The issue of the off centre vase

[SirBrandon]

Hello, peachy fan, and backer here. This is my first post on the forum, so hello all!

I've been concerned with an aspect of the peachy printer, that relates to the curing envelope, which Is the volume of not only the thickness of z, and beam area but the beam angle as well! My concern is that as the angle of the beam changes from vertical centre, the cross-section of the beam changes from | to \. For any given thickness of Z and beam area, '\' will be always be the longer line. This means that the farther any pixel is away from (0,0) the larger the pixel will be, which will deform the slice.

I was watching the latest update, and while I agree that the mirror memory Is probably the major factor in the deformed vase in the video, I believe the cross-section issue is a contributing factor. The distortion of can be reduced by increasing the print head height from the table.

Any ways, can't wait to get my peachy and start making some cool stuff. Goodluck with the dev, you guys are awesome!

[Spelljammer]

I agree. Although, it will mostly be a problem the taller and wider a print gets. You can float the peachy at a given height above the surface and the laser can be focused to that height, roughly. I talked about it before in another thread.

http://blenderartists.org/forum/atta...mp;amp;thumb=1

[Slatye]

I don't think it's likely to be a big problem. The Peachy's going to be maybe 30cm above the resin, probably printing parts on the order of 10cm across (ie 5cm radius around the centre point). The length of travel to the centre of the object is obviously 30cm; to the edges it's 30.4cm - just over a 1% increase. If the focus is good in the middle then it's not likely to be noticeably worse at the edges. The vertical movement of the printing surface will be a much bigger issue since that may well change by 5cm or more during a print, and in this case I think you'll just have to focus it at the best spot (ie in focus half way up the object) and hope for the best.

If I remember correctly there's been talk of an automatic focus for the Peachy Pro, which would solve this problem completely.

[JamesCooper]

For any given thickness of Z and beam area, '\' will be always be the longer line. This means that the farther any pixel is away from (0,0) the larger the pixel will be, which will deform the slice.

That's a good point. I don't have any plans for fixing that yet, but if it becomes a problem, we'll look into it. A focusing mechanism would definitely the be the most reliable approach, but given our budget, I don't think it's an option for the $100 printer. Another possibility would be to move the laser faster, curing a smaller area despite the bigger spot, which happens naturally as you get further away (it's actually something I planned to have to make up for in calibration). As with all the other possible distortions, we'll address that one if it becomes the critical factor.

[Keldor]

It may be possible to use Blender itself to compensate for the distortion. You may be able to use a lattice to distort your model before printing.

[Ocko]

Should'nt there be the same problem (of focussing) also exist with the height of things? The way formlab does their printing has the advantage that their focus does not change (as the resin height does not); however, they have the epensive movable bed and potentially the absorption of energy in the glas they have to shine through.

I have seen the recent column prints, where focus depending on height did not seem to be a problem... However, will it be possible to print something like 8x8x8cm with out any major efforts and distortions on the basic peachy?

Best,
Ocko

[Keldor]

Maybe someone can come up with a rig that floats on the water. That way the distance would always be the same, just like the Form1.

[Ocko]

Good idea, however it would make the calculations a lot different... possibly easier though...
Could of course be, that the "wobbling" of the floating rift is more of a problem than the "off-focus"...

[Anuvin]

Spelljammer made a killer design for just such a floating platform. Take a look at it, it's his first post on page 2.

http://forums.reprap.org/read.php?185,249062,page=2