Baby steps. Originally shared by John Davis So this is a first test of

3D Printing
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Baby steps.

Originally shared by John Davis

So this is a first test of using the height adjustment nut on the bed as an end stop. Based on an idea that @Whosa_whatsis threw out a while back, I decided to see if I could just wire each of the height adjustment nuts (in series) as an end stop.

The nylock nut is a little misleading, because the washer is actually welded to the bottom of it, but it essentially acts as the upper contact point and the current passes through the post from the washer that is under the PCB (it has one of the leads soldered to it). The other lead is soldered to a partial washer that is JB welded to the top of the glass bed so that when the nozzle presses down on the bed it opens the end stop.

I have one of these wired on each of the three height adjustment posts (in series), but the action is not smooth enough to encourage me that it will be repeatable and consistent yet. There’s just too much friction when compressing the springs. As you can see in the video, it actually pressed the whole carriage down some. More importantly, each post compresses a little differently, so there’s no way it would be accurate enough for automatic tram correction (bed leveling via software) at this point.

My next steps will be to make smoother and more easily adjustable height adjustment posts to see if I can get proper automated tram correction working without a probe. Fingers crossed.
http://www.youtube.com/attribution_link?a=3ZCffo-QLb8&u=/watch?v%3DDX9qn1A4Hlk%26feature%3Dshare

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Looks encouraging, but you’ll definitely need a stiffer carriage holding it.

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The carriage could certainly be stiffer, but the posts are not precisely aligned with the cutouts on the bed and a lot of extra friction is the result. That combined with the unpredictable fiction of the washers and springs on the threaded posts makes it NOT (yet) consistent/repeatable, but I’m confident I can address those things. If I have to replace the carriage after all that, then so be it. :slight_smile:

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You might want to go to a 3 pin bed levelling system to cut down on the flex across the bed while levelling.

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I did convert it to three points already. Much easier to get in tram that way!

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OK it wasn’t clear in the video.

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Yeah, it was four points by design and I left it that way forever even though I knew it was a problem. Finally got around to converting it last week when I got serious about trying this mod and I’ve been kicking myself for not doing it earlier.

8

Looking at this set up you need to support the build plate so the force of your probing goes evenly through the spring. That is causing your error.

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@Nigel_Dickinson Yes, I’m planning to realign the posts with the provisions in the bed and install a sleeve so the springs and washers aren’t riding directly on threads.