1 Topic by tonycstech

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Topic: Wanhao D7 bed leveling questions

Ill start by saying this: (in case you wonder) i have plenty of FMD printing and designing experience (4 years regular printing/designing etc)
I got my machine last night and without trying to print anything right away i ran the code just to look how it behaves.

What i notices was not very promising.
I noticed that (after leveling the bed per manual as well as youtube videos) FEP flexes by about 0.6mm when build plate touches it.
With that i had 3 failed prints where part stuck to the FEP.
I am assuming it is because bed was too close to the FEP.

So i decided to change FEP in case it was old (prepackaged who knows how long ago possibly stretched or deformed due to temperature spikes who knows).
After i changed FEP (carefully working my way away from the center applying tension) i ran the leveling again and this time FEP flexed by about 0.1mm
(I can test FEP flex amount by raising the bed and looking at the edge of the FEP to see if reflection moves)


So my question is: How in the world do you allign the bed rack if while tightening the screws, it tilts ?
As well as: How do you 0 the bed if it presses on FEP enough to move it down ?

Should i raize the bed after zeroing by (what ever value i think its pressing against the FEP) before i start the print or will it HOME once print started ?

I am using included GRAY resin they sent me with the printer.
Have extra 0.5L of clear also from them.

my thingiverse http://www.thingiverse.com/tonycstech/designs
my 3d models http://www.turbosquid.com/Search/Artists/tonycstech

2 Reply by kasper219

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Re: Wanhao D7 bed leveling questions

With mine I leveled once I had resin in it. Basically to level it I loosened the 4 screws that hold the plate, then level (home), then hold down the front upper lip and the rear upper lip (the part above the resin and below the screw points) while tightening in a cross pattern, but make sure to hold down (only need 1-2 lbs of force if that, just enough to keep from moving).

If they are sticking to the FEP it is generally because it is detaching from the build plate. Try setting your first 4-8 layers to a lot higher exposure time and slightly higher 1st layer height.

How high is the model getting before detaching or do you just have a blob attached to the FEP with no details (with the grey if it isn't sticking to the plate at all it should be fairly thin maybe .5mm - 1mm thick if that)

The other issue could be that your part has a very small foot print on the plate itself (I have ran into that where models printed essentially smaller first and bigger towards the mid section).

Example for the wanhao black:
Base layer/s Time: 70 sec
Base layer count: 4
Base layer height 75 micron

layer time: 12 sec
layer height 75 micron (10 sec for 50 micron)

Keep in mind clear may let the light pass through it, I had some issues with parts that would have details removed on earlier layers because the light passed through the model to easily with the exposure time, but as usual "your mileage may vary".

Hope that helps.

3 Reply by pirvan (edited by pirvan 2018-04-14 03:09:27)

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Re: Wanhao D7 bed leveling questions

kasper219 wrote:

Keep in mind clear may let the light pass through it, I had some issues with parts that would have details removed on earlier layers because the light passed through the model to easily with the exposure time, but as usual "your mileage may vary".

Hope that helps.

Light may pass through the clear resin, but not UV Light.  Clear resin has built-in UV blockers that prevent deep curing.  By that I mean the blockers do not prevent the resin from polymerizing on the outer layer, but will prevent it from polymerizing deeper than a few layers.  Depending on the manufacturer, the depth UV can penetrate is the maximum layer thickness x2.

In the case of FormLabs resin, the maximum depth that UV can penetrate through clear is about 0.4mm.

This is the reason why you're supposed to shake the bottle before using and stir up the resin already in the tray.  You want to UV blocker to mix thoroughly and evenly in your resin.

Opaque resins (white, grey, black, color, etc) also have blockers.  They don't rely on pigment alone to prevent deep curing.

To print or, 3D print, that is the question...
SD3 printer w/too many mods,  Printrbot Simple Maker Ed.,  FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.

4 Reply by kasper219

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Re: Wanhao D7 bed leveling questions

I do know that the UV resins are supposed to have "built-in UV blockers" I have just had issues with the Wanhao clear resin not blocking like photocentric or even the black that I got from Wanhao that worked very well (could have been a bad batch or container of clear/resin). I guess I should have been more specific than just saying "your mileage may vary."

Tonycstech Let us know if you still have any issues with it not sticking to the plate or popping off of the plate and staying on the FEP.

5 Reply by tonycstech

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Re: Wanhao D7 bed leveling questions

I dont have any more issues but only because i solved them.
I solved them by fixing some fundamental problems with the VAT and how it sits on the LCD screen.
Stock setup makes FEP bump into the LCD screen because LCD sits above the printer frame by about 6mm.
I designed a small frame that goes underneath the VAT, lifting the VAT by 0.6mm and making it absolute flat with the LCD.

Then i had to come up with my own leveling mechanism because stock kept shifting when i tighten the screws.
No matter what i do, no matter the tension i apply to the screws or to the platform while tightening, shift will occur.

so i came up with my own leveling system here
https://www.thingiverse.com/thing:2872852

The one thing i think i need to do with that design is to be able to make it completely rigid once calibrated.
Maybe someone can help me improve it.
So far its giving me perfect level and perfect 1st layer.

My logic with redesigning calibration mechanism was simple, if i cant get 1st layer perfect, i cant get the rest of it.
I understand its not true with STL printers because in most cases of STL printers 1st few layers are supports and adhesion layers rather then actual mode, so by the time actual model is printed, initial layers have already stabilized.

my thingiverse http://www.thingiverse.com/tonycstech/designs
my 3d models http://www.turbosquid.com/Search/Artists/tonycstech