Bed¶

Before I'll go into the steps about how to apply the insulation, I have to point out a few things first:

• You'll need longer spacers and screws due to the thickness of the insulation (which is about 9-10mm most of the time)!
• You'll need to raise the whole bedplate to avoid contact between the insulation and the motor mount at the back of the construction.
  If you use the beforementioned 25mm springs and longer screws, you should be fine as they are longer then the stock spacers anyway.
  If you'll use the stock spacers or silicone spacers of about the same size, you can add bolt nuts underneath to raise the bed. However, it's advisable though to get yourself longer spacers then!

• It's also advisable to have Kapton tape on hand to cover the whole underside of the bedplate with it (before you actually apply the insulation) and to secure the edges and sides of the insulation (after applying the insulation)!
  Make sure that no bubbles are trapped between the Kapton tape and the surface of the bed's underside then! And do a proper cleaning of the surface to avoid that the tape will (partially) come off!

• For adding the insulation, you need to dismount the bedplate from the gantry by taking out the four screws (remove the PEI coated plate first tho). Be careful with the wires when moving the plate. Put the plate onto the insulation (but don't peel off the protective layer of the adhesive yet!), align it and mark the four holes of the screws.

• Then place the bed upside down on a flat and clean surface - wipe the surface beforehand tho to make sure that there's no dirt or even metal chips which would press into or stick onto the magnetic surface. Now use IPA or (which I prefer) silicone remover to wipe the underside of the bed where the insulation should be applied to and clean off any dirt or grease from your fingers.
• Now lay down the insulation onto the bed like if you would apply it (but still with the protective layer on the adhesive!) and adjust the position. Mark the area where the wires are connected to the bed as well and cut away that part of the insulation.
  
• Place the spacers above the premarked holes and cut away the insulation in that area as well, so that the spacers will touch the plate later without any insulation between. I'd recommend to mark the areas that should be cut and then take the insulation away from the bedplate, so that you don't harm the surface when using a sharp knife or so.
• When it comes down to finally apply the insulation, I personally would suggest to cover the whole surface of the bed with Kapton tape first, just in case you'd have to tear off the insulation in the future. I also added two layers of Kapton tape especially above the contacts and the little piece of foam of the thermistor in the center of the bed and marked that area roughly at the insulation, just in case I'd have to replace the thermistor in the future.
  Make sure there are no bubbles trapped underneath the Kapton tape though!
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  Note: Looking back, I now would remove that piece of foam which covers the thermistor in the middle to make sure the insulation covers the bed without any air trapped in between! Cover that hole of the thermistor with Kapton tape though before you apply the insulation.
• Once everything is done and prepared, you can finally apply the insulation. Make sure you start at one side to avoid any bubbles, you want the insulation to stick on the bed equally. If some of the insulation protrudes beyond the plate, cut it off. The following picture shows the applied insulation.
  
• I highly recommend to additionally secure the insulation by using some pieces of Kapton tape as well to ensure that the edges and sides of the insulation won't come loose. Don't skip this step, as the insulation most likely will come off sooner or later at the sides and edges (at least mine did).
• Then add the spacers and the screws and mount the bed onto the gantry again. Make sure that the insulation doesn't touch the construction and the motor mount at the back, the bed has to move as free as before. So move the bedplate manually to see if everything is fine and if there's enough clearance between the insulation and the other parts.
• If you used adjustable spacers, tram the bed again.
• When switching on the printer, make sure you proceed with executing an ABL procedure, adjusting the z-offset due to the raised bed and execute a PID tuning of the bed now and save the new values to the EEPROM.

If you have to attach the magnetic foil onto a new or even your old bedplate, make sure to rigourously clean the bedplate before applying it.
If you use a new bedplate, peel off the protective film.
If you use your old bedplate, clean off any rest of old glue (if it's hard to get the glue off, you can use some e.g. WD40 to soften it and rub it off with a paper towel).

Use IPA to wipe off any oil or grease which already gets on the the bedplate by just touching it. Silicone remover spray actually works even better. You can also use car break cleaner for this, but it leaves minerals on the plate, so better use silicone remover or wipe off the bed with IPA after using the car break cleaner.

