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8th May 2015, 05:03 PM #31
SENIOR MEMBER
- Join Date
- Nov 2010
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- Gippsland Victoria
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- 25
Paul,
Many thanks for the fascinating links - I didnt know about that thing and clearly they were able to divide up circles and play with angles and geometry with a high levele of understanding and metalwork skills.
The manual cog cutting technique reminded me of something I'd read recently about dividing wheels where there could be (maybe ?) a way of estimating the dividing holes on a first attempt at a dividing wheel and then sticking it on the dividing head and then using the dividing head somehow to make the second one more accurate - I dont know enough about how that works but will find the book and post it here in case anyone is interested. Maybe I am raving - must find the book I was reading a few days ago and check it.
Found a link - I dont understand this idea yet but somebody may be interested. Probably discussed in many places.
http://www.homews.co.uk/page427.html
BillLast edited by steamingbill; 8th May 2015 at 05:20 PM. Reason: typos and added link
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9th May 2015, 02:41 AM #32
This is how I read it ...
Anyone can gauge a full rotation perfectly accurately, assuming the fit of the shaft and etc parts, with just a single mark.
If everything else is up to scratch, then 1 rotation will bring you to the same place every time,
and with eg a 40x reduction gear, each full rotation should give you precisely 9o on your workpiece.
So eg to mark 40o on your workpiece, you need to move 36o by full rotations plus 4o by a part rotation (of the divider).
The part rotation will be 160o on the divider, which we assume is accurate to +- x degrees.
So the resulting movement of the workpiece will be 4o +-(x/40) degrees ... total movement 40o +-(x/40) and you've increased your accuracy 40x now.
Cheers,
Paul
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9th May 2015, 09:32 PM #33
Taking a break
- Join Date
- Aug 2008
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- Melbourne
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- 34
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9th May 2015, 10:27 PM #34
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