new molds


2Printbeta proudly presents: New molds for our casted parts.

Within the last months we casted lots of prusa and mendel parts. The molds are made of very elastic silicone rubber, but they suffer from the demolding process.
Some of our molded bridges broke away and thus the casted parts had to be redrilled:

This postprocessing progress is very time consuming, so we tried another method to get casted holes without any redrilling.
Smooth rods made of stainless steel work perfect as bridges:

Treated with a spray which makes demolding easier they can be removed.
Therefore we grabbed the ends of the rods with pliers and rotated them with force. After a loud click the rods come out easy.
With this procedure the demolding is a little bit harder than before, but the holes are perfect:


The second experiment was to cast in M3 nuts into the motor pulleys:

Many customers asked, why there is no hole for a M3 nut in the pulleys.
The casting process has limitations and as mentioned in the description the m3 nuts have been replaced by threaded holes.
Although the threading is made of plastic it is capable to fix the pulley on a one side flattened motor shaft.
Without flattening the motor shaft the screw has to be fixed very tight - the plastic threading cannot resist this forces.

So we found a solution for this by inserting m3 nuts in the right position inside the pulley.

After demolding the m3 nut can be used as described in the assembly manual by gary hodgson.
The nut is already locked inside the hole:

The experiment has been a full success - using this mold the first time.

But our expierience with these molds an with such small briges as the 2.5mm holes inside the motor pulleys says it will not last very long.
The briges will break after about 10 to 20 times and then there will be nothing which forces the nut into the correct position.

The next experiment will be a mold with m3 screws as bridges. They can be used to place the nuts and will not break away after some time.