How to build a 3-point-level Printer bed

Markus64
Posts: 237
Joined: Thu Feb 27, 2020 4:57 pm
Location: Germany

How to build a 3-point-level Printer bed

Postby Markus64 » Tue Sep 29, 2020 8:31 pm

After I have received a lot of letters about the new construction of my print plate and it is impossible for me to send instructions to everyone who is interested, I show the individual work steps here.

First of all, I am convinced that there are big differences in terms of “pre-calibrated”. Some users have no problems, others cannot print correctly with the device from the start. So it was in my case, the print plate warped in a catastrophic way. ABS with a bed temperature of 100 ° C was hell.
At the beginning of the purchase I was not fully aware that it is practically impossible to carry out a leveling in a hurry. I also didn't feel like bothering with the problem for many hours or days. Every Chinese printer for a tenth of the price can do this better and more or less automatically. Industrial grade - sure enough ...
Leveling a print bed should, no - MUST be quick and SAFE to act. When I have a horror of it, I don't like doing it. Does that mean a machine is clouding my mood? I bought this thing to make money, not to ruin my life!
The removable plate may seem chic and practical at first glance. But if the thing warps like hell and you need pliers to loosen the fixing screws, something is going totally wrong!
So I decided to make a modification. Get the flawed stuff out and put something sensible in. I don't give a damn about the romance of the oven.
First I built a plate with 4 point leveling. That worked much better. But I was not satisfied and built a 3-point leveling system. THAT worked wonderfully!
Complete leveling in minutes. Yes great, “pre-calibrated” can stay stolen from me now I'm the boss again! :mrgreen:

Anyone who wants to rebuild will do this with my instructions - even users with two left hands.

The finely milled precision cast plate made of G.AL C250 in 8mm thickness is available everywhere. Instead of springs, medium-hard silicone dampers are used. With these dampers, bed leveling should be checked after a few months. The setting lasts incredibly long! I have constructed a mold and make the STL available for free download here. So you are able to cast the damper yourself. What kind of silicone you need is also below. The mold was designed by me for 5 dampers, you only need 3 of them!

You will quickly forget about leveling with a dial gauge. It complicates the process and is completely unnecessary. What you absolutely need is a set of feeler gauges! I recommend from 0.05 to 2mm in 0.1 'increments. I recommend using the feeler gauges 0.06 to 0.10 twice, you will need them later to adjust the nozzle distance. You can mothball the original 0.2 mm feeler gauge because you will never need it again.
I set the nozzle spacing and print bed at room temperature and everything fits as it should. It should be easy ...
I will explain exactly how leveling works later. Also where the nozzle spacing is set.

A measurement is necessary before you start.

According to the illustration you determine the height of the complete original structure with a caliper. Make a note of the measure, you'll need it later. Let's call it the "A" dimension.
You buy the cork sheet a little bigger than the aluminum sheet and cut it to size with a cutter. It is important that the screw points are cut out on the cork plate. The first three solid washers are installed at these points. These are 30 mm in diameter, the holes in the cork plate are 40 mm in diameter. Then the later underside of the cork plate is covered with pure aluminum foil. Anyone who thinks they can do without the insulation will later regret it bitterly!

The transparent and heat-resistant 3M film can also be ordered as a large-format cut. I got a bigger piece to have a replacement in case something goes wrong. The stuff is not without problems to stick! It is best to peel off one side of the protective paper and stick it to the pre-cleaned underside of the cast plate. Then you turn the plate over and cleanly cut off the edges. Turn the plate over again and weigh down the bond with weights. Let the plate rest for about an hour at room temperature so that the adhesive can activate.
Why is the heating foil glued? Quite simply: the heat transfer improves enormously.
Now cut a few small slots through the 3M foil at the three holes so that the screws can pass through better later and do not lift the double-sided foil.

Get to work!

First you switch off the printer!
Then you clamp off the heating bed and start to remove all screw connections on the underside and take the printing bed out of the printer. Turn the print bed upside down and carefully remove the brown hardboard. Then, with a lot of feeling, the heating.
Insert a screw into the hole in each of the new aluminum plate and also place it on the top. The screws serve as fixed points for gluing the heating foil to the cast plate.

Now carefully remove the second protective paper from the 3M film. It is to be avoided that the adhesive tape becomes detached. So take your time with this step.
When the protective film is removed, you take the heating film and stretch it over the cast plate. The screws will help you to find the exact position. Two more hands are an advantage.
If the alignment is correct, the heating foil slowly lowers down onto the adhesive bed and presses it on evenly. Then you put on the hardboard, put one of the large washers on it and screw the whole thing with a self-locking nut.
Now the assembly of the cork panel, laminated with pure aluminum foil, follows. Partially apply the J-B Weld adhesive with a small notched trowel. Not on the entire surface, otherwise you will never get that again! Now glue the cork board to the hardboard, weigh it down with weights and let everything dry overnight.
During this drying time you can pour the three silicone buffers with the mold.
Anyone who has mold release agents can use this, otherwise ordinary powder also works very well.
It is best to leave it overnight.

In the meantime, the three existing holes in the lifting table can be drilled to a diameter of 6 mm. I recommend covering the installation space with some foil beforehand because of the chips. Please countersink the holes slightly to avoid burrs.
Now the final assembly follows!

Open the mold and remove the dampers. The side with the enlarged opening is the side that receives the M4 nut. Put all dampers on the screws and put one of these strong washers on the underside of the damper. The best thing to do is to fix everything with adhesive tape so that nothing falls off if you turn the plate over. The whole unit must now be inserted into the holes in the lift table. A fumble, I know ...
If everything went well, a strong washer is attached to the underside of the lifting table, which serves as a pressure surface for the leveling screw.

All three leveling screws are now tightened so lightly that a slight resistance can be felt. Then each adjustment point is tightened by half a turn. This is the basic position of the new bed.
Now you can connect the electrical connections of the bed heater to the printer.
The printer remains switched off because the Z-Stop still has to be adjusted!
You remember that at the beginning we measured the height of the complete structure.
We do the same with the new structure. The measure is now called "B".
B - A = C
"C" is the dimension we need to move the Z-Stop upwards. I did this with little washers for simplicity. If you want, you can print the part yourself later if everything works as it should.

Permanent printing film:
Lokbuild (my favorite), Buildtak etc. - what is your favorite

The calibration:
Set the Z-Stop the first time so that the table stops between 1mm and 2mm in front of the nozzle. It is important that the motors are never decoupled!
Now, as shown in the picture, the first of the three points is approached. You now need the feeler gauges to determine the distance between the nozzle and the bed. For example, if the distance is between 1 and 1.5 mm, take the 1.5 mm feeler gauge and use the handwheel to set the distance so that the feeler gauge and nozzle are in slight contact. You do the same with leveling points two and three, or until all three level points fit.
Very important: the leveling points must be approached by entering coordinates!
That reads more difficult than it is. With a little practice you'll soon get the hang of it.

Adjust the nozzle spacing:
Basically in the middle of the bed (X 152.5 / Y 152.5).
Standard distance for me 0.09 mm. However, depending on the material and the print object, the nozzle distance can be between 0.06 and 0.09 mm. You can see this when you print the first layer at the latest. You develop a feeling for what fits best relatively quickly.

Raise3D Pro2 Print Plate 3-Point-Level.pdf
Dimensional drawing of the aluminum plate
(1.35 MiB) Downloaded 27 times

Mold silicone damper.stl
Mold silicone damper
(355.36 KiB) Downloaded 19 times

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Good luck with building it! :D

Sorry for translation errors during the battle! :roll:

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