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PostPosted: Mon Nov 16, 2009 2:47 pm 
Retro Guru
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Joined: Wed Jan 02, 2008 10:45 pm
Posts: 739
Location: Suffolk-Stratford-Suffolk.
Interesting to see who the CAD designers/ engineers are out there.

Sometime back, I briefly mentioned I had a scan project underway in this thread here- http://www.retrobike.co.uk/forum/viewto ... c&start=15

In Automotive design, one of the reverse engineering applications we use is called 'Photogrammetry scanning'. We use this to capture surface data ( normally from a clay surface ) and export the files into programs such as Alias, 3d studio and Icemsurf. This can also be exported into CAD/CAM packages to create a cutter path.
This scan of a crankset is part of a project to demonstrate the capabilities of our equipment ( we can't show our day to day stuff!! ). It also helps if your interested in retrobikes :D


The complete scan was completed in around 6hrs and was positioned and rendered using Alias software. The process does not damage the object in anyway... the powder spray wipes off!!

Would any of you be interested in taking this file into your own package and see what's achievable with it? ... basically I'm keen to see how outside suppliers/ engineers deal with our scan quality.

PM me if so.

Cheers,
Boy"O"boy


Attachments:
Crankset_full.jpg
Crankset_full.jpg [ 140.07 KiB | Viewed 498 times ]
crank_detail.jpg
crank_detail.jpg [ 169.6 KiB | Viewed 498 times ]
crank_inside.jpg
crank_inside.jpg [ 140.25 KiB | Viewed 509 times ]
crank_reverse.jpg
crank_reverse.jpg [ 242.96 KiB | Viewed 512 times ]


Last edited by boy"O"boy on Mon Nov 16, 2009 3:36 pm, edited 1 time in total.
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PostPosted: Mon Nov 16, 2009 3:32 pm 
Retro Guru
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Location: Suffolk-Stratford-Suffolk.
Here's some more pics of the Photogrammetry process.


Pic. 1
The object to be scanned is covered with reference dots. The 'odd looking' stickers are coded markers. Scale bars laying along side allow the tritop program to determine the size of the object.

Pic. 2
The Coded markers and reference dots are photographed from a number of positions. The images are processed in the Tritop software and provide a digital file of the reference dots. This is accurate to 0.04mm of the actual object.

Pic.3
The reference dots are then scanned to capture the surface data. The scan works by measuring the contrast of the fringe projection ( black lines on surface) against the recognised reference dots.

Pic.4
The Finished scan is processed into polygons and exported in an stl. file.


Cheers,
Boy"O"boy


Attachments:
File comment: pic 1
Framescan1.jpg
Framescan1.jpg [ 231.46 KiB | Viewed 492 times ]
File comment: pic 2
Framescan2.jpg
Framescan2.jpg [ 194.46 KiB | Viewed 492 times ]
File comment: pic 3
Framescan3.jpg
Framescan3.jpg [ 162.52 KiB | Viewed 492 times ]
File comment: pic 4
Aluminium_O_scan.pic2.jpg
Aluminium_O_scan.pic2.jpg [ 110.56 KiB | Viewed 492 times ]


Last edited by boy"O"boy on Mon Nov 16, 2009 4:00 pm, edited 1 time in total.
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PostPosted: Mon Nov 16, 2009 3:46 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader
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Location: The desolate flats of Cambridgeshire
Boy O Boy, Would love a copy of that file. I have used 3D scanners to produce cloud point models before, but never been overly impressed in the accuracy, everything I have tried has needed quite a lot of tidying up manually after scanning, to the point where it may have been quicker to model from scratch.

As for outputting to CNC directly, yes you do still need to do tool path files but most of this is automated and requires a check. Most of my output these days is using rapid prototyping, particulary keen on DMLS technology.

Would love to create a component in Titanium DMLSwith a honeycomb core.


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PostPosted: Mon Nov 16, 2009 4:13 pm 
Retro Guru
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Location: Suffolk-Stratford-Suffolk.
JeRkY wrote:
Boy O Boy, Would love a copy of that file. I have used 3D scanners to produce cloud point models before, but never been overly impressed in the accuracy, everything I have tried has needed quite a lot of tidying up manually after scanning, to the point where it may have been quicker to model from scratch.



No problems, PM me your address and I'll get a copy to you. Stl. format ok for you? Each part has been scanned separately and is about 6MB.
This file will also need some cleaning.... The threads for example don't capture very well... although I have done my best to clean up as much of it in the original scan as possible.

cheers,
boy"O"boy


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PostPosted: Mon Nov 16, 2009 4:32 pm 
King of the Skip Monkeys
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:shock:

why was it that when I went to college to do my so called 'electrical & mechanical engineering' and 'Art & Design' courses, nobody mentioned any of this sort of thing.

I expect quality CNC parts very soon.


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PostPosted: Mon Nov 16, 2009 7:02 pm 
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
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we also had a 3d printer at college from a company called z corps i think. would print 3d from a fine polymer powder i think. ideal for prototypes but damn expensive!


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