To make sure that everything really is clean, I'd suggest to wear disposable gloves, use paper towels and do more than one cleaning routine. Also make sure that no dust or anything else is left on the plate when attempting to attach the magnetic foil then.

When applying the magnetic foil, peel off about an inch of the protective film of the glued side of the foil and position the foil along one of the edges of the bedplate.
Avoid touching the glued side!
Make sure to position the foil correctly at the first attempt as you don't want to put yourself in the position where you have to pull off the foil again. Bend the foil a bit and then wipe along that stripe you already put on the bed from the middle to the outer edges with slight pressure. Pay attention to get the foil onto the bed smooth and even - there shouldn't be any bubbles of trapped air or even 'wrinkles' of the foil!
If everything worked out well for that first stripe, slowly pull off the protective film while applying the foil onto the bedplate in the described way. Means, go slowly in small increments and always apply pressure by wiping from the center to the sides for avoiding trapped air.

Once you're done, wipe from the center of the bedplate to the sides once again while applying a bit of more pressure. Then heat up the bed to about 40-50°C (so that it's still safe for you to touch it without burning yourself) and let it sit for about 5min like that. Then wipe over it once again while applying pressure to make sure the foil is properly attached. Pay special attention to the egdes and long corners and make sure the foil really is attached well there.

If you bought a 235x235mm or even bigger foil, cut off the protruding parts by using a scalpel or sharp knife.

If you need to adjust the sensor's spring tension, you can do so by turning the belonging hex head screw.

Turning it counter-clockwise decreases the tension, turning it clockwise increases the tension.
When increasing the tension (= turning it clockwise), push the allen key together with the screw slightly upwards while turning the screw.

• If you need to adjust the sensor's position, make sure that the sensor can freely move up and down - it must pop up by itself once released after being pushed down.

• Now place a flat object like the two-sided open end wrench onto the build plate.
  Let it stick out at the end, so that it reaches across the sensor. Make sure to press down the tool firmly onto the bed, so that it's actually really laying flat on the build plate!

• While holding the tool in this position across the sensor's button, now loosen the M2 hex screw which is for adjusting the sensor's height. See the following picture for identifying it's location.

  

• If the sensor was too low, it should now pop up and hit the tools's underside. Make sure this is the case and retighten the M2 hex screw again.

• If the sensor was too high, it's position changed due to the tool pressing it down. You can now retighten the M2 hex screw again.

• After you finished adjusting the sensor's height, check again if the sensor still can move freely and if it now really has the perfect height.

When using the rigid stock spacers the printer came with, dismount the bedplate from the bedgantry and take out those four silver metal spacers. Then put them next to each other on a flat surface and/or measure them using a caliper. They might not be all of the same height, which will lead to a somewhat crooked, tilted or 'warped' bed.

Now you could either look for other spacers you might be using, put washers or other suitable material (e.g. gasket material) of the needed thickness under them when remounting or (what I'd recommend to do) sand them down to the smallest of the four spacers for achieving an equal height.
When doing so, put the sandpaper on a flat surface and carefully rub the spacers across it - pay attention that you do this while holding the spacer absolutely perpendicular! You don't want to end up with a spacer where one end is sanded off tilted!

Once you're done and all four spacers are of equal height, reassemble everything. Then proceed with tramming the x-axis gantry in relation to the bed.

You could also use adjustable spacers like silicone spacers or springs instead of those rigid spacers. That'll put you in the position of really being able to tram the bed.
However, if doing so you not only need to be precise when tramming the bed, but you should proceed with tramming the x-axis gantry in relation to the frame first. This is really important as it will ensure that the x-axis gantry is parallel to the base frame.
Once this step is done, you can proceed with tramming the bed itself.

When you want to tram the bed by adjusting the tension of the springs or silicone spacers to pull down a side or an edge of the bed, be careful to not bend the bed itself by tightening up just one corner too much. Try to push down one side of the bed and adjust two screws at a time.
I personally tram the bed by adding just a little bit of load to the spacers, so that the bed doesn't wobble.

