April 18, 2016 at 9:06 pm #251283
Oh I bet it is not.
This is probably just the tip of the tidal wave that is to come in the up coming months.
Maybe Harbor Freight will start carrying a HP compressor, then at least you can spend a few bucks for full replacement warranty :3: :whistle:April 19, 2016 at 4:17 pm #251339
Can anyone else who has this compressor check their high pressure rings to see if they are also polymer?
Just check the spare ones that came with the machine. MrodAir really does believe they are silicon bronze.
I doubt this is outright misleading on the part of MrodAir, but more likely they got duped by the
OEM. They even have them colored to look like bronze.
No matter the reason, this is going to impact longevity of the high pressure ring if I get
the machine’s oiling issue solved.
Please just see if they conduct with an ohmmeter. Silicon bronze will conduct electricity.
Mine are completely non-conductive, and not cold to the touch like metal should be.
It is some sort of polymer.
[EDIT: Michael McKeown confirms that his replacement rings are not metallic]April 19, 2016 at 9:37 pm #251354
My spares the same as yours Guy, non conductive.April 20, 2016 at 12:52 am #251365quote guykuo:
I wouldn’t bet on this……..He reportedly “tested” a bunch of them, and “knew” the material used by the competitor….but then wants us to believe he doesn’t KNOW the material of the one he decided on after all this research?
Come on – he’s a SALESMANquote Mrodair.com:April 20, 2016 at 3:39 am #251393
I will continue to give the benefit of the doubt. At least, Michael is responding to me and has offered some support.
Can’t really tell from here what exactly to believe, but the guinea pig will try. Nothing to lose now.
I have written and asked for three things.
Let’s see what happens and if this machine can get improved.
I’m recovered a bit from the trauma of this weekend’s failure and more ready to move forward.
Let’s hold off on replacing entire assemblies. Instead, let’s do the simplest steps first.
There are a couple things that we can probably rule out as being problems based on
the fill rate and fact that I did get up to 4100 PSI.
The reed valves and poppets are probably functioning in both cylinders. Otherwise, I would
not have gotten to 4100 PSI in a Great White tank.
Also, I am definitely intimidated with working on the crank shaft and
possibly leaving the rods improperly secured. Last thing I want is
a rod coming loose during a run.
Given the above, let’s focus on the following
three issues to move towards success
1. Oiling problem in low pressure cylinder
Way more oil is getting into my low pressure cylinder than for some other owners.
Charles McKeown’s machine does not make his shop smell like oil and he says
he isn’t getting the oil staining that I am seeing with each bleed of the separator.
Plan: Examine the rings on the low pressure side.
Action:I remove the low pressure cylinder from the crank case and check
the rings and their clocking. If that looks OK, I replace those o-rings with
new ones. That won’t rule out the cylinder, but rings are easier than
an entire assembly
Need from Mrodair: I will need a set of low pressure o-rings and info
regarding the correct orientation and order of rings
2. O-Ring blowout at high pressure cylinder
My large o-ring that surrounds high pressure reed valve disc has blown
out. It really shouldn’t have failed at 4100 PSI, but perhaps detonations
of oil were subjecting it to higher local pressures. If we solve the oil
issue this would be less of a problem.
Plan: Replace blown out o-ring with new one. Also find out if higher
grade o-ring is possible.
Action: I obtain a new o-ring and dimensions/durometer of ring for future
Need from Mrodair: Replacement o-ring & size/durometer of the ring
3. High Pressure Rings are Polymer, Not Silicon Bronze
This is verified by at least two other owners that their rings are
not metallic. This means the high pressure rings will be a source
of more rapid failure than advertised silicon bronze rings.
Plan: Ultimately replace high pressure rings with silicon bronze rings.
Convinced dealership this is an issue for machine longevity.
Meanwhile, use the polymer rings currently available
Action: Replace existing rings using new spares to ensure full seal
despite prior fouling. Also, obtain more rings for expected early
failure of high pressure rings.
Need from Mrodair: More polymer, high pressure cylinder rings
Mrodair should investigate availability of the silicon bronze rings
that were specified. Once metal rings available, replace polymer
rings with more durable metal rings.April 20, 2016 at 9:39 am #251408quote guykuo:
Based on your detailed write up all over the Internet – I think I would go with the Squeaky Wheel theory at this point. There are probably 45 or so others out there who we have not heard of with similar problems who are NOT getting any replies and/or support.
Good LuckApril 20, 2016 at 12:01 pm #251414
Dude, he should offer you more than just moral support on all the hard work you’ve done for him on HIS product!
Good luck!!April 21, 2016 at 6:24 am #251475
While I await reply from MrodAir regarding my three requests, I examined the low pressure cylinder to see what has happened.
The amount of oil in the low pressure cylinder is as much as when it originally arrived. I had assumed all that was due to it being shipped with oil in its crank case. My pre-cleanup effort was in vain. Plenty of new oil has gotten into the cylinder during my Great White filling attempt.
This time I pulled the cylinder off to look at the rings and piston. There are three metallic rings. The top and middle are simple rectangular profile. The oiling ring has drainage holes around its center. The bottom (towards crank) edge of the oiling ring has a sharper edge. The upper edge is beveled. The sharp edge down towards the crank seems correct direction to me.
Clocking of the ring gaps was the only thing questionable. The oiling ring and middle ring were at 6 and 5 o’clock respectively (nearly aligned). The top ring was at 12. Ideally, none of the gaps should line up. On the other hand, I don’t know how much these rings spin during run time.
