Whatever happened to raised rivets ??

[Hubert Boillot]

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

[williamj]

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

I appreciate the technical applied explanation,and agree that things have changed.

But....some kit moldings ARE showing up with much better surface rendering than what has been contemporary for 30 years.

as I pointed out...Fly is doing some nice Hurricanes,check them out,and they didn't have to charge an arm and a leg for them...So???

I t will probably be a new game of follow the leader..many I'm guessing here,will follow with their wallets,I'm certain that'll be me anyway.

Edited June 19, 2016 by williamj

[MikeMaben]

Hey Bill, you still stirin' up trouble ?

Just for the sake of the discussion, the old Revell Spitfire referenced

earlier was released in 1967 along with the 109 and P-40. They all 3

had very fine surface detail that surpassed some of today's stuff.

The P-40 has recessed rivets and adjacent panels at different levels

(sorta like lapped). Pretty amazing for it's time and proof it 'can' be done.

 

But hey, don't get worked up now, remember your blood pressure

[Hubert Boillot]

I appreciate the technical applied explanation,and agree that things have changed.

But....some kit moldings ARE showing up with much better surface rendering than what has been contemporary for 30 years.

as I pointed out...Fly is doing some nice Hurricanes,check them out,and they didn't have to charge an arm and a leg for them...So???

I t will probably be a new game of follow the leader..many I'm guessing here,will follow with their wallets,I'm certain that'll be me anyway.

 

I am not saying modern technology makes this surface effect unachievable. Quite the contrary, it should be emninently doable, provided you feed the CNC programs with the right input. The Airfix 1/24 Typhonn has seven taken it one step further by trying to replicate stressed-skin effects. And to make it even clearer, a CNC mill with a high-speed chuck can take very fine burrs, which is why details nowadays can generally be finer than in the past, where a small burr run at 5 000 rpms took ages to remove any significant amount of material (even at today's 50 000 rpms, a 0.1 mm burr does not remove a lot of material in one hour, believe me ).

 

However, the trade-off seems to have been made to sacrifice some of this surface effects to cut down the costs of designing and then tooling ...

 

The SH Tempest is a lesson in reverse. It has apparently very fine surface detail. Bu - maybe I am wrong in that - I got the impression from the "in-progress" pics published, that the master was still done in an old fashioned way, with a lot of human intervention, and the short-run mold technology can be different from the block-of-steel milling applied to molds with a long life expectation.

 

Hubert

[Martinnfb]

That is exactly what we need a human input, not just a CNC driven mill that is popping out fine, but unrealistic rows of rivets.

[Big Texan]

On many many many aircraft with flushed riveting, you never see them, no matter how close or far you are to the real aircraft. Yet, model companies are producing  what I call "golf ball" models. So many dimples it ain't funny!

 

I agree on certain aircraft, there most certainly is raised detail, zus fasteners, etc. I also agree, some of the older kits have reproduced raised surface detail that is spot on, and then there are others that are just as bad as the dimpled golf ball models of today with so much raised detail, you just know that ain't right! LOL!

[Bryan]

On many many many aircraft with flushed riveting, you never see them, no matter how close or far you are to the real aircraft. Yet, model companies are producing  what I call "golf ball" models. So many dimples it ain't funny!

 

I agree on certain aircraft, there most certainly is raised detail, zus fasteners, etc. I also agree, some of the older kits have reproduced raised surface detail that is spot on, and then there are others that are just as bad as the dimpled golf ball models of today with so much raised detail, you just know that ain't right! LOL!

 

I agree with this....on most aircraft from the Spitfire/Hellcat/FW-190 generation onward, virtually all of the riveting is flush for aerodynamics.  These rivets cannot even be seen on the real aircraft unless you are within 10 or 15 feet (3 to 5 scale inches).  IMHO this cannot be accurately rendered "in scale"...at least not in 1/32 and smaller scales....because if accurately done it would disappear under the first layer of paint.

 

So to me the question is, should kit manufacturers omit this sort of detail entirely, or should they render it in a "representative" way with small dimples as they currently do?  Even the relatively subtle rivet dimples....like on Tamiya kits....are far FAR out of scale/inaccurate to represent actual flush rivets.  If scaled up they would be more like the aircraft was covered with dents from an extremely uniform hailstorm.

