Cracks in trim plate

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JohnB
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Cracks in trim plate

Post by JohnB » Mon Jan 07, 2008 12:11 pm

There are hairline cracks above each button in the face plate on my V2. (see pics) Is this the way they all come through or a warranty issue?ImageImage

Niko

Post by Niko » Mon Jan 07, 2008 12:23 pm

My VII has that too.
Haven't looked at my other S1 yet but I think it's normal. That may be just the way the plastic is poured into the mould.
They (sort of) look like hairline cracks but I don't think they're cracks, rather it's the process involved.

I just looked at Chris' site, they have an extreme close up of the VII panel but I can't really tell from the depth of field and angle it was shot if it has the same lines.
Last edited by Niko on Mon Jan 07, 2008 2:24 pm, edited 1 time in total.

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Post by coffeeowl » Mon Jan 07, 2008 2:22 pm

on mine as well - sharp eyes! I haven't noticed it!
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Post by Weska » Mon Jan 07, 2008 4:30 pm

Same on my S1, built May 2006. Looks like a sort of joint but is probably an artifact of the molding process for this particular plastic.

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Post by earache » Mon Jan 07, 2008 8:12 pm

They're not cracks, they're called knit or weld lines. As Niko and Weska state it's an artifact of the molding process. When molten plastic flows around holes and joins back together on the other side, the knit lines are formed. Some are more visible than others, but they should not generally be cause for concern. You may remember the Apple G4 Cube which exhibited "cracks" in the clear plastic... those were actually knit lines. Whenever two or more flows of material come together the leading edges of the flows will be slightly cooler and may not join together in a visibly cohesive manner thereby creating the knit line.

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Post by Niko » Mon Jan 07, 2008 8:57 pm

Ahhh...the Apple G4 Cube, how can I forget those little boxes?!
I've always wanted a 500Mhz model, they're actually a collectors item (or used to be).

I remember those "cracks" in the clear plastic...

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JohnB
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Post by JohnB » Mon Jan 07, 2008 9:17 pm

earache wrote:They're not cracks, they're called knit or weld lines. As Niko and Weska state it's an artifact of the molding process. When molten plastic flows around holes and joins back together on the other side, the knit lines are formed. Some are more visible than others, but they should not generally be cause for concern. You may remember the Apple G4 Cube which exhibited "cracks" in the clear plastic... those were actually knit lines. Whenever two or more flows of material come together the leading edges of the flows will be slightly cooler and may not join together in a visibly cohesive manner thereby creating the knit line.
So why don't we see this on every plastic control panel in our cars or on the plastic dash panel of motorcycles? Is it just a less expensive casting process that leaves these lines. Having done show quality paint work on vintage motorcycle restorations for many years little things like this jump right out at me. Looks pretty cheesy on a nice piece of equipment like this.

Niko

Post by Niko » Mon Jan 07, 2008 9:48 pm

I think it depends on who does the casting, some people (employees) are just better at it.
I'm just assuming, but I see your point.
I know someone who worked in plastics, it's a tricky process with the temps.

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Post by earache » Mon Jan 07, 2008 11:03 pm

JohnB wrote:
earache wrote:They're not cracks, they're called knit or weld lines. As Niko and Weska state it's an artifact of the molding process. When molten plastic flows around holes and joins back together on the other side, the knit lines are formed. Some are more visible than others, but they should not generally be cause for concern. You may remember the Apple G4 Cube which exhibited "cracks" in the clear plastic... those were actually knit lines. Whenever two or more flows of material come together the leading edges of the flows will be slightly cooler and may not join together in a visibly cohesive manner thereby creating the knit line.
So why don't we see this on every plastic control panel in our cars or on the plastic dash panel of motorcycles? Is it just a less expensive casting process that leaves these lines. Having done show quality paint work on vintage motorcycle restorations for many years little things like this jump right out at me. Looks pretty cheesy on a nice piece of equipment like this.
A lot depends on the molder and tool designer. Correct placement of gates (for material feed), vents (for outgassing) and tool/material temperature are key to help prevent problems. Some parts can't escape issues like weld lines. It's important to note that most plastic consumer products are actually painted... what you're seeing is not raw plastic. A good tool designer and molder are key to having a good cosmetic part.

What I see on the S1 part is pretty typical of normal consumer plastic parts. There are weld lines at every key opening and most LED openings, and there's quite a bit of sink as well. It's a pretty sloppy part and could benefit from some texturing which would hide many of the defects.

Niko

Post by Niko » Mon Jan 07, 2008 11:15 pm

earache wrote:could benefit from some texturing which would hide many of the defects.
"Key" word....TEXTURING.
I like that idea very much.
Nikon introduced a crinkle finish on many of their lens barrels years ago. I wonder if it's the same reason since more manufacturers are using plastics these days.

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Post by earache » Tue Jan 08, 2008 12:24 am

Niko wrote:
earache wrote:could benefit from some texturing which would hide many of the defects.
"Key" word....TEXTURING.
I like that idea very much.
Nikon introduced a crinkle finish on many of their lens barrels years ago. I wonder if it's the same reason since more manufacturers are using plastics these days.
Yeah, a little texture would do wonders for this part. They have a matte finish on there now but that doesn't do much. Can't put too much texture on or it would be a PITA to keep clean.

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Post by chas » Tue Jan 08, 2008 7:47 am

Those "cracks" are one of the first things I noticed when I received my V2. At that point I still had the S1 as well. I checked it out and it was the same way. Not sure why I never noticed it over the course of two years on the S1 and noticed in on day 1 on the V2, especially when the "cracks" looks pretty much identical.
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Post by Weska » Tue Jan 08, 2008 3:27 pm

I suppose the question comes down to whether we would like the costs for ideal plastic parts passed down to us, or whether the price difference would be trivial enough not to affect the retail price if someone had been aware of the distinctions.

It would not be something that I would want to second guess. For my own part, I wouldn't want to pay much more to make those joints disappear. What? Fifteen dollars? Certainly not more.

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Post by earache » Tue Jan 08, 2008 6:10 pm

It's really all upfront design work... wouldn't cost any more money to make a part that had better cosmetics. In fact it's quite possible that the problem can be fixed with a simple material or process change, no tooling mods. Sometimes all it takes is a call to the molder to get them to look at it and see what they think.

Niko

Post by Niko » Fri Jan 25, 2008 2:26 am

Do you work in plastics?

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