G3 Forum

In the Workshop : Constructors' Questions and Answers => Best Tool for the Job? => Topic started by: John Candy on January 12, 2018, 08:48:28 AM

Title: 3D Scanning and Printing.
Post by: John Candy on January 12, 2018, 08:48:28 AM
3D Scanning and Printing.

I am on the verge of taking the leap into 3D, with a view to producing my own scale figures ("British" folk in 1930s/40s/50s garb)since available items are either wrong scale or modern American/Continental fashions (women in Jeans, blokes in Stetsons, shorts or Lederhosen, etc.).

Also want to be able to produce patterns for casting loco and rolling stock parts (particularly carriage sides) as well as architectural subjects, to produce more authentic buildings.

I know that the finer the printer output, the better the finish and am looking at hardware in the 20 to 100 Micron range. The two technologies available are SLA (Stereo Lithography which uses liquid resin) and FDM (uses reels of plastic thread).

There are few affordable (for hobby use) printers which can print below 100 microns, one being the Cel-Robox-2 (FDM type) and the other FormLabs 2 (SLA and much more expensive and potentially "messy" but is said to give better results).

Since CAD is not my forte, I shall be relying in part upon being able to scan subjects and manipulate the scans to produce the correct scale output.

The first step will be to acquire the scanner and see whether I am competent to produce the necessary files (and that the scanner can capture sufficient detail to produce decent models).
The scanner I have been looking at is the Sense 3D , a handheld scanner which gives more flexibility than a fixed camera type.

I know some of you have experience of 3D (either as a producer or a customer of a scanning service) and hope you can provide feedback on experiences with this technology.

Title: Re: 3D Scanning and Printing.
Post by: Spitfire2865 on January 12, 2018, 01:18:37 PM
If you need help designing some components, I can give you a hand. Im good at artificial 3D design such as rolling stocm parts, but am absolutely hopeless at anything natural or organic.
Title: Re: 3D Scanning and Printing.
Post by: Gavin_B on January 12, 2018, 06:57:29 PM
I have 2 Wanhao I3+ FDM printers,  they can print a layer height of 40 microns.   Well setup they are good printers.  Also look at the Wanhao D7 resin printer which is similar but cheaper to the form2.

Title: Re: 3D Scanning and Printing.
Post by: LankyTank on January 12, 2018, 07:07:57 PM

If you haven’t done so, it might be worth talking to Alan at Modelu. Could save you a bob or two. These are the outfit that scan you at model Railway shows, suitably posed, then produce ‘mini me’s’
Title: Re: 3D Scanning and Printing.
Post by: John Candy on January 12, 2018, 11:36:11 PM
Thanks for the feedback, particularly Trevor for the kind offer of help with the CAD aspects.

 I have followed up Gavin's suggestion of the Wanhao brand which I had not previously looked at.

I particularly want an enclosed cabinet type (one reason for the Robox being high on the list, the other being the 20 Micron capability) and there is a new Wanhao enclosed model "Duplicator 6" which can also print down to 20 Microns but at not much more than half the price of the Robox, so it is now high on my list , see https://www.3djake.uk/wanhao-3d-printer-spare-parts/duplicator-6-with-cover#js-faq (https://www.3djake.uk/wanhao-3d-printer-spare-parts/duplicator-6-with-cover#js-faq)

Still mulling over scanning options.... have just become aware of "Photogrammetry", where software generates 3D images from a series of ordinary digital photos taken with camera or smartphone. Seems to involve a subscription with processing done "online" with uploading/downloading files from a remote server.

Title: Re: 3D Scanning and Printing.
Post by: cabbage on January 13, 2018, 02:08:42 PM
You are in the grip of an obsession!!! 20 MICRONS!?!?!? that equates to 0.02mm x 22.6 = 0.452mm in real world. I am printing on my machine at 0.2mm layer and to be honest I cannot tell the difference between that and 0.06mm other than the vast increase in time taken for the latter layer depth.

If you are going to print people at 20 Microns then there will be  3,982 layers for it to print a (scale) 1.8m high person....

Draw a circle 2mm in diameter with a 1 mm centre.
Move back until you can no longer see the circle, i.e. it goes solid.
This is the limit of the resolution of your eye. (Having Glaucoma this test is done every 3 months!)

Divide the distance by four and this is how close you would have to be to notice a distance of 0.5mm. Standard machine stitching is 2.1mm or four layers to every stitch on the shirt...


Title: Re: 3D Scanning and Printing.
Post by: Doddy on January 13, 2018, 03:38:45 PM
Keep going John, you are on the right track!

I have recently had my eye on the results of my friends industrial grade 3D machine with the following specification:
However, I wont be going with that machine as having had G3 scale Class 45 cabs printed at 16 microns per layer, I know well what the difference is, so for your stated purposes of producing masters for casting I know what I would aim for myself. I will qualify this in that I had the printing done commercially using layers of curable liquid photopolymer onto a build tray creating exceptional detail, surface smoothness and precision.
Secondly, - Scanning
Your proposed scanner only has a 1mm resolution. Since the quality of the 3D print depends on the quality of the scan, I would suggest this model is not going to deliver much, particularly as  talking to Alan at Modelu, he confirmed that the software has been optimised for scanning people and that items such as whistles and other locomotive fittings have caused him many problems scanning and printing, particularly as the memory of the unit is very, very small and cannot accommodate fine resolution scans of large items.

Talking to Alan about scanning class 40 and 45 bogie parts like buffers and axleboxes it became quite apparent that Alan thought it was thoroughly impractical.
There is a very good handheld unit which is independently powered (batteries) and has the finesse of very large memory capacity and a scanning resolution down to 0.00x microns- but you will need £20,000 for that baby!
Title: Re: 3D Scanning and Printing.
Post by: John Candy on January 13, 2018, 05:48:21 PM
A few years ago I was discussing with Mike Williams a proposal to buy a 3D printer and at that time the resolution of affordable types was more than 100 microns (which to me sounded very fine) but Mike said it would not be good enough for producing patterns, so I gave up on the idea. If I were printing scale figures (people) then I would not go down to 20 microns....50 to 100 would probably be good enough given the undulating surfaces. However, if I were making patterns for carriage sides (or the cab for LMS 10000.....that is still on my project list) then I would not be happy with striations which would have to be sanded down.
The limited printing footprint (approx. 8" square) means that long, flattish, patterns would need to be printed in sections.

Yes, I saw the hand held scanner which was advertised at "less than $20000" ....... it's not on my shopping list!

Thanks for the input from Modelu, I had in mind to use the 3D Sense (or similar cheapish handheld) just for scanning people and large objects which would be reduced substantially in size for printing and where minor striation would not matter too much (e.g. architectural subjects with textured surfaces). I have just taken delivery of a new HP laptop with the i5 8250 quad core cpu (latest Intel 8th generation chip) which I was assured can cope with 3D scanning and (via USB 3.0 connection to scanner) should overcome memory/storage difficulties.

For high resolution work (carriage sides, etc.) I am now veering towards photogrammetry and 3D CAD.