[AT] repairing machined arts

[Jim Thomson]

I worked at a dental company that 3D printed crowns, bridges, bars etc. I have a video on the process somewhere. They started with a fine powdered metal, ran the laser over the pattern, then had a wiper put another layer of powder, then repeat the process until is was completed. The issues I saw was that it was very slow compared to traditional casting, the accuracy was not that great, and the parts still had to have a great deal of had finishing. They ended shipping both printers back to Germany as it was not the most cost effective method.

Jim Thomson
Rehoboth, MA

> On December 6, 2019 at 10:03 PM Henry Miller <hank at millerfarm.com> wrote:
> 
> 
> Traditional casting is much cheaper, once you pay off the cost of the making the pattern. We (John Deere) had someone looking for a shift fork for the transmission in their 1991 tractor a few years ago. No spare parts left in inventory, and the pattern was destroyed years ago, so we 3d printed one from the engineering drawings. Cost was just under $500, without markup. If the pattern still existed the cost would be about $20 including markup to pour another one. 
> 
> Of course if you need a new block a pattern exists, so the 3d metal print is what you get. If you can find a few others who need one though investing in a pattern is the way to go. 
> 
> 3d printing plastic is cheap and works okay for a lot of things, but it isn't enough quality to replace most parts on our tractors, even ones where plastic would be better. 
> 
> -- 
>   Henry Miller
>   hank at millerfarm.com
> 
> On Fri, Dec 6, 2019, at 4:19 PM, szabelski at wildblue.net wrote:
> > If you remember the TV series “Myth Busters”, there is a new show 
> > emceed by one on the guys (believe it’s Jamie), who does a lot of 
> > similar things to what they did on MB. I caught one show where they 
> > were making an Ironman suit made from titanium so they could 
> > prove/disprove some of its capabilities. Some of the parts for the suit 
> > of armor were made using 3D printing and powdered titanium. Didn’t take 
> > that long to make the parts. I think I also saw a program somewhere 
> > were something was being made using powdered iron (????).
> > 
> > Don’t know how well other metals could be adapted to a process like 
> > that, but if the technology can be properly developed, and the cost can 
> > be kept down, could this be the beginning of the end for all types of 
> > machined/cast parts? If so, would a repair shop still have to carry a 
> > large inventory of parts, or just make a needed part using a 3D printer 
> > and the proper material on the spot as needed?
> > 
> > “Yes sir, you say you need a new engine block for your 1920 vintage 
> > tractor? Just come back tomorrow and it’ll be ready.”
> > 
> > Carl
> > 
> > 
> > ----- Original Message -----
> > From: Ken Knierim <ken.knierim at gmail.com>
> > To: Antique Tractor Email Discussion Group <at at lists.antique-tractor.com>
> > Sent: Fri, 06 Dec 2019 15:16:47 -0500 (EST)
> > Subject: Re: [AT] repairing machined arts
> > 
> > Some progress has been made toward taking digital photographs of the
> > original part and creating a 3D model from them (photogrammetry). I have
> > the software (as part of a 3D printer package) but have not tried it yet so
> > I cannot vouch for the accuracy. I'm still new to 3D printing but we've
> > already put several parts into production systems... it's got its place.
> > The photogrammetry process might be a decent place to start if you want to
> > make a casting but I'd question accuracy for finished parts. The laser scan
> > technique would be better in my opinion.
> > 
> > Something along similar lines for making parts is 3D metal printing. The
> > Rutherford rocket engines are made using this technology. It uses an
> > electron beam rather than a laser for melting the metal and requires a
> > vacuum chamber for manufacturing but obviously works with high pressures
> > and temperatures.
> > 
> > Photogrammetry software:
> > https://all3dp.com/1/best-photogrammetry-software/
> > 
> > Rutherford rocket engine:
> > https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)
> > 
> > I see these as interesting ways of creating parts. As with anything, it's
> > going to take some work to perfect. I doubt it would be affordable for
> > tractor parts for awhile.
> > 
> > Ken in AZ
> > 
> > 
> > 
> > On Fri, Dec 6, 2019 at 10:48 AM Jack <jacktractor at live.com> wrote:
> > 
> > > The shortcoming of this for the repair of unavailable tractor parts is
> > > that you need a Cad file of a good part first.
> > >
> > >
> > > https://www.imeche.org/news/news-article/feature-retrofit-transforms-legacy-machine-tools-to-keep-worn-parts-in-use?utm_campaign=PE%20newsletter%2C%206%20December&utm_source=email&utm_medium=PE%20Newsletter
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