While the weather was good for working outside I started to work on getting the new Type & Rule caster operational again, for now concentrating on the pot and pump side of things.
The caster is fitted with a bottom-crank mechanism for raising and lowering the pot, and in this particular case the crank was missing. However, a wrench could be used on the nut that was supposed to retain the crank to turn the shaft and lower the pot. Although I had oiled the raising/lowering screw threads this was still quite hard to turn. After a few minutes of hard work I had the pot lowered, swung out, and the pump removed along with a collar of hardened type metal.
The pot lowered and swung open
The pump, with attached lump of metal. Note this is the special pump for strip casting, which has the nozzle in a different position.
The ultimate goal here is to refit this caster with a top-crank mechanism, which I have as a spare from a scrapped English caster. The bottom-crank is unpleasant to use because to operate it one must bend down with one’s head/face right next to the pot, and it is not unknown for the pot to shift and slosh molten type metal when being raised or lowered. Furthermore the crank and screw have a plain (sliding) surface bearing the weight of the pot, which adds to the friction of turning the crank. The top-crank mechanism can be operating while standing erect, and includes a ball thrust bearing to reduce the effort required to turn the crank.
I plan on replacing parts back to the Swing-Frame Post (38H) because the replacement is fitted with tubes to lubricate inaccessible parts from a small oil tray on the top of the post.
To break things down into lighter individual parts I stripped down the Swing Frame, removing the pot and the entire pump lifter mechanism, leaving just the bare swing frame, which on this caster seems to combine the actual Swing Frame 37H and the Table 37H12 (under the pot) as a single casting. I also removed most of the pump operating mechanism, leaving only the Piston Operating Rod (19H) and its attachments.
It was essentially impossible for me to raise the Swing Frame again as turning the crank nut in the other direction merely removes the nut. So I proceeded to remove the Swing-Frame Screw 39H.
Or at least to try. It should have been possible to hoist the Swing Frame and have it and its raising Screw just slide up, and then turn the screw further to remove it completely out of the top of the Swing Frame and Swing-Frame Post. There was, unfortunately, some combination of rust and gummy dried oil that prevented this. I used our fork lift to lift up either under the Swing-Frame Table or under the bottom of the Screw with enough force to start to tip the caster over but nothing budged.
After swinging the Swing Frame while applying lifting force I got the Screw to rise up 2 or 3mm, at which point it jammed. This also raised the pot enough that it had to be in its closed position to rise any further. I lowered the fork lift and hammered the top of the Screw, and after a few blows it dropped suddenly back to its normal position.
A few up-and-down cycles like this allowed the Screw and Swing Frame to rise to the former’s upper (casting) position. At this point I should have been able to just turn the screw more and pull it out the top, but the screw refused to turn any further. The Swing-Frame Screw Washer 39H2 seemed to be firmly stuck on the screw, preventing it from threading any further upwards.
I applied a torch to this washer in an effort to try to free it, and eventually managed to remove the Screw completely using a combination of a wrench on the crank nut and a pipe wrench on the top of the screw which was now projecting above the top of the Swing-Frame Post. The washer fought me the whole way off, but I eventually removed the Screw and Swing Frame.
The Screw was scarred at the top by the pipe wrench (and hammering it down), and at the bottom by the Washer. I don’t plan on re-using this Screw but if it were needed the damage could be cleaned up on a lathe or, with a little more trouble, using a file.
Scarring at the top of the screw from using a pipe wrench
Scarring at the bottom of the screw from removing the washer
The cause of the problem appears to be an imposter 39H2 washer:
There is no way this is a real 39H2 as there is absolutely no reason for this part to include a keyway, and it also does not have the finish typical of Monotype parts. This looks more like a commodity driveshaft spacer that was used instead of the real 39H2, and because it was too close a fit on the screw the edges of the keyway dug into the shaft.
Anyway, now that all this is removed the next item is the Swing-Frame Post, which is just held on by a few large screws, and so far I’ve had little trouble with seized fasteners so this should be easy to remove. That will allow me to test if the newer part fits in its stead.
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