# 3D printing help - Shapeways won't print spures



## steam5 (Jun 22, 2008)

Hi

For a while I have been working on a 3D model of a freight car truck and last night uploaded it to Shapeways for printing. I received and email from Shapeways stating my model could not be printed because of the sprue:

_Here are some details to help you resolve this issue:_


_Reason: Weak Geometry _ 
_Description: Unfortunately we cannot print this model due to its sprue(s). For the printing process it’s required to add supports to the model. Support structures are difficult to generate for models with sprues. Additionally, there is a high chance of models breaking or supports being stuck to the model with sprues._
 
Is their a way to fix this? Or should I just make them as individual pieces and pay a bit more in printing?

This is a screen dump of the 'raw bits' to help pictures the bits in the following images on sprues.










This is the sprue version, but showing the sprew bits

Break shoes and journal covers









This is the Side frames and top and bottom bolster


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## armorsmith (Jun 1, 2008)

I believe the issue is the way in which you have assembled the parts, and a bit of the part details as well. MOST 3D printing is of a deposition method, meaning the machine deposits small bits of material on a bed with each pass of the printing head. You have several 'undercuts' which with out additional support are near impossible to print.

It appears to me that if you rotate the bolsters so the flat sides are common they can be joined by a sprue and print fine. The side frames, as best I can see from the picture, need the have the additional hub on the inside of the frame removed to allow the frame to be flat on that side, and again can be laid on that flat side and joined with sprues.

The manner you have displayed the brake shoes and journal covers is too difficult to make a judgment on, but I will take a stab that the issues are the same.

The above statement are dependant on the material you are specifying for the print to be made in. You may need to dig deeper into the material and printing method requested.


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## Burl (Jan 2, 2008)

What material were you trying to print it in? Also, they usually send screen shots with the areas in question highlighted in red. If they're not doing that, I'd ask for clarification.


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## steam5 (Jun 22, 2008)

I was trying to print them off in Black hi def acrylate.

Armorsmith, I do get what you mean and your description of an undercut, I'm new to this and didn't even consider that.

Burl, the last two pictures are what Shapeways sent to me to highlight to issues.

So maybe its worth giving it another go rearranging...

Alan


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## Burl (Jan 2, 2008)

The high def acrylate is a new material, and I don't have as much experience with it. 

I'm tending to agree with the previous statements about cleaning out support material.

Question: why do you want sprues with your parts? If its easier for them to print without them, I'd say let them have it their way.


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## SD90WLMT (Feb 16, 2010)

Sprues are for injection molding..
Welcome to 3D prep..class 101
..interesting parts..are you planning bushings as axle supports?
SD


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## Gary Armitstead (Jan 2, 2008)

SD90WLMT said:


> Sprues are for injection molding..
> Welcome to 3D prep..class 101
> SD


Dirk,

I love your 3D prep. class 101! 

During my die sinking career (40 years plus), I not only machined dies for NO DRAFT forgings, but I did some designing along the way. Undercuts are the nemesis of the designer of dies for precision forgings (ie no draft and very little machining done to the forging itself). With this said, I have parts I have drawn that I want 3D printed and I'm having a tough time doing it. I'm always going back to how I would design a die. It's difficult to change the "mindset"! Forging dies CAN be made to produce features with undercuts, BUT........instead of a two or three piece die, you end up with a 6-8 piece die costing 10 times more than the normal die! Aerospace and airframe designers deal with this everyday.

Of course, now the problem is that we have great technology to produce 3D printed items used in our hobby that was unheard of ten years ago. Most hobbyists are not familiar with undercuts and the pitfalls in getting parts produced. 

What a great time we live in !


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## SD90WLMT (Feb 16, 2010)

Gary...Thanks Buddy!

I'm in same boat..time to learn..much to learn..
I "know" T-squares or elipses..triangles..pen n pencil..
I knew..forget now..how to a write older CNC programs with just a basic code knowledge to operate CNC punch press..brake..or shears..

But...now..in 3D...I was exposed as a mill operator..vertical mills build aero space toys.. But ran the mill... Did not design the tool paths ..

In our future model world bursting forth currently..printers at home in a spare room are nearly reachable.. And easy to work with ...

