Patterns for Aluminium Sand Casting

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caxton3d
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Patterns for Aluminium Sand Casting

Postby caxton3d » Fri Jan 20, 2017 9:24 pm

This is a picture of the water manifold on a 1913 Dennis Fire Engine.

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The mounting flanges to the cylinder heads are cracked and the connection to the rubber hose is badly corroded. Aluminium of this age is especially difficult to weld with the only solution being to cast a new part. To cast a part like this, a pattern of the part is required. The pattern should be 1 1/2 percent oversize to allow for contraction as the casting cools and to feature 'core prints'. A core box is also required, in which a sand core can be prepared to make the part hollow during the casting process. This thread will describe the process from beginning to end, where hopefully my N2 + printer will play and integral part of the process.

The first thing needed is a CAD model of the manifold. This was drawn in Solidworks.

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Unfortunately the original factory drawing for this part was unavailable, so it was drawn taking basic dimensions with a vernier caliper and ruler. To be sure that my drawing was accurate I decided to print the part and have a test fitting. This would be the first trial of a large part on my printer.

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I ran out of the grey filament half way through and had to switch to blue. The part was actually printed on a raft and the supports were the heavy duty honeycomb type

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Total length was just over 19 inches.

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As you can see the surface finish is very good. The next stage is to see if it fits! Fingers crossed!
Pattern making for the restoration of vintage Dennis Fire Engines

GJohns
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Re: Patterns for Aluminium Sand Casting

Postby GJohns » Sat Jan 21, 2017 10:55 am

Awesome application and great print! Please keep us updated on your progress and casting.
Glenn

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NRHK
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Re: Patterns for Aluminium Sand Casting

Postby NRHK » Sat Jan 21, 2017 11:38 am

Hello caxton3D,

i love the idea of this pattern to cast
did you already calculate the risers and alimentation to exclude problems linked to Shrink?
as the core to involve?

if i can help on some points (the foundry is a passion and my background in scholarship: engineer)
i will be super happy :)
just send me a MP

but In my opinion:
the thread and the holes should be not produce in 3D printing and for sure it will be a mess for sand inclusions
in general you will need to finish it on machine (milling maybe)

Good luck
and happy to see that I am not alone to link 3D printings to foundry
Kokusai Nihon Bijutsu Rekishi Bunka Kenkyu Hozon Kyokai
Foundation for the international study and preservation of: Japanese arts, history and culture

国際日本美術歴史文化研究保存協会

caxton3d
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Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Sat Jan 21, 2017 4:17 pm

This morning I tried the printed manifold on the actual engine.

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As you will see it was a perfect fit on the cylinder head water jacket studs.

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However at the radiator pipe connection end the connection was a little low, perhaps by 1.5mm. I will make this correction to the model and then prepare a model for the actual printing of the pattern, taking into consideration the 101.5% scaling to allow for metal contraction.

I was pleased with how well it fitted!

Glen and NRHK, thank you for your kind comments. I hope that there will be more interest in the future for printing for 'real world' tasks. Pattern making is one of the most obvious applications. Most patterns today are still hand produced from wood.

For those unfamiliar with the use of patterns for sand casting here is a link to an excellent 'home foundry' video showing the use of split patterns and cores.

https://www.youtube.com/watch?v=bOrxSsnrqew
Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
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Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Sat Jan 21, 2017 8:46 pm

I have now modified the original model to include the 'core prints'. These are locations (shown in black) external to the actual pattern which provide location and support for the internal core. This will be a split pattern, so we will print both sides.

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Rather than print each side separately, I decided to print them together and join them together with bridges. The thinking behind this is that they are very tall prints (nearly 600mm long) and if printed together they would have a larger footprint and would provide support to each other. This picture shows the print with the support material shown in yellow.

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....and how long is it going to take? RAPID prototyping? Well, come back in a week!

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I will post pictures each day so you can see how it is progressing. Here is the first picture on Saturday evening as the raft is going down.

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Whilst this is printing away I can now think about designing the core box, in which the sand core will be produced. So far excluding printing time I have spent about 3 hours on this project. (Although this is not quite true, as I have wasted many a minute just staring at the printer as it proceeds on it's way).
Pattern making for the restoration of vintage Dennis Fire Engines

Charles
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Re: Patterns for Aluminium Sand Casting

Postby Charles » Sat Jan 21, 2017 10:51 pm

Curious... could you send this off to a service to get it printed in metal? Would a printed metal piece be strong enough for this application?

caxton3d
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Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Sat Jan 21, 2017 11:14 pm

Charles, to my knowledge it is not possible to print Aluminium, but only materials like nickel ( powders ) which are sintered with a laser.

An actual plastic printed part would probably work just fine in this application, but the key thing is - Authenticity.
The original part was an aluminium sandcasting so the replacement has to be one too. It is hard to imagine that 100 years ago a skilled pattern maker could probably make the patterns for this job in wood quicker than the Raise can print them!