For actually tramming the bed now, you'll have to move the printhead to all of the four corners and adjust the height of the belonging edge of the bed by tightening or loosening the belonging screw. I'd suppose to start with the left backhand corner and rotate clockwise.
Take off the PEI plate and place an object onto the edge of the bed. It doesn't matter if this object is like 5mm or 5cm high as you're not setting the z-offset yet. It's just being used to ensure that the bedplate will be at the same height in relation to the printhead at all four corners. You need to make sure that you'll still be able to access the screw form the top though, so don't place the object right above the screw.
Then lower the printhead manually until the nozzle or the ABL sensor just touches that object. Then move the object to the next corner and move the printhead across it. Make sure that you absolutely don't move the head along the z-axis by accident, so that you don't somehow change the height of it!
If the head is positioned too low and there isn't enough space to fit the object between the bed and the head, tighten the screw for lowering the bedplate. If there's too much space, loosen the screw a bit until the nozzle/ABL sensor touches the object again.
Proceed with the other corners like that. Once you're done with all four corners, do another round and check if everything still fits. Most likely it won't as it affects the other edges when adjusting the height of one edge. When you're done with this round as well, put on the PEI plate, move the lead screw manually for raising the head and place the object in the first corner again. Lower the head and check all four edges once again if everything is correct.
When you're done, make sure the screws won't turn themselves loose due to the vibration, so add e.g. an additional lock nut as well.

The first 'hack' is to actually just wrap some layers of duct tape around the plastic cap and the first inch or two of the wiring.
By doing so, you'll stiffen up the wires a bit in that first section right behind the cap, avoiding the punctual bending. You need to make sure that the whole construction won't be too stiff as it should still be able to bend overall though, otherwise you'll provoke the same issue right after the attached tape.
As I'm using my printers in an enclosure, this solution didn't last long though. The heat inside the enclosure made the glue of the tape warm and it lost contact to the black plastic cap. So I personally can't recommend this one.

The second 'hack' is actually kind of the same like the duct tape method, but instead of wrapping the self-sealing tape around the outside of the plastic cap, you wrap it around the wires.
I forgot to take a picture of it, but it's fairly simple, so let me explain it a bit.
- You cut the cabletie which holds the wire inside that plastic cap and take the whole wire harness thing out.
- Then you wrap self-sealing tape around it, also in the area which will be inside of that cap later. So I'd say cover an area of about 2-3 inches with several layers, while applying more layers in the front part (towards that soldered contacts).
Make sure the wire is still able to easily bend in that area, you don't want to have it too stiff which would just lead to the circumstance that the sharp bending would occur right behind the taped area. - Now fiddle that wire back into place at the plastic cap like it was before and secure the position with a new cabletie.
- That's it :)

For the sake of simplicity, I'd recommend this solution as it's easy to apply, even with the stock setup.
If you don't know or have self-sealing / self-welding tape yet, give it a try. It's really great and comes in handy in several cases.

The third option I tried is actually kind of similar to the one being previously mentioned, but instead of only using self-sealing tape, I used a piece of silicone tube in addition.
- First, I cut the cabletie which holds the whole wire 'package' to the black plastic cap.
- Then I took a piece silicone tubing which I cut at one side and placed it across that specific section of the wire.
- I then wrapped self-welding/sealing tape across it and secured everything again with a cabletie.
You can see this 'hack' at the following picture.

I have to admit though that I probably exxagerated it as the additional silicone tube made it quite stiff. So if you want to go with this solution, keep an eye on the thickness and stiffness of the tube as well as how many layers of tape you apply.

The last method I'd like to mention is the one using a semi-stiff spring and some heat shrink tubings.

• Disconnect the wires and pull the whole wiring harness through a semi-stiff spring as shown in the following picture.
  
• Then pull the wiring harness through a heat shrink tube which then goes in between the wires and the spring to avoid that the spring rubs on the wires and harms the insulation.
  
• Place the spring with the wires in the plastic cap and add a cabletie to hold it in place.
  
• Now pull the wires through a bigger heat shrink tube and place that one across the end of the spring and the wires that come out of it, to secure everything here. By doing so, you'll reduce the motion of the wires in the spring itself and stabilize the wire a bit. When the wires will be pulled/moved, they won't be bent at the spot right after the spring and won't be moved around in the spring as well.
  The following picture shows the final asssembly.
  

