdown in sheetcam.

Sorry for the long winded post, just trying to be as descriptive of poasible.

Thanks as always.

Phil B.

[Tautog13]

C

[Tautog13]

Any plasma that uses a high frequency starting system absolutely must be installed with a ground rod, and done properly...or you are asking for trouble. Air plasma systems today use blowback starting (except for older technology and low cost imports), producing very little "noise", and in most cases have no real need for a ground rod.

Listen to the recommendations from the manufacturer of your cnc and height control electronics....some strongly recommend proper earth grounding, some suggest it only if you have issues after installation, some say you do not need a ground rod.

Jim Colt Hypertherm

Jim,
Thank you very much for your detailed reply, it is very much appreciated and clearly answers my question.
Sorry for delayed response.....But I waited to reply as to not (further) "step on" OP's recommendations to check air supply pressure @ back of Hypertherm unit.

Wondering if OP condition could be ground rod related("only if you have issues"), or are OP issues unlikely related to grounding?

Best regards, and thanks again
Charlie

[philb86]

Tautog13,

That could be a possibility as that is one thing that I have no done. This process with finecuts being so finicky has me curious as of just to what extent does a machine or plasma cutter have an effect on using them. I do know as far as a grounding rod, I see no interference in my computer screen as in the beginning I was getting alot of various interference affecting my screen when I first set the table up at my house. I moved alot of components around, separating the Powermax from my Candcnc box significantly, wrapping all cables in a shielded wrap and separating all the power and ethernet cables from one another. I see no interference in my screen now, but that doesnt necessarily mean that I may not still need a ground rod.

I see that some people have just given up on the fine cuts due to having no luck with them, and as I stand at the moment, I will perfect my cutting with regular 45a consumables and as I have time will do experimentation with the finecuts.

Out of curiousity, if people will chime in I would appreciate it, can you let me know what manufacturer of machine you are running, what Powermax, and whether you have had success with fine cuts or not? It would be interesting to see if there is a range of success across different manufacturers of tables (including the guys who have custom built their table) and what Powermax they are running, maybe there are some correlations that no one has noticed between the two, or one for that matter.

Thanks guys.

Phil B.

[tcaudle]

To get interference on a PC screen takes a LOT of noise getting into the PC. The single most useful method to keep plasma noise out of the control electronics is to ground the table and shunt the noise to a local ground instead of pumping it into the control box and letting its (less than perfect) ground handle it. You can shield everything on the unit but shielded blocks mostly RFI and possible cross talk from adjacent signals BUT it the ground reference point for the shifted is poor or you connect both ends it becomes a conductor of noise rather than a block. In most circumstance there is no need for a ground on a table BUT most of the time you don't need a set of jumper cables. We have seen tables that work perfectly in a specific setting have all kinds of problems when move to another physical location. Building grounds and wiring differ a lot. There are many users of the same equipment you have that cut with Finecut and get excellent results.

[islander261]

Hello

Just my $.02 worth about the Finecuts. I have a much modified Torchmate 2 table with a Thermal Dynamics A60 power supply. Several years ago I was struck by results achieved using the Hypertherm systems with the Duramax torch using the Finecut consumables. I wanted to duplicate this success cutting 14ga HR that I use for my garden art. Alas the dollar outlay prevented me from replacing my equipment with new Hypertherm gear. So I horror of horrors grafted the guts of a Duramax torch onto the TD torch and set off to Finecut land. This shouldn't work according to the experts but I was hard headed. I was immediately rewarded with narrower kerf width but with bad low speed dross. I was using the book low speed charts because my table couldn't go fast enough or accelerate fast enough. The addition of new steppers and drivers got the table speed up and the acceleration barely fast enough. Still I sometimes had "random" problems with failure to cut all the way through. I went to Jim C's suggested increased cutting height and the incidence of failure to cut through greatly diminished but still happened occasionally. So after using this setup for three years I have reached the following conclusion. Every time I have a failure to cut through it is due to a height control issue, let the torch get too close for any reason (I know this is counter intuitive) and you are asking for failure to cut through. I have had too close torch height caused by failure to properly probe material surface (wonderful TM AVHC another topic), by torch diving in corners and arcs (TM AVHC again), worn consumables, worn shield, worn Z axis lead screw and or nut, probing on top dross piles from other pierces. I think you get the picture many possible causes here. In addition along the way I have tried all of usual suggested cures refrigerated air drier, desiccant drier, Moto Guard filter, pressure gauge mounted to power supply, I buy steel in 5k lb lots so I rarely have a chemistry change in the steel.

So for 14 ga HR steel I pierce at .09" and set initial cut height at .075" and try and maintain .075" cut height. I cut at what I think is 45A (can't really exactly set things on the TD unit because of no digital display, I have a pencil mark on the dial so I set it at the same place). I use no pierce delay (the AVHC has plenty built in for thin steel) and cut at 200 ipm. When cutting rectilinear parts and larger circular holes I get nearly perfect cuts with slight bottom dross in corners and leadins and outs on circles. I use book specs for 10ga to 12ga and get even better results. I can't cut thinner than 14ga because my table will not reliably go fast enough. I have cut a little stainless and found that my AVHC can't control height well enough to use the book .02" cut height so I cut at .06" and fiddle with speed till it works good, I haven't done enough to pass on numbers for others to try. My pieces typically require 10 to 100 pierces per piece so I really exercise the nozzles. Actually that is really my only complaint about the Finecuts is the exposed nozzle is easy to damage. I usually get 1000 to 3000 pierces per nozzle if I don't have an accident and damage it. I usually get two nozzles for every electrode used and always replace the nozzle if I am having problems or see any damage. Yes, the Finecuts work for me on my system and I will continue to use them YMMV.

Late addition. I don't have a ground rod directly connected to my table. My building does have good grounding and the rebar in the floor is connected to safety ground and ground rods (required by code for ag buildings here). I do however have a star connection for my work lead on the table chassis with star leads to the work clamp and slats. I always clean the mill scale off of the place I connect the work clamp. I have never had any known interference problems.

John

[plasmartist]

I have been using the cheap aftermarket finecut consumables on ebay and haven't had a single issue mentioned by others; but I find myself changing consumables after 6,000 inches of 10 GA. One thing I noticed with the aftermarkets is they seem to like cutting closer to the material rather than .08. I just ordered some genuine finecuts last week to see if I can get better life out of them, I'll let you know if I inherit your problems with genuine consumables.

[plasmartist]

Just wanted to give you an update. I switched from aftermarket to genuine finecut cons today. The genuine are working quite well, but they seem to be more sensitive to air pressure. I run my regulator at about 110 psi so that when the torch fires it stays above 95 psi. I hope you are able to get yours cutting correctly.