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Hemingway Kits
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Author:  Alpha1 [ Fri Mar 27, 2020 1:03 am ]
Post subject:  Re: Hemingway Kits

I have transferred all the drawing stuff onto autocad. so I can do what I want with it now.

teanews hmm whats next.
BED TIME. zzzzzzzzzzzzzz

Author:  Alpha1 [ Sat Mar 28, 2020 1:14 am ]
Post subject:  Re: Hemingway Kits

My lathe is a metric lathe so I have converted all the dimensions to metric in autocad.
My Myford ML10 is probably imperial but its only really any good for screw cutting. Its to small for anything else.

Author:  Ovenpaa [ Sat Mar 28, 2020 8:11 am ]
Post subject:  Re: Hemingway Kits

What is the all metric lathe you use?

I have a Chipmaster that although capable of metric screwcutting is only used for imperial work albeit I only work in metric!

To explain, I am of an age where I experienced the change to metric dimensions back in the 60s. At that point I chose metric and tried to stick with it yet I grew up with people who were imperial through and through so I worked with both. These days my DRO's are permanently set to metric yet I still mentally swap back to imperial for small measurements as I was brought up with British motorcycles. So when I am clocking in with a 0,01mm clock, when it is done I tend to convert the needle deflection to thousandths, so half one increment (0,005mm) is just under two tenths.

Anyways... It is not so bad, a 1/2"x20tpi (UNF) thread starts at 12,7mm and I take initial cuts at 0,1mm or four thou ish, halving it towards the end which gives a good finish as long as the machine TPM is at a decent level.

I dislike imperial drawings and always convert anything I am sent to metric and CAD so it is stored for future reference, plus CAD and metric is handy as I can very easily calculate the weight of an item by taking the material density which is always available. I am making parts for some two mile competitors and everything I do is metric even though they are using 'imperial' projectiles.

Next job when I get a chance is a DRO on the surface grinder even though the vernier scales are super accurate, I just like DROs

I need more coffee.

Author:  Mattnall [ Sat Mar 28, 2020 9:31 am ]
Post subject:  Re: Hemingway Kits

I have the opposite problem in that I was brought up working with Imperial units (although the metric was coming in) and have to convert the metric values to be able to understand the sizes involved. Then I got a metric Harrison lathe and had all sorts of trouble - I find I can visualise 10thou easily but fractions of a millimetre aren't so easy.
In the end I fitted a DRO to it and now I have the best of both worlds.

Author:  Ovenpaa [ Sat Mar 28, 2020 9:43 am ]
Post subject:  Re: Hemingway Kits

I always thought you were younger than me Matt, I was born in '57. Having said that, I deal with people in the trade who are a couple of decades younger and still insist on sending me imperial drawings.

Author:  FredB [ Sat Mar 28, 2020 12:05 pm ]
Post subject:  Re: Hemingway Kits

Although I am almost a dinasaur, I was mostly educated at school in the metric system. I should say "a metric system". It was the MKS system of units---metre kiligram second---in which the kilogram could be unit of force and the Newton did not exist.
When I joined Leyland Motors in 1960, the company was very much an imperial unit organisation, with a leaning towards american standards such as UNF threads. Having completed a student apprenticeship, I went to work in the truck design office. Chassis fasteners were UNF but the engines and transmissions were BSF. In the mid 1960s, with the formation of British Leyland, the company decided to adopt the ISO metric system. By the early 1970s, we still had UNF chassis fasteners, some BSF engines and one metric one. We also fitted Cummins engines on the bigger trucks and these were UNF/UNC.
As a result of all this, I am able to think in virtually any system, but I prefer the Imperial. The units are sensible in size, where many metric ones are not. A pascal, for example, is a newton per square metre of pressure. Since a Newton is roughly the weight of an apple, this amounts to the pressure exerted by an apple spread over a very large manhole cover. It is a stupid unit and brings about the need to use gigapascals in every day use. What was wrong with pounds per square inch?
Many metric calculations use powers of ten. It is easy to forget wether you need ten to the power six or then to the seventh and this leads to many mistakes.
Most imperial conversion factors are not used for anything else, such as 2240 pounds in a ton and 1760 yds in a mile. Once learned, these numbers are not used for anything else and are easy to apply.
There are 7000 grains in a lb of powder and 15.43 grains in a gram. I am not intending to change my reloading systems.
Imperial for ever!

Author:  Mattnall [ Sat Mar 28, 2020 12:07 pm ]
Post subject:  Re: Hemingway Kits

Dave, I'm about 10 years younger, but engineering at school was taught by an old boy who refused the metric system (although we had to know it, just not use it so often), my whole early working life was with aircraft testing and hardly any of them were metric, everything was psi,, unified, and my works were so old we still had original test machines for Merlins, Griffins and we even worked on many B17s. When I started flying most everything was in imperial and now many firearms parts are also either imperial and unified threads or some strange made up threads that no one else uses.
Then when I went farming it was still acres, lbs/acre, gallons, etc, but litres were making an inroad, now I leave the hard work mostly to my kids and they have the metric system down pat.

I can 'do' the metric system but I find it easier to visualise fractions/decimals of inches when working on small parts.

Author:  Mattnall [ Sat Mar 28, 2020 12:43 pm ]
Post subject:  Re: Hemingway Kits

I'm with you Fred.
The Unified system was meant to unify the US, Canada and the UK but somehow the metric system (and no doubt with some considerable pressure from European countries and the UK's choice to join the EEC) dominated here. It is easier to manipulate figures from a calculation point of view but the elegance of the Imperial system is what I like.

Going back to flying it is the mix of units that I find strange. For height, altitude or flight level we used to set inches (of Hg) then it metricated to the Bar, but that was too big so millibar was used, but as mBar is not metric enough we now have to use Pascals - but that is too small so it is hectoPascals (hPa) which coincidently is the same number as the mBar.

So now the world above ground is recorded in an imperial unit (feet) that is measured in a metric unit (hPa) and converted. Where's the confusion in that?

Author:  kevinww [ Sat Mar 28, 2020 10:13 pm ]
Post subject:  Re: Hemingway Kits

I am happy working in either metric or imperial and converting, goes back to my days working for a well known aircraft manufacturer where we would be making parts for Harrier GR5 and AV8B aircraft always imperial or Hawk 100 and 200 aircraft always metric.

You normally had your own dedicated machine that was either metric or imperial so you would have no choice but to mentally convert, I have a preference for imperial though.

Author:  Alpha1 [ Sun Mar 29, 2020 12:11 am ]
Post subject:  Re: Hemingway Kits

I was born in 1951 I can easily visualize small diameters in imperial but not in metric.
When I started in my current job 15 years ago it was and still is up to me to supervise discharging the reactors all the measurements during the process and there are a lot were in metric I was allocated an Engineer to over see the process because the measurements meant nothing to me.
Obviously I have learnt since then.

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