How I fixed Z banding on my 12" i3v. AL Y bed and solid state heat bed relay/PID

I have fought Z banding with my 12" i3v since I bought it and assembled it. I tried all sorts of things to fix the issue but never could get the Z banding under control.

The two things that I did to finally get it under control were.

1. Replace the wooden Y axis bed with Aluminum.

My Y bed would warp so badly on long prints that the rollers under it would crash into the cross support at the back of the printer.

2. Replaced the mechanical relay with a solid state relay and enabled soft PID within Marlin.

With the stock mechanical relay I would see the heat bed and glass print surface warp ~.3 mm every time the heat bed turned on and off to maintain the bed temp. This would happen every 5 seconds or so depending on the heat setting so ever 5 seconds the print surface would warp more than a full layer height when printing at .2 mm producing very prominent Z banding, poor first layers and in some cases layer separation when printing ABS. After installing the solid state relay and setting up PID the bed only moves ~.03 mm once up to operating temp.

The Y bed was replaced with a sheet of .125" 6061 that I ordered from Amazon

http://www.amazon.com/gp/product/B00...rch_detailpage

I used the stock wooden bed and some transfer punches to mark the aluminum plate to drill the holes for all the components. I also remixed a Y bed belt holder that I found on thingiverse to work with round mounting holes instead of the stock square holes.

http://www.thingiverse.com/thing:880755

This took care of the Y bed warpage issue that I was seeing. A side note, Makerfarm is now selling its own aluminum Y bed plate as an add on to the 12" kit.

The stock mechanical relay was just setup to control the heat bed in bang bang mode. Meaning that the heat bed would either be 100% on or off and it would swing high and low of the actual temp setting of the bed so when the heat would turn on the bed would warp one direction and when the heat turned off the bed would return to its normal position. This was instantaneous and the print surface would distort as the relay turned on and off.

I purchased this DC-DC solid state relay from Amazon

http://www.amazon.com/Lightobject-ES...id+state+relay

This relay seems to be fairly well made but I can't vouch for its longevity. I measured a .41V voltage drop across the relay while it was on with the heat bed hooked up to it and I don't notice any difference in the time required for the heat bed to reach operating temp.

along with this heat sink also from Amazon

http://www.amazon.com/Aluminum-Solid...PWQKFZSZFP7VZR

You will also want to get yourself some heat sink grease to put in-between the relay and the heat sink. Don't think about using the relay without the heat sink and grease or it will burn up on you and a solid state relay can fail in the on state that would keep your heat bed on without control so be careful.

As far as hooking up the solid state relay there are plenty of diagrams out there, just google it. One thing to note is that solid state relays are polarity sensitive so make sure you get the + and - correct.

Here is what I did to get the PID settings to enter into my Configuration.h file.

In Simplify 3d machine control I entered

M303 E-1 S100 C8

This will enable PID auto tuning and will heat up your bed to 100° and then cycle the bed around the set point 8 times. It will then return the P, I and D settings that you will need to enter into your Config.h file. You may need to preheat your heat bed if it takes a long time to reach operating temp as the autotune can timeout if it takes too long.

Now once you have your P, I and D settings you need to edit your Configuration.h file

You will need to find and uncomment

#define PIDTEMPBED

That will enable PID heat bed control.

You will then enter your P, I and D settings in the following location

#ifdef PIDTEMPBED
//120v 250W silicone heater into 4mm borosilicate (MendelMax 1.5+)
//from FOPDT model - kp=.39 Tp=405 Tdead=66, Tc set to 79.2, aggressive factor of .15 (vs .1, 1, 10)
#define DEFAULT_bedKp 460.33
#define DEFAULT_bedKi 87.81
#define DEFAULT_bedKd 603.32

Those are the P, I and D values that my Autotune resulted in.

Once you get this done you need to upload the changes to your printer.

That's all there was to it.

Here is a picture of before and after print results. These were all printed with the exact same settings of .2mm layer, 250° Extruder and 110° bed temps with no changes to the printer other than installing and setting up the Solid State relay.

Right was with the heat bed off, middle was the stock relay setup with no PID and left is with the Solid Sate Relay with PID tuning.

Attachment 7169

Hope this helps others facing the same Z banding frustration that I did.

Thanks,
Chadd

Order everything. Thanks for the write up. Should be here in a few days. That's the reason why my heat bed relay clicks in and out every so often. The period in cools and warms up makes for a noticeable difference. Do you think the relay and heat sink have space maybe for a fan also. Or it should be fine the way you set it up. I got artic silver 5 with my order. Also have you checked to see if print quality have improve in other print's that are not the cube.

