BA and MOD D.P. change wheels for modern boxford lathe

[Tony RayParticipant @tonyray65007]

Steve,

Thaks for the dimensions. There may be other metric standards but it doesn't appear be this one:

BS 5686:1986, ISO 14-1982: Specification for straight-sided splines for cylindrical shaft

an excerpt is here

http://www.roymech.co.uk/Useful_Tables/Keyways/Spline.html

Unfortnately standards in general are not freely available. It would seem a bit crazy if it isn't based on some standard.

I'm seriously considering trying to pull changewheel data together for the most popular lathes & publishing it to the web – perhaps Tony Griffiths would put it on his lathes.co.uk site ?

Tony

[Tony RayParticipant @tonyray65007]

John,

Any spline info you could contribute would be most gratefully received.

Pehaps you'd better get back before Obama & Putin fall out completely !

Tony

[Sub MandrelParticipant @submandrel]

Hi Steve1

My Machinery's Handbook has trucklodads of data for involute splines, involute serrations and straight splines, but the latter only in SAE (Society of Amercan Engineer's sizes, all imperial).

It could be an imperial size although it would be a rather sloppy fit on a 7/8" shaft.

Neil

[SteveIParticipant @stevei]

Neil,

I of course can't be sure if they are imperial. However note that pretty much everything that I can check and measure or find in the manual on this lathe is metric.

Regards,

Steve

[Clive FosterParticipant @clivefoster55965]

Steve

Mystery solved. These are "Straight sided splines, bottom fitting. Shallow." to BS 2905:1953.

I have an electronic copy of that standard if you need it complete with all the fit data but for the dimensions you have measured the lower and upper limits in proper imperial units for a 7/8 inch (nominal) shaft are :-

D = 0.905 / 0.915, d = 0.7880 / 0.7890, W = 0.2180 / 0.2195,

Note that this is a hole refrenced system so the fit is defined by shaft clearance relative to a tightly specified minor diameter d.

The actual major and minor diameters are derived from an acane concept called effective diameter so its not possible to get the nominal size from shaft measurements. Fortunately this standard is said to be simplified compared to earlier versions as "due to the considerable developments in involute splines in recent years it is considered that 6 splines are sufficient for all classes of work requiring straight sided splines". The original standard covered 4, 6, 10 and 16 splines whilst its replacement provided tables covering from 8 to 80 splines on shafts from 1 to 10 inches diameter. Yikes!!

Side comment.

Your metric measurements are what is known as a "soft" conversion so great care is needed to accurately sort the clearances and fits. Funny numbers are likely. Hard conversions adjust the sizes slightly to get sensible numbers for nominal dimensions comprehensible variations for limits and fits. Hard conversions are great in the drawing office and factory but can be a right pain in the field where replacement parts made to hard conversion standards are just different enough to the original not to fit as intended. Something to be wary of where replica parts for old stuff is concerned.

Clive

Edited By Clive Foster on 18/06/2013 21:24:11

[SteveIParticipant @stevei]

Hi,

Thanks to all the help I am getting somewhere. My hope is that I if I can find some free time I'll calculate the tooth count of the gears I am missing. It will be nice to be able to post the complete specification of what is needed.

Regards,

Steve

[Michael GilliganParticipant @michaelgilligan61133]

Excellent input, Clive !!

MichaelG.

[Author]

Posts