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M10 SAE Flare Line Nut for Unloader valve needed (solved)

Motofixxer

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PXL_20260731_005238105.jpg


So it appears to be around an M10 flare. It's smaller than 1/4" flare but larger than 3/16" flare. The outside of threads measures 10.36mm.

Update CONFIRMED: It's M10-1.0, by a nut that seemed to fit well. But now where to find an M10-1.0 SAE? flare nut

It's on an ALL Power APC4005 Twin stack air compressor. I believe also sold under Sears, Lowes, Strikeforce and others somewhere around early 2000's or so. They don't sell compressors anymore and only a few random parts left from later models.

I need to add the unloader line from this valve up to the switch since it's not there anymore. I bought the thing for a whole $10...but guy didn't know much about it. Thought if ya put a cap on there it would fill. He stuck his finger over it and it started filling. The pressure switch end seems to be a fairly common M10-1.0 inverted flare that I can work with.

The problem seems to be nobody has an M10 flare nut that would fit it. So looking for options that might work for it.

This is actually kind of a nice design unit with wheels and a moving handle. Otherwise it's nothing special but decent output at 4.2CFM @90PSI

AllPowerAPC4005.jpg


UPDATE:
I found a "UXCELL 10mm Hex Nut 200mm Length Air Compressor Exhaust Tube Copper" or 8" long on Amazon for about $8. It is a 1/4" line and has the correct nuts on each end. It just ended up being a bit too short. But I can work with that. I need about 3" longer or 11" 280mm. The nuts are the harder part to find. The key terms I think are Air Compressor Exhaust Tube or M10 Pilot valve line, in a search they show on alibaba and all over in links. Just have to find the M10 and length. In a quick search I couldn't find a longer one like I need but I have brake tube I can use. Or just make a new flared end section to add to the end valve end of a union, swap the nut and it's done.

I talked to a service shop and they suggested Makita compressors are normally metric. I also found the same M10 valve listed for Central Pneumatic. So maybe some searching for the line for one of those can yield some info.

20260816_165843.jpg
 
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Motofixxer

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Should be M10. How’s it not fitting? Too big? Too small? Not threading?
I did indicate M10- flare nut doesn't seem to exist in the US. 1/4" flare is too big, 3/16" flare is too small. I tried an AI that says it's a compression fitting just not common used in US. But supposedly a 1/4" compression nut is nearly identical to M10 and often mistaken
 
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Motofixxer

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From here the threads look fouled up, maybe try a chasing file?
Problem is finding a fitting that fits it...I have nothing for it. Can't seem to find an M10 flare anywhere. I'm gonna try to buy some M10 nuts and see if they fit right. Some info says it's an import valve sold in bulk to manufacturers. Not common otherwise, others say it's just standard 1/4" compression and threads are nearly identical to M10
 
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Motofixxer

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I ran into that a few years back and I ended up replacing the check valve & nut
That is a last resort, I was hoping simple and cheap. Otherwise maybe a hydraulic shop has an adapter or nut
 
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RoninB4

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Not common otherwise, others say it's just standard 1/4" compression and threads are nearly identical to M10
-Thread pitch (TPI) is real important, better identify the pitch before attempting a fit. Several inch-to-metric threads fit ok for the first couple of threads but the difference shows up (tighter) after a few threads. Compression angle of the fitting can/will make a difference too as you're probably aware. I'll bet @andyvh1959 could offer better info than I can.

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Motofixxer

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-Thread pitch (TPI) is real important, better identify the pitch before attempting a fit. Several inch-to-metric threads fit ok for the first couple of threads but the difference shows up (tighter) after a few threads. Compression angle of the fitting can/will make a difference too as you're probably aware. I'll bet @andyvh1959 could offer better info than I can.

1785659952623.jpeg
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Yea I'm familiar enough with threads and pitches...just trying to find the right fitting. I found a reference that said that fitting is a 1/4" compression just kinda unusual style with a cone and it's 1/4" compression threads which are so close to M10 they're frequently mistaken.
 

RTM

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Problem is finding a fitting that fits it...I have nothing for it. Can't seem to find an M10 flare anywhere. I'm gonna try to buy some M10 nuts and see if they fit right. Some info says it's an import valve sold in bulk to manufacturers. Not common otherwise, others say it's just standard 1/4" compression and threads are nearly identical to M10
Boy, what a *****. When I search for m10 flare nut, it shows me what you have. When I look for flare ferrule, shows me mostly the same things. What’s the term for the mating female piece?

Google AI says it should be an M10-1.0, so if you have a metric pitch gauge, I’d verify that before going too crazy.

Good luck.
 
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Motofixxer

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Is it big enough to tap 1/8 NPT? You could step up from there.
No not really, I had considered using a die to change the outside threads. But AI says it would require downsizing it too much and high risk of rupture from repeated pressure and temp cycles.
 
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The Cobbler

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replacing the check valve it's probably the easiest, but if it was me, I might try to tap the inner to 1/8" pipe like posted before .
mine was several years ago and I don't really remember what happened, I think the cap blew off and I replaced the valve. somehow I'm thinking the old thread was 1/4 NPT but with a flare nut and not std flare nut threading
Is it big enough to tap 1/8 NPT?
 
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Motofixxer

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edit, might be 1/8 NPT
A 1/8" NPT male thread has an actual outside diameter (OD) of approximately (10.3 mm) and 27 threads per inch
I confirmed with a nut that it is M10-1.0 with the nut smoothly and consistently threading all the way on. It seems NPT is close but wouldn't be consistent being NPT. But now I need to find a flare nut
 

whateg01

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Looks like a 5mm tube, but I only find down to 6mm, which is M12.

I guess if I was going to look for one, I would look in the chuck on my lathe.
 

KnurledNut

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Looks like a 5mm tube, but I only find down to 6mm, which is M12.

I guess if I was going to look for one, I would look in the chuck on my lathe.
It’s not uncommon for tube nuts to combine SAE line and metric fittings. A M10x1.0 nut can be found for 3/16 line.
 

RTM

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Confirmed it's M10-1.0...but where can I find a flare nut
Maybe these? Mostly looking for a name to look further for. Some of these prices look silly stupid high.

Here is my search

m10-1.0 flare "tubing" fitting -coupler -union female




Or this to convert it to something standard.

 
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Motofixxer

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It’s not uncommon for tube nuts to combine SAE line and metric fittings. A M10x1.0 nut can be found for 3/16 line.
This seems like it might be right eh? M3-3 - 10mm x 1.0 Fine thread, female steel nut - SAE flare Then says use with the fitting shown below it. Which seems to be a union that matches what I have
 
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Motofixxer

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Maybe these? Mostly looking for a name to look further for. Some of these prices look silly stupid high.

Here is my search

m10-1.0 flare "tubing" fitting -coupler -union female




Or this to convert it to something standard.

The first one seems to be an inverted flare which I think the pressure switch end is. That seems to be available most anywhere as a M10 unloader line or similar. But there isn't much for specs on em. Then there's only a nut on the 1 end.

The 2nd seems to be similar to 1 I just found and listed previously. Seems like it's what I need. So a double flare on the line and seems like it should work right?

3rd seems to be just an adapter. I'd like to keep it simple with the line and the fitting if possible...but it's in the right direction.
 
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Motofixxer

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but it says use with 3/16 line , unloaders are usually 1/4"
3/16 will be fine but now you have to deal with the other end that's 1/4
( unless you can drill it out ??? )
Well I'm really not concerned with most...I just need this specific situation solved. I do need the nut for the other end but that should be easier with a compression fitting.
 
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