Renshape for scratch builders

[rshousha]

Greetings, 

 

I have come across a very interesting product that I am going to use for a project at the Modeller's Workshop. This product, Renshape, a high-density foam, is excellent for scratch-building parts and making molds. However, it comes in large sections and is quite expensive. 

 

I am considering buying some of this stuff and cutting it into small pieces so model-builders can use it. 

 

Please let me know if you are interested. If there is enough interest, I will start selling the stuff on my website, in small pieces. 

 

Best Regards, 

 

Rick Shousha

Modeller's Workshop

Montreal

[druxey]

High density foams have been around for a while. I've used them in theatrical set construction in the past. They work very well for carving in detail but, as mentioned, are very expensive and only available in large chunks. My only reservation would be the longevity of the material, but for most folk this probably isn't a big consideration.

[rshousha]

Indeed, the stuff has been around for years and this is encouraging me to use the stuff for this project. From this, one can infer the excellent longevity of the product. I don't think most people can actually outlive the stuff, in fact. 

 

So, this is now a survey of what sizes of Renshape would be interesting. I have 4-inch and 2-inch blocks and can cut them to any size. 

 

Cheers, 

 

R

[rtropp]

I am interested in finding out more about Renshape.  Do you have a link to a description or demonstration?

 

Richard

[rshousha]

Hi Richard,

 

This is the first link that comes up when you look for Renshape, for me, anyway: 

 

http://www.freemansupply.com/RenShape460MediumH.htm 

 

here's an excellent article on machining and they talk about Renshape about half way down. 

 

http://lcamtuf.coredump.cx/gcnc/full/

 

Again, the problem is not availability; the stuff is easy enough to get. The problem is it comes in large pieces and is expensive. Since I have access to the product, and a website that people find easy to use, I am considering buying some of this stuff and cutting it up to usable sizes for modellers. 

 

Cheers, 

 

Rick 

[hexnut]

Renshape is actually the reason I haven't worked with wood in the approx. 30 years before I tried messing with model ships again.

 

It is a cast urethane material. Bonds with CA or epoxy, machines like a dream, much easier to carve accurately than wood, bonds nicely to autobody fillers, primes and finishes really well. 

If you are modelling anything where you want to simulate metal, composite or fiberglass components, you can achieve a mirror paint finish without too much work.

 

It comes in a variety of densities, I find the 460 (48lb.) and 450 (41 lb.) the most useful density, as it combines easy work with nice crisp edges. it works nicely w/ hand tools lathe, mill, etc.

 

Durability is similar to basswood, it is nice and dimensionally stable, but if you drop a tool on it, it will dent.

The dust is somewhat nasty, but wearing a standard dust mask is fine.

 

I use it for work, so I have a large chunk of 450 sitting in my shop. My Ren needs are set for now, but the potential offer of smaller pieces is pretty intriguing to me.

[rshousha]

Great! This is exactly what I wanted to hear. 

 

However, I am having a hard time getting the mirror finish you mention. I've used automotive primer to seal the material and, after painting with Tamiya spray cans, I don't quite get the identical finish I am getting on straight polystyrene. It seems fine when I sand the two pieces, side by side, but then the paint still seems to be absorbed a little by the Renshape. 

 

Can you let me know what you do to get a perfect finish? If I am going to sell the stuff, I also want to be able to give instructions on use. 

 

Cheers, 

 

Rick 

[hexnut]

What density Ren are you using? The following process works well for the 460:

I usually prime with Tamiya grey for smaller models, sand @ about 400 grit or so, do final patch filling with red lead-type filler.  Ideally, allow a day or so for the filler and primer to outgas and settle.

 

 A coat or 2 of tamiya white primer, sand, lay on color coat (mist, let dry for about 20 minutes, cover coat) It helps if you warm the spray cans a bit in a hot water bath. For small areas, tight inside radii and intricate detail that may get lost under the spray can coat, I will sometimes tape a straw to the nozzle and decant some paint into an airbrush.

 

I use micro mark sanding pads http://www.micromark.com/soft-touch-sanding-and-polishing-pad-set-set-of-6,7787.html

to knock down irregularities, and lay down a smooth base. I use the coarser pads after the white primer, sometimes after the mist coat if I still have some bad spots.  then I use the finer pads up to about 6000, to get a smooth finish, but still leave enough tooth for the clear coat. This stage is where I do any decals, graphics and effects painting.

 

I use (surprise) Tamiya clear coat, again mist and cover coats, ideally let dry for 24 hours before final polishing.

Use the fine pads with a bit of water, so they don't build up particulate and scar the finish,

 

Finish off with a fine, high-end auto wax or Novis 2-part plastic wax/spray.

[rshousha]

Hmm, that's pretty well exactly what I've done. I used to do car bodies (you can see them on my site at www.modellers-workshop.com ) and was working with those pretty well the way you described. I don't know which Ren product I have here. I'll have to check. Perhaps there is a difference between the qualities. 

 

What I've done is place a small piece of Styrene on the Ren and have been comparing the finish as I lay on each product. Since the Styrene starts smoother, it's easier to get the nice finish. I'm trying to find a combination of products that can get to the same finish as the Styrene, either in the same amount of time, or faster. 

 

The methods we've both used (primer, color, sanding, compounds, etc) is slow and laborious. I am hoping to create a magic bullet.

 

Cheers, 

 

R

[rshousha]

There's also perhaps the fact that I'm blasting the hell out of it with sunlight to get it to dry. Perhaps the Renshape is a little more porous than the Styrene, and is drying too quickly. Again, I'm trying to build a magic bullet here for another project (soon to be announced here!) 

 

Cheers. 

 

R

[hexnut]

In my experience, if you want good results, there really is now way around "laborious".  The stuff that I do for work is on deadline, so I push the drying times and skip steps sometimes, but it is a tough compromise.

 

If you want perfect, slow and laborious is the best way to do it.

 

Also, don't just compare flat surfaces, compare curved forms to get a better feel for what's going on.

[rshousha]

Interesting. 

 

Hah, you are right about the laborious work and that's one of the reasons I switched from car models to ships. With ships, i find the fun is in creating detail and not perfect surfaces. So, perhaps I should just focus on that for now. The stuff is easy to cut, sand, and carve. it paints easily enough and will be just right for guns and decorations.

 

I am working on a project where I still need a decent surface and for that I will get a piece cut in a curve and see what gives.

 

However, in the meantime, do you have suggestions on sizes of pieces that people may want?

 

Thanks,

 

Rick