Hasegawa - moment of madness or sloppy work?

[Whofan]

Generally I've seen nothing but good reviews of Hasegawa kits here. Indeed, the one I've made so far was a very god kit to put togather.

 

I am umming and aaahing about starting a new kit, choice between a Tamiya motorcycle or the Hasegawa J7W1 Shinden, and I was busy fondling plastic when I noticed this;

 

 

A sprue gate directly attached to the moulded gunsight.

 

This seems to me to be either sloppy design, or one of those moments where it seemed ok!

 

Is this a thing with hasegawa kits, kit parts attached to the sprue by the most awkward of points?

[stever219]

If you want awkwardly placed sprue gates I suggest you look no further than the pilots' seat frames from the Airfix 1/48th Scale Merlin HC. 3; all buried within the "V"s of the frames and almost totally inaccessible to sprue cutters.

 

All kit manufacturers are prone to gotchas lije this; Eduard's practice of putting sprue gates halfway along incredibly fine and flimsy dipoles, pitot probes, aerial masts drives me to tears.  At their end it's,all about getting hot liquid plastic into every last nook and cranny of the mould tool but at lowest realistic cost.

 

In your case I'd suggest slow and gentle use of a fine razor saw to separate that particular part and making that the first point of separation from the sprue although it looks as though the attachment is on what should be the reflector glass and you'd probably want to replace it anyway 

[Whofan]

@stever219, thanks for the helpful suggestions.

 

I've got a couple of Eduard kits in the stash, I'll look out for those gotchas! I#ts fair to acknowledge the reasoning as you point out, but sometimes it makes life difficult. But if modelling life wasn't difficult, we'd probably moan a little more!

 

Fortunately I do have a fine razor saw, and had already thought about cutting it off the sprue first, rather than a bull at a china shop approach!

 

 

[alex]

honestly, I don't think it's a bad place. If it was on the cowling in front of the windscreen, it would be on a visible part, and since it's curved, it often needs some filling and sanding. Where it is placed now, put it on the cutting mat, take a exacto cutter and push it flat to cut it. Short, straight line to cut, no need for sanding afterwards.

 

Alex

[Graham Boak]

Presumably this was to ensure good flow into a fairly large part that was only attached to the fuselage by a small flow route.  Which might have been significant even if there was a flow gate on the fuselage nearer the gunsight.

[Whofan]

@alex, and @Graham Boak, thanks for your observations and tips.

 

 

[hendie]

3 hours ago, Whofan said:

A sprue gate directly attached to the moulded gunsight.

 

This seems to me to be either sloppy design, or one of those moments where it seemed ok!

 

Rule number 1 in injection molding:  Uniform wall thickness.

Rule number 2: Gate from thick to thin.

 

It's all about plastic viscosity, plastic temperature, delta pressure and a gazzillion other variables.   Look at the thickness of the gun sight, compare that to the section immediately adjacent, then on to the fuselage itself.  How far is that gunsight away from the sprue?

if there was no gate there, the plastic would have been coming from thick (fuselage) to thin (coaming) back to thick (gunsight).  Without that gate, the gunsight would either have had sink marks, a short shot, or worst case, not filled at all

 

I'd say Hasegawa did a pretty good job of mitigating a very real problem.

 

[Whofan]

21 minutes ago, hendie said:

 

Rule number 1 in injection molding:  Uniform wall thickness.

Rule number 2: Gate from thick to thin.

 

It's all about plastic viscosity, plastic temperature, delta pressure and a gazzillion other variables.   Look at the thickness of the gun sight, compare that to the section immediately adjacent, then on to the fuselage itself.  How far is that gunsight away from the sprue?

if there was no gate there, the plastic would have been coming from thick (fuselage) to thin (coaming) back to thick (gunsight).  Without that gate, the gunsight would either have had sink marks, a short shot, or worst case, not filled at all

 

I'd say Hasegawa did a pretty good job of mitigating a very real problem.

 

Hendie,

 

please allow me to move to the dunces corner and stand corrected, and apologixe to Hasegawa.

 

I hadn't thought of it in those terms at all, simply the position of a gate on a tiny part of the kit.

 

I do believe this well has been exhausted with yoor explanation - and that of Grahame's, so perhaps I will ask the Mods to lock it as complete.

[hendie]

No problem at all.  Injection molding is probably one of, if not the most complicated manufacturing processes out there, and for the most part it is not well understood by the average Joe. 

There is a thread here buried in the chat section somewhere that I started on injection molding a while back. (I'm writing this on my phone and it's too complicated to find and post a link)