This is actually my preferred solution, BUT: you have to pay attention to use a spring which isn't too stiff! I had one laying around in my drawers at my workshop, so I can't give you any further specs. Best would be to check at a hardware shop and bend the spring to make sure it bends easily. You don't want to stiffen it up too much, you just want it to act as a guide for when the wires are being bent.

You can check the wiring of both the 24V line and the thermistor by measuring the electrical continuity of the wires. If your multimeter doesn't have this function, you can measure the resistance instead.

However, it's advisable to measure the resistance, even though your multimeter offers the function of probing for continuity, because it might be the case that a wire still passes the check for continuity, but that individual strands of the wire are broken. This causes problems if those strands lose contact permanently or during movement of the bed, as it leads to a higher resistance.

• At the 24V wires this can lead to the circumstance that the wire will get hot at that spot, that the insulation will melt, that a shortcut might occur and it might even occur that it causes a fire.
• At the thermistor wires this can cause the ERR: MINTEMP error message. When the problem of breaking strands starts to occur, you'll experience the upcoming of this error message when the bed is moving and reaches a certain position. In that case those broken strands lose contact, which leads to a suddenly changing resistance value. As the temperature is interpreted by the reisistance value of the bed's thermistor, a suddenly changing resistance is interpreted as a sudden change in the temperature. If this change is 'big' enough, the belonging error message will be triggered.

Procedure:

• Unplug the belonging connector and check the belonging wire(s) by probing at the beginning and the end of the wire. So place one probe of the multimeter at the connector and the other probe at the solder joint of the wire you want to check.
• If continuity is given and/or no or a very small resistance (it should be really close to zero resistance though!) is measured, start bending the wire slowly and pay attention to the measured resistance. Take a few iterations when doing so, bend the wire in different radii, at different speed, at different spots. If at one point the resistance suddenly changes, the problematic and broken part of the wire is detected.

You can check if a thermistor is working or if it's broken by measuring the resistance of it using a multimeter. As described above, at a temperature of 25°C the resistance should be ~100k Ohm (nominal restistance: R^25°C = 100 kΩ ± 1%). If the temperature is lower, the resistance value will be higher; if the temperature is higher, the resistance value will be lower.
The following table gives you some typical resistance values of a 100K thermistor type 3950 (generic) for temperatures around room temperature. The values might slightly vary from the one you'll get, but they should be pretty close.

Set your multimeter to resistance testing for a higher Ohm range - in most cases the multimeters have different settings, usually 200/2000/20K/200K/20M -> use the setting "200K" here.

You can measure by probing the belonging wires at the plug of the mainboard (unplug it!), that would be the white connector labeled as "T1" with the green and blue wire (see the chapter "Mainboard" -> "TriGorilla V_3.0.6 (Stock)" for a picture of the location).

• Keep in mind though that by probing at the connector, you also measure the wiring itself, which would be needed if you want to check if you maybe have a broken wiring. Means, if there are e.g. broken wires, the thermistor won't work even if the thermistor itself is still fine.
• If you don't want to check the wiring, you could measure at the soldering joints right at the bed - in this case you also check the conductor path of the PCB itself (keep in mind that some glue across the solder pad area might prevent a successful measurement, so make sure you really make contact to the solder joints!).
• If you really want to only measure the thermistor itself (which is advisable if you're in doubt and are thinking about changing the thermistor), then you'd have to pull off the little foamy piece in the middle of the underside of the bed and measure the resistance right at the soldering joints or legs of the thermistor itself.

You can also check the 24V heating circuit of the PCB itself, like when the bed doesn't heat up (in this case make sure to also measure if 24V are coming from the belonging screw terminal for the heated bed at the mainboard!).
Besides inspecting it closely if any visible damages like scratches or abraded spots are visible, measure the continuity and resistance of the 24V circuit as well.

Then set your multimeter to resistance testing for a low Ohm range (in most cases the multimeters have different settings, usually 200/2000/20K/200K/20M -> use the setting "200" here).

For checking the 24V heating circuit, disconnect the wires from the mainboard's screw terminal.
Then probe at the ends of the wires (which connect to the screw terminals) - by doing so, you also check the wiring as well.
Double-check and probe at the solder joints right at the bed as well (keep in mind that some glue across the solder pad area might prevent a successful measurement, so make sure you really make contact to the solder joints!).