The most interesting advance in pattern making is direct sand printing. Rather than taking a pattern and impressing this into sand, sand printers, print the sand impression directly. The sand has a binder agent, so that all the grains are glued together.
Last edited by caxton3d on Sun Jan 22, 2017 8:22 am, edited 1 time in total.
Pattern making for the restoration of vintage Dennis Fire Engines

Charles
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Re: Patterns for Aluminium Sand Casting

Postby Charles » Sat Jan 21, 2017 11:56 pm

Yes, the work done long ago by skilled craftmen are amazing. Thanks for showing us this cool example of 3d printing.

caxton3d
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Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Mon Jan 23, 2017 10:19 am

Monday morning, 36 hours after print started and it is looking good!

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You can see that I have selected the honeycomb form for the support columns. This is necessary as the support columns are very tall. On previous prints when the default setting was used the support columns broke away at their base.
Pattern making for the restoration of vintage Dennis Fire Engines

MrOnkelChiller
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Joined: Wed Jan 04, 2017 9:12 am

Re: Patterns for Aluminium Sand Casting

Postby MrOnkelChiller » Tue Jan 24, 2017 10:23 am

Would be great to have some more pictures of the print! :)

Even if it's long time since you started printing...

caxton3d
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Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Tue Jan 24, 2017 2:44 pm

A couple of hours after the last picture was taken, I returned to the printer to find that the filament was hanging out of the print head. :cry:

The print head wasn't blocked. It was almost as if the printer had just unloaded itself. Has anyone seen this type of thing before?

Unfortunately it had been 'printing' without filament for some time, as the print nozzle was well clear of the job so I decided that it was a case of starting again. I don't think that there is a way of finding a 'resume point' in a failed job and restart printing from that point?

Once we get going again I will post regular pictures.
Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
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Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Sat Jan 28, 2017 4:55 pm

After several false starts this week we are back printing the manifold. 25 hours into the job at the moment. Just under half the printing is taken with printing the support. As the support columns are long and thin it is necessary to use the heavy duty support option.

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Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
Posts: 29
Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Mon Jan 30, 2017 11:20 am

Just under 3 days into this print and all is looking good. At this stage most of the actual part is surrounded by support columns so it is difficult to separate part from support visually.

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Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
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Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Fri Feb 03, 2017 6:11 pm

170 hours into the print and the end is in sight! All looking very good despite the structure being tall and thin. There has been no problems in pausing the print and changing the filament spool to a new one.

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Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
Posts: 29
Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Sun Feb 05, 2017 1:55 pm

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Finally finished after 200 hours of printing. Standing just under 2 feet tall


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Seen here with the support material broken away and the print separated by cutting through the 2 bridges which were inserted to join the print together for greater stability


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They join together beautifully. I was concerned with the height that there might be warping, but they printed completely flat on the mating face.


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The split line is barely visible!

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This shows the surface finish printing with a layer thickness of 0.15mm.

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However, all is not perfect, as it was necessary to use the honeycomb type support rather than the thin ribbon kind. When this breaks away the surface finish is destroyed. Does anyone know how this can be improved when printing with the stronger type of support?
Pattern making for the restoration of vintage Dennis Fire Engines

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walshlg
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Re: Patterns for Aluminium Sand Casting

Postby walshlg » Sun Feb 05, 2017 8:53 pm

EPIC!

my thoughts on support is that if you want it right, design it youself - build the support with your model!

3D MAKE
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Re: Patterns for Aluminium Sand Casting

Postby 3D MAKE » Tue Feb 07, 2017 4:32 pm

175 Hour!!

caxton3d
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Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Thu Feb 09, 2017 9:28 pm

Walshlg, this is a good idea. I have made a test print where the model had a support column just stopping short of the overhang that I needed to support. I then used the automatic ribbon support feature, so that the support was only 10mm long and did not have issues of flexing due to it's length.
Pattern making for the restoration of vintage Dennis Fire Engines

caxton3d
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Joined: Tue Dec 27, 2016 1:59 pm

Re: Patterns for Aluminium Sand Casting

Postby caxton3d » Thu Feb 16, 2017 12:21 pm

It s now time to print the core box so that the sand core can be molded.

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This will produce one half of the core. A mirror will be required to produce the other half. The two half sand cores are then glued together with core glue to form the full core.

This is the shape required and obviously it is too large for the bed of the printer, so it has to be split in two.

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When the left an right halves are printed they will then be bolted down to a bed plate to form a continuous core box

This part is 285mm wide, and I thought it would fit onto the bed without any problem as the stated printable area for the Raise3D printer is 305 x 305mm. This isn't really truthful as the printable area by a single printing head in the x axis is only 280mm. This is revealed by Imakr when I came to slice the .stl file.

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The yellow lines represent the maximum area that may be printed by a single head

I will now try and squeeze the model to fit I with this constraint.
Pattern making for the restoration of vintage Dennis Fire Engines

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jmp
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Re: Patterns for Aluminium Sand Casting

Postby jmp » Thu Feb 16, 2017 1:06 pm

caxton3d wrote:This isn't really truthful as the printable area by a single printing head in the x axis is only 280mm.

There is some confusion about this, usually you subtract the head difference from dual nozzle to single but one does get the full 305x305 on a single nozzle on the N2+. I've done it and it was something I was very specific asking about during the kickstarter campaign because for me losing 25mm in x would have been a problem.
RL Name: Jason Preuss Thingiverse: JMP Website: http://www.patterntoprint.com


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