I have an issue with the alignment of the tailstock on my lathe that in its previous life was used for some or maybe a lot woodturning. I have created a previous thread or two on the shimming of the tailstock to compensate for the wear probably caused by the use of sandpaper while turning but I'm thinking now that the tailstock dips towards the front left hand side.
So far, my attempts to measure the situation have been a bit Mickey Mouse. For a test bar I've used a 200mm length of 5/8" precision ground :rolleyes: 4140 in a Rego Fix collet mounted in a Schaublin 2 Morse chuck. Probably reasonably accurate but the 0.004" droop along 170mm of its length when mounted in the TS could be gravity, collet and chuck runout or a worn tailstock.
The 4 thou has been measured by simply traversing a dial indicator mounted on the carriage. The 4 thou is pretty consistent along the lathe's long bed.
The real drama is when I run an headstock mounted indicator around the outboard end of the bar. Using a Centricator ( http://ift.tt/1xepVku ) for measurement, there is a staggering 0.017" reading.
I'm not sure what's going on. I've ordered a replacement used tailstock base from Mal Colomy at Australian Metalworking Hobbyist based on the thinking that whilst it will be worn, it probably will be worn more evenly that mine and I hopefully will be able the scrape and shim things back into some semblance of accuracy. Hopefully.:-
To facilitate a more precise survey of the situation I need to improve on the test bar. Chronos in the UK offer this bar - http://ift.tt/1xepWop Shipping is about 20 bucks.
Something cheaper would be nice but Chronos suggest their bar is accurate to two tenths.
Any other recommendations?
BT
So far, my attempts to measure the situation have been a bit Mickey Mouse. For a test bar I've used a 200mm length of 5/8" precision ground :rolleyes: 4140 in a Rego Fix collet mounted in a Schaublin 2 Morse chuck. Probably reasonably accurate but the 0.004" droop along 170mm of its length when mounted in the TS could be gravity, collet and chuck runout or a worn tailstock.
The 4 thou has been measured by simply traversing a dial indicator mounted on the carriage. The 4 thou is pretty consistent along the lathe's long bed.
The real drama is when I run an headstock mounted indicator around the outboard end of the bar. Using a Centricator ( http://ift.tt/1xepVku ) for measurement, there is a staggering 0.017" reading.
I'm not sure what's going on. I've ordered a replacement used tailstock base from Mal Colomy at Australian Metalworking Hobbyist based on the thinking that whilst it will be worn, it probably will be worn more evenly that mine and I hopefully will be able the scrape and shim things back into some semblance of accuracy. Hopefully.:-
To facilitate a more precise survey of the situation I need to improve on the test bar. Chronos in the UK offer this bar - http://ift.tt/1xepWop Shipping is about 20 bucks.
Something cheaper would be nice but Chronos suggest their bar is accurate to two tenths.
Any other recommendations?
BT
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