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DIY compressor, variable performance


SPendrey

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Hello,

I have a 50ltr Wolf Sioux compressor (link), and a hand-me-down (big) Snap-On impact wrench for it. When I used this as new, about two years ago, the wrench made light work of removing wheel nuts from my Disco. More and more lately though it seems to struggle and even fails completely once in a while to remove the nuts.

I have oiled the wrench itself (not before each use to be honest, but more like every other use (which is monthly), I have oil in the compressor reservoir itself, and I have what I believe to be the 90PSI needed (possibly more?) at the wrench but it sometimes operates quite slowly and poorly.

So, what can I check to identify the cause of the variable performance? I have read and looked at a few search results like these, but they don't point to anything that i can specifically check or test other than adjustment to the regulator to ensure the 90PSI needed is delivered at the tool.

Links and more links.

Thanks in advance,

Scott

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Well yes, I did install a retractable Clarke thingy which has a smaller diameter hose than original (from memory it is 8mm vs 10mm?), but I made an assumption the pressure may increase and therefore flow wouldn't be adversely impacted. I can visualize the actual flow may be reduced by the smaller diameter, but compensated by a higher PSI within the hose. I'll go home and measure them both to be sure!

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When you say you've lubricated the tool, some need airline lubrication and 'gearbox' lubrication. Have you done both?

If you have enough pressure gauges and fittings you could see what the pressure is at the compressor and tool end of the line to see if that is causing your drop in performance. Whilst your doing it see if the pressure is holding at the compressor end in case you have a fault.

Mine is only a CP or Clarke or something but there is a huge difference in performance under load when I'm using it on my 25 litre 1.5hp home compressor with a springy hose and the work 900 litre variable speed screw compressor with a 10mm line.

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Best to use Hi-flo fittings as well ;)

Yep, am doing that already.

Re. the air hose change, I can see the flow will reduce as there is less volume of air to move over the fixed length, and given the pressure is constant the flow is reduced.

Never-the-less, why would the tool perform well sometimes and not others? Simply a case of needing oiling more?

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When you say you've lubricated the tool, some need airline lubrication and 'gearbox' lubrication. Have you done both?

If you have enough pressure gauges and fittings you could see what the pressure is at the compressor and tool end of the line to see if that is causing your drop in performance. Whilst your doing it see if the pressure is holding at the compressor end in case you have a fault.

Mine is only a CP or Clarke or something but there is a huge difference in performance under load when I'm using it on my 25 litre 1.5hp home compressor with a springy hose and the work 900 litre variable speed screw compressor with a 10mm line.

The pressure testing mentioned in another recent thread is what got me thinking... I have a tyre inflation tool which has a gauge on it (albeit about as accurate as the bad guys in the A-team), so I'll compare that to the regulator gauge on the compressor.

Re. 'airline' vs. 'gearbox' lubrication, erm, no idea. There is no obvious port for lubrication on the impact wrench, so I'm popping a couple of drops into the air inlet.

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If you do that pressure test, it will/should show exactly the same as the reservoir as there's no flow, so no pressure drop.

If you teed into the airline at the end (as close to the windy gun as possible) and then ran the windy gun whilst looking at the pressure, that would tell you if it's dropping significantly.

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What you really need to do is get a pressure gauge on the tool while it's working.

That will demonstrate what the working pressure is on the tool and whether you have a restriction problem. I feel this is likely.

I've recently fault found a similar situation - An enormous 3/4" Atlas Copco impact wrench with as much puff as an asthmatic kitten. Turned out that when working it was getting only 2.5 bar at the wrench rather than the 8 it should have been. It was the dodgy chinese pipework between the compressor and the tool that was the problem for me.

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What are you oiling it with? I nearly killed a needle gun with EP90 - to begin with it would run slow till it blew some oil out then slow all the time - till I blew the oil out and flushed it before re-oiling with something thinner.

Looks like air tools need something thinner - like the proper stuff!

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What are you oiling it with? I nearly killed a needle gun with EP90 - to begin with it would run slow till it blew some oil out then slow all the time - till I blew the oil out and flushed it before re-oiling with something thinner.

Looks like air tools need something thinner - like the proper stuff!

Er, yes. EP90 is a bit thick! I'm using "Smith & Allen, Airtech ATO". ;)

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Mine has an Allen key screw I'm the side for gearbox oil.

Do you drain the compressor? It's not something like water coming through periodically and clogging it up? Do you have a water trap? We had no end of problems at work when the air drier packed up :/

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It does have a water drain plug, and I do drain it, although probably only twice a year. I have rust stains on the garage floor to prove it!

So, I'll drain the water again, double-check the tool for a gearbox oil input, and then I'll give it another go.

Thanks for the ideas.

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May be a rust flake stuck in the line? (try back blowing the line)
Water can also ice blocks as well (the expansion of air can cool things down creating ice if there is water)
Also check that the exhaust vent on the tool is not blocked/clean it, a lot of tools have mufflers that might be blocked with oil residue, etc.

The inner lining of some types of air line can collapse over time, even if the outside looks good. Test with different lines of similar length/ size

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On my old Draper (shortly to be retired) I could never get air tools to work properly through the supplied output, so I took one of the bungs out of the end of the receiver and put a quick release connector in it, all problems went away. Any sort of restriction will impact the flow rate and cause a pressure drop, a bit like unwanted resistance in an electrical circuit.

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