 

I'm not saying I know what the answer should be....a lot of things that are done with scale models are "representative" rather than precise scale replicas of the original.  I'm just saying I don't think true, accurate, in scale flush rivets are possible on 1/32 kits, so that is not an option.

[Tnarg]

The designers of the F4B-4 and the other Hasegawa planes of the 30's actually had their eyes open. They made a copy of what they saw in miniature. They didn't do so well inside the plane, where you aren't usually looking, but the exterior looks very fine.

 

Why is it that everything is "perfect" and smooth, when the metal prototype sometimes has subtle wrinkles and dimples, long before stress cracks could cause fatigue and damage. Why can the molds be cut with a tool to leave completely vertical standing posts in the metal to create all those giant holes representing rivets but they can't cut a round hole in the metal to represent a domed rivet actually looking like the real thing? It would seem easier to program the machine with a simple model of the shape and go in after to add rows of rivets, still removing metal from the mold and adding to the plastic like the old days. That would seem to be the "lazy" way out. Or maybe we are just too lazy to use Archer rivets to fix those details.

 

I think that it takes time and real effort to do it right, and "close enough" is good enough for many managers. The designer and artist may be driven from an internal desire for perfection, making a good of first intent, one that you would pay to have the privilege of creating. The manager and bean counter (accountant, lawyer, etc.) is more motivated to create a good of second intent, or one that someone will pay you to create. That drives the desire to make it only as good as you can get away with, while separating the customer from their cold hard cash.

 

On occasion we see that the drive for goods of first intent comes from the top, such as Wingnut Wings. For example, G Factor gear versus their competitor seems to be a perfect illustration of the contrast. G Factor gear have the strength and detail required for a metal gear with no worries about shape or security. The competing product may be strong enough for a 1/72 kit, but the weight of a 1/32 kit could just bend the gear over. One bend to straighten that alternative gear sometimes breaks the gear in two. And don't expect any detail even compared to the original plastic. It boggles the mind why anyone would buy a second example, but they seem to sell quite a few.

 

That same "sell quite a few" keeps less than "perfect" companies in production. Some of our number like to make their own perfection, starting with crude beginnings (like vac form kits) and others are very happy with something close enough to the correct shape and details, because their creativity finds expression in the colors or history and not in the subtle detail. I still find myself wanting better surface details, but understand that others might prefer another choice.

 

Tnarg

[williamj]

"a lot of things that are done with scale models are "representative" rather I'm just saying I don't think true, accurate, in scale flush rivets are possible on 1/32 kits, so that is not an option"

 

Thanks for all the comments people,gives a good idea of what is acceptable or needs change...And Bryan,I have seen right here on LSP more often than anywhere else,modelers taking their beading tool sets and pressing recessed and flush rivet heads into the surface of the scale aircraft they're working up....as a matter of fact there are decals made now that represent patterns for you to follow,

"Can't be done,not an option" Of course it can,and it's always an option.it only takes someone who wants to.

And Mike is probably right,should watch my blood pressure...but I loath complacency in all things,it's just me.so I'll close by saying. Keep it real,keep it fun.

Edited June 20, 2016 by williamj

[LSP_K2]

So to me the question is, should kit manufacturers omit this sort of detail entirely, or should they render it in a "representative" way with small dimples as they currently do?  Even the relatively subtle rivet dimples....like on Tamiya kits....are far FAR out of scale/inaccurate to represent actual flush rivets.  If scaled up they would be more like the aircraft was covered with dents from an extremely uniform hailstorm.

 

I would certainly hope not. My Hasegawa Ki-61 is mostly devoid of rivets, and would definitely have benefited from a Tamiya type approach, especially in so far as the front area of the fuselage is concerned. My machine, being natural aluminum, shows each and every rivet in the immediate vicinity of the engine area (on the real deal). No way I can figure to recreate that appearance, short of having to resort to the old needle in a pin vise trick, and I would have really preferred not to have to.

[Bryan]

"Can't be done,not an option" Of course it can,and it's always an option.it only takes someone who wants to.

 

 

What I was trying to say....is that it cannot be done accurately as molded in detail from the kit manufacturers...maybe I wasn't clear.

 

If the builder wants to go in with a beading tool or whatever and make flush rivet marks at some point during the finishing process, I think that is certainly possible to do.

