Chriske

Jim, Depending on the sensitivity and the range of the camera you could observe the boundary layer of the primary, see how long it takes to get rid of.

Not only will it be difficult to remove that mirror, but cooling the mirror before observing would go a lot faster if there is a gap between mirror and holder. Astigmatic error will be an issue imo. I've done lots of repairs in the past, lots of these secondaries were glued like yours and suffered from that problem. I would do what Nigel suggested using silicone-blobs.

Indeed, in a situation like this I'd use threaded rods, Make a slit with a hacksaw or a dremel(grindingdisk) and you're done. That slit doesn't have to be very deep at all. I would make the slit just wide enough to allow the spider to fit in without any play. To prevent these parts from moving I use a small bolt instead of a pin. Tightening that bolt will secure it all in place. So a (M6) 1/4" bolt or threaded rod would do fine in this case.

I think it is something like this. But I'd use a threaded rod instead, so fastening can be done with 2 nuts/washers for each vane. And there is absolutely no need to use two rods for each vane Jim.

Correct Gina, We never had any problems with these A4988 drivers in the past either, let that be clear. But in the end the result is far better with these TMC2100 drivers. And maybe, just maybe it also could be a combination of different items I integrated in my own designed printer.

Dave, You should consider using TMC2100 drivers, at least for X and Y-motors. It improves perimeter quality a lot as it uses microstepping. And also quieter movement of the XY-carriage is the result. If you do buy them take care: they should be mounted reversed..!!

Like I said, changed a few settings : lowered printingspeed drastically to 30mm/s, lowered printtemp, enlarged retraction to 2mm, lowered retractionspeed...same result as before... As I read it, it seems to be very difficult printing PETG without stringing. Maybe some other brand worth trying..?

Done some printing with PETG myself, lots of stringing. Changed slicersettings a few times to no avail...

Dave, Make that printer as sturdy/stiff as you possibly can..!! During the past 3 years we've(3 friends - telescope and printer nerds) built about 20 different types of 3D-printers. None of them produces 100% perfect perimeters. I now have finished a printer of own design. It's casing is a very strong wooden box and that is one of the main reasons it outperforms all previous printers we've built in the past. No more ripple on the perimeters and no more ghosting around holes. As a matter of fact, it was very strange to have these perfect perimeters after 3 years of building and testing printers. Second reason why it performs so well is that I abandoned these LMUU linear bearings. I make my own (adjustable)bearings. So there's absolutely no play on the axis at all.