Okrasa Special

[Barry]

: Well, yes, there is the measuring rig (nicked off of the jig), what I meant was how to actually compile the measurements, and more to the point get them onto the model in a way that didn't involve machining, and didn't involve starting off with a big block and shaving it down a bit, measuring, shaving some more, and so on. Oh yes, and a simple thing, how to measure downwards, dead vertical, to a point, but knowing exactly how far down you're reaching: not easy with restrictive height (the ceiling, not me). That had me stumped, but a friend wandered in, and straight away showed me the method.

Anyway, I'll sort some pics out, and show how I went about it. Rest assured it's deeply un-impressive and low-tech, although ended up being quite effective.

[Pandora]

MDF? Crikey Barry, you're a masochist!

Anyway, here is an example of a 1/10 scale model rig. 1/10 and 1/5 are good scales to use 'cause the sums are easier! You might just be able to make out the high tech pointer - a needle dipped in red paint (well, nail polish actually!) taped onto the movable arm....... Heath Robinson has nothing on the home car designer!

(Steve still in the shed embracing his artistic side???????)

Al

[roy mawbey]

Goodness,

There are some clever bu**ers on here without any doubt. And nice ones too for advising. Am I the only one that was foxed by all this? Understand much more about it now but as you ( the clever ones ) can probably guess, its not all the story because this special material? comes into the story regarding the body?

Great thread, one of the best.

Roy

[Bruce M]

The really clever b**ger is the one (Barry ) who transferred the measurements to the wood

You either start over sized and cut it down. Perhaps by marking up the rough shape with a grid in two planes and use a pillar drill to cut lots of precise depth holes (sanding down to match the pattern of holes. Or start under sized and build it up. Maybe using small pin nails to mark the final surface height and build up to that height with filler (sanding back to match the nail head heights).

Either way, the level of accuracy and precision would have me throwing it out the window long before it got to that stage.

[Pandora]

As I understand it, what Barry did was to confirm the location in 3 dimensions of points in a grid over the entire surface of the car relative to fixed datum points. Using this he was able to identify the vital points at 'slices' through the car, which he could then transfer onto sheets of MDF. By building up the layers / slices you then remove the excess to smooth the curves across the slices.

Imagine trying to make a scall model of a loaf of bread - you make scale models of each slice, then add them all together, then smooth the transitions etween the slices to form the rounded top of the loaf.

Only, Barry didn't slice the car up.

And it's a LOT harder to do than typing it! It's so easy to transpose a width for a height measurement, or miss-read a dimention and then it all gets VERY confusing.

Once you are in a rythm it's quite absorbing taking the measurements, but when you loose concentration it becomes incredibly frustrating.

Can't find the records I kept from the above model, but here is a scan of the data William Lyons gathered to create the C Type Jag. (I have to say I only found this out after I'd worked out my own system, which made me quite chuffed at the time!) I think the figures relate to position along the car's length and width from centre line along the main axis, and then where these columns intersect the heightc fom the ground or chassis bottom/ car floor.

Oddly though, William Lyons designed the C type (and the D) using mathematics - he worked out the figures THEN made the model........ He was a clever guy!

The good news is that Barry can now build C Type bodies too.......... ;0)

[roy mawbey]

Guys,

Thankyou all so much for that information. The loaf of bread makes a good example. To do that work 60 years ago manually makes you realise they were no fools back then. While today you have 'touch probes' on CNC machines constantly comparing in process to datum references automatically, with glass linear scales and encoders operating all axes, you also realise the electronic boffins are very clever as well. The trouble is, its push button not many operatives really know how it all works, they make a program and off it all goes much like everything else in todays world.

Again thanks,

Roy

[Pandora]

Exciting news: the announcement of an environmentally friendly new race series!

Race report 1.

Rather than burning fuel in the race and all associated travel, the new series takes place in the competitors garages.

Challenging Steve's early lead is a new competitor, who has made a phenomenal start after his delays, using just basic equipment and zero preparation time, he has made up a load of ground in just one day.........

Who will be first to the finish, which in this race is actually the starting grid?????



Al












(Just a silly thread hijack to keep you all in the car designing mood whilst work progresses on the Okrasa (and it is progressing)

[louis356]

This all reminds me of the story of the development of the TVR Griffith or Chimerea.

Don't know if it's true or not. But when it was being designed they had a big block of Styrofoam that they were shaping and sanding when Peter Wheeler's dog came along and took a chunk out of it. The modification stayed. don't know if this is true or some marketing myth.

You might have to get a dog in there to help you out!

[911hillclimber]

Nice classic Clubmans racer.

Will the English wheel soon be rolling?

[Pandora]

For the Okrasa, hopfully.
Not for mine though, as I'll be using GRP (assuming I fail to sell it first)

[911hillclimber]

You may sell it on www.uphillracers.com
Graham.

[Pandora]

tried there, but no one 'bit' or at least not at a price that would tempt me to sell.

Anyway, Steve, you finished yet?

[steve wright]

Yes I love a race but starting new job has got in the way unfortunately. I've created one version in foam that comprises the door, rear quarter panel, and then three different variants on the rear wing and boot. I finished these on Tuesday and decided to return to them at the weekend to look at the afresh. Unfortunately the foam doesn't photograph well so I'm planning to purchase some primer and rattle can top coat this weekend, spray them next week one evening, and then post images shortly. I have to say its been fantastic finally after three years being able to directly express my ideas in 3D. Up till now it's been through drawings (not mine) or via Barry doing the wireform buck. That's no criticism of either but it's not the same as creating it yourself. It's also harder than it looks, so it gives me a newfound respect for what Barry and Al do, seemingly with such ease and aplomb!

[Pandora]

Meet the aplomb special!

Needless to say, I'm not practicing what I preach, and no models were harmed in the project so far.

I really should practice what I preach!

[steve wright]

full scale! Blimey you're upping the ante! Paint & spray filler bought today, hoping to get up there next week....