 

 

I would certainly hope not. My Hasegawa Ki-61 is mostly devoid of rivets, and would definitely have benefited from a Tamiya type approach, especially in so far as the front area of the fuselage is concerned. My machine, being natural aluminum, shows each and every rivet in the immediate vicinity of the engine area (on the real deal). No way I can figure to recreate that appearance, short of having to resort to the old needle in a pin vise trick, and I would have really preferred not to have to.

 

I hear what you are saying...often it makes a very sterile looking model....

 

All I am saying is if we want flush rivet detail from the kit manufacturer, to some extent it will have to be overdone in a scale sense.  I think it is nice that to some degree we have some choice nowadays to choose which way we want to go....

 

[LSP_K2]

I hear what you are saying...often it makes a very sterile looking model....

 

All I am saying is if we want flush rivet detail from the kit manufacturer, to some extent it will have to be overdone in a scale sense.  I think it is nice that to some degree we have some choice nowadays to choose which way we want to go....

 

Agreed on both counts. "Scale accuracy" regarding such things, has never been a desire of mine, but some representation would be better, from a modeling standpoint, at least for me. I'm still trying to determine if, and/or how much riveting I want or need to do to get the visual result I'm after, and I'd really rather not have to do it at all. (I really wish the Tony was a Tamiya kit,... problem solved then.)

[Bryan]

Agreed on both counts. "Scale accuracy" regarding such things, has never been a desire of mine, but some representation would be better, from a modeling standpoint, at least for me. I'm still trying to determine if, and/or how much riveting I want or need to do to get the visual result I'm after, and I'd really rather not have to do it at all. (I really wish the Tony was a Tamiya kit,... problem solved then.)

 

Yeah...you and I are pretty much in the same place.  

 

The primary step that would make models look more "real" to me, would be for kit manufacturers to tackle the "stressed skin" look, with dimples, ripples, flaws, etc that real planes from the era actually have.  So far as I have seen, no manufacturer has even touched that one....not even Tamiya.  And to me this characteristic is far more visible than flush rivets are. 

Edited June 20, 2016 by Bryan

[LSP_K2]

Yeah...you and I are pretty much in the same place.  

 

The primary step that would make models look more "real" to me, would be for kit manufacturers to tackle the "stressed skin" look, with dimples, ripples, flaws, etc that real planes from the era actually have.  So far as I have seen, no manufacturer has even touched that one....not even Tamiya.  And to me this characteristic is far more visible than flush rivets are. 

 

The big Airfix Typhoon attempted that, and with a pretty good result too, except that it's perhaps a bit too uniform. Still very nice though, and definitely a step in the right direction.

[moldmkr78]

"Divots" are actually a function if technology. Back then, molds would be carved out if a block of steel using a

pantograph, and rivets drilled one by one in the hard steel mold.

Now the cavity is carved by CNC machines, and the finishing done using a spark-erosion electrode. The electrode, in carbon or copper, is itself CNC-machined as a positive (i.e. looking like the final part). It is a lot easier to drill holes in the electrode shape than to machine it with raised rivets.

Technology (spark-erosion) has allowed a lot if benefits in most intances, but not when it comes to reproducing some surface details.

I guess the 1969 Revell Spit Mk1 will remain for a long time a reference when it comes to surface rendition

Hubert

Sort of. The first part is right. Back in the 70's when I started building molds, a pantograph was used to create most fine details in a mold. Raised rivets in the plastic were made by small drill points, divots, in the steel. This is easy enough on the wings or other horizontal surfaces. The only problem is when it got to near vertical such as on the center of a fuselage. If the divots were put in perpendicular to the surface of the cavity, the "rivets" would either shear off when the mold opened and the part stayed on the B side (ejector side) or the part would stick in the A side (cavity) of the mold because of all the little teeth "rivets" holding it the cavity. You always have to have draft or no undercuts on the cavity side of the mold otherwise it will stick on that side. Not good. Today, as you say, the cavities are made by a CNC milling machine and the EDM (spark erosion) process, but much of the textures and raised detail that we see is done with a photo etch process. I believe that today's recessed rivets are created by a laser and is done post molding. It would be virtually impossible to polish a mold with all of the tiny rivets standing proud from the main surface of the steel cavity which is what would need to happen for molded recessed rivets. Back in the day, raised rivets were the only possibility. As technology progressed (lasers and photo etching) we now have other methods to create rivets and small standing detail.