Lets all keep learning ..trying ..helping each other here..
...we have the skills
..we are loosing manufacturers..

Band together modelers..
Now is better than ever!
SD


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## steam5 (Jun 22, 2008)

Thanks for the help and interest.

Burl, the reason for the sprue was to save a bit of coin as compared to printing the parts individually. But the time spent stuffing around I would have been better off just uploading them as individual parts. Hindsight ?

I plan to place bearings into the side frames to make the freight car roll nice and free.

FYI its and Fn3 bettendorf truck

Alan


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## Burl (Jan 2, 2008)

One thing to look out for, if you do remove the sprues, Shapeways will re-orient your parts to optimize their print tray. With low-res materials, like nylon or steel, it can mean multiples of the same part might have striations in different directions. If you're going with a high-res material, you probably won't care. So, sprues can be a way of ensuring all the parts are oriented in the same direction, if needed.


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## steam5 (Jun 22, 2008)

Fingers crossed, I've removed the spures... Now I have to wait and see.

Been working on and off for 12 months on this on, it will be great to see how it looks in person.

Thanks for the help
Alan


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## steamermeister (Feb 20, 2013)

*Sprue size?*

Perhaps you need to increase your sprue cross section? Here's a pic of a matrix of post pockets I've successfully printed in the Shapeways Strong & Flexible Plastic (SLS Nylon). I haven't used the Hi-Def Acrylate because of the cost but this model passes the automatic checks that Shapeways does when you upload a part to your account on the site.


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## steamermeister (Feb 20, 2013)

*Another matrix*

Here's another matrix I've uploaded that passed the automatic checks for Hi-Def Acrylate. I haven't printed it yet but it would certainly be doable in Strong and Flexible plastic because it's so forgiving of delicate designs. The last time I had these parts made they were separate components done in matte bronze stainless steel. Anyway, it's worth making part matrices if you can because the individual "per part" cost adds up fast if you need a lot of the same thing, which for small parts is usually more than the material cost.


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## steamermeister (Feb 20, 2013)

*Material Resolution*

Please post some pictures of your parts when you get them in. I'm curious how the lettering turns out.


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## rdamurphy (Jan 3, 2008)

I know, I know, dumb question... But those brake shoes are readily available as castings, why bother having them printed? And they would be cheaper?

Robert


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## steam5 (Jun 22, 2008)

Steamermeister, I do believe your right, I could have made it work, but I just wanted to get it ordered  Next model I'll try a bit harder assuming theirs benefit in ''spruing''

Alan


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## steam5 (Jun 22, 2008)

Robert,

The break shoe is only a small part of a larger project, and my first goal was to develop my own truck. If I can make it work I will consider the larger project.

However what you say is correct.

Alan


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## steamermeister (Feb 20, 2013)

In comparing available castings to Shapeways printing I've found the cost to be pretty similar. The real benefit to printing is that you have control over the design and can make the exact parts you need. You don't have to worry about how someone else's parts will fit.


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## lathroum (Jan 2, 2008)

Send me the STL Files... I am a teacher we have 6 3d Printers here at my school... I can do ABS or PLA... easier to print without the sprue so I can re-position pieces as needed...

let me know

Philip


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## CliffyJ (Apr 29, 2009)

Alan, I'm coming into this thread belatedly. I'm not a pro on this, but here's some thoughts.

This will be academic, but based on your first posts, I agree with Steamermeister that the cross-section of the sprues might be too small. Did you follow the Shapeways dimensional rules for that specific material? It should have been ok with nylon SLS.

FYI all, spruing used to be important when making parts thru Shapeways. If multiple parts could be made into one part, via spruing, the cost would go way down due to handling fees. If the tiny parts are separate, it's more labor-intensive for them. This has zero to do with casting or injection-molding or FDM 3DP, only handling of parts in the powdery SLS context. (At least with their usual approaches).

However, due to SW price restructuring as of over a year ago, that spruing trick was eliminated, and parts cost more. So it was probably best that you submitted your models individually, and let SW take the responsibility / cost of efficient orientation and nesting.

Still, I've never seen that error you posted... maybe new restraints being added...

