Author Topic: General questions regarding having parts printed  (Read 1162 times)

Offline Craig DeShong

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General questions regarding having parts printed
« on: January 21, 2022, 02:00:27 PM »
Iím looking forward toward the fabrication of the intake tubes of the LeRhŰne model Iím building and Iím thinking it might be near impossible for me to make the nine intake tubes for the engine, at least not without sacrificing a realistic shape for them.  These things are out in front of the model so it would be nice if I could have a realistic shape to them.   Iím thinking about having them 3D printed.  I know some of you folks either print your own parts or send them off to be printed.  I know nothing about 3D printing; at least nothing that couldnít be said in a sentence or two.

The general shape of  tube starts as an ellipse and changes to a circle toward the top of the tube.  The top of the tube flares to fit against the intake manifold on the head.  The tubes are made in two parts, one fitting inside the other, since the cylinders are screwed into the engine case, the total length of the intake tube will vary slightly from cylinder to cylinder and the slip joint between the two sections accommodates that.

The literature states my Alibre CAD software will make STL files that can be used to print a part.  Iíve produced the STL files and they will open with Microsoft paint.  The renderings look pretty good so I have hope they might Ďprintí ok.  Iím ready for any advice you might want to offer and I have a few questions.

Printing in metal?  These are engine intake tubes that connect to the cylinder heads.  I canít see running the engine more than a minute or two, so the heads shouldnít get too hot; still Iím wary of a plastic.

The tubes will carry gasoline, air and oil.  I'll need the tubes made of a material that will be impermeable to these materials.

The intake tubes on the full size appear to be brass.  It would be nice to have brass or maybe a brass ďlook alikeí.

Where do you send your STL files?  What is the procedure?


« Last Edit: January 21, 2022, 02:11:50 PM by Craig DeShong »
Craig
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Offline Dan Rowe

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Re: General questions regarding having parts printed
« Reply #1 on: January 21, 2022, 03:14:24 PM »
Craig,
You can upload a .stl file to Shapeways and get a free quote of the print price in several metals including brass and bronze.https://www.shapeways.com

I use them for my metal parts and master patterns.

Cheers Dan
ShaylocoDan

Offline crueby

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Re: General questions regarding having parts printed
« Reply #2 on: January 21, 2022, 04:19:37 PM »
I've also had some parts printed in metal on Shapeways, as well as a few plastic ones before I got my own printer. The prices go up quickly as the overall size of the part gets larger, I think they are geared for good prices on smaller jewelry sizes.

You have to ensure that the wall thicknesses are above thier minimums, if not they will flag it when you upload. Also ensure that the sizes show up right on the web site, they assume metric sizes in the file, though you can switch to inches if needed.

On some pipe elbows I had them make, it worked out cheaper to combine the individual parts onto a little 'tree' in the CAD program before uploading and have them cast it that way than to buy the individual pieces - try it both ways and see what the total comes out to.
I had mine printed in bronze, came out quite well. The alloy was still mill-able to get the openings to fit my tubing, the dimensions on small holes can be a little over/under, typical of castings.
I'm sure there are other places that will do the same printing/casting too, but SW is the only one I have tried so far.
Chris

Offline bent

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Re: General questions regarding having parts printed
« Reply #3 on: January 21, 2022, 07:27:09 PM »
Protolabs.com is another shop that can quote sintered metal 3d printing, they offer copper and aluminum, amongst other materials.  With any 3d laser-sintered part, you may want to discuss sealing options with them, especially for thin walled parts (the as-sintered condition may be pretty porous and leaky).

Offline FKreider

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Re: General questions regarding having parts printed
« Reply #4 on: January 21, 2022, 10:48:30 PM »
The other alternative is to have them printed in "castable resin" basically a lost-wax equivalent and then send the "waxes" to a jewelry foundry to have them cast. In my experience this is far far cheaper than the direct print to metal services such as shapeways.

Shapeways does have its place, expecially for small one-off parts as Chris mentioned.
-Frank K.

Offline crueby

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Re: General questions regarding having parts printed
« Reply #5 on: January 21, 2022, 11:48:47 PM »
The other alternative is to have them printed in "castable resin" basically a lost-wax equivalent and then send the "waxes" to a jewelry foundry to have them cast. In my experience this is far far cheaper than the direct print to metal services such as shapeways.