Quote:

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Originally Posted by rhonal89

Order everything. Thanks for the write up. Should be here in a few days. That's the reason why my heat bed relay clicks in and out every so often. The period in cools and warms up makes for a noticeable difference. Do you think the relay and heat sink have space maybe for a fan also. Or it should be fine the way you set it up. I got artic silver 5 with my order.

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You could put a fan on it if you wanted but after a 15 - 20min print mine was just slightly warm. My relay didn't come with mounting screws so you may want to pick some up if you don't have any. I think they were 4mm if I remember right.

Just placed my order a few min ago too. Thanks for the write up!

Got any pictures of your wiring setup?

Thanks for the detailed explanation.

I do think metal (I prefer steel, which expands only half as much as aluminum) is a requirement for the Y, and for the whole frame. I have a steel i3 from Createc with the mechanical bang bang relay. I like the clicking, which tells me it's working. And the steel Y (with glass on top of MK2 pcb bed) is unaffected by the heat swings.

Quote:

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Originally Posted by 3DPBuser

I do think metal (I prefer steel, which expands only half as much as aluminum) is a requirement for the Y, and for the whole frame. I have a steel i3 from Createc with the mechanical bang bang relay. I like the clicking, which tells me it's working. And the steel Y (with glass on top of MK2 pcb bed) is unaffected by the heat swings.

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so im wiring up my solid state relay, and the common from the PS goes to the input - and the + from the PS goes to the +.
However, coming off of that are 2 black wires, that arent labeled + or - and the bed doesnt seem to care and colins instructions dont have a positive or negative marking...
so thats throwing me off a bit... any help?
Edit: so i just took the + from the same block as the + from the PS and marked it +. so that should be good.. and the same for the common.... so i think the above is resolved.

EDIT :2 = seeing the above may be wrong also... Thomas Sandelar has a good video on wiring these, but its AC... this is obviously a DC relay... still searching

now im not sure how to hook it up to the rumba board... there are no spots to connect those 2 wires that go from the board HB out , in to the relay.... thoughts?
thanks

man, reading diagrams etc just confuses me more...
id love some help.

So... here is how i have it wired now... im stumped as to the next steps. or even if im right.

I have the DC to DC relay you recomended btw.

Input side
- to - side on the rumba board HB
+ to the + side on the rumba board HD

+ side on the output (its not labeled) going to Power supply +
- side going to the heat bed

one of the heat bed wires going back to the PS - slot.

i dont know if any of this is right :) i wont power it on til i know though. dont want to fry something.

You hook up the control wires off the Rumba just as they were hooked up to the stock relay but be sure to observe the polarity of the Rumba output and of the relay input.

On the relay output you want the + positive wire from your power supply to go to the + Positive terminal on the SS relay then you want the - negative terminal of the SS relay to go to one of your heatbed wires, the other heat bed wire goes back to the - negative terminal on your power supply.

Thats all there is to it.

Here is a simple diagram, the source is your power supply and the load is your heatbed. 1 and 2 are the output terminals on your SSR and 3 and 4 are the input terminals. In our case you don't need to worry about the diode. It is used to snub out spikes caused by inductive loads, our heat beds are resistive.

Attachment 7305

Quote:

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Originally Posted by dunginhawk

man, reading diagrams etc just confuses me more...
id love some help.

So... here is how i have it wired now... im stumped as to the next steps. or even if im right.

I have the DC to DC relay you recomended btw.

Input side
- to - side on the rumba board HB
+ to the + side on the rumba board HD

+ side on the output (its not labeled) going to Power supply +
- side going to the heat bed

one of the heat bed wires going back to the PS - slot.

i dont know if any of this is right :) i wont power it on til i know though. dont want to fry something.

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Here is a picture of my wiring setup. In short:

(+) from PSU goes to (+) on SSR (Labeled as 1)
(-) from SSR (labeled as 2) goes to one input on the heated bed (They do not have polarity so either is fine)
Unused wire from heated bed comes back to (-) on PSU.

That takes care of the load side.

Connect the labeled connections "3" and "4" on the other side of the SSR to your board while making sure to match the (+) and (-) correctly since the board does have polarity.

This is how I have my 12" heated bed wired up through the SSR on my Rumba board. I then ran the PID config and input the results into my config file. So far after a few prints things are good and my house hasn't burned down.

