My struggles with Bambi or A Compressor Too Far?

[Seadog]

Having had no compressor up until about 18 months ago (other than a direct drive jobby that a friend lent to me that nearly gave me a heart attack every time it fired up) I gained, in the space of a few months, two Bambis and a big old Ingersoll-Rand. Of the three only one was in working order, the smaller of the two Bambis, which I bought from Johnnybravo. The IR you know all about from the rebuild thread. The second Bambi, however, has sat under a tarpaulin since getting it, chucking a few quid at it, and finding that, surprise surprise, it didn't work. Well, when you buy £400-500 pounds worth of compressor for £50 on FB, it's not really that much of a surprise, is it? I thought that it was worth the price for the receiver, so there

Today being sunny and warmish, and me being in a bit of a lull with my other restoration, I thought I'd have another look Bambi II.

I'd previously removed the tops of the cans when I found that there was no life in the beast and, other than draining about a gallon of water out of the receiver and a good couple of pints out of the two heads , that's how it was left.

Sorry about the orientation, Picasa just will not save the rotation.

The pump head was removed and I set to work. I managed to drain some more foul liquid .

It took me well over an hour to work out how the disassemble the beast. Partly due to poor lighting, i.e.very bright sunlight and poor eyesight. I eventually realised that the spring mounts hooked into three brackets that were spot welded to the can, and were not all one piece that was welded on.

It took a while to find bits of bent metal to lever the beggars out, but it did eventually happen.

View attachment 223251

But, it still didn't want to lift out, being attached by a piece of pipe. I'd always wondered about the large loop of pipe over the top of the motor and, after another seemingly endless age, I worked out the the pipe run looped around the inside of the bottom of the can, came up the side and then looped over the top purely to allow movement of the pump and motor, which of course are spring mounted. It finally dawned on me that I'd have to unsolder the pipe loop, which fortunately was soft soldered, and came apart without too much of a struggle.

Out came the pump assembly

The offending curly pipe.

Here endeth Episode I.

 

[Seadog]

Where was I? Oh yes.

The field windings were simple enough to remove, just four 8mm AF bolts and off she popped

Leaving the still seized rotor behind. I had imagined that it might be seized in the laminations but got lucky

Next came the outlet pipe manifold and what I assume are two filters

Followed by the cylinder head

And then the valve plate

For stainless steel reeds they don't seem to have held up too well

The bottom pivot for the crankshaft came off without a fight and was found to be rust free, at least, where it mattered on the journal

It was at this point that I could feel a couple of degrees of rotation in the crankshaft so started to work it back and forth and, with the help of a brass drift, managed to get the piston to move.

Surprisingly it wasn't badly rusted in the bore, more like just gunged up. The bore turned out to be perfect but there was a patch of heavy scoring on the piston, not sure what we'll do about that

The rings are fine though but, you knew this was coming, the big end, which is ali and just runs on the crankpin, and the crankpin itself , are worn. Will these be available as spares? NO WAY.
I was surprised to find that the valve plate, gaskets and various filters and seals are available for the very reasonable sum of £99 +VAT.

The final hurdle in the strip down has yet to be overcome and that is to remove the rotor so that the crankshaft can be removed and inspected. This is another conundrum and will have to be attacked after more cogitation. There is what looks like a locking ring in the centre (I've no idea what the long tube is for, btw).

An old MKI Commando swinging arm pin was pressed into service as a makeshift tool but even with my strap wrench I couldn't get the ring to shift

The "tool"

A couple of minutes on the offhand grinder had it looking about right

Oh well, tomorrow's another day, let's see what happens. But I have to say this may be a bit of an impossible job. Bushing the rod wouldn't be impossible, but what state the crankpin is in is impossible to ascertain until it's out.

Time for my cocoa.

 

[Ton-up]

I always wondered what was in these 'quiet' compressors. Well done so far Seadog!

 

[Seadog]

Thanks Ton-up. I think I'm going to need a lot of ingenuity to sort this out. It makes the Ingersoll-Rand look like a walk in the park.

 

[Barking Mat]

Ahh, bambi, I thought it was a sad deer related story...

You might just finish with a working compressor Graham..

Coat / door.

I thought my ceiling was looking good.. Ah carp...

 

[Seadog]

Ahh, bambi, I thought it was a sad deer related story...

I couldn't leave you on tenterhooks for too long, Mat. A bit of venison would go down nicely though

I have one worker, but it's a little too small for anything interesting, such as testing my LIDL plasma cutter.

 

[Matchless]

the scoring on the piston is not too important, it only has one job. to hold the rings at 90deg. to the bore, provided the ring grooves are ok,

 

[Seadog]

the scoring on the piston is not too important, it only has one job. to hold the rings at 90deg. to the bore, provided the ring grooves are ok,

That's the conclusion that I reached as well, Patrick. There's absolutely no evidence of scoring in the bore, which is what I find so surprising. Providing I can extract the crankshaft, without the use of a BFH, there is some chance that I can get it running again. Then I've got the other head to do.

