|BARRY HILLIER||07/03/2012 15:07:42|
|3 forum posts|
Hi just got my first lathe, an old Myford ML2, with some missing change gears, amongst other things. Anybody know where I can get hold of some, please?
|Swarf, Mostly!||07/03/2012 15:24:40|
|527 forum posts|
Hi there, Barry,
You refer to 'missing change gears'. I can sympathise with your enthusiasm to complete the various aspects of your newly acquired lathe but I'm moved to offer a comment on the concept of 'complete set of change gears'.
I wouldn't know nowadays how to discover what change gears Myford supplied with the ML2 at its original sale but it wouldn't have been every number of teeth from 12 to 500! They most likely supplied gears that would cut the most common thread pitches, i.e. Whitworth & BSF. Furthermore, I'd venture to suggest that few owners ever used ALL the gears supplied.
I suggest that your approach should be first to acquire change gear tables for Whit, BSF, maybe BA, ANC, ANF & metric. You could compile those tables for the ML2 leadscrew pitch yourself or find them in the various model engineering handbooks.
Then decide what threads you're likely to want to screw-cut and shop first for those gears, say on eBay and/or at Model Engineering show flea markets. If a large number of ML2 gears shows up at an affordable price then go for it. But in the meantime, don't break your heart because you don't have the change wheels to cut a 3" Whit thread or other rare & exotic threads.
I hope this helps.
|BARRY HILLIER||07/03/2012 16:16:07|
|3 forum posts|
thanks for your reply, and I did say some, not a complete set! To be specific, I need a 20, 55 and 60
|11 forum posts|
if its similar to my ml4 modern myford gears fit drill your own pin holes or if you file keyways in your existing gears you can use ml7 sleeves and pins with a bit of fiddling lathes,co is useful
587 forum posts
|Harold Hall 1||07/03/2012 20:29:32|
|418 forum posts|
I agree with Swarf, if you purchase a full set of gears it is very likely that many will never get used. This, unless your activity is likely to frequently need a lot of differing threads to be cut and having odd pitches.
What is often overlooked is that for any relatively common pitch there are very many combinations that will achieve the required result. Typically, my changewheel charts,( using the Myford standard series of gears plus a 21 tooth gear for metric pitches) lists 45 combinations that achieve 14TPI, Of course, some are easier to set up than others, even so, there are still 12 combinations that use either two or four gears.
Even an odd number pitch, 13 TPI, lists 33 combinations.
The moral of this is that, if it is found one gear is missing that is listed on the lathe's screw cutting chart for the pitch required, almost certainly there are many other combinations that can still achieve the required pitch. This, even if a few gears are missing.
The charts can be found here,
However, it is impracticable to print the lists as there are 37,293 possible combinations between 6 and 50 TPI. Other than returning to the web page, the text files can be copied onto the PC's hard drive and kept for reference using a word proccessor
To use them for metric threads on an imperial lathe, convert the metric pitch to an imperial TPI and again you will find very many combinations that come very close. These are often more accurate than the combinations that the lathes standard chart lists.
Edited By Harold Hall 1 on 07/03/2012 20:31:52
|Keith Long||07/03/2012 21:01:15|
|827 forum posts|
If you can run *.exe files on your computer there is a handy utility program called npthread.exe freely available from various place on the internet - a quick google search should find it. This allows you to enter the list of available change wheels, the tpi of your leadscrew, the thread you want in imperial (tpi) or metric (mm pitch) and the error that you're happy to accept. The program then works out the best fit between these and gives you the change wheel combinations that will fit your criteria or betters it (lower error).
Worth having a look for as you can play with this and see just what you can and can't do with the wheels that you've already got and see what other's you may want to get.
|BARRY HILLIER||08/03/2012 16:12:14|
|3 forum posts|
many thanks for everybody's input, I am learning lots here, thank you especially that stuff from Keith, really useful.
I think I may have found a bloke with some old Myford change wheels and will go and see him tomorrow.
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