Good luck.

Attachment 7320

sweet.. thats how i had it wired in the end :) yay me...
thanks guys for clarifying though.

SO i am running my first test print on the new metal bed, with the new SSR and its looking great.
I will run a test cube in the same color as my other test cubes, after i finish this print.
I hope it is as good as it appears. :)

Quote:

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Originally Posted by dunginhawk

sweet.. thats how i had it wired in the end :) yay me...
thanks guys for clarifying though.

SO i am running my first test print on the new metal bed, with the new SSR and its looking great.
I will run a test cube in the same color as my other test cubes, after i finish this print.
I hope it is as good as it appears. :)

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Right on, did you already determine your PID settings and enable PID control in the config.h?

I copied and pasted the Block of text in to my configuration.h file and altered the PID data to reflect what mine said after the PID command i ran.
so my values were changed to reflect my own.
its holding its temp well, and the print is still kicking it. unfortunatley its a 6 hour print, with clear PLA, so i wont be able to really tell if the issue is better.
ill test it in PINK when its done like all my other test cubes :)

so ive been printing on it for a full day now and cant really tell if the quality is a ton better, but it is improved. for the cost of this upgrade, i will definitely say its worth it. Cleaner lines, not as much banding... Now i just gotta figure out what my next printer will be :)

Just finished my swap. Was pretty easy and the print quality is marginally better. It isn't night and day, but noticeable. I will have to try it on some trickier prints and report back.

What at I do notice is a more even draw on my power supply. Before, whenever the bed relay kicked in the lights that I have mounted would flicker. Almost to the point it seemed like they were turning completey on and off.

Now, they Slightly flicker but the voltage is much more constant. Before the swap, the voltage would cruise at 12.2 and then drop almost to 10 as soon as the relay kicked in. I had to turn it up to 13 just to keep the voltage above 11 when heating. I was able to back down the voltage at idle to 12.3 and it never drops below 12 now.

Here is a video of the current flicker. You have to look at the wall to see it. It kinda matches the pulsing of the communications led on the rumba. I'm looking for a vid of the previous flicker. Think strobe light!

http://youtu.be/0KAfG17Sjgw

Quote:

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Originally Posted by tsteever

Think strobe light!

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Think Totally Unreliable! You need good, clean power that can accommodate the surges.

As I mentioned before you either have a bad power supply, a poor connection, undersized wiring or a combination of the above. You shouldn't see that much of a voltage drop off of a 30A PS.

Quote:

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Originally Posted by tsteever

Just finished my swap. Was pretty easy and the print quality is marginally better. It isn't night and day, but noticeable. I will have to try it on some trickier prints and report back.

What at I do notice is a more even draw on my power supply. Before, whenever the bed relay kicked in the lights that I have mounted would flicker. Almost to the point it seemed like they were turning completey on and off.

Now, they Slightly flicker but the voltage is much more constant. Before the swap, the voltage would cruise at 12.2 and then drop almost to 10 as soon as the relay kicked in. I had to turn it up to 13 just to keep the voltage above 11 when heating. I was able to back down the voltage at idle to 12.3 and it never drops below 12 now.

Here is a video of the current flicker. You have to look at the wall to see it. It kinda matches the pulsing of the communications led on the rumba. I'm looking for a vid of the previous flicker. Think strobe light!

http://youtu.be/0KAfG17Sjgw

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I am using 14 gauge wire. Two sets going to the board from the power supply and a third to the heatbed relay. I have checked, but will triple check that all connections are solid. I would think that 3 sets of 14 gauge wire should be enough to run this short of a distance. Heck, my 2000 watt speakers are running 12 gauge wire across 50 feet which is pretty my industry standard.

Are you measuring voltage across the power supply output or somewhere else?

Quote:

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Originally Posted by tsteever

I am using 14 gauge wire. Two sets going to the board from the power supply and a third to the heatbed relay. I have checked, but will triple check that all connections are solid. I would think that 3 sets of 14 gauge wire should be enough to run this short of a distance. Heck, my 2000 watt speakers are running 12 gauge wire across 50 feet which is pretty my industry standard.

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I am measuring at the power supply. I read a fair bit more on wire gauge from all my text books, online, etc... I am sure that the 14 gauge wire is more than adequate from the job here. I still need to check the connections. I am getting even more convinced that the cheap power supply is just not up to the job of a 12" bed. It is a 30 amp model. I only paid $28 or so from Amazon. I think I may go with this one as it has a higher output and reads to be of better quality. I think a more stable power source may help with my Z banding issues.

