The inside of an Expert Drum

[Paul Ewins]

Ever wondered what secrets the inside of a Jobo Expert Drum holds? You know, the magic that makes them cost hundreds of dollars? I got to find out today when a couple of second hand 3010 drums arrived from Germany. One of them had been advertised as "making a rattling sound" and sure enough, there was somthing loose inside.

After a bit of careful work with a craft knife the bottom plate was prised away from the drum and here is what I saw:
http://members.optusnet.com.au/~paulewins/resources/photos/expert_rear.jpg

and the rattling sound turned out to be a plastic ring that should be glued in the centre of the tubes:

http://members.optusnet.com.au/~paulewins/resources/photos/expert_ring.jpg

So now I know, and I still don't think they are worth much more than $100. There is some sort of white coating on the back of the front plate but I have no idea what it does.

Turns out this drum has a slow leak in one of the tubes, but that should br easy to fix, especially while the back is still off.

[Robert A. Zeichner]

Thanks for sharing your findings. It's always a little easier to grapple with a problem if you have some idea of what to expect.

[Chuck Pere]

I've always heard that the walls of the Expert drum are really barrel shaped not just vertical like a piece of pipe. This helps flow behind the film sheet. And probably also adds to the cost.

[Robert Ley]

I have one of these drums that has a slow leak in one of the cylinders. How do you propose fixing it and how difficult was it to remove the bottom? Please let me know how your repair job works.

[Paul Ewins]

The first step was to fill each cylinder up with water and leave it sitting in the kitchen sink. A couple of hours later the water level in one of the cylinders had dropped 50mm (two inches). I left it for another couple of hours and there was no change so the problem is two inches down into the cylinder. I marked the level in that cylinder with a large felt tip marker.

Removing the bottom was quite easy. It is glued to the side walls at five spots and all I did was run a craft kinfe along the seam between the wall and the base until the seam cracked.

A quick inspection inside and out showed no holes or other signs of damage and the leak was so slow that it can only be a fine crack in one of the seams.

I'm just going to run a bead of MEK (Methyl Ethyl Ketone aka "Testors Plastic Cement") along that first 50mm of both seams inside and out. I will of course test the MEK on the drum bottom just to make sure it doesn't eat its way through.

The cylinders are slightly barrel shaped, probably only 2mm difference at the middle to the ends. The barrel shape is probably why the cylinders are assembled from two halves rather than the whole thing being moulded in one piece. I still can't see it taking much more than ten minutes to assemble.