3d scanning

[28ten]

I was sent a link to this today, interesting use of 3d scanning for restoring a ng loco
http://blog.jaggeree.com/post/36201798235/preserving-the-past-with-the-near-future

 

[taliesin]

The Loco is at Bala Lake Railway if anyone is interested, cheers Rob

 

[Dog Star]

There was a sound-bite about the matter in a Radio 4 programme yesterday afternoon.

 

[Osgood]

Following on from this - I would like to scan some small items with a view to getting them 3-D printed in 1/43 scale.

The first item is a 1/25th scale dumptruck which when printed in 1/43 scale will be about the same size as a 16T mineral wagon. Other items will be already at 1/43 so reproduction would be at the same size as item scanned.

I know it is possible, but I'm trying to ascertain if it is practical and cost effective to scan an item of this size and create a file suitable to send for 3-D printing.

For the first project I assume if I remove any glazing then the scan and printed version would include all cab detail?

Could this be a much faster solution than creating 3-D drawings for complex items that might not require such accuracy?

Can anyone offer any advice please?

 

[Osgood]

So it looks like I need to search for REVERSE ENGINEERING - has anyone used such a service successfully?

 

[SimonT]

Just a couple of thoughts, based on 18 months of 3d drawing and 6 months of hands-on 3D printing.
1. What file format do you get from the scanner? The universal file format for printers are .stl however, not every .stl from a package/device is the same as other .stl, as the IT geeks cannot resist playing with things. You only know if it is good file when it prints.
2. While the scanner may give you the shape of the object you want to model, it may not be a shape that prints properly. The model needs to be designed to suit the printer. It may need a support system, it may need the model to be made strong enough to print as a fine window frame might be too slender to survive printing and small details may need to be made bigger so that they will print (they scaled real detail may be smaller than the minimum feature size that the laser and resin can build accurately)
3. The scanned model may need engineering to fit your real railway bits such as wheels, bearing, etc.
4. Is the scanned file suitable to take into a 3D drawing package and to than manipulate?
5. Will your scanned object fit into the build volume of the printer? Different printers have different sized build volumes.

It is possible to produce an object this way, it just needs some consideration. This all sounds a bit negative, which is not my intention as I am an enthusiast for what 3D modelling and 3D printing can and will bring.

Simon

 

[Osgood]

Thanks for your comments, Simon.

My idea was to have items scanned by a service provider, and get them printed again by a commercial printing outfit. They would be essentially static/decorative items, so no requirement for the high fidelity print file design that allows for running clearances etc. This resolves your points 1, 3 and 5.

It looks like scanning service providers will produce whatever file type is required by the printer (whatever that may be - e.g. that required by Shapeways?).

Your point 2 is of great interest - I wonder how to resolve that one, other than relying on the assumption that if say a resin kit were a strong enough structure then a 3-D printed version should be ok?

Other items I am interested in are individual large excavator crawler track plates (in all probability the printed version would be only strong enough for use as a static item - not for a moveable track). These could be drawn but may be just as economic to have scanned using either a full-size item or one from a large scale model.

Tony

 

[SimonT]

Tony,
Shapeways take .stl files but they do refuse jobs that might have an element of risk at print. They refused a job of mine that was designed to the limit of their specifications; both Dave Finney and I have abandoned Shapeways.

Most of the printing resins are described as having the properties of ABS. There are some 'high strength' ones starting to appear on the market for which the jury is still out. Using my normal resin I have just delivered three prototype N gauge fixed link coupling bars to a customer which take the load of the train through two .7mm diameter pins at each end. The test running has worked and he has just ordered a larger number of production prints with no changes. This strength might be enough for crawler track plates.

Simon

 

[adrian]

Tony,
Shapeways take .stl files but they do refuse jobs that might have an element of risk at print. They refused a job of mine that was designed to the limit of their specifications; both Dave Finney and I have abandoned Shapeways.

Not relevant now if you have gone down an alternative route but I think I remember reading a recent thread on RMWeb where Shapeways have added a button "print it anyway", basically they'll print it for you whether they think it'll work or not, but offer no guarantee as to the outcome. You might end up with bag of mishapen lumps.

 

[Len Cattley]

Is there a way of 3D printing a wax model of locomotive wheels?

Len

 

[SimonT]

Not yet, although Formlabs are working on a resin/wax for investment casting; they have a baying horde of jewelers pestering for it.

Simon

 

[Len Cattley]

It's a shame there isn't a baying hord of modellers after them too lol.

Len

 

[Overseer]

Is there a way of 3D printing a wax model of locomotive wheels?

Len

I would say yes there is. Most jewellery lost wax casting firms now have high resolution 3d wax printing machines and they would have no difficulty with a wheel as they are less complex than most of the rings they make. You might need to do a trial to check if there is any shrinkage due to the metal cooling. It should be possible to find a reasonably local firm to produce them for a reasonable price.

