For RTR Irish Models - will 3D printing ever be as good as injection moulding?

[Noel]

Currently 3D printing for 00 scale Irish RTR models seems a long way behind injection moulded plastic in terms of finish quality and fine detail.

 

However is 3D in the future ever likely to evolve to the higher quality and level of precision that is currently only achieved by injection moulding (IM)?

 

Obviously IM is vastly more expensive to set up for small production runs, but 3D is fairly inexpensive if one can accept the quality differential enough to be able to run rare Irish RTR stock. Is current 3D technology like the early days of 'ink jet' printing before the quality issues were resolved and mass market appeal drove costs down as quality improved?

[Glenderg]

No.

 

3D printing is the equivalent of a dot matrix printer, and won't ever get to inkjet level.

 

It's an additive lamination process. The next step is the reductive or removal by laser process.

[Noel]

No.

 

3D printing is the equivalent of a dot matrix printer, and won't ever get to inkjet level.

 

It's an additive lamination process. The next step is the reductive or removal by laser process.

 

Thanks Richie. What do you think about Laser based SLA v FDM? It seems to be able to get down to 25 microns on some new consumer models costing approx €1550. There seems to be quite a difference in finish quality between SLA and FDM.

[Glenderg]

FDM is the roll method and is limited in it's resolution - effectively you'll still get a toothpaste finish. 0.01mm resolution is too coarse for finescale modelling and just looks rubbish.

 

SLA is stereolithography printing where UV light dictates where liquid resin cures, so has a much tighter resolution. https://all3dp.com/best-sla-3d-printers/

 

Way forward for making home grown masters from which to make moulds for resin from.

[Richard EH]

I've been 3d printing for over five years now, it's developing all the time. It'll get there, the same way other technologies developed in their own time. I really enjoy it, but its' not for everyone at the moment - that's fine, but there are ways to improve and get a smooth finish.

 

Cheers for now.

Richard.

[David Holman]

Very much agree with Glenderg, for though I have no knowledge of 3d printing, resin castings from your own masters is easy and relatively cheap for small runs. Many of Arigna Town's wagons are resin cast and the moulds even pick up 'wood grain' made by scuffing the surface with a fibre glass pencil.

[Glenderg]

Ultimately, it boils down to detail. To make a mould for anything, be it injection moulding or resin, the master is key. Look at mayners mgwr whitemetal axle boxes and you can tell he's put effort it. It shows in the end product, but that was most likely hand made with some etched brass.

 

3D printing has an enormous way to go, but when it gets there, you'll be able to have cottage industries producing master tools at a fraction of the price a spark eroding company would.

 

Whether you manufacturer in China or Charleville, getting the moulds right is king. If the accuracy and detail are there,and the resin product and the fellow behind it are squared away, you can get RTR levels of detail, without compromise.

 

Brittania Pacific Models in th UK are case in point. Best resin casting I've ever seen....

[DJ Dangerous]

What is it that causes the bowing with some 3D prints?

I’m a little hesitant to go for 3D prints, as I’ve seen cases where a model looks fine and true when brand new, but bows over the course of a few weeks or months.

The curve seems to grow progressively, but I assume the model will eventually arrive at it’s final shape?

Is it to do with the resin cooling and contracting?

Is there a way around it?

Can the curvature be allowed for while designing and printing, so that the model is curved when new, but slowly morphs into it’s correct form?

[Mayner]

3 hours ago, DJ Dangerous said:

What is it that causes the bowing with some 3D prints?

I’m a little hesitant to go for 3D prints, as I’ve seen cases where a model looks fine and true when brand new, but bows over the course of a few weeks or months.

The curve seems to grow progressively, but I assume the model will eventually arrive at it’s final shape?

Is it to do with the resin cooling and contracting?

Is there a way around it?

Can the curvature be allowed for while designing and printing, so that the model is curved when new, but slowly morphs into it’s correct form?

There are a lot of variables in resin printing process that may contribute to bowing/distortion in the finished model.

Most of my production printing was carried out by 3D printing/rapid manfacturing companies in New Zealand & China using full size (bottom up)  machines in engineering resins with abs properties.

Print programming/set up of model for curing

Curiously there was an odd bow in one side though no other noticeable defects of the test prints for the GSR/Ranks Grain wagon perpared by our New Zealand supplier, the defect did not reappear on subsequent production prints. Possibly a programming error by the technician who set up the initial test print (too high a print speed/insufficient rest time between layers), a different technician set up the production prints and problem did not re-occur after I shifted production to China.

Curing

Resin prints will continue to cure/harden when expossed to UV light during the lifetime of the model which maay contribute to brittless/distortion. Theoretically painting is supposed to protect a model from UV.

Potential solution.

Most of my collection of 3D printed wagons (20+)appear stable after 4-5 years, though the axleguards on a small number of wagons have bowed slightly outwards with the wheelsets sometimes dropping out.

I found that placing the model in hot but not boiling water relieves the built up stress/distortion in the resin allowing the model, the model should return to its original shape or can be formed to shape before it cools.

Similarly chassis tended to distort while in transit from the factory to my workshop, I usually placed the chassis in hot water so that I could adjust the axle guards so that the wheelsets would roll freely before shipping a model.

[DJ Dangerous]

7 hours ago, Mayner said:

There are a lot of variables in resin printing process that may contribute to bowing/distortion in the finished model.

Most of my production printing was carried out by 3D printing/rapid manfacturing companies in New Zealand & China using full size (bottom up)  machines in engineering resins with abs properties.

Print programming/set up of model for curing

Curiously there was an odd bow in one side though no other noticeable defects of the test prints for the GSR/Ranks Grain wagon perpared by our New Zealand supplier, the defect did not reappear on subsequent production prints. Possibly a programming error by the technician who set up the initial test print (too high a print speed/insufficient rest time between layers), a different technician set up the production prints and problem did not re-occur after I shifted production to China.

Curing

Resin prints will continue to cure/harden when expossed to UV light during the lifetime of the model which maay contribute to brittless/distortion. Theoretically painting is supposed to protect a model from UV.

Potential solution.

Most of my collection of 3D printed wagons (20+)appear stable after 4-5 years, though the axleguards on a small number of wagons have bowed slightly outwards with the wheelsets sometimes dropping out.

I found that placing the model in hot but not boiling water relieves the built up stress/distortion in the resin allowing the model, the model should return to its original shape or can be formed to shape before it cools.

Similarly chassis tended to distort while in transit from the factory to my workshop, I usually placed the chassis in hot water so that I could adjust the axle guards so that the wheelsets would roll freely before shipping a model.

Thanks, John.

For clarity, I have a good few of your wagons and there is no distortion.

I’ve just seen photos here on the forum, and online in general, and when I went researching, some of the answers were beyond my pay grade.

So, placing a bowed 3D print into hot water may coax it back into it’s correct shape?

[Mayner]

There are a lot of variables in the 3D printing process, placing a bowed resin print in hot water may solve the problem, but a badly bowed/distorted print probabably best avoided.