[AT] OT: Cast iron work on a replica cannon

[Rena Glover Goss]

THAT'S NO FAIR, SPENCER.  You were not supposed to figure out how simple those relationships are in the metric system when compared to any other system of threading.  I used a reduction by 1.5 millimeters so the thread engagement came closer to 75%, as is used in the SAE system.  There are no charts for pilot drills in the metric system--they simply aren't needed.

Larry
---- Spencer Yost <spencer at rdfarms.com> wrote: 
> I’ve been giving this some more thought, and I am actually now a little more serious about metric if you can tolerate the idea of a metric bolt on a canon.. All you need are:

15 mm x 1 threads per millimeter tap.
14 mm drill for initial boring prior to tapping.
A 15 mm x 1 threads per millimeter bolt at the length you need.

No special tooling, no  excessive drilling diameters, etc.  A single thread per mm is a course pitch so it meets that requirement.  This is all fairly cheap, straightforward, available from major Internet retailers and probably your local fastener store if you have such a beast. I am lucky - I have three.


Anyway you go, best of luck.

Spencer Yost

> On May 4, 2019, at 9:58 AM, James Peck <jamesgpeck at hotmail.com> wrote:
> 
> About 10 years ago I was on a flight to Kansas. I can't quite remember the sequence of events. I heard large men speaking a language I do not remember hearing before as I got on the flight. One ended up seated next to me. Turned out they were from Dronningsborg and were going to Agco in Hesston for a project meeting. 
> 
> I asked what they were doing about metric fasteners. The Dane said that they had been all metric until Agco purchased them. They had been switched to mixed metric and SAE.
> 
> It may be irrelevant. Agco shut down Dronningsborg and bought into Laverda. Are the combines made for Agco by Laverda all metric? Why would they not be?
> 
> https://en.wikipedia.org/wiki/Randers
> 
> [Al Jones] Metric is the work of the devil...…..
> 
> Helicoils are wonderful.  Very easy to do and they WORK!
> 
> My white demonstrator Super A that I have been tinkering off and on forever had four badly stripped holes in the torque tube.  Somebody had tapped the 5/8" holes out about 7/8 or so and it was BAD.  There wasn't any threaded inserts that I could find that would be direct replacements.  A machine shop friend of mine was nice enough to make a set of inserts, kind of like the KeenSerts, and install in the torque tube.  Once it's painted I don't think you'll be able to tell that anything ever happened to it!
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