another beveled edge cut case

[bLouChipBlacksmith]

I recently came across a used-very-few-times PMX65 unit w Duramax hand torch at a great price so I jumped on the purchase. It was mfg in 2010 if that matters. It came with a few new HT genuine 65A and some new 45A KEMAO nozzles. I also found a brand new 2016 mfg Duramax machine torch at a great price, so that's in the stable too. And finally I found a new CPC kit at a great price due to open box. To get cutting quickest on the CNC table, I purchased a set of KEMAO 220817 mach shields to match the 45A nozzles in case it mattered. In the meantime, I'm waiting on delivery of my genuine HT 851511 45A consumables kit for mach torch, which arrives next week. So yesterday I spent a day in the shop gloating over such a nice, basically new, HT PMX65 setup. First test, 10gaHR cut with hand torch. excellent. Second, 1/2" plate with hand torch, cut like no buddy's business, easy and excellent. both on 65A consumables. Next install the CPC kit. No problems. btw- absolutely no dust what so ever inside the PMX65 unit, it even smelled brand new. At this point I'm gloating. Next is CNC table cut testing with mach torch.

Prior to acquiring the PMX65 unit, I had been cutting some 14gaHR recently with my other unit (PrimeWeld Cut60 w Tecmo UPM105 mach torch) and it was cutting with very good edge quality, albeit slow w 45A @ 2700mm/m, but that's book specs. The cutting speed was the reason I became interested in the PMX65, over 2x the speed (w higher arc voltage). btw- The UPM105 uses what appear to be PMX45 prior generation consumables (no spring on electrode) from Tecmo. The KEMAO brand for PMX45 have worked equally as well on that torch, hence I didn't hesitate to get the KEMAO mach shield for the Duramax torch. Cut height 1.5mm, 70psi.

So here is the problem: cutting 14gaHR with PMX65 unit, Duramax mach torch, HT swirl ring, HT electrode, HT cap, KEMAO 45A nozzle, KEMAO mach shield... book specs of 45A @ 6600mm/m yields a great cut in terms of zero dross, but the cut edge is beveled all the way around; positive angle, 0.5mm slope outward top to bottom; thus the part measures 1mm larger on the bottom than on the top. Cutting CW [corrected] direction. PSI set to automatic. THC off. Cutting a 50x5mm shape w arc at turnaround end. In fact, the edge bevel is most diminished at the start and end of the cut, and at the arc'd turnaround, but with appreciable dross due to the slow down in feedrate at those points. So this suggests that a lower feedrate improves the edge squareness in this case. I logged the feedrate on the gcode sender as the cut made the turnaround and it dropped to 3000mm/m in that 5x8mm arc'd turnaround zone, grbl does this automatically and intentionally, this is not a programmed feedrate reduction, it has to do with acceleration and junction deviation config. Accel is relatively slow at 400mm/sec2.

The same steel cut by with PWCut60 w UPM105 w all KEMAO stack w 45A nozzle yields 0.2mm of positive angle slope, or 0.4mm larger on bottom than on top, and this is with a 1/2 worn (~400 pierces) set of consumables ! I can work with these results just fine; I was expecting the PMX65 w Duramax torch to at least be equal if not better.

I've tried adjusting the cut height of the Duramax torch down to 1.1mm, still get similar edge bevel with perhaps 0.2mm overall reduction in bottom dimension width of part. But that cut height is awful dang low and still not as square a cut edge as the prior gen technology. I've tried varying the feedrate +/- 1000mm/m, more dross, same bevel. Thinking it might be feedrate related, I've tried reducing amps to slow down the feedrate but to no avail; in fact this has proven to be quite difficult to get a quality cut below 40A @ 4000mm/m with the PMX65, seems like the feedrate window for low dross cut quality diminishes quite a bit at this threshold. I switched to manual air pressure at 70psi but no difference.

So I'm waiting for my genuine HT PMX45xp consumable stack kit and I'll resume test cutting next week, will report back. Thus far, its been disappointing cut edge results. Just curious, are others using the PMX65 w 45A stack cutting 14gaHR getting similar bevel on their cuts ?

