Chriske

I've put in 'some' telescope to see what the result would be. On the right you see the printer settings.

Ok now this little thing works I need to figure out how it works. It is not my goal to use and finish a mirror with it to the very end. Parabolizing is a delicate task. I need figures to see how close or near I am from a perfect mirror. And that is done, as you all know, by using Foucault.

Just tried it myself, works perfectly... So the story about only running in 32bit is pure nonsense ... What a waste of time...🙄

You tried it..???

It will only work on a 32bit Win system.

Found this : https://web.archive.org/web/20130420122726/http://www.atmsite.org/contrib/Holm/invron/invron.html

I see there are a few downloads of InvRon. Somebody tried it..?

This what I call quality plywood.! hard to find these days here.🇧🇪 Most of our plywood comes from ROC, and-it-is RUBBISCH...!!! Nice platform btw..!..

Some amateurs use Ronchi testing technique, I never did in the past. Ronchi is a good testing methode but it lacks accuracy. So most of amaterur mirror grinders end up with Foucault testing because it gives the necessary figures to know whether a mirror is close to perfect or not. Foucault is not the only, there are a few other, and also 'null'testing like Dall or Ross. Null testing is also very good to because you end up checking on a spherical surface. Needless to say the eye is very sensitive when it comes to checking on spherical mirrors. Differences of 1/50 Lambda can be seen, that's about the limit. Straight lines are also good to be judged because the eye is very sensitive to it. A minor bump in a straight line will be seen no matter how small the bump or curve. There's the Ronchi test that uses a straight line grating to project curved lines on the mirror to judge the accuracy of your parabola. If you see a bump in the curves of in your test result, you immediately will see it. There too the eye is very sensitive. Problem with Ronchi is how far should the curves under test bend. How does a Ronchi user deals with it. Because every other mirror need a completely other set of projected curves. But there's a solution using a (different) Ronchi test, the 'Inverse Ronchi test'. Its goal is exactly the same as the original Ronchi test, except it uses curved lines in it's grating instead of straight lines. There is that little program(1.9Mb) developed in 1998 by Mark D. Holm. InvRon he called it. The software calculates the curves for a specific mirror, the only thing you need to do is print the pattern onto transparent and there you have your grating. Well the thing is you need to start parabolizing until you end up with straight lines. And again the human eye is very sensitive to straight lines. I'd like to try it and compare the result with regular Foucaulttesting, Years ago I've downloaded InvRon but never used it. A few days ago I've tried installing InvRon but I get error messages, Even in Linux it does not work. My question : has someone ever tried to install InvRon or used it...? Caution : maybe the file needs to be scanned for viruses, in my case there were no problems with 2 OS'ses. I have no scanner on board. There's a readme file with lots of explanation about InvRon. Opened a few URL's mentioned in the readme, but got a few times 404...:-( InvRon.zip

This threaded rod and brass nut will give you a far better result. If you have the complete set, you should have received a three part nut. The nut itself a counterpart and a spring. This is to get rid of play between rod and nut. If these two parts are not present, you could always add a spring or a rubber band a the end of the board, to do just the same. It will give you a smoother action while tracking. If there's enough load on top of the plank no need to add that extra tension. You must also consider that spring or rubber band in case there's to much friction on the hinge. In my case, using it as a eq. platform for telescopes, it will not be an issue of course. There's always more then enough load. As matter of fact if the load on top of my board is to high I need to just the opposite. In a few of my earlier BM's I've added an pressure pump (out of the backdoor of a car) to get rid of the load sitting on top of it. But this time this new BM only 65mm high I have to come up with another solution because there's not enough room to add a pressure pump between the two sheets of multiply. The rod and nut are no match at all for the weight of my 14" DarkStar.

From now on we will be adding parts every other day or so, depending how fast we can 'deliver'. Next a crane will be added. There was non we know but we thought it would be fun to go this way. Especially for the many children visiting our local observatory.

