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| Fixing Ralph's Chucks |
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| Bogstandard:
You can criticise all you like Ned, I never get upset over it, because no matter how a job gets done, if the end result is correct, then the method must also be. That is why I usually say something like 'this is the way I do it', because I know for sure, someone will have another way to achieve the same result. In fact it can be good, people showing different methods, then the ones with less experience will have a choice, and will find which way suits them the best. Bogs |
| madjackghengis:
Hi Bogs, a small question, when I bought my first Logan, with a threaded spindle, I bought the cheapest three jaw universal, and a threaded back plate. I machined the back plate to fit the chuck, and machined it on the machine it was used on, and ended up with a chuck which holds less than half a thousandth at a number of different diameters, still, twenty years later. When I switched it to another Logan lathe with the exact same spindle, it was no longer accurate, but taking it off the backing plate, machining the plate on the new lathe, with a fresh spigot sticking in the back of the chuck and a fresh facing, it returned to the same level of accuracy to the extent I can grind Harley valves with 3/8ths stems, and have them run true to two tenths every time. Every chuck I've ever put on with its own backing plate has been less than acceptable in accuracy, and each trued up when the backing plate was machined in situ, so it may end up needing to be trued up on the lathe it will be running on. It helps a lot when the owner of the chuck is the only person to use it, as goes with all machine tools, I think. More often than not, it is the spindle which has unique qualities which cause a chuck to be less than accurate, particularly with threaded spindles. While I still have both my '42 Logan and my '48 Logan, I can't swap chucks between them and if I need to swap a face plate and the work needs dead on accuracy, I've got to take a couple thousandths facing cut. Just to put my two cents worth in. Good luck and hope things come out accurate :beer: mad jack |
| rleete:
One question: WHY? Was runnout too great? What was the reason for the fix in the first place? |
| NickG:
Good method John, this is what one of my chucks needed but I didn't have the tools required to do it so I bought a new cheap Axminster chuck as I did on my previous lathe. Once the back plate was trued up it gave very good results again. I am sure a lot of people will require this work carrying out so a useful thread. Nick |
| Dean W:
John, thanks for this thread. I know of the method, but seeing it done is always great for a guy like me. Glad you are getting some shop time. Hope things are going well in your corner of the world. Will be watching for your second part. Dean |
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