Modify UM2 bed to four point?

[twistx 0]

Has anyone tried this? It looks like it might be a simple job.

This is what I'm thinking... remove the whole Z platform/carriage/bed. Remove the heated bed from the Z platform. Remove glass clips from the heated bed. Use the heated bed to mark the Z platform where the two corner screws hold the rear glass clips in place. Drill out the holes, reassemble with some longer screws in the corners and one additional spring. Now you have four point calibration.

I can get the flat head socket screws and springs from mcmaster-car, not sure about the round thumb screw/nut thing though. Where could I source one of those?

Can anyone poke any holes in this plan before I go ahead and try it?

 

[Dim3nsioneer 558]

Maybe I missed the point. Why exactly do you want to change from three point levelling to four point levelling? It only brings disadvantages imho.

 

[IRobertI 521]

Why on earth would you want to do that? The three point system is much better. People have modded the UMO to get three point leveling because it's superior.

 

[eldrick 65]

Three points define a flat plain. Four points define a saddle-surface, and would be much more difficult to level. A lot of work that would give worse results.

 

[twistx 0]

Advantage being you turn one less knob? In theory three points work fine, until your plate or spring are not completely square.

My bed is not even between the back corners, and rather than spend hours trying to get mediocre calibration I can use four points to fine tune by adjusting each independantly.

For example, my original has a four point bed and despite the wood platform being badly warped I never had a problem calibrating it's height.

[nallath 1,124]

Being square has little do with it. It is possible that your glass plate isn't quite flat.

 

[Daid 306]

For example, my original has a four point bed and despite the wood platform being badly warped I never had a problem calibrating it's height.

 

Because the plate on top of it is straight. If your glass plate is slightly curved (Which I suspect from your comment) then you will never correct this with 4 point leveling. But it could also be that one of your axis is bend, as this causes the print head to move up&down while it's moving.

 

[zumfab 3]

My bed is not even between the back corners, and rather than spend hours trying to get mediocre calibration I can use four points to fine tune by adjusting each independantly.

 

It sounds like you are trying to compensate one problem with another. If the bed is not even it would probably be best to figure out why that happens and correct that, rather than adding an x amount of leveling points until you get lucky, while complicating leveling with each addition.

 

[twistx 0]

I didn't even think the glass could be the problem so I never checked it. I'll take a closer look at the glass and axis rods this weekend. All these little gremlins are getting the better of me.

Thanks for the feedback.

 

[twistx 0]

So I checked my glass with a square and one side is definitely not level. I'll check the axis rods next.

 

[muttstang 8]

What would be nice would be to have a 5 point for flattening the bed then 3 point below it for leveling. Keep them separate to make it work.

 

[twistx 0]

Well I requested some glass in a support ticket. Hopefully the new one won't have such a defect.

My axis rods all appear to be straight. No wobbling when running the print head back and forth. None of my prints show any wavy patterns.

Now the wait begins for replacement parts.