My next step in getting rid of Z banding is to replace the M5 screws with M6 lead screws. I'm not really sure what gains that will give me as the 5mm screw has pretty good resolution. I think the biggest gains may be had by a backlash nut of sorts.

Do you guys see the M5 rods as a possible source of Z banding? I was thinking of getting a pair of these.

PS - sorry for seemingly hijacking the OP's thread. Trying to keep this as close to getting rid of Z banding so people can use this thread to serve as a resource.

I would say you have a power supply issue then.

Are your stock rods bent at all? Do you have anything trying to constrain the top of the rod? Did you change the wooden Y axis bed for an aluminum one?

Quote:

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Originally Posted by tsteever

I am measuring at the power supply. I read a fair bit more on wire gauge from all my text books, online, etc... I am sure that the 14 gauge wire is more than adequate from the job here. I still need to check the connections. I am getting even more convinced that the cheap power supply is just not up to the job of a 12" bed. It is a 30 amp model. I only paid $28 or so from Amazon. I think I may go with this one as it has a higher output and reads to be of better quality. I think a more stable power source may help with my Z banding issues.

My next step in getting rid of Z banding is to replace the M5 screws with M6 lead screws. I'm not really sure what gains that will give me as the 5mm screw has pretty good resolution. I think the biggest gains may be had by a backlash nut of sorts.

Do you guys see the M5 rods as a possible source of Z banding? I was thinking of getting a pair of these.

PS - sorry for seemingly hijacking the OP's thread. Trying to keep this as close to getting rid of Z banding so people can use this thread to serve as a resource.

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I have nothing holding the top of the rods and yes, I have upgraded to the Aluminum bed.

I don't think Z backlash is a problem, because the weight of the X always pushes down on the Z nut.

Agreed, I have not had any issues with Z backlash either.

Quote:

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Originally Posted by 3DPBuser

I don't think Z backlash is a problem, because the weight of the X always pushes down on the Z nut.

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I ordered the relay and heatsink. looking forward to trying this out. how likely is the relay to fail if using a heatsink?

My relay doesn't get hot at all. I did order the heatsink and was a bit concerned by the size. It seems to be working fine. A review on Tom's youtube page suggests that adjusting the frequency could help but I haven't figured that part out yet.

I ordered the heatsink and some thermal paste as well. I have the whole thing attached to my enclosure and it's never been remotely warm. Not sure how warm it would be without it.

Quote:

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Originally Posted by adamfilip

I ordered the relay and heatsink. looking forward to trying this out. how likely is the relay to fail if using a heatsink?

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Not sure but I wouldn't want to find out. If the relay fails there is a chance that it would stick in the on position and since it is wired directly to your power supply your bed temp would run away. Not that this is any different than the mechanical relay because it would do the same thing if the contacts stuck on with the relay.

You can turn on the Thermal Runaway protection in Marlin.

Quote:

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Originally Posted by tsteever

You can turn on the Thermal Runaway protection in Marlin.

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Not really. Thermal runaway protection still depends on the heater control circuit working properly.

EDIT: I should qualify this. IIRC, if the printer is wired so that the printer power supply can be controlled by gcode commands, the thermal runaway protection will shut the printer off and turn off the heater. Otherwise, a stuck heater circuit is a stuck heater circuit and the heater will stay on. BTW, both mechanical relays and MOSFET-type solid state relays tend to fail in the "ON" state. Mechanical due to contact arcing and MOSFET because of the substrate nature of the device.

Ahh, I see. At first I was very puzzled by this, that can't be true. It is a safety feature. It will cancel the print. It does, but unless your printer can shut off the power supply (or at least power to the heatbed) then it wouldn't do any good. Thanks for the clarification!

Is there a thread about using a ATX power supply and how to wire it? I am thinking about switching power supplies and I had toyed with the idea of a computer power supply. I'm not too keen on the extra steps needed but if it is safer/better it may be worth it. The power supply I linked to earlier is 36amps but appears to be better quality. It is $80. I can get a morepowerful ATX power supply for less. If it also works better...bonus.

Quote:

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Originally Posted by tsteever

...Is there a thread about using a ATX power supply and how to wire it?