[adbuch]

I personally only use OEM Hypertherm consumables with my Powermax 85 and 45xp. I get very minimal edge bevel. I would wait until your get your OEM consumables and try again.
David

[weldguy]

I am with David on using genuine HT consumables when you can but with your aftermarket consumables it sounds to me like you simple need to reduce your cutting height to eliminate the bevel. The same bevel on all 4 sides is almost always solved by adjusting the height. See image below taken from this topic viewtopic.php?t=30283

Give that a try and post back

[bLouChipBlacksmith]

agreed on both points, use genuine HT and lower cut height. I had dropped cut height to 1.1mm but only minimal improvement. Tomorrow is HT happy day, parts delivery.

[weldguy]

agreed on both points, use genuine HT and lower cut height. I had dropped cut height to 1.1mm but only minimal improvement. Tomorrow is HT happy day, parts delivery.

That 1.1mm you dropped the cut height to, did you actually pause the machine and measure the height? A lot of folks enter that in the software and assume that is what they are getting but often that is not the case due to any number of reasons so I like to always measure with feeler gauges.

[bLouChipBlacksmith]

@weldguy. no and yes. I did not measure it the other day with feeler gauges, but I did today after you mentioned it. It was right on. and same cut result with beveled edge. Although I have the THC off for my cut testing, I still perform a torch probe cycle (limit switch method), and I weight down the work surface to eliminate flex. I'm somewhat OCD so I frequently check the accuracy of the probe cycle Z0 with a ping/no ping drop test of the floating mount, and then test for backlash with 0.1mm reverse Z motion. All good.

Well, I received the genuine HT 45XP mach torch consumable kit today ! albeit too late to conduct any cutting tonight. I may not get to it tomorrow until noon or so. However, that didn't stop me from a visual inspection and some dial caliper measurements and hasty compare with KEMAO brand. The nozzles seem very close to identical, only .001" to 0 variance in dia., length, depth, jet orifice, pretty much the same as my compare on the HT 65A nozzles I already had.

However, the mach shield has significant and naked eye visual differences. The HT nozzle nose is recessed further into the shield+cap assembly by a full 0.012", at 0.055" (1.4mm) total vs. 0.043" (1.1mm) KEMAO, and the nozzle nose gap to shield is noticeably larger as a result. Translation perhaps, more bypass air flow?, and perhaps a better formed flame? I'm guessing. I recall Jim Colt writing about the engineering of the nozzle and shield dimensions and interaction with cool air vs. ionized plasma jet. Also, the 12 bypass holes near the tip of the HT shield are 0.035" vs. KEMAO 0.028", measured with oxy/act tip cleaners.

The 1.4mm nozzle recess dimension, + the typical 1.5mm cut height = 2.9mm nozzle to work cut height is a near match to the nozzle recess on the HT hand torch drag shield assembly (I measure it at 3.0mm). So that explains that dimension difference I noticed the other day.

Despite the KEMAO positive edge bevel, I cut some parts today that I needed on a small project that didn't concern edge squareness. I have to say, cutting at over twice the speed as previous plasma unit is a little nerve racking, I'll have to get use to that. The absence of even minor dross was really nice. So the KEMAO stuff will cut with no dross at HT book specs, but you gotta like the bevel, or don't care about it, either way.

I also made numerous attempts today (while waiting on UPS) to find a lower amperage + slower cut speed quality combination but the dross build up really piles up going below 80% of book amps and speed. If anyone has the secret sauce formula or process for this, please advise. Maybe it'll be possible with the genuine HT consumable stack.

Hopefully a good report tomorrow, which = no bevel.

[SegoMan DeSigns]

He's a couple of curve balls thrown your way,

Have you pulled the factory filter / settling bowl off the back of the unit and looked at the screen and filter itself?

What about a thorough inspection of all o-rings? They were discussed here:

viewtopic.php?f=60&t=35414&p=224740&hil ... ng#p224740

[bLouChipBlacksmith]

@sego- good advice. thanks. I did check the air filter bowl and filter element upon unpacking the unit, both clean as a whistle. And I checked the torch head o-ring, was dry so I lubed with swipe of thin film of high temp silicone grease around it and cleaned off the brass. But now I have the genuine HT lube in the consumable kit, so will wipe and re-lube today. I did not know about the red o-ring on the fastconnect, good tip. I will check and lube later today first thing.

btw- I did pick up on the rotation of the threads, good wood on 2 but foul tip on 3rd.

