The tear down

So I did some work on ScanRap recently.
Dave from THS was nice enough to donate a third scanner to the cause.
At first glance, it appeared to be more flat than the first two, and I was considering using it as my base axis.

So I get into the process of tearing these three scanners down and taking some measurements.


Here you can see Dave's scanner with the top off. On the right, the silver round thing is the stepper motor, with the scanner electronics above it. The black box in the middle is the scanner head.

Do you notice all the black tabs sticking up from the bottom of the case? If I were to use this case directly as the base, those would all have to come off, as they stick up above the top of the scanner head. Thus, anything I attach to the head would bump into and bind up on these tabs. So I went to work cutting them off.

I had to do the same to the other scanners. In fact, the deconstruction was far worse on them, since the entire case extended above the head.

Once I had them torn down, I could start taking some measurements. My main concern was that the scanners were not actually level. I suspected that they were actually on a slight incline. So I set off to hopefully disprove this hypothesis.

I started by taking a level measurement of my work surface (otherwise known as a floor):

As you can see, my floor isn't exactly level, but that is ok, so long as I am not a marble. :)
So, the theory is that, if I were to set the scanner in exactly same spot, and throw the level on top of the head, the bubble would be in the same place if the scanner were level.
Here is the results:

Houston, we have a problem!

Getting curious, I decided to do a height comparison from each end of travel of the scanner head.

I moved the head to one end and set the engineering scale on the floor:

then I sent the head down to the far end and set the scale back up....

That's a pretty big gap!
If I were to attempt to print a square block on a RepRap made this way... well let's just say it would be riding the short bus.

So, while I mill about figuring a way to remount all the mechanics in a truly square frame, I will have to satisfy myself with tearing into the scanner heads. Check the next article for the innards of scan heads and fun things you can do with the parts!