Whatever happened to raised rivets ??

[moldmkr78]

Fair pont William. As i tried to explain, but maybe not well enough to make it understandable, spark-erosion technology is great to achieve fine details, but involves more time (therefore more money) to achieve certain results, especially if you add CAD technology.

To summarise, in the past, you carved a cavity out of a steel block, using a pantograph to represent a negative of a positive master, whch represented fine surface detail, based on the master crafter's skills.

Now the part will be represented first as a CAD model. If the designer is skilled enough and is given enough time, the part will be represented as a positive model (i.e. looking like the part to be molded). Surface modelling is a skill different from volume modelling, and takes time (read money) to be perfect.

Then the CAD design is transferred to a CNC machine, to mill a spark-erosion electrode, in graphite or copper. This means that, from a block, matter will be removed until the remaining looks like the final part. Milling fine surface details like raised rivets or overlapping panels, assuming they have been included in the CAD design, takes time, and, paradoxically, probably more time than doing the same in the steel cavity of the past, especially as any surface imperfection of the electrode will carved into the steel mild. The electrode will then be used to generate the cavity in the steel-block.

Because of this, it is paradoxically more difficult, at least apparently, to represent varying surface detail, compared to what was done in the past. BUT producing a mold is a matter of weeks rather than months, the cost for it is in absolute dollars, not even considering inflation, one third to one tenth of 40 years ago.

All in all, we have won from the technology (no way a T-28 in 1/32 could have been produced and sold at acceptable costs in 1970, based on sales potential, compared to a Spit), but some trade-offs, though explainable, seem nevertheless frustrating ....

Hubert

Again, sort of. Many textures, such as Zimmerit on a tank, or rippled surfaces, while possible with an EDM, is done using a photo etch process. This process, along with EDM, can be used to create many different types of surface detail. You still have issues when you get to the near vertical surfaces. Just look at any rivet detail, or any other detail at the near vertical surface of a fuselage. All of the detail has a slightly elongated appearance because of the need to not have any undercuts in the cavity side of the mold. The detail cannot be perpendicular to the base surface. There are limitations because of the mold making and molding processes.

 

I use 3D cad to design plastic parts and molds for a living, and I face these challenges every day. There are many considerations that go into mold design and construction. It's not a simple process. Most single cavity molds that I have built in Asia take 6-8 weeks and even up to 12-14 weeks to complete. Then there is mold testing and tweaking which can take an additional 2,3,4 or 5 weeks depending. And that's for a single cavity. Most models have 20-30 cavities per sprue. (Actually the correct term is "runner". Technically, the "sprue" is the point where the plastic is introduced into the runner, typically the center of the runner system, and is clipped off prior to packaging.) It has always seemed that those who complain about why some companies don't make the correct geometry on a given model, don't understand the process. Sometimes, it's just not possible to do at the price point marketing says they need to reach.

Edited June 20, 2016 by moldmkr78

[Darren Howie]

I think I'll go with Mr Tamiya and the impression of reality is more important than technical accuracy.

In miniature Creating the impression of reality is more important than a perfect reflection of it as the impression will always look more real.

At the end of the day I guess it's a personal choice do you want something technically correct or something that "looks" when completed technically correct?

In scale simply having it reflected in miniature doesn't mean it will look correct when finished.

For me I want it to look correct how you get there is not an issue.

[mydesign]

I believe that a model indeed as some people stated is an "illusion" and has a feeling to it. When I walk to an old propeller aircraft in a museum, I expect to see rivets. In all different shapes, sorts and locations , let alone some buckled surfaces etc.

 

The same for helicopters, most full of it. And some slower jets and even fast jets at places, for example the rear tail areas of a BAe Hawk..

 

In these cases, I sometimes put in some raised rivets. Not all of them at all panels but at some visible scattered locations on a model. This adds again to the illusion that the model looks like a real aircraft.

 

A great cheaper alternative to many "raised rivets" decal brands I can recommend is MICRO-MARK from the USA. And you get quite some raised rivet decal sheets for a good price!

 

These are rivets train modellers mostly use and for 1/32 are very usable as well. I even use these decals for "restoring" any sanded surfaces where there were raised rivets like on fuselage spines of old kits in 1/72 !

 

I don't know of any European supplier, but I ordered with a couple of modelling friends directly from the MICRO-MARK USA website to share postage costs.

 

Check out how I used these MICRO-MARK decals at my 1/32 Lynx at: https://designer.home.xs4all.nl/models/lynx-32/lynx-5.htm

 

or T-2 Buckeye: https://designer.home.xs4all.nl/models/buckeye/buckeye-3.htm

 

and even on rear tail areas on the Hawk: https://designer.home.xs4all.nl/models/hawk-32/hawk-32-2.htm

Edited June 26, 2016 by mydesign