Oval looking parts

[paulson games]

I've been working on casting some of my battletech models and I've noticed quite a few of them are getting slightly oval shaped parts that should be round. Like the gun barrels.

I'm scratching my head as I don't recall this happening on previous models and I haven't changed anything in the way I do the casting. I'm not sure if it's due to silicone shrinkage while it's setting up or maybe I'm over tightening the rubberbands and compressing the molds?

What is odd is that it's even occuring on faces that don't have a mold lines centered on them, making me think it may be an issue with over tightening.

A lot of my molds are stored near a heat duct for my basement maybe the heat has warped them?

Another possible source is I stack them about 3-4 molds high maybe the weight is compressing them?

The obvious first test is to loosen the molds slightly on the next cast but do you think maybe the mold wall thickness isn't enough if it's distorting?

[mangozac]

Surely it's just over-tight compression of the mould by the rubber bands? I've had similar issues in the past and they were solved by simply being a little more cautious with rubber band placement on those moulds during casting...

[Fleafa]

Perhaps this should be dubbed 'The Forgeworld Effect'? Almost every part I have bought from Forgeworld which could have this problem has had this problem. I would have thought over-zealous use of elastic bands would be the cause. Try loosening them. A little flashing is preferable to compression.

[mangozac]

I wouldn't stand for that for FW prices - it's not like flash or mould slip which can be rectified (albeit to a limited degree for the latter).

I find that the trick with the rubber bands is to ensure that not only are they not over-tight, but also that the pressure is distributed evenly around the mould.