[weldguy]

Curious to see how the genuine consumable work for you. You may find that all your woes go away. If your getting too much dross at lower amps lower speed you may have simply reduced your speed too much. Speed up the cut rate until it can't cut through anymore and then back it off a bit. I wouldn't even bother before putting in the genuine consumables. Curious how it works out for you.

[bLouChipBlacksmith]

Genuine HT 45xp consumable stack cut testing yesterday- by now you likely know I would have posted sooner if it was stellar results. Sadly, not. only about 50% improvement on 14gaHR positive edge bevel *on average* all the way around the part. So the measurements work out to be a 7.5 to 10 deg. bevel *on average* from outward from top to bottom. The difference in top to bottom part width is 5mm top, 5.5mm bottom, those are average as measured over a couple parts 5x50mm as described in earlier post. The bevel disappears on the radius turnaround end of the "rectangle" and at the begin and end of cut, suggesting that much lower feedrate is correcting it, but at the expense of heavy dross of course for those few mm in the zone. Hence my desire to find lower amps and slower feedrate. Also could explain why I get nice square edges from PW unit, it quality cuts 2x slower. @weldguy- I appreciate the tip on the secret sauce to find the slower combination of cut parms, I will give that technique a try.
So the question now becomes- is 7 to 10 degrees of bevel normal ?

The improvement of bevel by a full -0.5mm on bottom dimension did expose a machine issue; torch needs to be shimmed in the mount front to back. I must have checked it too hastily when mounting last week. The bevel now is visibly asymmetrical on along X axis front to back of part, the figures above are assuming symmetry, so actually the bevel is slightly greater in front than in back.

I'll post some pics later today. I cut some 12ga stainless steel artsy/crafty parts despite the bevel. cut quality is great if you tilt your head. The book speed seemed a little high given the sparkage and minor top side dross, so I'll dial it down for some more stainless cutting later today.

before cutting yesterday I checked the red o-ring in the fastconnect, it and the brass has some visible dust/lint on it so I swabbed it to clean and lubed with HT silicone. Thanks @segoman for that tip. I'd like to find a cap that fits that fastconnect when not in the machine, perhaps a pvc pipe size ? or zip lock baggie

today's punch list:
* install a pressure gauge on the air inlet rear port to absolutely know the inlet pressure is good and stays good throughout.
* shim the torch square X and Y. Triple check frequently. (note to self- I need bump up the priority to rebuild the torch/floating mount slide. I have plans from Tom to do this for other reasons too, so I can use a scriber).
* cut some 1/4" plate to compare edge angularity.
* mow the lawn

[weldguy]

I would suggest keeping the speed at the Hypertherm recommended value and working on finding a cut height that eliminates the bevel to an acceptable level.

[SegoMan DeSigns]

I checked the red o-ring in the fastconnect, it and the brass has some visible dust/lint on it so I swabbed it to clean and lubed with HT silicone. Thanks @segoman for that tip. I'd like to find a cap that fits that fastconnect when not in the machine, perhaps a pvc pipe size ? or zip lock baggie

I leave the hand torch wrapped up on my machine (for harvesting the skeletons) with the fast connect pointing down to prevent dust buildup. If your looking for a cover check with your local hydraulic shop for the thread protectors that comes on their fittings.

Your first post said you run with the air pressure set to automatic have you tried the manual set with different pressure levels? When my 65 was new I had the fault code 0-21 pop up intermittently (along with the bevel cut problem you listed) after convincing the Hypertherm Tech my new 20Hp 2 stage compressor would put put enough air through a 1" line to feed their machine they sent me a new pressure sensor (Hypertherm #228689) and it cured my problems.

Bring up your code window and see if it has any 0-21's listed on it. Search the forum for it as well for more insights to your problems.

[adbuch]

I checked the red o-ring in the fastconnect, it and the brass has some visible dust/lint on it so I swabbed it to clean and lubed with HT silicone. Thanks @segoman for that tip. I'd like to find a cap that fits that fastconnect when not in the machine, perhaps a pvc pipe size ? or zip lock baggie

I leave the hand torch wrapped up on my machine (for harvesting the skeletons) with the fast connect pointing down to prevent dust buildup. If your looking for a cover check with your local hydraulic shop for the thread protectors that comes on their fittings.

