Using 3D prints for casting

You make a good point.

Ketan

There are a lot cheaper and reliable outfits to send parcels Jason. I have just checked the cost of sending 20kg from UK to Australia using the people I normally use....£77

Eric

Thanks Eric, I'm sure I could have looked about a bit more but that does actually make the cost not a lot different to what those castings cost to get from the states to here. But then the guy I got them from just went with US postal service and could probably have got it cheaper too.

One other thing to think about when sand casting if you are not burning out is that it may also need core boxes or loose pieces printing so the part can actually be cast and the pattern pulled from the sand which will all add to the costs

Eric,

There is no simple answer to this. All I will say is 'there is no level playing field'.

examples:

a. China and India are still regarded by the developed nations of this world as 'third world countries' in terms of import duties. Imports from China into E.U. attract very low duty rates. the same is not the case if you export a British made product to China. For example, into U.K. we pay maximum 2% import duty on Chinese origin goods, where as exporting to China - China import duties are 50~60% +

b. Regulatory and compliance requirements in developed countries are far more strict in comparison to China = more cost for a British manufacturer.

c. Chinese work legally as well as illegally through platforms such as eBay and Alibaba, and the average model engineer who 'imports' from there is very happy and satisfied with the 'facilities' these guys provide to beat the systems in their countries.

I could carry on. Perhaps our politicians will get their heads out of their anuses one day to see the light. Heres to hoping..

Ketan at ARC

I have found pla burns out nicely when printing lots of precious metal items (it's the day job) but more importantly things like this:-

or

which is the pump body for a sweet pea so I could practice on one before butchering the the real thing on the left since it is for the new club loco.

This shows the model sprued up ready to invest with another scaled up model and the original brass cylinder with a 1 to 1 copy in pla. All steam passageways are cast in but I should leave some meat on the valve openings to clean them up.

cast in gunmetal as a test and the brass pair now adorn my MarieE, it is the normal method of address for my particular SWMBO.

Now if I could just melt cast iron .........

Andy

Edited By AndyP on 19/02/2015 21:43:00

Hello all,

Following on from DMB's post re the Brighton and Hove SMLE brake shoe rings please see attached photographs of the said shoes, including the CAD 3D drawing, the CI rings and pattern and an as received cast iron ring.

Regards,

Bob Youldon

Bob,

Personally, I would have gone the laser cutting route for those brake shoes. It may have been easier. Provided of course that you could get cast iron solid, to then cut into slices of appropriate thickness.

Regards,

Chris P

Seems a shame getting a pattern done like that without taking the opportunity of getting a bit more detail into them.

Eric

I fancy printing tank tracks. The thought of milling 200 links from aluminium and then having to anodise them to make them a decent colour fills me with dread.

A dark grey ABS print would be fine for what I want, and only a few holes to drill in each one.

Neil

Good morning all,

Re:

Personally, I would have gone the laser cutting route for those brake shoes. It may have been easier. Provided of co urse that you could get cast iron solid, to then cut into slices of appropriate thickness.

Chris, laser cutting was considered and in the prototype passenger car the shoes were originally laser cut in steel, but it was the opinion of the building group cast iron against the steel bogie wheel is a much better propersition so therefore the decision was taken to go the cast iron route.

Seems a shame getting a pattern done like that without taking the opportunity of getting a bit more detail into them.

Eric, as the shoes are destined for use under passenger cars, there was a need to produce a simple repeatable component, there was a requirement for in excess of a hundred and in normal use they will never be seen.

I will say the effectiveness of eight shoes per car in stopping a loaded vehicle is very impressive.

Regards

Bob Youldon

.

Neil,

That would be a printed product wouldn't it ?

... I thought the idea here was to use the print as a pattern.

Is it 'efficient' to print 200 identical items ?

MichaelG.

> Is it 'efficient' to print 200 identical items ?

If the alternatives are:

• Milling them
• Fabricating them(!)
• Paying for 200 little castings

Then yes!

Neil

Mill one mould in Al and build a small injection moulder?

> Mill one mould in Al and build a small injection moulder?

That was the fourth option I meant to reject!

Neil

.

Neil,

Do you already have a 3D Printer?

... Or are we witnessing the 'Purchase Justification' process?

MichaelG.

Good evening Wallace,

Re the castings, as received from the foundry they had been fettled and any risers or in gates had been removed, they must have spent some considerable time on them; the photograph of the stack of brake shoe rings is exactly as we received them from the foundry. I'm afraid I cannot help with their moulding and casting process, off went the pattern, back came the rings, simple as that!

Regards,

Bob Youldon

OK, print 1 mould, lost PLA cast it in Al and build an injection moulder?

Less costly & time consuming than printing 200 of them!

It all comes down to the job in hand as to what will be the most ecconomic and that will also vary from one person to another depending on what equipment they have and what they would have to buy in.

If plastic is suitable for Neil's tracks and he had a 3D printer then his only cost is a reel of filament and he could go and walk the dog while it was printing. If Neil also had a CNC mill then he may look differently at the milling option as that could be making a pile of swarf while he walked the do and his costs would be the raw material and a cutter or two.

Now if somebody else wanted 200 track links but needed them in metal then they could outsource them to be CNC cut, printed in metal from the likes of shapeways. Print one off in plastic then take an RTV mould, cast up 200 wax replicas and make them into a tree and have them lost wax cast, or if they were big tracks (neil has not given a size) then maybe print oversize, cast an alloy pattern and then sandcast 200 from that pattern, still cheap if you have a home foundry but pricy if you sub it out.

Or just go out and buy some aftermarket tracks in either PU resin or light alloy as they are readily available for the AFV and site plant modeler.

All the above and more would have plus and minus points so you can't generalise. Though from Andrews earlier post it looks like it was more econonic for him to print out several hundred of his component housing boxes than have them moulded.

J