3D printing surface finish help

[Dave Schneider]

Dave,

That is some pretty nice design work. Really nice. What wall thickness did you use on your foot board side kick plate? Looks to be maybe 0.010" or less. If it wasn't for the print lines, that shell would have turned out darn nice.

I purchased this and a H12-44 off Shapeways. The design work is by South Boulder Modelworks. I agree. The design is top notch.
http://www.shapeways.com/model/715594/n-scale-fm-h-10-44-kit.html?li=productBox-search

The best looking finishing job I have seen in a long time is on these CNW ore cars.
http://www.shapeways.com/model/611732/cnw-ore-car-four-pack-n-scale.html?li=productBox-search

Best wishes, Dave
 

[robert3985]

Wow.  Perfactory is an order of magnitude less, ~$60,000 last I checked.  Wonder if there is a speed or build volume issue with them buying better machines than the FUD ones.

My communication with the Perfactory rep puts the machine I inquired about at $135,000, give or take a couple of grand.  The main differences between this one and the less expensive "table top" model are the materials the more expensive one can use, which for me included high resolution materials specifically engineered to withstand the rubber vulcanization process for making rubber molds for injecting wax masters for investment casting, and...the print envelope is large enough to allow printing of long items such as passenger car bodies or (haha) U.P. Turbine shells.

I'm still thinkin' about it... 

[randgust]

I'm of the belief that until somebody actually does more 'on-model' FUD testing, I'm willing to wait.   I'd love it if it actually worked, and until its been tried more and proved or disproved...well, everybody is guessing.

The things I've tried to assemble have relatively rough surfaces to begin with. 

I look at it this way.  A couple short years ago we were looking at the 'make my model' stuff in terms of quality, material, and resolution.  Then shapeways rolls in and it's kind of a mindblower.  I can hardly wait to see what happens in the next generation. 

For smooth steel surfaces, I'm still conflicted and like scratchbuilding my masters for resin work out of styrene.  But I expect that to change.

One of the next breakthroughs should be when the metal powder printing equals that resolution and you can print your own frames.  Think of it.   There's a lot of steam locomotive ideas out there that have to use metal boilers or they are just nice decorations.

[Chris333]

I'd like to know specifically what tooth paste people are using with good results. I have FUD to try it on.

[Philip H]

I had some old Colgate around the house and it worked ok - but my ability to do anything in the bath room for more the 15 seconds seems to be limited these days with a 2 1/2 year old in the house.

[Alaska Railroader]

The main differences between this one and the less expensive "table top" model are the materials the more expensive one can use, which for me included high resolution materials specifically engineered to withstand the rubber vulcanization process for making rubber molds for injecting wax masters for investment casting

Casting, another thing I know about (I am a retired goldsmith, my husband is a dental tech and makes gold crowns). If you take shrinkage into account, or the margins don't matter too much let me suggest another way to make your rubber molds. I still have my vulcanizer and knowing the pressure it takes to get a completely detailed mold would most certainly crush the plastic. Also, the uncured rubber needs to heat up to at least 300 degrees to melt the rubber around the master. What would that do to your model?

Instead, use a warm wax pot and brush or tool molten wax on the surface, then when cool smooth the wax out with a cut piece of pantyhose. This gives you very decent master to burn out in a kiln and cast into brass or silver -THEN you make your rubber mold. Again, you need to allow for shrinkage. I have seen this done by another company but won't mention their name as I wouldn't recommend then to anyone, ever. But it works.

Here are some pics of the failed attempts to cast FUD without any treatment. You'll see that the metal shows the porosity in FUD that you can't see otherwise.

[robert3985]

Casting, another thing I know about (I am a retired goldsmith, my husband is a dental tech and makes gold crowns). If you take shrinkage into account, or the margins don't matter too much let me suggest another way to make your rubber molds. I still have my vulcanizer and knowing the pressure it takes to get a completely detailed mold would most certainly crush the plastic. Also, the uncured rubber needs to heat up to at least 300 degrees to melt the rubber around the master. What would that do to your model?

Instead, use a warm wax pot and brush or tool molten wax on the surface, then when cool smooth the wax out with a cut piece of pantyhose. This gives you very decent master to burn out in a kiln and cast into brass or silver -THEN you make your rubber mold. Again, you need to allow for shrinkage. I have seen this done by another company but won't mention their name as I wouldn't recommend then to anyone, ever. But it works.

The Perfactory process specifically details a material that is hard enough and heat resistant enough to use as a "hard" master.  I have all the investment casting equipment, including mold frames, the vulcanizer, wax injector, spin caster, burnout oven, vacuum table, vibrating table, and a gas melting furnace.  I used to build masters and cast parts for a certain HO scale detail parts company about 20 years ago.  I quit when I started hating the hobby. So...I know all about casting brass, bronze and beryllium copper.

I asked the rep about the material, and he assured me that it will take the temps and pressures of a vulcanizing press.  However, I am skeptical also, so...he's offered to print me some samples as soon as I get him a 3D model.

On the other hand, the Perfactory process will also print material that will burn out, eliminating the need for making a vulcanized rubber mold with multiple cavities.  But, it'd be a lot quicker to just let the wax injector heat up, get out the molds and inject away. I can pop out several hundred wax parts in a few hours with four or five molds depending on the size of the parts.

I also thought it'd be really nice to be able to get the parts just right to compensate for shrinkage.  That's be very easy if all I had to do was just print 'em out rather than build a whole blinkin' new brass master if I mis-guessed the shrinkage.

Somewhere in the back of my head I've got this idea that I'd like to turn this into a business, but the front of my brain says "Don't turn your hobby into a business again"...which is most likely what will happen.

[Sokramiketes]

This was created via Perfactory to Brass.  Yes those are Z scale rivets and clean surfaces from RP.

[Alaska Railroader]

Somewhere in the back of my head I've got this idea that I'd like to turn this into a business, but the front of my brain says "Don't turn your hobby into a business again"...which is most likely what will happen.

+1

I will never again get into cast brass rolling stock for money as I found out its not there.