Sprues are a way to get around this minimum part cost – a sprue is just a small rod that connects the parts together, this removes the minimum part cost.
Sprues are only necessary in this instance, not for example, if you have 5 parts that have a bounding box of 100x100x100 mm3. Sprues can have the added advantage of not adding anything onto the price since they can go between parts to connect them together.
When adding sprues to your part please be sure to follow these rules:
– The Sprue must be 2mm’s thick all the way to the end, no thinner as this will snap when we clean the models and defeats the purpose of the sprue.
– The sprues must not taper to a point when they make contact with the surface.
– The best way to position a sprue is to run it between the model so that it does not add to the bounding box. Sometimes we have models come through that are sprued like an air fix model i.e. with a square connecting sprue all around the outside of the model- it looks good – but it is not economical as it adds to the XYZ dimensions. Try to connect sprues to unimportant parts to get a blemish free surface.
– If the sprue goes through the surface, try to remove the intersecting geometry yourself. We can do this our end but it adds time and will help to make you a better modeller! :)