Hey thanks for printing...!! Cura does a rather good job with it. Far netter then the PrusaSlicer.

In such a case I print the man upside down, to avoid using support. Because of the very delicate parts(fingers) these parts break while removing the support. I add a small disk, 1mm high to secure it's head firmly to the buildplate. Afterwards I cut it off and file to smooth the helmet. While printing its head is embedded in that small disk. skirt 30x1.stl

In case someone wants to try and slice with his Slicer.... Scaled-Arbeiter_5.stl

My son has a PrusaMini and wants to print these workers I mentioned higher up in this thread. When slicing he gets a very strange result, the Prusa Slicer decapitates the figures(not all). Even after a repair in the P-Slicer itself. Slic3r does the same job perfectly. What's wrong here...?

A stalling stepper when using a barndoor tracker..? You do have serious problem. There are in fact no forces involved at all in a regular barndoor tracker. You have a mechanical problem or the current on the stepper is far to low. Or you need a bigger stepper.

Nope not at all, the 'polaraxis' is tucked away nicely between these two sheets of plywood. You need two printed parts(that's what I do) and a few angled blocks. The polaraxis is set at 51° and the (gliding) blocks at the opposite site are cut at 39°(in my case) But you living in or near London it would not differ that much from mine I suppose. Look at the drawings higher up and you'll notice a few holes in both sheets of plywood. These holes are there to allow passage to both blocks at the upper and lower sheet of plywood. This is not necessary of course. The only reason I made it this way is the challenge involved to make this EQ platform as low as possible, 65mm in my case. It is indeed a ridiculous low platform, I know, but I like a challenge from time to time..:-) If I were you I'd make it like the Boxmount I made for my Kutter Bino a few years back. Far more easy to construct. This page explains it all...

Nope there's no Decl axis involved. Just RA. But now that you mention it, maybe a good idea in case the polar axis is not correctly aligned and small corrections are needed. A second axis would be overkill imo. Just a polar-axis correction should suffice. Anyway a second axis would not correct Decl errors. Yes it would but only when observing at culmination point. But observing more East or South there's no way you can compensate for Decl errors. A device could be added at the rocker of the Dob itself...just maybe. Now that I come to think of it, how do regular-equatorial-platform users correct Decl errors while taking pictures. For years now I used this Boxmount, never had any issues with it because I exclusively used to observe visually . But now, planning to use it for astrophotography, it's a complete different problem. Sven's solution is absolutely perfect to track in RA, but what if (small)corrections are needed in Decl....? Think with us...🤔

Thanks... Another project were Sven is involved...

and now...?

A dual axis platform...? Explain please...

Launchplatform installed, spots included and first parts of the LUT. From now on every other day we will install more parts. To make things easy during assembly I installed a hinge at the bottom of the LUT. So when adding parts we tilt LUT to horizontal position and reposition afterwards. When LUT is complete we will secure it with a thick bolt to the launchplatform. The lower-frontpart of LUT is removed to make room for the tilting of LUT. When all is done that frontpart will be re-installed to make it complete again. The elevator part is not complete. Now it is 'just' 2.5m high. Meanwhile SaturnV is busy 'growing' on my printerplatforms...😃

The most important part in a tracker this accurate is the quality of the threaded rod. A standard threaded rod out of a 'normal' hardware shop is a no-go. Even with a integrated PEC system it would not be feasible imo. These threaded rods are good enough to track the stars if you don't mind the objects floating up and down constantly in the FOV. As my little lathe can't handle thread cutting I will use the threaded rods very often use in 3D printers for the Z-axis. They're available with different pitch. From 2 to 8mm if I'm not mistaken. The 2mm pitch would be the best choice. If I'd have a lathe capable of cutting threads I'd go for that option. These would be the perfect choice. My point : using 'everyday' threads in combination with Sven's software-solution would be a waste of time. Lead screw with T8 brass nut should do the job nicely.

Thanks Sven for joining in...!!!