hardware design questions

[IrgendwerAusIrgendwo]

Hi everybody!

I'm currently on the way to design a rigid machine base and as I want everything perfect on my digital model I got some questions regarding dimension- I don't want to buy a projector before beeing sure that everything is as I want it to be.

1.) dimension
On this site the focus of the machine at 100x100mm is around 250mm:
http://www.instructables.com/id/DIY-hig ... r/?lang=de
In my eyes I should switch my projector at highest resolution (1920*1080) and measure the distance so that the projected image has 192*108mm: I would to this on both dead centers of the focus to find the mid-position.
To change dimension and focus on the machine hardware I would make the plate hight-adjustable (app +-30mm).

2.) What type of endstop do you use?
When printing at e.g. 0,03mm layer hight you'll need a VERY good endstop.
As far as I have seen now (I'm developing a lot at RepRap 3D printers) simple switches, opto endstops and Hall-sensors are very common - which one would you prefer?

3.) linear motion
Most of the self built machines and even the commercial machines use dovetail guides. As I want to create my machine open, cheap and buildable by everyone I'm planning to use 16mm rods and fixed guides on top and bottom!?

4.) printbed size
As mentioned I plan to have a printbed of 192*108mm (resolution therefore 0,1mm): has anybody got experience with moving the projector + mirror so that you have e.g. 3 steps of the 108mm side and therefore 192 * (108*3) mm?

[Finhead]

Not sure I understand some of what your asking but since I am building a variation of the printer you have linked to I'll say what I know from my build process.

If your using the Acer H6510BD that is listed on the Instructables the focus for 1:1 (1920X1080) at center on focus and zoom will be approx 225mm from lens to surface.

I'm going to be using Hall endstops since that is what I have, but I have seen that all the types you listed have been used so I doubt it matters as long as it is correctly calibrated.

16mm rods seem to be overkill since your going to be adding a lot of weight IMO. I am using Delrin rollers with press fit bearings riding on a aluminum extrusion. You could also use what Tristram did and go with a 16mm linear guide and 5mm pitch acme screw.

Clinton

[IrgendwerAusIrgendwo]

[Finhead]