Shapeways does have its place, expecially for small one-off parts as Chris mentioned.
Do you know of some good jewelry foundries? Not sure how to find one...  Thanks!

Offline Craig DeShong

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Re: General questions regarding having parts printed
« Reply #6 on: January 22, 2022, 12:23:58 AM »
Shapeways gave me a quote of around $100 for a single top & bottom set in bronze.  That x 9 is some serious cash (at least for me). 

These are, basically, thin wall tubes.  Were I to get these cast Iíd need to supply the core, yes ?  I suspect I could get these out of Alibre by modification of my parts.  I would think casting these as thin wall tubes using a core would be difficult and thus expensive.  Again I have no experience with this.

Maybe a stop-gap measure might be to have them printed as cheap as I can get by with, install them and see if the engine will run.  If it runs, I might be more receptive to put out some serious $$$$$ for quality intake tubes?

Just thinking and typing.
Craig
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Offline Dave Otto

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Re: General questions regarding having parts printed
« Reply #7 on: January 22, 2022, 12:37:53 AM »
Printed parts in a different material and painted satin black might look pretty nice.

Dave

Offline crueby

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Re: General questions regarding having parts printed
« Reply #8 on: January 22, 2022, 12:41:00 AM »
Sounds well worth some experiments with turning and bending jigs. Very rewarding too if you can work it out.

Offline FKreider

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Re: General questions regarding having parts printed
« Reply #9 on: January 22, 2022, 03:08:18 AM »
Shapeways gave me a quote of around $100 for a single top & bottom set in bronze.  That x 9 is some serious cash (at least for me). 

These are, basically, thin wall tubes.  Were I to get these cast Iíd need to supply the core, yes ?  I suspect I could get these out of Alibre by modification of my parts.  I would think casting these as thin wall tubes using a core would be difficult and thus expensive.  Again I have no experience with this.


Yes I agree $900 is a lot of cash!!

The beauty of the 3D printing is that you do not need a core, you simply print the part with the hollow part or required void and the casting investment will then flow into it. Cores are necessary for sand casting OR if you made a traditional mold to shoot the waxes for investment casting. That's the beauty of directly 3D printed waxes, so simple.

Unfortunately in today's day and age castings are almost always more expensive for us hobbyists vs. fabricating from built up components out of bar stock. The economics of castings really start to make the most sense when you are looking at volume.

VOG on YouTube has some really good videos showing the process of 3D prints to castings using the methods common in the jewelry industry. Its certainly well within the means of a home-shop machinist these days, the equipment is less than the cost of a lathe or milling machine.

« Last Edit: January 22, 2022, 03:19:37 AM by FKreider »
-Frank K.

Online cnr6400

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Re: General questions regarding having parts printed
« Reply #10 on: January 22, 2022, 03:43:23 AM »
Another method to make your induction tubes is chemical deposition of copper , or electroforming. A gent called Mr Stephen Wessel had some articles on this a few years ago in Model Engineer out of the UK. He was making induction tubes and water jackets for a WW1 V-8 aircraft engine as I recall. Essentially copper was plated onto accurately made forms that were later removed by melting out (forms were wax I think.) There is an article index floating around the web to aid finding such articles. His articles were quite in-depth about exactly how to do it, pitfalls, tips for good results. His engine looked stunning, and the water jackets and tube parts were masterpieces of the method and he said they were quite durable. Just food for thought. It would be a lot of hours to make them this way (the forms, particularly) but costs would be much lower than various flavours of rapid prototyping / 3D printing. :cheers:

Offline Jasonb

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Re: General questions regarding having parts printed
« Reply #11 on: January 22, 2022, 07:43:27 AM »
As well as printed parts Shapeways will also print waxes and lost wax cast them in several metals such as copper, brass and bronze so you could get a price for that too.

If investment (lost wax/foam) casting then you don't need to make cores as the investment material will flow into the inside of the wax pattern and form the core.

What is the wall thickness? if too thin you may have a job getting the metal to flow but if done with a vacuum lost wax may well be able to do it where simply pouring a sand mould would not.

Some images of the electro formed parts mentioned above https://www.enginehistory.org/ModelEngines/Wessel/Wessel.shtml
« Last Edit: January 22, 2022, 07:56:09 AM by Jasonb »

Offline wagnmkr

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Re: General questions regarding having parts printed
« Reply #12 on: January 22, 2022, 12:10:02 PM »
Very interesting article Jason ... Thanks
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