My struggles with Bambi or A Compressor Too Far?

[Matchless]

can you try the second rod onto this crank, dry, check for excess play, don't get over fussy, it's a compressor not a Le Mans race car.

 

[Rig Pig]

I'd suggest something softer than phosphor bronze, maybe an aluminium top hat insert pressed into an oversized end bore?

 

[Seadog]

The first problem is is the pin round? The second is what is its size. Tigging the rod is a possibility, if I had a TIG welder. I've a small MIG and some ali wire, but only Argoshield light.

 

[Seadog]

can you try the second rod onto this crank, dry, check for excess play, don't get over fussy, it's a compressor not a Le Mans race car.

Of course

I'd suggest something softer than phosphor bronze, maybe an aluminium top hat insert pressed into an oversized end bore?

Yes, ali might be the way forward, but it has to be split.

 

[Matchless]

I would offer to TIG it but I don't know how to TIG and my welder is not working due to waiting for my electrician mate to come over and fit a 63 amp breaker and socket, apart from that I could do it, can you wait a few years?

 

[Seadog]

can you wait a few years?

By then I should have my TIG set up going using my LIDL cheapo inverter and a HF unit I bought from @Bladevane

I think it has to be working within the month or it's out the door.

 

[Barking Mat]

Your setting yourself a challenge there Graham...

Tig torch, gas?...

Steep learning curve...

 

[Seadog]

I do my best, Mat, I do my best

Why make life easy?

 

[Seadog]

Well I thought I'd give the big compressor a rest and play with Bambi.

I cleaned the bore to do a quick ring gap check and saw this...

Yes, a chromed bore with chrome missing in places. So that just about writes this head off too. I did check the ring gap and it's not too bad (definitely worn), but considering the condition of the bore I don't hold out too much hope of it pumping well.

That's saved me £124 on a service kit, anyway. I cleaned everything and reassembled the bottom end and field coil for something to do. I've plenty of gasket paper, so the plan is to make gaskets, finish the assembly and reinstal the pump and see what gives. I may get a working compressor, I may not. At worst I've a receiver and a few other bits I've bought. At least it's been a good learning experience.

I'll post when I've more news, but with the dodgy weather for the next week or so I won't be outside reassembling it.

 

[Seadog]

Time for some gaskets. There are two sets, some simple round rings for the outlet pipes and the head and reed plate. I needed to clean the "mufflers" which go in the outlet ports first. They've been soaking in DCM over night

Before and after. As it happens, the second one is so bad that I'll use one of the other pair once I've dipped those.

On to the fiddly ones

The inlet cover is pretty easy and that was made first

Followed by the head to reed plate gasket

Not really the right material, but it's all I have to hand in the right thickness. If it all works I'll strip it down at some point and use a decent high temperature material.

Then I needed to do the reed plate to cylinder gasket. It was at this point that I noticed something nasty. The seat for the inlet valve has corrosion

The "Bambi hole" is getting deeper and deeper

Never mind I've a spare, a very grotty one, but a spare

At least the inlet seat is OK. To inspect the exhaust seat I have to drill out the rivets holding the limiting bracket in place, so I might as well do both

The reed from the first plate is warped and possibly unusable. Although it may be that in operation there is sufficient pressure to flatten it. But there are enough issues with pressure loss in the bore so I don't want to risk it.

 

[Seadog]

On to number two. The seats on both inlet and exhaust are perfect

BUT, the reed isn't

It's flat but corroded.

Anyone out there with a laser cutter and a small piece of 0.018" stainless spring steel?

I've gone so far with this that I'm not going to let it beat me. At least not until I get to the point that it's running and either producing useful air pressure or not.

 

[Seadog]

Well, After a lot of thought, and suggestions from the forum, I decided to have a go at making the reeds with what was to hand. I wanted stainless reeds. Why? the originals clearly weren't. Spring steel, too. Well, I dug out a piece of shim stock of the right thickness and, to all intents and purposes, it has about the same amount of springiness as the original. So, unto the breach dear friends.

Sadly, my packet of Roebuck shim stock suffered from being in a friend's garage for several years, but still enough clear of rust to use.

I cut it out with snips and then dressed it to within a few thou on the off-hand grinder. Final finishing was done with a Dremel with a hard disc and a sanding band for the concave faces.

Quite pleased with the outcome. I found a small carbide drill to spot the holes from each side then finished off with a 2.5mm 3-flute cutter.

The larger redd didn't really present any serious problems, despite the more complex shape. In fact I think it was more true to the original than the finger reed.
I did have the advantage of being able to use the reed plate as a drilling guide.

Next step, make a couple of rivets, clean the stop plate and valve plate, make a new gasket for the cylinder head side and we're ready for reassembly.

