To make a good lens prototype, you have to pay attention to the following points.

1. Make sure you pick up the good PMMA block. It is really painful when you finish a PMMA model and then you find some bubble, dust on the part, or you find the material is bonded.

2. To use the right cutter is very important. for PMMA milling prototype, we always use wolfram steel cutter.

3. When you mill a PMMA part, always leave 0.05mm allowance on each surface. In this case, the part will not be thiner than the 3D data after polishing.

4. To polishing the Lens, you have to be patient enough, normally, you start with 220 sand paper, then goes up with 400, 600…until 1500. Don't try to skip. otherwise, you may have to restart from the beginning. We never used polishing machines, because it is not even, you will get waviness, fisheye. The temperature goes up too high, it will melt the material.

5, Use the correct glue, we have used LOCTITE 201 to glue PMMA component for quite a lot time. If you are lucky enough, everything will be prefect. but you still got chance to have bubbles on the glue area. As we know, the parts are clear, very visible concept model, you will see the bubbles easily. Now, we have turn to UV glue. It is brilliant. The only problem is the glue is not as strong as LOCTITE 201. It is not a good idea if the wall thickness is too thin.

6. The prototyping for car lamp is getting more and more complex. To make the car look better, the designer add lot of features to the part, like the waviness, teeth. etc. Let's say a lightguide prototype for BMW. You will find lots of teeth on the part. For this kind of Auto prototyping, you need a very experience guy to handle it. A tiny mistake may kill the whole part.

Check 3E Rapid Prototyping official blog for more Prototyping technical