Re: 3D printing (Was: New early P&R steel.....)

Bill Lugg
 

I gave up on Shapeways a while ago, mostly due to their exorbitant pricing.  Try https://print.all3dp.com/ the next time you need some printing done.  I found the results to be quite satisfactory and the prices to be about a third of what Shapeways was asking for the parts I needed printed.  Admittedly, my prints were not nearly to the level of precision these are, but it might be worth a try.  I'm looking at them for bolsters and end beams for a narrow gauge tender I'm working on.  they will be printed in casting wax and cast in brass. the total cost will be about $45 for all four parts.

HTH
Bill Lugg

On 12/20/19 7:59 AM, dalemuir2@... wrote:

Re: Shapeways issues.

I have had inconsistent results from Shapeways printing long (205mm) bridge girder parts. Parts I received were off by 1mm or more. This makes it impossible to assemble parts that must have consistent dimensions. Imagine printing car sides, roof, and floor with convenient locating pins only to discover that nothing fits.

The following illustrates the issues.

The model is a seven track underpass with two independent single track bridges and a five track bridge.

There are a total of six full height girders and four "split" girders consisting of a top and bottom part. The floor is sandwiched between the top and bottom part.

Total part count is 14. (Split girders are two parts each.)

One of the four split girder top parts was about 1mm too short, so the locating pins didn't line up.

All four split girder bottom parts were useable.

IMG_1733_SplitGirder_2019_10_06_19_27_OK_GoodExample

IMG_1732_SplitGirder_2019_10_06_19_27_OK_tooShort

Two of the six full girders were about 1mm too short.

In summary, 3 of 14 parts (about 21%) were unusable. All 3 unusable parts were duplicates (same 3D model) of parts that came out near perfect.

Anyone with a little knowledge of process control would recognize immediately that Shapeways' process is out of control.

Shapeways just dismissed the issue claiming that the parts meet their specifications for Fine Detail Plastic. They won't refund or re-print.

I had to re-order (and pay for) the defective part to finish the project. The re-ordered parts were about 0.5mm too short, but I was able to make them work.

Because of this, I can't add this model to my Shapeways store.

The following is an excerpt from an email exchange I had with the Shapeways Quality Control person.

Begin quote from Shapeways QC person

The print resolutions are as follows:

Smooth = 29 micron
Smoothest = 16 micron

Indeed, that ±0.3- 0.7 range is for models that are 100mm or shorter.  The accuracy range can be a bit greater for models larger than 100mm.  I do understand you are looking for increased accuracy, however, the process does not allow for this.

We are hoping that as the technology and printer abilities increase, we will be able to provide tighter tolerances in the future but this is currently not the case and not something we can guarantee.  I understand this is disappointing and I'm sorry about that. Our production team is constantly working to improve our processes but this is currently the best accuracy range we can promise.

While certain processes do involve batch printing, this works a bit different with models printed in Fine Detail plastic as there is no stacking or "packing into a printer" involved. We explain the process on our Fine Detail Plastic materials page <https://www.shapeways.com/materials/fine-detail-plastic>:

End quote

To me, the frustrating part is that Shapeways can produce accurate parts, but they won't. They seem to be more interested in cranking out parts a cheaply as possible.

Dale Muir

Geneva, IL

*From:*main@RealSTMFC.groups.io [mailto:main@RealSTMFC.groups.io] *On Behalf Of *Tom Madden via Groups.Io
*Sent:* Thursday, December 19, 2019 5:05 PM
*To:* main@RealSTMFC.groups.io
*Subject:* [RealSTMFC] 3D printing (Was: New early P&R steel.....)

[Edited Message Follows]

On Thu, Dec 19, 2019 at 01:50 PM, Dennis Storzek wrote:

Thanks Tom, very informative. This proves to me that Shapeways is just maxed out and still found wanting. It's no longer an issue of resolution, but designing around the "wax tracks". It seems the SLA process is better suited to our parts. Compare these pix to the pix of the D&RGW coal hopper Eric presented a week or so ago.

I believe Corey Bonsall, who does the D&RGW and Utah Coal Route gons, uses a Form 2 "upside down" SLA printer where the part is built from the bottom up as it's lifted, layer by layer, out of the resin. For best results parts need to be oriented at an angle and parts of any complexity require a literal forest of supports. Shapeways had a similar process, Hi Definition Acrylate,  but they dropped it because  their trimmers lacked the skill to trim such parts quickly and without damage. In this field you can't have low prices, low wages and high skill levels across the board. For a while they offered HDA parts untrimmed but they've dropped that as well.

If you _can_ design around the wax track problem the 3D Systems' multi-jet modeling process (which Shapeways calls Fine Detail Plastic) is faster and much less expensive than any SLA. For large parts, like passenger car sides, the Form 2 and other small SLA printers won't work at all. Here are three images (front, back and detail) of a pair of car sides I got from Shapeways on Monday. These are images of passenger car parts, but they're shown for the technique and not the product. On the PCL and some other forums any discussion would involve the parts and not how they were made. I'm not ready for that discussion yet!
http://www.pullmanproject.com/3989A-1.jpg
http://www.pullmanproject.com/3989A-2.jpg
http://www.pullmanproject.com/3989A-3.jpg

Those are flat with no sidewall detail. Shapeways Smoothest Fine Detail Plastic process (16 micron layers) shows minimal stairstepping on sloped surfaces. That encouraged me to design some Pullman blind and solarium ends with full rivet detail on the end sill and in the upper ends. Both regions are sloped. I also included the handrail mounting flanges and bolts on the door frame, a vertical surface on the print.
Here's a photo showing four different ends They're castings, but the masters were printed:
http://www.pullmanproject.com/EndsC.jpg

Here's what the sidewall detail is supposed to look like:
http://www.pullmanproject.com/EndsD.JPG

And what it does look like: (Best I could do without a macro lens.)
http://www.pullmanproject.com/EndsG.JPG

There is a wax track below the detail, but in this case it's not objectionable. Since it's the only such detail in the area, and the wax track is short and hidden under the handrail, it's not at all noticeable. You need to pick your battles.

Tom Madden

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