Anyway, I'm looking forward to seeing your results!
Cliff


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## steam5 (Jun 22, 2008)

Cliff

The sprue was 2mm in diameter which was within Shapeways guidelines, it was the manual inspection by a human that initiated the rejection. So I'm guessing if I arranged differently I could have got it past the checks.

I did submit the parts individually and it came out to $117, and from memory the sprued version was $20 cheaper!

I'll take some snaps of the truck when the parts arrive.

Alan


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## toddalin (Jan 4, 2008)

steam5 said:


> Cliff
> 
> The sprue was 2mm in diameter which was within Shapeways guidelines, it was the manual inspection by a human that initiated the rejection. So I'm guessing if I arranged differently I could have got it past the checks.
> 
> ...


Which is why 3D printing is good for prototyping and mold making, but not production.

For me to use the commercial 3D printer, I pay $10/cu inch of material. And I thought that was expensive. But you probably have less than a cubic inch of material there.

People at the Workshop where I go have tied the printer up with "hollow" stuff that uses just a couple cubic inches of material, but can take 18 hours to print.

BTW, I design using the DesignSpark Mechanical software and it will automatically hollow your project out where you specifiy how thick you want the surface layers. That saves beacoup media.


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## steamermeister (Feb 20, 2013)

toddalin said:


> Which is why 3D printing is good for prototyping and mold making, but not production.





toddalin said:


> For me to use the commercial 3D printer, I pay $10/cu inch of material. And I thought that was expensive. But you probably have less than a cubic inch of material there.
> 
> People at the Workshop where I go have tied the printer up with "hollow" stuff that uses just a couple cubic inches of material, but can take 18 hours to print.
> 
> BTW, I design using the DesignSpark Mechanical software and it will automatically hollow your project out where you specifiy how thick you want the surface layers. That saves beacoup media.


I'm not sure if it's just me but a lot of the talk about 3D printing on this website and elsewhere treats 3D printing as though it is a singular technology, or that the various technologies are interchangeable. There are in fact multiple printing technologies currently in use and they are not created equal. 

Shapeways currently offers 6 types of plastic, most in an array of colors, as well as ceramics, semi precious metal, precious metal, casting wax, and my personal favorite, stainless steel. 60 material/color/finish options in total.

Anyone interested in getting into 3D printing owes it to themselves to learn about the benefits and drawbacks of various printing methods. Especially before buying a printer, which I don’t recommend.

Shapeways Hi-Def Acrylate is at the more expensive end at about $20 per cubic inch of machine space but there are less expensive options available. Shapeways Strong & Flexible Plastic (SLS Nylon) is an excellent substitute for plastic parts traditionally made via injection molding and under $7 per cubic inch of machine space.

As for the cost being too much for production, unless you're making thousands of parts, 3D printing is the way to go for semi-mass production.


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## steam5 (Jun 22, 2008)

toddalin said:


> Which is why 3D printing is good for prototyping and mold making, but not production.


That's what I only printed 1 truck  Going to get quotes for castings, because I plan to make a few cars using them.

Alan


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## Dick Friedman (Aug 19, 2008)

You can put all the parts in a single file and print them all at the same time. You want the smoothest side of each piece down. All the detail of the side frames should be up. If there's no detail on the inside of the brake shoes print them inside down. You might find a local place to print them, at least the first one. Try your local library (where I do MY 3D printing), or perhaps a college.

Welcome to the wonderful world of 3D printing.


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## Scott (Jan 29, 2008)

Like many modelling procedures in this hobby it takes time to develop and understand the process as well as making mistakes along the way. 

Sprues can be added to an item if you are casting and at the present I do advise you to add the sprue after the 3d print. Use casting wax or styrene to make the sprue you want for your master along with any vents or channels. Any added material to your print will add extra costing to your fee, like many modellers - money is a precious resource and is better off in your pocket not someone else's unneccessarily.

I like the look of your work, please keep us updated with your progress. Looking fowards to see your finished product.


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## steam5 (Jun 22, 2008)

Hi All, I received the prints a few weeks back. However I have a complaint in with the printer. I'd rather wait until that is completed before I share.

Very happy with how my complaint has been handled so far.

Alan


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