Your first post said you run with the air pressure set to automatic have you tried the manual set with different pressure levels? When my 65 was new I had the fault code 0-21 pop up intermittently (along with the bevel cut problem you listed) after convincing the Hypertherm Tech my new 20Hp 2 stage compressor would put put enough air through a 1" line to feed their machine they sent me a new pressure sensor (Hypertherm #228689) and it cured my problems.

Bring up your code window and see if it has any 0-21's listed on it. Search the forum for it as well for more insights to your problems.

???

[SegoMan DeSigns]

Fat fingers strike again..

[bLouChipBlacksmith]

@sego- good info, thanks. I did try manual air pressure a couple of times, up to 78psi I believe, no help though, so I went back to auto.

So... the brief update, all PMX65 operations in the shop are suspended until further notice; not a completely bad thing, but a smart thing temporarily.

The verbose update... In general a good day in the shop yesterday, learned a lot, again.
Installed pressure gauge at air inlet to PMX65. At first it seemed to indicate all was fine. Pressure while flowing air through the torch never dropped below 100, line regulator at tank set to 110psi. Tank regulator for compressor ON to 110, compressor OFF at tank 140.
Check 1 OK.

Next up check 2, the torch plumb/square to table (aka slats in water pan). Dead on, both X and Y. However, I did have residual shims in the torch mount from the Tecmo torches used with PW, and I forgot why I had them there since they measured equal top to bottom in the mount, albeit they were rubber, so I assumed it was for grip on the torch body. But as is expected with HT equipment, the Duramax torch body is well engineered and has zero compression, so no rubber needed most likely, so I removed the shims and went bare metal mount. Recheck plumb... ut oh. slight negative tilt top to bottom, so bottom towards back of table. "Slight" as in I can get a 0.030" feeler gauge over 3.5" between the torch body and the speed square used to measure; according to Mr. Pythagorean that's less than 0.5 degrees. The edge bevel is 7 to 10 degrees avg, in the opposite tilt (positive) more so on the front edge of the test pattern than on the back edge. Next I measured the plumb of the Z plate positioned at various XY positions around the table, dead on every time. So the torch mount has a 0.5 degree negative tilt, it should help the cause, I left it as it.
Check 2 OK.

Check 3- I never got around to test cutting 1/4" plate, probably a good thing as it turned out.
But as a lead in to preparing for that test, I resumed what was intended to be a quick repeatability test on 14gaHR and an attempt to find the sweet spot of low speed, low amps per the suggestion above, (before the suggestion to fa'get about it). Oh- I also used a new nozzle and electrode from prior day, the 220777 electrode flavor this time, noticing it was recommended for not only long life but under 12mm cutting, and it has a noticeable smaller radius on the cylinder tip, so that's interesting, could affect air flow I thought. Well, the cut edge bevel improved another 0.1mm, nice, so now the top to bottom dimension differential is 0.4mm on avg.

So I thought, 'Hey, maybe more torch tilt? " But that doesn't make sense, the bevel is all the way around the test pattern, meaning when I cut the rectangle along the Y axis or the X axis it has the same degree of bevel. So I thought, 'What if I rotate the torch 180 deg. in the mount?' That's easy. That made more improvement! So basically its at 0.3 to 0.4mm top to bottom dim. differential, or 0.15 to 0.2mm of positive bevel all the way around cutting at book specs. I can live with that at 14gaHR.

So I proceeded to cut a small job on 14gaHR...
Disaster on the 3rd pierce, 4th, 5th, all stop. Pierce not penetrating nor is jet for 5 to 15mm then it cuts. Pierce delay? I bump it from 0.2 to 0.3. No help, same behavior on 3rd+ pierce. UT OH!. air pressure ? air flow ?
Go to the handy dandy pressure gauge at PMX65 air inlet, run job, AH HA!. Negative pressure spikes at 3rd+ starts, right when the HT valve cycles to make a pierce, upon opening of the valve; the cycle time between cuts is about 4 seconds (motion to next cut and torch probe time). The neg. spikes are down to 85psi, possibly lower give mechanical reaction time of gauge, from 110 momentary static.
Translation I believe: I don't have the air flow required for the Duramax torch, which I believe is 5.1 - 7.5 scfm@90 according to book. Marvelous. That would explain a lot.