 

[Seadog]

Rivets found inside a rusty old piece of 1/3" rod, so that saved me having to make them

And assembled

I'm not 100% happy with the rivets, but I'm looking on this as a short-term solution. If it produces air I'll be happy. If I need to strip it again it will take me an hour or so to do.

After that it was out with the Wellseal and time to assemble all of the extraneous parts

It will be popped into the case tomorrow, the loop will be silver-soldered in (not soft solder as I originally mentioned) and we can try it out. The first job tomorrow will be to attack my storage shed to try and find my silver soldering kit.

 

[Seadog]

Rods and flux found and after de-greasing the surfaces some Easy-Flo paste was mixed and the loop inserted into the two pipes

First one soldered

And the second

Very happy with the outcome since the last time I hard soldered something must be 14 years ago

Time to assemble and test. I won't bore you with that. Besides, I didn't take any photos.

The first run proved that it was pumping air

After sorting out a few leaks, I tried again. Something was definitely amiss. There was pressure, and the receiver was getting air, but not very fast and there was a distinct sound of leaking air from the pump head.
When I removed the cover there was a cloud of smoke

Nothing electrical, but there is obviously something very amiss

The air is clearly escaping back through the pump from the receiver. This suggests:
A) The non-return valve isn't non-returning
B) The reed valves are not performing well
C) There is a gasket failure

A is a given and B & C are both possible
Back to the drawing board, I guess

 

[Seadog]

Went back outside and as I walked up to the compressor I thought, "Ah, did I close the drain cock?"

Closes drain cock and switches compressor on again. After a minute there is a small amount of pressure building, not as quickly as I'd like, but definitely there. Then the run capacitor decided to let its magic smoke out.
Only it's a start capacitor There is a disconnected cable running to the second start pack (it was a twin head compressor), which I had coiled inside the box. It was laying face down at the time and I'm wondering whether or not by some absolute freak occurrence, one of the loose wires touched the capacitor. But the other ends, I'm sure were in free space so it would have had to have been the earth, which would have tripped out the RCBO. Fortunately I was able to press the spare into service, an original Facon

Things are definitely moving in the right direction now

It seems to be running more cleanly now. Perhaps it was just burning itself in. The smell of Wellseal is still noticeable, but nowhere near as strong. And, maybe these types of compressor do produce some fumes. I've another smaller one that I may pop the top off at some stage to see what's what.

It's seemingly slow to fill, but then I haven't timed it and there are a couple of small niggling leaks. One being the drain valve which is leaking both around it's boss and from the thumbscrew. The other leak is around the outlet from the pressure switch.

The drain valve was a doddle. It had an O-ring which was quite chewed in several places. For once, my drawer of odd O-rings produced the right animal. In fact, there were about 30 or more.

The leak on the outlet was remedied again, hopefully for the last time.

Once the thread seal has hardened I'll try here again and time the fill. I may adjusted the hysteresis on the switch to bring it in sooner but, since I'll be running a small spray gun at 40-50psi I may not need to.

 

[slim_boy_fat]

since I'll be running a small spray gun at 40-50psi I may not need to.

Since these are as used by Dentists et al, I don't suppose their drills consume much air in 'treatments'?

 

[Seadog]

They don't, but bigger practices will need more air. There is (was, it's am obsolete range now) a three-head version that has a 100l tank. Provided it keeps going for long enough I think it will be fine for my needs.

 

[Seadog]

This morning saw the elimination of the final leaks. A combination of parallel and taper and poorly made fittings has made this a real pain in the bum. I resorted to Loctite 577 which I thought might be a cure-all. It's past its sell by date but still liquid. It worked, except for the nipple connecting the pressure switch to the outlet tap. My third attempt reverted to thread tape. I wound about 10 turns on, way more than I'd normally use. It screwed together like there was nothing there. Another 10 turns were added and finally a bit of resistance. I tried it - it doesn't leak
BUT, there another annoying little hiss It turns out that the PSV had a small leak. A quick nip up with the spanner and that was fine.

I can now report that it has held pressure for 3 hours and has been signed off by none other than Bambi himself

Fingers and other appendages are now crossed in the hope that it will last me at least as long as it takes for me to finish preparation and to spray the Ingersoll-Rand.

Job's a good'un. Back to my first project


( Apart from the fact that I've just realised that the cable is sitting on top of the pressure line. That'll never do )

 

[RWD3M]

Good effort Seadog! Really enjoyed reading this.

 

[Seadog]

Thanks RWD. I had serious doubts that this would end well. Everywhere I looked had problems. Mind you, considering that it was abused beyond belief, and used in a environment that it was never intended for, I suppose it's testament to the ruggedness of the design.

Now I can get back to the big compressor