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| Congreve Clock Repair & Rebuild Project |
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| raynerd:
Many of you know I'm in the process of moving house and so I've no workshop and I am already fed up doing nothing. I've been looking for a project I can work on at the dining room table with little tools and last week came across this small non-running congreve clock at a good price for the work that has gone into it. A congreve as always been on my "maybe but probably not" list of build projects. They look a stunning clock but there is a heck of a lot of effort that goes into them, a lot of material and they are poor time keepers - there are certainly clocks I'd prefer to make with the time. However, as a project, this was too good to miss. Apparently it has run but with problems and also, if I can get it running, there are many improvements I can make to improve the clock as well. Here is the clock when first purchased: These clocks are apparently incredibly sensitive to dust, any dust on the bed can stop the ball. This bed doesn't have dust, it was caked in oil and crud!! As you can see in the video, one of the first major steps would be to find the plans from which this clock is based. John Wilding has plans for a congreve, but I'm sure this isn't based on those plans. Not only is Wildings a 30 second bed, as with all other congreves I've seen, they have the two dials on either side of the main clock face and this clock wouldn't be able to have this due to the position of the arbours - they just don't match Wildings design. Any thoughts or suggestions, it would be great to hear anyone's thoughts! There are not many clock repairers that have worked on a congreve so everyone's opinion is more than welcome! I think the issues purely are to do with the bed & ball section of the clock and the gearing looks fine and runs ok! |
| raynerd:
So I was curious what a quick wipe of the bed would do to remove some of the rubish... This video is misleading as it would stop every few 3-5 minutes. It just showed how sensitive the bed is to dirt on the bed. I think I have a deeper issue of how the bed is built but I'll post more on this later. Next step I think is to fully strip down the bed and get it in the ultrasonic cleaner. |
| raynerd:
I've cleaned and inspected the bed and I think the problem lies here. The bed in my opinion is too complex in its construction. It is a single sheet of thin brass with lots of additional brass triangles cut. The brass triangles are screwed down to the plate and the gaps between the triangles form the rolling bed. The edge pieces that are cut into semicircles make the balls jump over and onto the next channel. I see two issues. 1. The triangles are screwed down in the centre and glued along the bottom. The thin ends of the triangles are lifting on some, which means the channel goes uphill before the corner and the ball stops. 2. The corners where it swaps to the new channel is based on the ball being guided around by the end piece which forms a barrier edge. What this means is that the ball needs to have enough momentum to jump up off the channel and fall into the new channel. In other congreves, the ball runs through a continuous channel so there is no jump to make for the ball to get out of the channel - I think that is the case! I have a few options now. I think for a start all the brass triangles need removing but the old glue will be a pain to get off. I then would need to re glue but then am I setting myself up for the same to happen in a few years time when they start to lift again! Sadly, this project was meant to be a table top project while I wait for my new workshop - i think the best option is to make a new table but I haven't the equipment available. I could draw it up and see if I can have it laser cut or see if anyone would cut me a new table. Your thoughts would be really welcome. |
| awemawson:
Thicker slab of brass and cut the channel with a ball endmill on a CNC milling machine. (Personally I'd make an aluminium test piece first to prove the design due to the price of brass.) Always fancied a Congreve having seen one in action in the South Ken Science Museum as a teenager MANY years ago, but I certainly don't have the patience to make one. |
| raynerd:
Yes, I agree. And so comes the end of the dining room table project lol :Doh: unless I can find someone with a CNC!! :wave: I've got the brass. I don't think you'd need it too thick due to the weight of it, just enough for the groove, but to be honest, like in other congreves, should it be a ball end groove or cut right through the sheet? |
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