The Google SketchUp Thread

[marc_reusser]

Well...I would have to say, that for the quality of results, the speed of turn around, and the freedom to have any shape or part I design made, and goof around with 3D ideas,.......and so far none of my prints has cost me more than $37........it pretty much is the best game in town when all is taken into consideration. Laser cutting, & PE are more expensive, even for just the first set-up and test shot...and the higher resolution green 3D printing would be about 6 or 7 times more expensive at best.....

So...a little clean-up is nothing...I have to do that anyway on regular kit and model parts.

I kind of feel that this attitude or concept of wanting the perfect printed part that requires no additional effort, is kind of like the guys that want everything RTR, or the shake-the-box-and-hope-it-builds-itself, RR crowd.


A little work never hurt anyone...besides...if you don't learn the ins-and-outs of proper clean-up and prep, you'll never be a good model builder.

M

[JohnP]

So are we the only ones that are testing PAP for modeling to the limits? Any other forums out there discussing it?

I was satisfied with my PAP experience and plan on doing it again as needed. I assumed that if it took my file I did it right so I didn't have to ask questions. Their business model on the PAP side seems to require very little human intervention.

OK Marc I guess I read into your statements wrong. Your official title says CURMUDGEON so I made assumptions. Were you labeled such as a child in school? That stigma will carry with you forever I'm afraid.

John

[lab-dad]

Guys,
What about using the air eraser or similar w/ baking soda to "clean" the parts?
Then a dip in alcohol?
Just a thought.
-Mj

[RoughboyModelworks]

Marty - a gentle soda blasting might work fine , certainly worth testing.

My PAP advisor has not encountered the "snowy" issue Marc. He says that the parts sometimes develop a frosty appearance after a "slosh in solvent" as he puts it, but there is no dimensional change. As far as archival properties are concerned, he had no input. His parts are masters for molding purposes so their use is temporary.

We have to remember that rapid prototyping is just that, prototyping. The parts produced are meant to be temporary, part of the assessment phase of the product design process. We are, in a sense, stretching the purpose behind the process by making final parts. It will therefore be very interesting to see how these parts endure over time.

Paul

[james_coldicott]

Couple of points/ ideas- was discussing this thread with a friend in the automotive industry over the weekend and he made a couple of interesting comments from his experience as a liaison engineer who is using this technology professionally...

for longevity he recommended either using the PAP output for lost wax production in brass/nickel silver (in the US I imagine a company such as Back Shop would be able to do this) OR getting the parts metal plated- don't know if PAP offer this service but he is using 2 providers in Europe who will copper plate their output. I guess this would solve most of Marc's issues- though he did suggest adjusting the drawings to account for the plating thickness.

His second suggestion was getting PAP to print dies for plastic injection and transferring those into brass- I'm quite keen on trying this idea where greater numbers of parts are required as I don't have the equipment to machine lumps of brass into plastic injection dies. The advantage here is that you can keep the material thickness even rather than having parts of the die heat up quicker than other parts- apparently he uses this technique to quickly attain parts in plastic prior to investing in full machining for injection molding. Drawing would obviously have to be of a 'shell' around the eventual part required.

James

[marc_reusser]

OK Marc I guess I read into your statements wrong. Your official title says CURMUDGEON so I made assumptions. Were you labeled such as a child in school? That stigma will carry with you forever I'm afraid.

John

I have been working hard for many years to achieve that public perception and stigma. I'm trying to find the right combination of the John Becker, Dr. House, and Hemmingway approach to life and those in it that I must suffer  (though, I have curtailed the drinking aspect of the Hemmingway part, and I have no plans to blow my brains out at some lake in Idaho.)

M

[RoughboyModelworks]

I have been working hard for many years to achieve that public perception and stigma.
M

Well by all accounts, you have succeeded in your quest...  though I do take offense to you usurping the title of "Curmudgeon" since my days as a curmudgeon predate your birth... just ask my wife...

James, sounds like an interesting discussion and approach. PAP doesn't do plating but their parent company, Fineline Prototyping does offer that option, I'm sure at much greater expense.

Paul

[lab-dad]

in the US I imagine a company such as Back Shop

HA HA ha ha!!! ROTHF LMAO!!!
If there is any question about longevity of the PAP parts that would be one way to find out!
The PAP parts would be dust by the time you got them cast from there!!!!!

[Chuck Doan]

Funny yet sad too Marty!

I first heard of PAP in a Finescale Modeler article several years ago. That article advocated using the printed parts for models.

Hope they don't dissolve or turn into pumpkins.

[marc_reusser]

There is a model company in Australia called 'Hard Corps Models' (David Harper), that sells high end aftermarket detail kits and parts (primarily for WW2 US Pacific theater) that has a number of its items printed by PAP (a link to one of the items http://hardcorpsmodels.com/shop/product_info.php?products_id=107&osCsid=b4ba624d4fd81a8ba1be395e998ef285 ).  From what I have seen and understand, he has been working closely with PAP for his parts, for quite a while (several years), ...and from what I understand he is quite the perfectionist.....so I doubt that he would continue using the process if he had experienced any issues with part degradation over time.

Marc

[RoughboyModelworks]

Agreed... the fellow who has been advising me on the process has been using PAP for two plus years producing very fine masters for commercial scale parts, 1:48 mostly I believe. Like all technical adventures, there's a learning curve and period of trial and error before you learn enough of the ins and outs to be able to adapt the technology and your application of it to suit your end needs.