The other option is to buy a suitable 3d printer, for example the Asiga Pico https://www.asiga.com/products/printers/pico/ ,which are not horrendously expensive but still more than most modellers could justify. This has been reported as achieving 16 micron layer thicknesses so no visible ridging.

I have heard that Slaters are doing their 3d wax printing in house for the 16mm scale Simplex, as well as casting. Not sure if they are offering a commercial service to others.

 

[SimonT]

Mick,
initially I became disenchanted with the finish and quality of the Shapeways prints but the final straw was when I designed some point rodding stools to their specifications and they refused to print them. I had already ordered the Form 1, so I held on until it arrived. The point rodding stools print perfectly on the Form, so that solved that problem for me and confirmed my decision. Dave does things slightly differently for his business but had similar concerns with Shapeways. He has stayed with agency printing and uses PD Models (http://www.pdmodels.co.uk/). Their quality is outstanding and they can print to 16 micron.

I am about to try sending some 2mm FS GWR coaches to PD. Using the Form 1 with these prints, I am on the limits of the peel process causing a small amount of distortion to the model. There seems to be a mass/structure limit where distortion occurs; I can print ridiculously small and fine with no distortion but there is a size/mass where distortion occurs. I have some experiments in mind to see if I can beat the problem. I will bring some of the stuff to Brightwell. This weeks project is S7 flexible tie bars, GWR of course!

Simon

 

[SimonT]

Mick,
I already do. I will do design for those who cannot and I will print items for those who would like me to. If I do the design and it goes for printing elsewhere, that is fine with me.

If I can help, let me know. And yes, I know that I need to design a web site!

Simon

 

[Bill Bedford]

Is there a way of 3D printing a wax model of locomotive wheels?

Yep, see these guys.

 

[Pugsley]

Look forward to seeing the stuff at Brightwell, hopefully have some of mine done by then (already planned for tonight is a 3DSM session), you know, you could run a handy side line printing off small bespoke parts for clients with your Form 1

I offer a similar service, but on a B9 Creator which seems to cope with small details better than the Form 1 (in my experience). Drop me a pm if you're interested.

 

[SimonT]

Martin,
are you coming to Brightwell? It would be interesting to compare what we get from the two printers.
Simon

 

[Pugsley]

Sadly not, I've already got other plans for that weekend. I'll be at Railex, Aylesbury, in May, if that's any good to you?

The B9 does have a direct lost-wax option, but I found that it wasn't great for fine detail, although a bit of experimentation with pigment levels may cure that.

If you want to send me a file that you've already printed on the Form 1, I can run it on the B9 - drop me a PM if you're interested.

 

[Arun]

3. The scanned model may need engineering to fit your real railway bits such as wheels, bearing, etc.
4. Is the scanned file suitable to take into a 3D drawing package and to than manipulate?
Simon

This is my first post and whilst wandering through past posts I found this one [and the two previous ones from Osgood] upon which I feel I have something to contribute.

It is entirely possible that events and inventions have overtaken me but as far as I know, only two 3D packages allow the importation of *.stl files such that they may be edited meaningfully. By that I don't mean cleaned up/holes filled/meshes repaired etc., suitable for 3D printing - I mean fully reverse-engineered.
The packages are "Space Claim" which has a limited ability to take an *.stl file and turn it into a fully featured and editable parametric 3D model and 3D System's "Design X" [formerly "Rapidform XOR"] which is designed specifically for that purpose and exports parametric versions of *.stl files in Parasolid, Catia, Inventor and Solidworks native formats. Essentially it acts as a manual [or alternatively, semi-automatic] three dimensional version of what "Corel Trace" does for 2D bitmaps. Alternatively, think of it as the equivalent of a 3D optical character recognition package dealing with lines and freeform surfaces rather than dots.
So the answer to Question 4 above is yes - but the Design X software package costs around £18k and requires a fair amount of experience to use.

There are a number of agencies such as Europac [in Crewe] and Central Scanning [in Bromsgrove] who will do this work - both the scanning and the reverse engineering - and they can also 3D print the finished article in whatever scale and material [including a complete burn out wax] you might need. Their work is excellent but costs are high [a 1/24 truck cab reduced to 1/43 (or 1/76 enlarged to 1/50 etc.,) will cost about £900 less VAT] - Hardly surprising when you consider the costs of the software, scanning equipment and the labour intensiveness of the reverse engineering process.
Additionally there could be copyright issues when dealing with masters that are not the intellectual property of the person wanting [modified or otherwise] copies.

I don't see this situation changing in the near future as it is very much a seller's market at present. For purposes not wholly related to model railways, I do actually possess an ultra high resolution scanner and the Design X software so can claim to have some idea of what I'm talking about.