Re: Small scale manufacturing


Generally I agree with Dennis' assessment of the RP/3D printing technology. I first became aware of 3D printing in 1993 - 94 when ads for such machines appeared in "Cadylist" (though one can assume it had been around even prior to that). So it has taken 20 plus years to come this far. That being said one should keep in mind that its companion technologies of computer capacities and 3D programs also had to improve.

On the other hand I've watched the resolution steadily improve over the last half dozen years and I am not so pessimistic about it. I think it could reach an acceptable level in the next 5 - 10 years. There are already home type machines available starting at around S1200.00. (Not surprising since, like regular 2d printers, they will make up the profit on the "ink"!! (Grrrrrrr!))

I've seen some pretty awesome products of RP but, like so many new ideas and devices the initial purpose wasn't meant to tackle the likes of ultra fine part making required by scale modelers. We've been an unexpected beneficiary(?) - just lucky I guess.

I've had the understanding that some companies employ "Air Honing" (sand blasting) to clean up the parts. This is where Jack's Paache Air Eraser might come in handy. NWSL has been using RP as a means of developing some of their products and there has been an attempt to use the technology directly in the same manner Sergents Eng. has done. This would be for gearbox components, which would not need the fine detail of car parts to work. But in this case they haven't found a plastic that is suitable for that purpose.

I have a batch of coupler striker plates that I had printed a while back. I should obtain an Air Eraser and try my hand at cleaning them up...

Just some thoughts....

Derrell Poole

--- In STMFC@..., "soolinehistory" <destorzek@...> wrote:

--- In STMFC@..., "Arved" <arved_grass@> wrote:

The ant climbing over the chess set is pretty darn amazing to me. By biggest concern has been the layering effect of most printed materials, such as those from Shapeways vendors. but I don't see any in that green chess set.
That is because, as in most of these sales demos, the part was chosen for attributes that minimize the process problems. Note there are no real angular surfaces, they are either flat, or vertical.

"The (Micro Resolution) process features resolution as fine as 30-40 microns in X and Y, with 25 micron layers. We have built parts for some beta test customers that were measured to be accurate to within 15 microns anywhere on the part. There are limitations still regarding the thickness of the first layer of a feature, but it is about half that of the (High Resolution) build process that represented the previous state-of-the-art." (from the above site)

Is much more really needed?
Yes, I say it is.

40 microns is 0.001574" or, in HO scale, just a bit more than 1/8" (0.1370954 scale inches)
And 25 microns is just under .001", about the thickness an HO scale shingle should be. The question is, if you were building a tankcar dome, would you want it to look like a shingled roof?

Although the price of this kind of quality and fidelity is relatively high, certainly there's a possibility of making masters for relatively inexpensive resin castings.
I have been watching this technology for better than fifteen years now. There is always one little phrase inserted between the beginning of the review that says how easily the part can be modeled in CAD, and the end that tells all the good things that can be done with the resulting part... <after a minor amount of hand finishing>... The problem is, most of our parts are too small for hand finishing, or the hand finishing precludes including small details, like rivets, that are the whole reason for wanting to use this technology. Yeah, you can do a Dreadnaught end, and you can sand the pattern smooth. But then you can't include the rivets, and with no rivets, you might as well have used the solid model to program a CNC mill. In fact, I've done several this way in 1/4" scale, where the rivets are large enough to add one at a time.

Sergent Engineering is already using this technology:

"Sergent Engineering uses high speed 3D printers to produce parts one at a time. This allows us to provide a wide variety of variations of the product that simply would not be financially plausible with other manufacturing technologies due to tooling cost. This has also allowed us to quickly produce some special products for customers' unique circumstances. While some other companies have used similar technology to produce master patterns for soft tooling, Sergent Engineering is probably the only model railroad company to use the technology on a production basis." (from their home page).
Also from the Sergent Engineering home page:

"This technology works great when it works. However when troubles arise, causes of problems are not typically simple to identify and correct. This is where we are today. Stock levels on investment cast products are dwindling and production capabilities for replacements are offline...."


"Update January 2012

While we continue to work to find a solution to the problems in manufacturing the investment cast products, we are also in the process of moving some castings to a die cast process instead. This will lessen the manufacturing load for the equipment and allow the printers to be used only for the really special products. This is not a quick or easy solution, but will be worth it in the long run. "

While I applaud Frank Sergent's putting some money out to explore new technology, I think it proves my point that the technology 'ain't quite there, yet.' Tom Madden worried that he may not see some of this technology mature in his lifetime. I'm ten years younger than Tom, and I have doubts about my lifetime.


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