Paul

[james_coldicott]

in the US I imagine a company such as Back Shop
HA HA ha ha!!! ROTHF LMAO!!! Grin Grin Grin Grin Grin
If there is any question about longevity of the PAP parts that would be one way to find out!
The PAP parts would be dust by the time you got them cast from there!!!!!

Marty,

Really? That is too bad... you'd have to be very inept as an investment caster not to get good results.

Spoke again to my friend regarding stability and he has some surface degradation on (admittedly larger) parts that are still knocking around his office after 3 or 4 years- apparently the surface has started to powder. No doubt this is dependent on resin type and painting parts will make a difference. I've asked him to send a few photo's when he gets chance but he is a pretty busy guy so don't hold your breath.

My investment caster here is such good value I'll probably use my parts from PAP as masters and get molds made so I can repeat them in brass rather than getting them reprinted in resin- I'm adding the shrinkage rates for investment brass onto my drawings- I've had so many issues with styrene and resin deforming over the years I'd rather make the extra effort- speaking of which...

Marc, maybe not the best place for this question but as we were discussing stability of resins...how is your Smoky Bottom critter conversion holding up? I was working on a similar conversion and came back to it last week to find the frames had bowed by about .5mm along their length. Not flexed- that could be expected but if you lay the sideframes on a flat surface with a rule across the top they have visibly bent- attached a quick pic to show why I am increasingly mistrustful of resins- this has been in a drawer in my studio (so not subject to great ranges of temperature) and had a lead/ plasticard deck similar to the end beams you can see here to add weight to the finished model but never seen anything as bad as this... again, no doubt down to resin type etc.

James

[marc_reusser]

James,

It's not only the issue of results with Dave Braun....but the fact of actually ever getting the part made....or after waiting years for it the guy has lost it, or just plain ignores you and never returns it (and no I am not spreading rumors I speak of personal experience with the SOB.)

The powdery surface your frinds parts have developed are probably the same stuff that we were talking about here earlier.

Insofar as the SBLCo frame, I'm sorry to hear you had this problem after starting construction. So far my frames are still perfectly flat in all directions. Before strting the build, I had the kit sitting in a cabinet for about 6 years...so hopefully it had enough time to work out it's issues over that time. I did find that the kit had some of the more common resin issues when I bought it...the large bonnet piece had "sunken" in in the center areas....probably .05+, same with the thicker more blocky end sills. The cab walls had some serious warpage, and the side sills had a slight arc like yours on the bottom side....however after carefully  measuring it became apparent that the piece had either shrunk in width in this area (as the ends were the same dim, and the center narrower)...or that the mold had flexed/compressed during casting. When I started the build I merely sanded the sill flat/square (they needed to be anyhow, as the two sides were a diff height right out of the box). As far as I know this was one of his early first kits, so his casting skills may have left something less than quality....I have not purchased or personally seen any  of his kits since then, so I cannot speak to what his quality is like these days. 

...as an afterthought.....could this bow have been caused by the adhesive you used to glue the deck and weight in place?....I have seen times where the glue, due to different expansion and contraction properties, will cause a piece to warp (sim to how paints can do this when only one side of something is painted).


M

[finescalerr]

The more I hear about resin, the more wary I have become. Quality control of the materials, even from reputable sources, can vary and result in problems a few years down the road. And the problems one can expect from older styrene masters are legendary. That doesn't mean everyone will have problems or that all resin castings will deform. It does mean we should hope for the best but expect the worst. Err on the side of conservatism, James.

Russ

[JohnP]

I must now come to the rescue of resin. Fear not Russ.

I dug out my rev 0 bridge castings. They were made when I first investigated bridge parts made of resin five years ago. They were made with the either the Micro-Mark kit or Smooth-On moderate cure time resins. The snapshot attached are of floor beams with and without sprues, a stringer and several chord beam parts. The dark one has color added to the resin.

These parts are straight except for the built-up beams (gray part and the one above). They have been left out on the bench, on a shelf, in a Tupperware and now reside jumbled in a bag in a box. They have sat inside in the sun and in a hot closet. The two beams that have a slight bow caused me to redesign the beam method early on in the process. They were cast as one piece with the top and sides together. I had a thick fillet on the inside corners. I believe the variation in thickness caused a slow curve in some of the early parts although not all did. My mixing and other processes were not as controlled as they are now.

My new parts are mostly rather thin. The only problem I have been having is if I am not orderly with the parts in my storage bins. They can sag or twist if piled together. I am more disciplined now.

My built-up truss bridge (http://www.jpstructures.com/ (top photo) is in a window that gets afternoon sun. It is holding up great and is still straight. after about one year now.

I believe if the cast part has a fairly uniform cross section it will age much better than parts like my first beams. The time it takes for resin to cure is dependent on its volume or mass, so a part with a heavy and thin side may end up with differential strains. That's my conclusion anyway.

If the resin is assembled, painted with mild paint, and kept out of direct sun and heat it will preform well. Resin is used for many outdoor amusement park decorations, although on a much grander scale. Resin is used for climbing wall handholds, movie props, frequently handled prototypes and lots of other stuff. For our modeling, a small part that is .10" out of true can be a disaster. It is up to the manufacturer to create a careful part design, use appropriate, quality, fresh resin and pack it in a stable arrangement. When we buy a resin kit we should handle it carefully and store it supported until it is assembled and painted.

Also, who hasn't purchased an plastic injection cast kit with some parts warped?

John