Anatol
Aluminum
- Joined
- Jan 19, 2018
- Location
- Los Angeles
Hello Everyone.
I've been thinking about Joseph Whitworth and his 3 plate method. In the 1830s, Whitworth formalised a method for creating flat (reference) surfaces, using scraping, correct to around 1/1,000,000”. (Not‘smooth’, but geometrically flat). This was called the three plate method - because it involved three plates. As I understand it, he did not actually invent the three plate procedure, it had been used with grinding (paste?) techniques). But he increased its accuracy and was able to measure it with the bench micrometer he built, accurate to 1/100,000”. This was a milestone in the history of precision engineering.
Question 1. Is it necessary to have 3 plates? Is there a simpler method to create flat surfaces?
Discussion.
Imagine we have two 1’ square plates. For arguments sake, imagine they’re the kind if concrete pavers you get at Home Depot.
Put the undersides together and label the the ends NSEW for both plates.
Line them up N over N.
Rub the plates back and forth in a NS direction. What kind of surfaces may be generated?
A.Both might get NS striations.
B, the rubbing make create a longitudinal valley or valleys - big striations effectively.
C. transverse hill or valley may develop on the lower or upper plate.
D. a combination of 3 and 4 will produce toroidal surfaces
E. by some miracle, both might be flat.
Assuming not E, rotate the top plate 90 deg, so its N is over E on the bottom plate.Continue rubbing as before, on the NS axis of the lower plate.
Question 2. will this remove all the possible errors induced in the previous process.
Question 3. if not, what procedure, if any, using two plates, will result in two flat plates?
I'd be very interested ty hear any opinions, or preferably, proofs
with thanks,
A
I've been thinking about Joseph Whitworth and his 3 plate method. In the 1830s, Whitworth formalised a method for creating flat (reference) surfaces, using scraping, correct to around 1/1,000,000”. (Not‘smooth’, but geometrically flat). This was called the three plate method - because it involved three plates. As I understand it, he did not actually invent the three plate procedure, it had been used with grinding (paste?) techniques). But he increased its accuracy and was able to measure it with the bench micrometer he built, accurate to 1/100,000”. This was a milestone in the history of precision engineering.
Question 1. Is it necessary to have 3 plates? Is there a simpler method to create flat surfaces?
Discussion.
Imagine we have two 1’ square plates. For arguments sake, imagine they’re the kind if concrete pavers you get at Home Depot.
Put the undersides together and label the the ends NSEW for both plates.
Line them up N over N.
Rub the plates back and forth in a NS direction. What kind of surfaces may be generated?
A.Both might get NS striations.
B, the rubbing make create a longitudinal valley or valleys - big striations effectively.
C. transverse hill or valley may develop on the lower or upper plate.
D. a combination of 3 and 4 will produce toroidal surfaces
E. by some miracle, both might be flat.
Assuming not E, rotate the top plate 90 deg, so its N is over E on the bottom plate.Continue rubbing as before, on the NS axis of the lower plate.
Question 2. will this remove all the possible errors induced in the previous process.
Question 3. if not, what procedure, if any, using two plates, will result in two flat plates?
I'd be very interested ty hear any opinions, or preferably, proofs
with thanks,
A