So I knew I had an undersized air supply system as far as compressor recharge rate, its 4.5 scfm@90psi. With a 26 gal tank, it worked fine with the Tecmo torches and PW unit, basically matched the PW duty cycle at 4 minutes of continuous cutting before a machine pause to let it catch up on tank full. I figured I'd just run a 3 minute pause interval with the PMX65. Hell, I can't even run a 30 second interval. That explains why things started going weird when I added the 8 foot 3/8" hose pig tail on the air inlet and dedicated to the plasma unit, replacing the 50ft. hose reel, I gave up a gallon or so of air storage capacity after the line regulator. Of course it makes sense now. Odd though that I'm not getting 0-12 code low air pressure, or 0-21 low flow. I got 0-12 once while cutting 1/2" test with hand torch, which didn't surprise me since the torch was flowing air for a couple of minutes, so I noted that, cranked up line regulator, and went on.

Apparently the engineers at Kobalt put a 5 or so scfm capacity line regulator on a 4.5 scfm compressor system, what were they thinking? The gall of those guys. Oh well This whole PMX65 transition experience reminds me of purchasing a B.O.A.T. years ago. Look it up, Break Out Another Thousand.

Today... I'm playing golf, I'll make the other side of my brain miserable perhaps; maybe I'll win some money, going to need it.
Thanks to everyone for their help. I'll update this thread when I make improvements, but I suspect a correctly sized scfm capacity and flow rate air supply system will solve this bevel problem in the long run. Sorry for the false alarm. Maybe this thread will help someone going forward... from being a dumb ass like me.

[adbuch]

I am using a Speedaire compressor with 80 gallon tank and 7.5 HP motor. I seem to remember the cfm rating is around 25 cfm at 90 psi. I run a PM 80 with Duramax torch. Mine runs the whole shop. It sounds to me like you need to think about investing in a larger compressor.

David

[bLouChipBlacksmith]

Well that planned suspension didn't last long
After a day off golfing, and winning, I was in a good mood and got the bright idea to give the PMX65 another meal at the table. But first and foremost, know that I have a plan to replace my air supply system soon with a proper 11 scfm@90psi unit.

So I got the bright idea to bypass the assumed troublesome and scfm-restrictive line regulator on my P.O.S. air supply, and just feed 135psi tank pressure to the PMX65 through 3/8" hose, and also add back the 50ft of 3/8 hose in the circuit. [ After initial testing on the PMX65 last week with quick hookup to the 50ft air supply spool, I replaced that connection with a 8ft pig tale 3/8 hose on the inlet and right to the dry and regulated air supply, and thus dedicated to plasma unit, to minimize the chance of moisture condensation, just a practice I've been doing for about a year now after I got my dry air system setup. But of course in theory, there should not be enough moisture to condense at that point, but error on the side of simple.. sometimes]. I just wanted to see how unrestricted flow and slightly more static storage may improve the edge bevel situation AND perhaps allow more than just two sequential 20mm cuts with 4 sec intervals. So I made a 13 line (because I like to challenge unlucky numbers, and that fit well in the scrap remnant) pattern of 20mm or so line lengths and let'r eat on 14gaHR.

So that little experiment revealed the next issue, the dreaded first pierce f'up. I'm not using the Arc Transfer/OK signal as my CNC controlled does not have that input programmed, thus I have to rely on pierce duration timing only. Side bar: The PW unit was not at all finicky about the difference between pierce delay without post flow vs. with it, so it was not an issue. Of course the Maserati of Plasma is not so forgiving, so 0.2s worked fine on first pierce, but not the other 12. So after some discovery, aka trial and error, 0.34s is the magic PD during post flow for 14gaHR, including a PH to CH plunge rate of 2400mm/m. So now what to do about that pesky first pierce?, since I have effectively several of those per job given I have built-in machine pause intervals at 2 minutes so the undersized air supply can catch up on tank storage.

