how to make an accurate cylinder

Hello,

Automatic generation of gages method is used to make accurate and precise flat surfaces.

I am very interested in knowing how can one make an accurate cylinder using similar techniques or other techniques.

How accurate? Well, as accurate as it can get for a machine part or something, just very accurate, maybe like as accurate as cylindrically shaped parts inside a modern car engine.

(SI) Basically, to make a very accurate cylinder, for example 200mm long and 50mm diameter, without using any accurate modern tools.
I when I measure the diameters in multiple places along the cylinder, result be 50mm +-0.01mm at worst.

(US) Basically, to make a very accurate cylinder, for example 8000mil long and 2000mil diameter, without using any accurate modern tools.
I when I measure the diameters in multiple places along the cylinder, result be 2000mil +-0.4mil at worst. (mil=thousandth of an inch)

Basically an ancient man, who knows how to cast metals into crude/inaccurate shapes (as accurate as can be handmade), (and maybe also knows how to make a surface plate if thats definetely a requirement for a cylinder?), trying to make an accurate cylinder.

Hope I could explain my thought and hope to get your very good helps.
For years this question puzzled me. No one likes prisons.

Thanks in advance.

roboticmehdi said:

Hope I could explain my thought and hope to get your very good helps.
For years this question puzzled me. No one likes prisons.

Thanks in advance.

Click to expand...

Please explain......

Generate a flat surface as a bed for your lathe. Turn a cylinder.

If you insist on not using a lathe. Generate a straight edge and a make a diameter gauge, keep scraping your rough cylinder until it is straight and to size.

I imagine you're looking for something analogous to the three plate method of generating flat surfaces. You could generate a square with the surfaces too, but an accurate cylinder requires that you hold a specific dimension, which is a different puzzle.

fciron said:

Generate a flat surface as a bed for your lathe. Turn a cylinder.

If you insist on not using a lathe. Generate a straight edge and a make a diameter gauge, keep scraping your rough cylinder until it is straight and to size.

I imagine you're looking for something analogous to the three plate method of generating flat surfaces. You could generate a square with the surfaces too, but an accurate cylinder requires that you hold a specific dimension, which is a different puzzle.

Click to expand...

The OP is not "looking" for anything...only google rankings, which they have achieved by posting here.

Perhaps two stones cut with a harder stone and rubbed together to make a taper that would expand the diameter as the stones were brought together and the taper moving the stones outwardly...perhaps also using a grit of sand or other particles.

No opinion on whether the OP is posing a legitimate question, but presuming he/she/it is.

For generation of reference tools it makes a lot more sense to develop a right angle square rather than a cylinder. This you can do by generation to the limit of your measuring instruments.

If he/she/they really want an accurate cylinder, lapping would be the way to go, again limited only by patience and measurement ability.

Think the OP is asking a history/ archaelogical question ,needs a pass in history to offset the F- he s getting in English ....Actually James Watt faced the same problem in building large atmospheric engines .....the 10ft diameter x 20 ft stroke cylinders were hand finished by scraping and chiseling "accurate to the thickness of a shilling" out of round and straight by using a taut string as a measure.

A lathe is not a modern machine tool, but very ancient. A crude conical point poked into a crudely-matching conical hole in one end of your only-roughly-cylindrical workpiece will hold its position. If you do that at both ends, it will revolve around an axis. If you maintain contact as your rough centers wear-in, you may achieve stable, accurate rotation around that axis.

Then generate two intersecting accurate flat surfaces: a prismatic way. Set it up approximately parallel to your workpiece's axis of rotation, and use it to guide a cutting tool. The deviations form true cylinder will guide you to get the alignment closer and closer, until your workpiece becomes "cylindrical" to the limit of your ability to measure.

That is the theory looked at through wrong end of a telescope. Hundreds of years of practice is available for study.

magneticanomaly said:

. A crude conical point poked into a crudely-matching conical hole in one end of your only-roughly-cylindrical workpiece will hold its position. I

.

Click to expand...

A crude conical point will not genarate a straigt line
It will wobble

I would sugjest to do it like its done
Start with a rough machine and with that make a better one with a lott of skill
With that make yet another better one And so on
No shortcuts found so far as I know of

Peter

Lathe history.
History of Lathe from Beginning of Machine Tool Invention