metric plans

[Chriske]

Hi,

This is how my screen looks like while drawing.
The conversiontool works very well and very fast.

 

[Swifty]

The problem is that bar stock in either system of measurement has reasonably large tolerances, so buying a 6mm piece of x material may yield a bar that measures anywhere from 5.5 to 6.5 mm and the same goes for imperial, a 1/4inch round bar may measure from .225 to .265 inches. Metric drill bits and reamers are just as much of a problem also, a 6mm drill bit may actually measure 5.8 to 6.2 mm,

I would be definitely changing suppliers if I were you. Want closer tolerance steel, buy cold rolled. As far as drill bits go, in over 40 years as a toolmaker I have never found a drill bit to be as far undersized or oversized as you have.

Paul.

 

[Chriske]

I would be definitely changing suppliers if I were you. Want closer tolerance steel, buy cold rolled. As far as drill bits go, in over 40 years as a toolmaker I have never found a drill bit to be as far undersized or oversized as you have.

Paul.

Indeed,

I would change supplier to. If I'd buy say a 9.2 mm drill-bit I'd expect it to measure exactly that...!
And if I buy a 6mm brass rod. I expect it to be a h8 tolerance, no more no less. !! Bronze is another story, the production process does not allow close tolerance, so bronze will differ an few tenths of a mm.

Chris

 

[lensman57]

am i being to fusy to expect to buy plans in metric?

i,m looking at my 1st build, and i know its relatively easy to convert, but to start changing a fraction to a decimal then x 25.4 is becoming a pain i can do without. ok doing 1 or 2, but they just dont convert ? or am i being stupid.. ie 1/2" = 0.5 x 25.4 = 12.7mm !!! now come on... 12.5 or 13mm i can cope with...

i have been trying to find metric plans for a simple (ish) static beam engine for ages now, without success.

any help guys for a simpleton ?

Hi,

I used to be metric guy like you too. In uni never came to terms with imperial units. Once I started this hobby things changed, I can move between imperial,metric and fractional without even thinking about it. I bought a cheap fractional vernier and converted all the plans dimensions to metric to start with after a while it became second nature to me. Most of the plans for these model engines were drawn a very long time ago and then imperial was the accepted standard, you need to adapt if this is going to work. I have fitted cheap calliper s and dot into my lathe and mill and conversion between the two is not a problem.

Good luck,

A.G

 

[lennardhme]

I would rather be machining than working on plans [ too old to learn a cad program - time is the problem ] I get around the issue by establishing the shaft & thread sizes then drilling, reaming to suit. Everything else is sized from there.
Because of the Imperial/ Metric conflict I have never built an engine to plans. keeps the grey cells ticking over, which is my main interest in machining.
I was recently going to purchase taper pin drill/reamers & decided to go metric till I found the taper pins available in Oz. are imperial. Just have to keep your wits about you, but can be frustrating, especially for newcomers.
A you make more engines you will gradually work out a system - keep at it.