To to ensure Hot end is perpendicular to the bed?

Just wondering in the build process of a Delta. The J-head hangs down 3-4 inches. I understand about the auto bed leveling. but, how do you guys ensure the end effector and hot-end, are not skewed in a direction? even a couple degrees?

Thanks

Max

disneytoy Wrote:
-------------------------------------------------------
> Just wondering in the build process of a Delta.
> The J-head hangs down 3-4 inches. I understand
> about the auto bed leveling. but, how do you guys
> ensure the end effector and hot-end, are not
> skewed in a direction? even a couple degrees?
>
> Thanks
>
> Max

If the arm lengths are exactly the same and each pair of arm attach points are horizontal, the end effector and hot end will be horizontal. The geometry dictates this.

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In slightly clearer terms, the arms *must* be equal length AND parallel to each other. Even a slight non-parallelism between a pair of arms can cause the effector to rotate about the X or Y (Cartesian) axis.

Another way it might make sense: each pair of arms creates a planar four-bar mechanism, specifically a parallelogram linkage. A consequence of this type is that the orientation of opposing pairs of links never changes. With the delta we want to constrain three degrees of rotation and leave only three degrees of translation, so each of the three four-bar linkages in-essence constrains one of the rotational freedoms. It's not that the X-tower constrains rotation about the X-axis, but the general idea holds true.

Also, so that you're aware, the auto level feature does not correct for geometry errors in the linkages. It is intended to correct for flatness errors in the build surface.

Edited 1 time(s). Last edit at 09/19/2013 12:55PM by edwardh.

Hi!

Yes, I understand about the equality of the arm lengths. I was mainly thinking with a handmade DIY delta, the J-head extends 3 inches or so from the bottom of the end effector plate. I bet a 1-2mm play from the mounting point would create a non perpendicular nozzle.

Have you ever needed to hold a hand drill at a perfect 90 degrees to drill a straight hole. being out of level in any direction results in a diagnal hole. Even if it is minuscule.

I guess, I will just make a small T square and make sure it is 90 degrees in all axis.

Thanks

Ah ok, now I understand the central point of your question

Well, I'm sure that someone can argue otherwise, but I would say that there are more important things to worry about on a Delta that affects the print performance. As with many Rostocks/Kossels/etc., the effectors and mounting pieces are printed, so I wouldn't say that those parts align the hotends to exactly 90 degrees. Very close, but not exact. As long as the mounting orientation is not changing and the non-perpendicularity is not obvious to the unaided eye, then you shouldn't have to worry. I, for one, have a RostockMAX with a modified, printed, effector and a printed groove mount. All screws are tight, and I've never even checked its squareness.

I would concern myself more with the towers and arms.

Good luck!