I'll put it under my hydraulic press tomorrow, with the makeshift tool in place, to see if it can be persuaded to shift without camming out.

 

[mike 109444]

And to think this probable spent it's life in a medical environment
Still at a push you could always get some ex fridge/freezer pumps to replace them, could probable fit three on there turned the other way. Plenty of people seam to chuck a fridge out (working) and scrappy don't want then due to foam and gas.
Sure there was a post some time back of a member using some big air con pumps he had... just a thought

 

[Seadog]

It probably started out in a dental surgery, but it ended up in a paint shop. When i bought it it was covered in paint dust, with no filters or pressure switch. Clearly no-one had told the b***ends you had to keep the oil level up and drain the tank daily

Around here, if a fridge is left out, the compressor disappears almost before the person has walked back inside their house

I am enjoying, at the moment anyway, the challenge. Getting the rotor off of the crank is going to be a bit trying I fear.

 

[Agroshield]

The nut that will not undo is not left hand drive is it?

Are the two halves identical? Perhaps the other one could help unlock the mystery of the first one.

JB Weld on the piston skirt and skim to size.

 

[Seadog]

The nut that will not undo is not left hand drive is it?

Are the two halves identical? Perhaps the other one could help unlock the mystery of the first one.

JB Weld on the piston skirt and skim to size.

I've tried in both directions. I've half a mind to lash the thing together to see if I can get it to spin under power so that I know the direction of rotation.
Not sure what you mean by "the two halves"?

I had thought about using something like JB weld. However, there are too many other potentially terminal issues to resolve before I get to that stage.

 

[Agroshield]

Not sure what you mean by "the two halves"?

I am not sure what you call it. There is one half with the teacup on top of it and the other half to the left of it. They look identical. Is it a twin compressor or twin motor?

 

[Seadog]

Ah It's a twin pump. I dismantled the second one today, it's in much better condition and will rebuild nicely. Apparently the crankshaft and rotor were never made to come apart and the whole unit was sold as an assembly. How wasteful. I just need to decide whether or not to buy a spares kit at about £120. New gaskets, reed valve plate seals and exhaust mufflers.

I also lashed up the second unit and got it spinning. Clockwise from the top, not that's going to help me by the sound of it

 

[Seadog]

Not a great deal to report other than a day spent degreasing and cleaning parts. I've definitely one good pump head, so that will be rebuilt. Whether I spend the money on a service kit is another matter. The reed valve plate clened up fairly well in DCM and the cylinder head and manifold are pristine. Conrod and pin OK, but I'll have to live with the rings that are there since these are NLA and I don't think I'll waste time trying to source or make replacements.

A very helpful chap in CJS Direct Compressors in Brum, Jeremy Foster, was able to find me a copy of a service bulletin, and also offered me another compressor with single pump head for £300. I wonder if I can negotiate the price down?

Decisions, decisions.

It's a real struggle with one square foot of bench space and two live projects. How I envy all of you chaps with large areas to fill.

 

[Barking Mat]

DCM? Graham?
I've not had a hugely productive day either...

 

[Seadog]

Dichloromethane or Methylene Chloride

 

[Seadog]

Having been told that the crankshaft is not made to be disassembled from the rotor I was resigned to scrapping one pump head and just running the one, since the other looks to be in fair condition. But a thought occurred to me whilst packing things away this evening, that I'd only looked at the state of the crank and conrod but not actually cleaned the surfaces up for inspection. The rod is definitely kaput Since the good one measures 22.25mm the knackered one between 22.45mm and 22.85mm, slightly oval I think you'll agree. On to the crank. Since I can't disassemble it I'll have to try to clean it in situ.
That's when I came up with a cunning plan

I have a lathe, I have fine emery tape, I have a collet chuck; you see where this is going?

After several feet of tape I ended up with this

It doesn't look too spectacular, I'll agree, but it's a whole lot better than when I started and, despite apparent wear, there are no detectable grooves in the journal. What you can see is, I think, just rust staining. Since both heads were filled with water and not very much oil, it's not very surprising.

This is the only photo that I have of the crank before I started

Now, it seems that the later rod had shells, but this one doesn't and runs directly on the aluminium eye. "Can I make some shells?" is the question and, if so, from which material. I have phosphor bronze which I think may be suitable. First off, though, I need to measure the size of the pin and whether or not there's any ovality. It's physically impossible to access the pin all the way round so I'll be limited to TDC +/- 10° or so.

But what do I measure it with.

Any thoughts on the conrod and measuring technique will be welcome

 

[mike 109444]

I know it will be a fair bit of work but yo could make up your split bush (big end) then maybe some plastigage might give an indication

 

[Matchless]

or maybe tig up the rod and re-machine, you would have to machine it to fit shells anyway! not much to loose?