Inspection of the rings and cylinder wall didn’t show any obvious defects.
Cleaned things back up and then reassembled with oil, middle and top rings at 12, 6 , 12 clocking to make each successive ring gap 180 degrees apart.
Recompressing the rings was pretty easy. The cylinder end has a taper that can do the last half of the compression. I just held the cylinder with both hands, fingers extending beyond bottom of cylinder. They I could curly my fingers around and compress each ring before it engaged the cylinder.
So, the gapping wasn’t ideal. I’ve improved that as much as possible. Don’t know if the gapping with change during run time. Also the ring gaps are simple straight butts. They are neither tapered or stepped. At least these rings are metallic.
No word as yet from MrodAir. I still need some replacement parts before I can fire this up again to see if the oiling issue is improved.April 21, 2016 at 8:24 am #251482
Guy , You are more likely the Ernest of compressors . Even Mrodair didn’t go through their product as well as you have done .
Shame on them for trying to make a fast buck by selling Chinese garbage to the masses without being totally 100 % knowiedge-
able about the product that they are selling . Seems like they only know halve-ass of what the compressor is . They should have
taken one apart totally completely to inspect all of its’ parts to make sure that their product was in proper working order and it
had all of the correct components to make it function properly . Looks like that never happened and now besides yourself how many
others who purchased this compressor is going to get burned and have to take a loss ? Mrodair knew from the get go that they were
dealing with a Chinese product and most items made in China as far as quality goes generally will come with a big ? Mark . They will
not be able to give each buyer a refund if their compressor turns out to be a total lost . Sad but true you get what you pay for . I
know because I got burned on Two Chinese Scopes that everyone said was a good scope and both came brand new and both were a
broken piece of shit . Sometimes it is hard to have to learn the hard way . :3: :3: :3:
FROM : THE BIRDMANApril 21, 2016 at 12:19 pm #251492quote birdman:
I agree they should have gone thru WAY MORE inspection then they did. Heck they “advertised” (and are STILL advertising) the rings as being “Silicon Bronze”……..and they even had a spare set with each compressor………now how did they NOT know the rings weren’t even metallic? Come on, they didn’t even have to do anything to get to them, they were spares!
No way they can pull the “we didn’t know” routine here…….they should be PAYING Guykuo for all his R&D done after the fact……..of course these compressors are old news, they now have the MK II’s that just left the manufacturer on April 14.April 21, 2016 at 1:28 pm #251499
Michael at MrodAir says I now have the ring clocking correct and he is getting the items out to me.
He also mentions something about the gap clearance.
Once parts arrive, I’ll put this back together and see if the oiling problem is improved.
We still have the non-metallic high pressure ring issue, but one step at a time is still better than nada at this point.April 21, 2016 at 5:39 pm #251519
Yesterday I bled my Great White down to 3500 and filled it back up again to 4500 with the Airmax compressor (I didn’t go down to 3K in case I had a failure I’d still have some air…it is turkey season after all ). It took 9 minutes and the head temperature reached 180 degrees f. (I’m using the small reservoir it came with). I bled several times getting slightly oily water each time. Very very little oil. The water on my hand would dry in short order and not really leave any oil behind, just the slightly sweet smell of the Chemlube 501. I do not have the auto-cut off gauge and I accidentally allowed the pressure to climb dead headed for a minute or two while I was looking at something and the pressure hit 8,000psi! I think I want one of those shut off gauges!
I carefully measured and calculated and made a list of what I think are the o-ring sizes used on the Airmax. After I get my order from theoringstore.com I’ll report back as to how they all fit and any changes, but it’s a cheap enough order if anyone wants to mirror the experiment:
water jacket x2 N2.50X053
water jacket: x2 N2.00X005
2nd stage head: N3.00X016
separator inlet fitting: N1.50X011 (Guy used) I think it should be N1.80X011.2 I ordered both.
media holder: N3.00X17
Michael McKeownApril 21, 2016 at 7:35 pm #251530
miksatxParticipantApril 22, 2016 at 10:49 am #251572
These o-ring blowouts are all over the machine. I think part of the reason they happening is how the o-rings are sized.
For instance, the supplied o-ring on the water separator poppet was too large in cross section. That causes the seal to be a section of o-ring resisting huge pressure without metal supporting it against that pressure. Instead, only lateral friction keeps the o-ring seal and that eventually fails. You can improved it a bit by using more torque, but ultimately, it’s just squished rubber between two flat surfaces resisting force parallel to the metal faces.
With a smaller cross section 0-ring, the seal acts more like a dowty washer. The rubber only seals. Metal reinforces the rubber against the force. The smaller o-ring sits inside its channel. Directly metal to metal contact seals in the o-ring and buttresses it fully. The compliance of the rubber lets the pressure push it up agains the now, much smaller gap to form a non-failing seal.
There are multiple places on this compressor where you have this situation and need a dowty washer (if the joint is flat metal to flat metal) or a smaller cross section o-ring (if there is a channel for the o-ring to fit within). An oversized o-ring can make things worse because it could prevent full metal metal contact that forms the reinforced seal. At the very least, you need to be able to torque down far enough to make the sealed gap very small.
[Edited for spelling and grammar]April 22, 2016 at 1:08 pm #251578quote guykuo:
Lack of proper engineering and design.
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