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Auto touch Z end-stop

by radus Jan 6, 2014
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can you do this thing for trapezoidal spindle?
SW = 17 mm
L= 15 mm is the mother :)

thanks a lot

I wanted to print out a pair of these to use on my MakerFarm Prusa i3 printer, but there's not enough room between the Z motors and the X motor/idler assemblies. There's barely enough room for the Z rod couplers.

Clever idea very nice!!

Video I tried to photograph the opening of the contacts at the highest zuum, but it's not really as contact really opened a couple of microns =)

That mean, the contact are normaly close and when the noozle hit the bed it open up ?

Sorry, but cant you show on video of your device in action when it touch the bed

You want to see the process of opening the contacts?

Yes, please. A zoomed-in video of the yellow and green pieces while bed levelling, so we can see the contacts.

Yes, a video that shows the contacts process please, thanks

Ok cool, now I can figure how it works.
Thank you so much.
This is a top idea.

You want to see the process of opening contacts?

i like this except the fact that the only constraint is a little finger around the smooth rod, I believe it would be better to add a bearing there in line with the nut trap because as you use this more that finger will get wider and you will add backlash to the Z.

I'm also guessing that the .4 offset is to adjust for the weight of the extruder flexing the bed?

Yes. Smooth rods on Y flexible on 0.4 mm. Need better rods on 10 or 12 mm.

Do you use just one nut at the top of the yellow piece, or is there another at the bottom? Or is there a nut? I can't tell from your pictures.

Nut only in yellow piece. I did nuts from PTFE

My configuration for marlin




To improve the contact detection, a nice solution would be to use a strain gauge. But I never used such gauge. Does anyone know how to implement this (from mechanical and electrical point of view)?

Such gauge could be mounted on the X carriage...

I agree, some detailed instructions would be nice. What are you using for the electrical contacts on the yellow pieces? I see you're using two yellow pieces. Are both wired? How are they wired, in series or in parallel?

As the contacts are normally closed, they must be wired in serie... and you have to set the correct level in your firmware (a lot of people use normally open contacts, closing at end-stop; this is a bad idea, as they can't detect a broken wire, and axis won't stop).

Yes left and right yellow pieces connected in series.

I think I see how this would work. A more zoomed out video and photos would put things in more context. Some basic instructions would go a long way to making this more easily understood.

If I understand correctly the Xaxis carriage floats free and the yellow pieces are driven. The X axis just rests on the yellow ends keeping the circuit normally closed. When the hot end touches the be the Xcarriage basically stops but the yellow keeps moving causing the circuit to open.

It looks like you have this installed on a Prusa I3. Has anyone used this on an I2?

What if any firmware changes did you make?

With the X carriage free floating one good thing would be no clogs from the hot end being jammed to the bed. The force of the filament pushing out would actually raise the hot end. That said it I could see there not being enough force to get the new layer of filament squished onto the prior layer. Any example prints you can show pictures of?

I really like this concept because there is no need for a servo and the associated weight.

A lot of people have free floating X axis, including me, and have no problem with layers. It could however be a problem if you have a very lightweight X axis, in a Bowden config, for example. But it would be easy to add some weight on the non-moving parts of the axis (there is already a motor at one end)...

Great system! That's a long time I'm planning to make a Z end-stop based on hot-end touching the bed, instead of independant switch (to avoid dilatation problems or so). My idea was to put it on the hot-end itself, but it would require to mount it on a Z translation... Not easy to do. Your solution is simple and elegant (I also have such anti-wobble system, so it will be easy to try).

Good job! Thanks for sharing.

How does end stop get activated by Extruder making contact with a surface??? I am missing something big time.... Does not appear to be related to bed leveling? Please explain so I don't have to pull my hair out. Da!!!

That is cool! I am going to try it. Thanks

I'm a little confused by the pictures with exactly how this works. Care to explain it?

anthony, the xends doesnt hold the z nuts, the yelllow piece hold each nut. So, when going down, the extruder will touch the bed, and the axis will keep on that heigt, since the yellow pieces are not glued to the axis, they will continue going down and the circuit will get opened, then, zmin is on. At least i think it works that way

Hi, could we just mount Zmin in one side only?

That's right! Works that way;)