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  #11  
Old 07-08-2020, 11:27 AM
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Superleggera Superleggera is offline
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Simple adage is "you get what you pay for". Think about how many thousands of hours you might have in actually building of a ground-up project. How much money in materials, consumables and driveline components along with creation of bucks, fixtures and more does one have invested? Why waste all of that because the basis for the whole design revolves around a $99/set of sectional files that you have no clue if they are correct or not!

Recently I visited someone who spent three years (@1700 hours) building an aluminum bodied Porsche 356 spyder over a 550 styled tubular chassis. He never once actually validated the measurements until he realized something wasn't right. I got a call to come take a look. The cockpit wasn't sized for a person to fit within -- it was several inches narrower than original. The wheelbase was wrong. Cowl height was wrong. Every dimension was wrong. It was a 7/8th scale version at best and a bit distorted. He has something that looks "somewhat correct" but will never be finished as nobody aside from his young teenage son could fit within the cockpit. The project is going to become wall art now. He has about $6000 in materials wasted. Three years of time wasted which he can't recover. And for what -- because he didn't validate what he received because the plans were from someone "who had sold several sets of designs and all were being built". I'm guessing there will be thousands of hours of wasted time to become wall art at best once they realize the same.
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Last edited by Superleggera; 07-08-2020 at 11:42 AM.
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  #12  
Old 07-08-2020, 07:39 PM
cliffrod cliffrod is offline
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With the prevalence of so many scale models of popular vehicles on the market, especially ones loudly touted as "accurate" and "authentic" on the label, and the increasing availability of 3D digitizing equipment & cad, it seems likely that the two will come together to provide such electronic buck files at bargain prices.

The problems involved with enlargement of model and proofing them are significant. Accurately scaling up a smaller scale model is best done in small steps, with each enlargement properly corrected before the next enlargement. Dimensional Information is lost when the shape is reduced in size and is added when the shape is enlarged in size. Simply put- if given two points, at least one point will be added between them as they move apart when enlarged. Repeat, repeat, repeat until done. Assuming or guessing is bad technique. Enlarging more than 2x per step can be done, but is risky and inaccurate.

Just like many original coachbuilt cars vary in symmetry from left to right, great looking small models regularly have significant problems. It's not uncommon in my sculpture work to spend many billable hours, if not days, measuring a small scale model with compasses to then correct it before proceeding. Even with digital scanning and 3D milling, the foundry I use will typically enlarge a brilliant-sculptor-friend's work no more than approx 2x at a time. To produce an 8 foot final statue from an approved 1' tall initial model into an 8' tall finished statue will take 3-4 steps. 1', 2', 4', sometimes 6', 8'. At each step, the job will be completely modeled again in clay over milled foam core to add information and correct discrepancies, then scanned again for the next round of the same process. For the best & most accurate work, there are no shortcuts.

Those station buck e-files are even more seductive. If you want to build a Cobra 550 Spyder, you already see the result in your mind and justify the goal/job with the proposed buck/model. Lots of shape information isn't there. But all you see is a shiny metal finished body because that's what you seek.... Don't make assumptions.

When you know the scale of the original model or source vs the job, you'll have a better idea of the value of the item/file/buck at hand. A full size, 1:1 (model:job) ratio is always the most accurate model to use.
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  #13  
Old 07-09-2020, 12:16 AM
Jaroslav Jaroslav is offline
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Yes, if a toy model is used for scanning, everything is different. In college, design teaches that if, for example, the real thing shrinks, it must be done in proportion and adjusted. This means that a sharp reduction or enlargement does not work. If you just shrink the thing, it looks bad. It needs to be fine-tuned.
But it's tempting with today's technology.
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  #14  
Old 07-09-2020, 03:29 PM
vroom vroom is offline
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I have spent a lot of time and some money building a buck for my 166MM project and have a couple conclusions:

Using scan data AND learning to manipulate it is WAY too expensive and involved. Requiring multiple iterations to get even close to right

Accurately reproducing any early (pre 80s) hand built car is a fools errand. They weren't building duplicates. They were building sculpture.

Sitting in front of a computer is boring. Metal working is enjoyable!

My advice, not that anybody cares, is to buy a bunch of aluminum and wire and form what looks good to you. Aluminum has good scrap value.
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  #15  
Old 07-09-2020, 03:39 PM
Jaroslav Jaroslav is offline
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Yes, when it comes to free fantasy creation, you can create any monster you like. If this car is well known and there are comparable originals, you have a problem. Unnecessary work and smiles.
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  #16  
Old 07-22-2020, 09:53 AM
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Kerry Pinkerton Kerry Pinkerton is offline
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I ran across the Russian guy Kitcarik.ru again and asked him if he scanned real cars or based his bucks off scaled up models. His reply:

Quote:
I myself make electronic drawings for car buck. I do not scan cars, I already work with ready-made 3D scan models for example from the Forza game. Precision 1:1 with original cars.
Forza is a video game. Somehow he has gotten access to the data that the game uses and manipulates it into a buck. I'd not expect these to be accurate at all compared to the real thing. I don't know what Forza uses to create the 'primitives' that they display in 3D but I doubt it's a scan of the real thing. My technology level with solid modeling is about 30 years old which, these days, is prehistoric.
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  #17  
Old 07-22-2020, 03:37 PM
Chris_Hamilton Chris_Hamilton is online now
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The various Forza models have been on the web for years. The protection was cracked and the models have made their way into other Racing Simulations like GTR2, rFactor, Assetto Corsa, etc. by people who mod (modify) those games. Legal? No. But according to what I have read, some of the Forza models were based off real scans.

https://www.cnet.com/roadshow/news/j...ed-into-forza/

https://www.google.com/search?client...4dUDCAs&uact=5
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