OK, but wait... to save the trouble of a well meaning reply on this point, I understand the right answer is to get a minimum 8 scfm@90psi air supply system in service. This was just a quick follow up test of verifying the real and hopeful only problem that the issue is the air supply, at least in terms of flow rate. Recharge capacity rate is slightly separate, yet still important, matter; I just wanted to nip away at this and settle the issue in terms of it having been, perhaps mostly, unknowingly insufficient flow rate to begin with.

So I added some gcode at the start of job, and after any machine pause event, to "prime" the PMX65 post flow condition with a 0.3s dry fire with the torch retracted to max Z. That did the trick! I was able to cut for the predicted 2 minutes of continuous runtime at 4 sec or so intervals between cuts (4 secs to retract, rapid to next cut, torch probe cycle). The air supply pressure as measured at the inlet was 90-95psi after 2 mins of cutting, then programmed machine pause, and operator resume when compressor OFF. Granted not the best solution, but adequate for testing a few times.

So I cut a small job of 41 pierces and almost 4 mins of runtime, thus there was one programmed machine pause for air supply recharge. It came out good enough considering the small overall size of about 8"x6", and the large amount of detail and text. Dross backside was only in zones of automatic retarded feedrate due to cornering, not that uncommon but I suspect it can be tuned better.

So I tried the same small job with FineCut. However, I thought I'd also experiment with the effect of removing the 50ft air line from the circuit, and replace with the 8ft dedicated pig tail. That made a significant difference in allowable time for continuous cutting, it revealed that the machine pause interval could easily have been lowered to 1.5 min, so having left it at 2 mins the big edge bevel began to reappear in those last 30 secs of cutting on the 2 continuous intervals. Inlet pressure was negative spiking to 80psi at/near the end of the intervals. So there is more proof, if I needed it, that inlet pressure and flow rate are significant influences on edge bevel. It's interesting though that the PMX65 codes 01-12 or 0-20 (low pressure) aren't yet thrown. Good to have those built-in warnings, but it seems that in order to trip, things have really gone south already. So the 50ft of hose acted like a capacitor in an electrical circuit, it smoothed out the low pressure spikes I see at the inlet gauge when using the 8ft. hose, and it gave a little more capacity to get through those last 30 secs of the 2 min. continuous cut intervals.

Resuming suspension of PMX65 operations until 11 scfm@90psi dry air supply system is in service. Soon I hope.

[bLouChipBlacksmith]

view looking down the 6" straight edge at bottom of part.

[weldguy]

Your part looks great! Time for a new compressor no doubt and I think your all set to do some fine tuning of your slow downs but looks great!

[bLouChipBlacksmith]

@weldguy- thank you. I'm a little embarrassed about the dross but it certainly appears to all be in retarded feedrate zones, the long straight cuts are spot on. I may have a problem with tuning it to near zero dross, simply because my CNC is built for milling, and thus has a lot of mechanical resonance due to high center of gravity, and a lot of mass in all motion parts gantry, X carriage, and Z plate. And the Y rails are hollow extruded AL (although I thought about packing the Y rails with sand). So I like to run 400mm/sec2 XY acceleration, but I have cranked it up to 800 since putting the PMX65 into service, just for this reason, to help mitigate the slowdown in cornering. The motor and electronics can handle up to 1450mm/sec2 accel, but that's insane unless I'm doing raster laser etching at 16000mm/m feedrate. Perhaps with sufficient air flow and capacity to feed the beast, I will find a slower feedrate for quality cuts since the retarded feed for cornering will be less of rate change. I seem to have come close to 23A @ 3100mm/m with the 45A nozzle on 14gaHR last week, but of course that was before the realization of choking the beast on air flow, 'he' doesn't like that.