If the circuit is ok, continuity will be given and a resistance of about 3.2 Ω should be reported.

If you need to replace the thermistor, you should be able to do so by pulling off the piece of foam for being able to access it. You can then unsolder it and replace it with a new one.

Note:

• If you have problems heating up the solder joints because the plate acts as a conductor and draws the heat of the soldering iron, heat up the bedplate first - but don't heat it up too much, you don't want to burn yourself! Make sure to switch off the bed then, switch off the whole printer and unplug it from the power outlet. Unplug the wiring from the mainboard as well then before starting to solder.

• If you need to replace the wiring of the 24V heater circuit of the bed, use highly flexible wire with many thin strands and a silicone insulation! Don't use a wire with a PVC insulation!
• Use at least AWG14 wire, preferrably thicker.
• Add [ferrules] to the end of the wires which connects to the screw terminals of the mainboard!
• Pay attention to proper soldering! Avoid any shortcuts, cold solder joints etc.
• If you can't solder and you absolutely don't have any other possibility to have the soldering done by someone who is experienced in this, you might use special connectors.
• In that case you leave e.g. an inch of the original wiring at the bed (assuming that the faulty spot isn't located there - check that beforehand!) and then connect the new wire with the existing one.
• If you do so, pay special attention to add a proper strain relief - no strain or movement at all should occur at the fixed part of the wire!
• There are shrinkable solder connectors available on the market, where you insert the stripped ends of the wires at each end of the connector and then you heat up the soldered area of the connector, which then melts and connects both ends of those wires.
  Attention: Make sure to get yourself the correct size for the specific wire thickness you're using! Don't use soldering connectors which are too big!

• If you need to replace the wiring of the thermistor of the bed, use highly flexible wire with many thin strands and a silicone insulation! Don't use a wire with a PVC insulation!
• Use at least AWG22 wire, preferrably thicker.
• Pay attention to proper soldering! Avoid any shortcuts, cold solder joints etc.
• If you can't solder and you absolutely don't have any other possibility to have the soldering done by someone who is experienced in this, you might use special connectors.
• If you want to do so, leave e.g. an inch of the original wiring at the bed (assuming that the faulty spot isn't located there - check that beforehand!) and then connect the new wire with the existing one.
• If you do so, pay special attention to add a proper strain relief - no strain or movement at all should occur at the fixed part of the wire!
• There are shrinkable solder connectors available on the market, where you insert the stripped ends of the wires at each end of the connector and then you heat up the soldered area of the connector, which then melts and connects both ends of those wires.
  Attention: Make sure to get yourself the correct size for the specific wire thickness you're using! Don't use soldering connectors which are too big!
  The following picture shows one of those connectors - note that it shows the biggest one though, coded with a yellow stripe, which isn't suitable as it's too big (I just didn't had smaller ones for taking a picture).
  
• However, as the wires of the thermistor are pretty thin, you might won't be able to find and use proper shrinkable solder connectors (they DO exist for thin wires though!). In that case you might also use special WAGO clamps to connect the wires as shown in the pictures below. As mentioned before, pay special attention to a proper strain relief, especially because here the wires can come out again due to just being clamped!
  The following picture shows WAGO clamps of the type 221-2411 (at the top) and 221-412 (at the bottom). The difference between these two is that at the 221-2411 the wires will be inserted facing each other, at the 221-412 the wires are installed running parallel to each other. Both type of clamps connect the wires and close the electrical circuit.
  
  The following picture shows a WAGO clamp of the type 221-412 with two wires assembled.
  
• There are small, gel-filled button-like wire connectors to find as well, where you just stick the two ends in and then clamp/crimp it together, those one should work as well. You need to try though as the product pages say that you can use them for wires of 0.4-0.7mm² diameter, but the thermistor wires are AWG22/~0.32mm². So keep an eye on that and measure the connection after you installed them.
  
• Keep in mind that you need to add the belonging connector (JST XH 2.54) to the end of the wire for being able to plug it into the mainboard! If you don't have the belonging crimping tool and can't solder a piece of the old wire to the end of the new wire, you can use the beforementioned connectors as well.