Frontal view of gear selection needed for gears when cutting thread!
|Gareth Wilkinson||22/01/2020 12:20:47|
|4 forum posts|
Hi there I have a Granville senior model Lathe and was wondering if somebody could please show me a pic of gear layout for metric thread cutting? I can't even find a pic of the model that I have on Google, so I am contacting you guys to see if you could help me! It cuts metric and imperial threads! It has 8 slots on the tumbler. None of the others I have seen have a tumbler on the lead screw!
|2433 forum posts|
Maybe some pictures Here may be of help?
|Brian Wood||22/01/2020 14:27:19|
|2072 forum posts|
I think I can help you with tables, not pictures but the information in the pdf is all clear in telling you what fits where
The Granville lathes were I think Myford copies with 8 tpi leadscrews and 20 DP 14.5 degree pitch angle change wheel gearing. I don't know if Myford supplied gears can be used directly but it wouldn't surprise me if they can
I have a pdf of all manner of gearing for 8 tpi leadscrew lathes without gearboxes but due to some irritating problem I can't solve I can't add that to my albums, the relevant button to make it happen is hidden from view.
Send me your email address and I will send you a copy
wood_y(at)btinternet(dot)com all in lower case, no spaces, note there is an underscore [ _ ] between the d and y
|Clive Foster||22/01/2020 14:50:15|
|2032 forum posts|
When you say it has "8 slots on the tumbler. None of the others I have seen have tumbler on the lead screw" it sounds as if you are saying it has a screwcutting gearbox fitted. Tumbler normally refers to the mechanism by which the lead screw direction of rotation is reversed using tow gears on a lever operated pivot.
If it has got a gearbox the only Granville machine documented as having gearbox is the Star, essentially a slightly enlarged and improved Senior. See this link for details **LINK**. If it is actually a Star or has the Star gearbox fitted this unit is essentially a Southbend 9" gearbox copy and therefore functionally the same. Boxford and Denford also used a SouthBend copy.
Alternatively the machine may have been fitted with a home built gearbox such as the Sparey and Agola designs or the Hemingway kit shown here **LINK** .
It is of course possible that a SouthBend, Boxford or similar small lathe gearbox has been grafted on by previous user.
Whatever the metric screwcutting conversion will be done in the same way using 127-100 compound gear pair to do the metric conversion with appropriate other gears fitted. An internet search for Boxford Metric Screwcutting Gear Chart will give several to choose from. In general the method is identical with the extra gear choices being governed primarily by the lead screw pitch and gears available. Published charts are arranged for clarity and simplicity with a simple linear format and need a selection of extra gears. Versions using fewer gears can be found but then to be harder to follow as the changes hop around rather. If slightly imperfect, but still adequate for faster use, conversion is acceptable you can get away with even fewer gears. Various examples can be found on the internet.
|Gareth Wilkinson||22/01/2020 19:18:39|
|4 forum posts||
That would be fantastic if you could!
Thanks so much, really appreciate your help
|Gareth Wilkinson||22/01/2020 19:20:17|
|4 forum posts||
Thanks so much Clive!
Appreciate your feedback!
|Gareth Wilkinson||22/01/2020 19:21:58|
|4 forum posts||
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