Compressor timer switch question

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Greg_Lewis
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Re: Compressor timer switch question

Post by Greg_Lewis »

Well, folks, the timer is done and I thought I'd post a follow-up. There is good news and bad news. First, the timer passed the smoke test. As Bill predicted, it cost more than the initial estimate and took more time. Three orders from McMaster and one return, three trips to the hardware store and two purchases off Ebay.

I couldn't find a timer that would run off 240 volts with contacts rated for the motor, so I am running a 110 volt timer that then trips a contactor that will handle the motor current. The pressure switch trips the timer which trips the contactor. It all works just fine; the timer will switch off the compressor if it runs too long. The compressor takes just a little over six minutes to fill the tank from empty, so I set the timer for about 15 minutes.

Now for the bad news. The compressor lives in a building behind my shop and the air is piped back into the workshop, so I barely hear the compressor running. While working on it and experimenting with run times etc., and standing with a few feet of it, I heard it make a horrific squealing noise like metal on metal. It was so loud that I couldn't stand close to the machine without ear protection. Not encouraging. In the hopes that it might just be a bad belt — this thing is 37 years old with the original belt, I took a look and sure enough, the belt was glazed over and full of cracks. So I replaced said belt. There was no play in the crankshaft but I did notice more oil around the top of the compressor head than I'd seen in the past. Flipped the breaker on and off she went. As the pressure built up the squeal came back just as bad, but went away in a moment after pressure started to build. But this still was not a good thing.

To add to the joy, in the several drainings of the tank, both the bottom and side outlets were briefly blocked with something.... rust chips no doubt. There are inspection plugs in the tank, but a 4-foot pipe on the breaker bar would not budge them.

Ok. Now we are into unhappy territory. I decided to do a little exploratory surgery on the compressor unit itself, and the results are in the second photo below. The source of the squeak was obvious. It doesn't show fully in the photo but it looks like someone ran 60-grit sandpaper over the bearings. Plus the oil around the top end suggests worn rings. I never ran it low on oil, but in all things there is a lifespan and considering the hours I put on it, I probably got my money's worth.

So now I've got a nice timer unit that probably cost me $150 or so and no compressor to attach it to. Tomorrow I'll be shopping for a new compressor. I'm going to start a new thread here for advice on that.

Compressor timer unit
IMG_8514.JPG

Bad rod and crank bearing
IMG_8515.JPG
Greg Lewis, Prop.
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Bill Shields
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Re: Compressor timer switch question

Post by Bill Shields »

Stay away from stuff built in asia
Too many things going on to bother listing them.
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Greg_Lewis
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Re: Compressor timer switch question

Post by Greg_Lewis »

Bill Shields wrote: Mon Feb 15, 2021 10:42 pm Stay away from stuff built in asia

Yeah, but aren't they all? I did a search on this forum and found a thread from several years back that said even the "USA" ones have Asian parts in them.
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Steggy
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Re: Compressor timer switch question

Post by Steggy »

That munged-up crank journal suggests you've had a lubrication problem in that pump for some time.  What were you using for oil and how often have you changed it?
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Greg_Lewis
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Re: Compressor timer switch question

Post by Greg_Lewis »

BigDumbDinosaur wrote: Tue Feb 16, 2021 2:00 am That munged-up crank journal suggests you've had a lubrication problem in that pump for some time.  What were you using for oil and how often have you changed it?

I thought of that just before your post. The noise of the bad bearing was so loud it's unlikely I'd have missed it in my shop if this had been going on for much time. Going back to my original post, this adventure began when I came out from lunch to find a hose popped and the compressor running. I'd been away from the shop for about three hours, and have no idea of how long the compressor had been on. It could have been for most of those three hours. Now if you look at the bearing cap and crank, you'll see that there are no oil holes or entry points for oil other than seeping into the bearings through the clearance between the rod bearing and the crank. And there are no oil grooves to facilitate this. The only way oil gets in there is when the rod dips down into the oil sump. My Model A Ford used the same splash lubrication method, but the rods each had a little cup on the bottom of the rod cap that dipped into the pan and scooped up a little oil, which passed through a hole right above the cup and into the rod bearing, which was grooved for oil. In the tens of thousands of miles I drove that car I never had a rod bearing fail. So the theory is that the compressor is designed for intermittent running, the rod getting oil when it comes to rest at the end of a cycle that's not supposed to be more than a few minutes. Thus the rods overheated, lost oil and died. Nuts! All for a coiled plastic air hose that probably didn't cost me more than ten bucks.
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Bill Shields
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Re: Compressor timer switch question

Post by Bill Shields »

IF YOU LOOK HARD ENOUGH, you can find a USA built compressor

https://usamadeproducts.biz/tools-power ... ssors.html

https://www.saylor-beall.com/

https://www.quincycompressor.com/about-us/

i have had very good luck with my Quincy
Too many things going on to bother listing them.
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Greg_Lewis
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Re: Compressor timer switch question

Post by Greg_Lewis »

Thanks, Bill. I'm going to move this chat over to the other thread I started about a replacement:
http://www.chaski.org/homemachinist/vie ... 4&t=110369
Greg Lewis, Prop.
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Harold_V
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Re: Compressor timer switch question

Post by Harold_V »

Bill Shields wrote: Tue Feb 16, 2021 11:20 am i have had very good luck with my Quincy
Oh, yeah! They're bullet proof. I've had a 5 horse Quincy since 1968. High and low pressure cylinders, all cast iron head. Talk about a work horse. 80 gallon horizontal tank, on @ 150 psi and off @ 175 psi. Three phase, of course. Provides almost 20 cfm with those specs, and will operate a small blast cabinet and keep up, resting between cycles.

H
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Steggy
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Re: Compressor timer switch question

Post by Steggy »

Saylor products are very good. A client of mine has a 20 HP Saylor compressor in their shop that is going on 25 years of daily service. Other than regular oil changes and some new air filters, I don't think they have ever had to do anything with it to keep it running.
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armscor 1
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Re: Compressor timer switch question

Post by armscor 1 »

Gave my brother 10HP, 41 CFM Broomwade water cooled with after cooler, bronze tubed heat exchanger with carbon rings which makes it oil less.
They were popular in the seventies for the pearling industry for breathing air for divers.
Still going strong after 50 years.
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Bill Shields
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Re: Compressor timer switch question

Post by Bill Shields »

but the big question for all of us...

are TODAY's compressors as good as yester-years ?
Too many things going on to bother listing them.
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