Friday 14 June 2013

1 Clean Slate

Have not posted for a while and when looking back at the blog I realized that it served no purpose to keep the old stuff on. Having had no real reason to post about miscreants for some time I have taken down older material and am going to start with a Tabula Rasa as it were. The only post I have kept is the one I started the blog with: both out of sentimental reasons and because it still holds.

Thursday 1 October 2009

1 According to the References

Denigrating an entire kit for tiny errors nobody else gives a toss about

Did you ever get the feeling when some reviewers have used the above phrase, that it should be accompanied by the sound of reverential heavenly music? (see clip below)



I am not referring of course to reference pictures - but measurements, and sometimes how it appears that a perverse pleasure is taken in slagging off an entire kit for the sake of a few millimetres on a dimension which they have measured from a scale drawing. The same type of person can impart a massive importance to small discrepancies, and this can adversely affect the success in terms of sales of any particular kit.

I studied engineering drawing for seven years, and additionally in the last 12 months have completely redrawn many WWII blueprints for restoration purposes in 1:10 and 1:25 scales using CorelDraw. From my studies I already knew that taking a measurement from a scale drawing is a very inexact way to obtain an accurate measurement, and is fraught with dangers. This has been borne out by the work I have recently done on the blueprints. Even a high resolution scan at full size does not mean that lines are straight, or even that time and the elements have not adversely affected the paper itself.

There are only two ways to obtain an accurate measurement:
1. Go to the subject and measure it
2. Use a written dimension already on a drawing placed there by someone who already carried out point 1.

So what do they mean when they say "according to references"? Firstly, since 99.99% of people who use that particular phrase never actually gets to take actual measurements on a vehicle, we can safely rule out option 1 above. Secondly, reference books with measured dimensions are extremely rare, so what they are actually relying on is a 1:35th scale drawing without dimensions. How is that a bad thing I hear you say? Let's take a look in closer detail.

The better reference books contain drawings that have been generated from measured dimensions. However such books usually carry a disclaimer that the drawings are not to be taken as perfect due to the margin of error that can apply. Where does the margin of error come from? It starts when a graphic is printed - distortions can occur when the print file is read by the printer. If the drawing crosses the gate fold then don't even bother to measure it. Secondly there is line thickness - scale drawing lines can vary from around 0.2mm up to 0.5mm where lines are superimposed due to scale reduction of the original diagram. This is a margin of error of between 14 and 35mm at 1:1, and that margin of error itself is the minimum you can get by using a digital calliper - if you are using a ruler it will be far worse. If you were building a toothed gear would you be able to accept a 14mm - 35mm margin of error? Of course not - so why accept it as gospel from somebody who says "according to the references"?

The next time you see this phrase used with regards to a measurement, where the person using it is relying on a scale diagram, remember that what they should be saying is the following:

"When comparing the dimension on the kit to a (1:35/16/72) scale drawing (with/without) measured dimensions - using my (calibrated/uncalibrated)( ruler/digital calliper) I found a discrepancy of 'X' mm. The margin for error on the drawing, when measuring from the outside/inside/middle of the line is Y to Zmm. As the manufacturer based their mould on (measured/diagram) dimensions, the error is a minimum of Y minus Xmm and a maximum of Z minus Xmm."

Without this detail you cannot really make an informed decision as to the methodology and equipment used, nor accuracy of any error that may or may not be there.

Now here's the thing that makes all of the above mostly redundant anyway: Most times no one will know what the manufacturer used to make the kit, so that variable means you can never get a fully accurate comparison unless you have an indicated, measured, dimension for every aspect of every item on the kit.

Additionally, once the model is finished, painted, weathered etc and sits in a display case who is going to know that the hull is 1.5mm too short? Only you, unless your guests are allowed to pick up your models and apply digital calipers.

Makes you think doesn't it?