So after conferring with a few shop hacks like myself re. the best 8+scfm@90psi plan given what I have already, the choices (no specific order) that we came up with are:
a) $1,400 for 11scfm, 60 gal, 5HP 240VAC, twin cyl w oil sump, 90dB, w dry air (condenser/cooler before tank and large desiccant dryer on regulated air). Obviously not a portable solution, but I can keep the current unit also for those cases.
b) $700 for 11scfm... rebuild a 20 gal horizontal tank unit w working 5HP 240VAC motor, w- new V-twin cyl w oil sump, new regulator w oil sep filter, new pressure switch, gauges, check valve, same dry air as a). Portable on generator, but 90dB.
c) $550 for a 9scfm solution... second unit matching my current air supply system, and running in parallel as tank to tank for a total 52+ gal and 9scfm@90psi; so a new 4.5scfm, 26 gal, literally a clone of the Kobalt unit I have now, w condenser/cooler before tank, and plumb it through 3/4" copper tubing from other side of shop (35ft run) and connect tank to tank. Both tanks feed the same upgraded 3/8" ported industrial regulator and 1 qt. desiccant dryer and regulated line delivery system. Still portable as 4.5scfm system, shoreline or generator for other pneumatic needs I have, and merely 73dB in the shop (both units running at 70dB). I shouldn't have to run both compressors from a common tank regulator switch since the beast is sucking >>more cfm than just one can supply in recharge, so eventually but rather quickly the secondary compressor will engage due to further pressure drop, then the system builds up joined and common tank pressure. Someone please correct if I'm wrong on this.

I like the options/function of c) and of course the price. My shop is as much hobby as it is business, in fact the shop motto is: "We're not look'n for work, work finds us". I don't believe there is much risk in selling the clone if this doesn't work out as expected, these are nice 4.5cfm systems, quiet, and with very dry air when tricked out, so no issues with air brushing or other artsy/crafty tasks.

Does anyone see a PMX65 performance problem with option c) given the gross requirements stated ?
Primarily: supply the PMX65 beast sufficiently while in the shop, at least 4.5scfm is portable on 125VAC for other jobs, and always regulated dry air.
Opinions welcome. Thanks.

[acourtjester]

my question is why are you running 23A @ 3100mm/m with the 45A nozzle on 14gaHR, for 14 Ga you should be using 45 amps at close to 5000 mm/m.
Running stereo compressors is not a good solution, requires more power, make more noise and take up more room. Trying to run 2 at the same time will mean they both start and stop at about the same time, controlled by the pressure switches. You want a bigger compressor with a big tank so the cycle time is longer. No sure where you live but I would put the compressor outside with a cover for the weather, that will cure the noise. That is where mine is ( for 30 or more years in Florida).

[adbuch]

my question is why are you running 23A @ 3100mm/m with the 45A nozzle on 14gaHR, for 14 Ga you should be using 45 amps at close to 5000 mm/m.
Running stereo compressors is not a good solution, requires more power, make more noise and take up more room. Trying to run 2 at the same time will mean they both start and stop at about the same time, controlled by the pressure switches. You want a bigger compressor with a big tank so the cycle time is longer. No sure where you live but I would put the compressor outside with a cover for the weather, that will cure the noise. That is where mine is ( for 30 or more years in Florida).

Tom - his reduced cutting speed could help to explain that low speed dross. I cut 14 ga. steel at book specs, with the exception that I reduce the cut speed to about 195 ipm. This is with FineCuts at 45 amps. Probably best to sell that small compressor and put the funds towards a decent size unit. I have my Speedaire 80 gallon/7.5HP compressor located in the main shop. But I do know of several locally who have their compressors located outside the shop with covers over them to keep the rain off.

David

[weldguy]

My choice would be option B Lou.

[SegoMan DeSigns]

5hp 80 gal dual stage would be my recommendation, the bigger the tank the less cycles. The less cycles the more money saved as starting motors are costly. Some offer a continuous run option which is great for running sand blasters.

I'm a fan of Eaton Compressors as they use a larger pump then slow it down for quieter, cooler and a longer lasting pump life. If 3 ph is available go that route for even cheaper operation.

I have 15 years on the 20 hp 3ph and it's still doing great..

[adbuch]

5hp 80 gal dual stage would be my recommendation, the bigger the tank the less cycles. The less cycles the more money saved as starting motors are costly. Some offer a continuous run option which is great for running sand blasters.

I'm a fan of Eaton Compressors as they use a larger pump then slow it down for quieter, cooler and a longer lasting pump life. If 3 ph is available go that route for even cheaper operation.

I have 15 years on the 20 hp 3ph and it's still doing great..

I agree!! When I purchased my Speedaire about 40 years ago, I was originally going to go with the 5hp/80 gallon tank unit. When I discovered that the pump was rated for 7.5 hp, I went ahead and spent the extra $150 or so for the larger 7.5 hp motor. This compressor has served me well and I've never had a problem with it.

David