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Your i3v build guide at least has the basics regarding wiring the 12v output, jumpering the power supply PS_ON signal to force the ATX to turn on, and dealing with a load on the 5v rail if necessary. Being able to turn the ATX power supply on and off by gcode or turning it off in the case of thermal runaway adds complexity. Maybe someone else has links to a thread talking about it - I know this has been discussed. This How to wire PS_ON to control PC Power Supply reprap wiki thread may help.

The printer electronics needs to stay powered on even when the ATX supply is off. Details might vary depending on the type of printer electronics. One option is to power the electronics from USB all the time. Some have used a separate 5V source (5V STANDBY from the ATX, a 5V wall-wart, or some other 5V supply) to power both the electronics and their Raspberry Pi setup. For at least RAMPS, powering the electronics from an external 5V source requires 12v power-or'ing diode D1 on RAMPS to be removed. Otherwise you're shorting the 5V output from the MEGA2560 5V regulator to the other 5V source and D1 is removed as a precaution. Diode D1 is underneath the Y-axis stepper driver board on RAMPS. I don't know if other electronics types have similar issues.

In Marlin, your pins.h file likely has PS_ON_PIN defined to -1 for your motherboard type. Figure out some Arduino pin you can access on your electronics. RAMPS has a PS_ON terminal that is wired to Arduino pin 12. Change pins.h to reflect the pin you want to use and upload the new firmware. Wire the power supply PS_ON pin (see the build guide or other ATX reference for pinout of the ATX connector) to whatever Arduino pin you defined for PS_ON_PIN.

This should get the power supply control working. With pins.h set to something other than -1 for PS_ON_PIN, there should now be a new menu item on the LCD that will toggle between being able to turn the ATX on and being able to turn it off. Gcode commands are M80 to turn the ATX on and M81 to turn the ATX off.

For completeness, configuration.h has a few additional settings related to the ATX power control. The define for POWER_SUPPLY controls what logic levels turn the supply on/off. For an ATX, POWER_SUPPLY is set to 1. When I was using a separate relay to control a dedicated 12V supply, I needed POWER_SUPPLY set to 2. PS_DEFAULT_OFF can be commented/uncommented depending on whether you want the ATX power supply to be left off when the electronics starts up.

The other option would be to put in thermal fuses in series with your heat bed and hotend. If something were to fail and stick on the thermal fuse would blow and stop supplying power to the heatbed/hotend.

Quote:

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Originally Posted by tsteever

Ahh, I see. At first I was very puzzled by this, that can't be true. It is a safety feature. It will cancel the print. It does, but unless your printer can shut off the power supply (or at least power to the heatbed) then it wouldn't do any good. Thanks for the clarification!

Is there a thread about using a ATX power supply and how to wire it? I am thinking about switching power supplies and I had toyed with the idea of a computer power supply. I'm not too keen on the extra steps needed but if it is safer/better it may be worth it. The power supply I linked to earlier is 36amps but appears to be better quality. It is $80. I can get a morepowerful ATX power supply for less. If it also works better...bonus.

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I recently purchased the SSR and heat sink and have questions on wiring.

I understand the output wiring, but for input does the positive and negative leads from my Rumba board go to the corresponding positive and negative leads on the SSR?

Thanks for the help.

Quote:

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Originally Posted by BLKKROW

I recently purchased the SSR and heat sink and have questions on wiring.

I understand the output wiring, but for input does the positive and negative leads from my Rumba board go to the corresponding positive and negative leads on the SSR?

Thanks for the help.

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At the bottom of the first page I have a picture posted of my setup. However, what you are saying is correct.

Quote:

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Originally Posted by BLKKROW

I recently purchased the SSR and heat sink and have questions on wiring.

I understand the output wiring, but for input does the positive and negative leads from my Rumba board go to the corresponding positive and negative leads on the SSR?

Thanks for the help.

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Yes they do.

Thanks for the help I was just making sure before I wire it up.

I am getting lost on the configuration file.

I found the #define PIDTEMPBED that you mention but I can only find it in the section with //. Which I believe is the comment section. Is that where you would uncomment or remove the #?

Quote:

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Originally Posted by BLKKROW

I am getting lost on the configuration file.

I found the #define PIDTEMPBED that you mention but I can only find it in the section with //. Which I believe is the comment section. Is that where you would uncomment or remove the #?

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To uncomment a line you need to remove the // from the front of the line.

The text I posted in the first part of this thread is what it should look like when uncommented.

Quote:

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Originally Posted by Chadd

To uncomment a line you need to remove the // from the front of the line.

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Thank you! I don't know much about programming/C## or anything. All I can use is Matlab ;) thank you for your time!