Migbot Prusa i3 Unofficial Support Thread

As I'm getting sick of waiting over 20 minutes for my heat bed to get to 90 degrees has anyone successfully added a relay to the bed getting power straight from the power supply?
I see that people are using solid state relays but having absolutely no experience can anyone suggest what to look for and how to wire this in?

I'm using a hot air blower (500C air temp, 2000W) to heat up the bed. It takes 2 minutes max of blowing air onto the bed to get it to the required temp.

Still having great luck with the 24v setup. I've got my bed wired for 12V feeding it 24v with the max PWM setting at 165. If you have not upgraded your PS and bed wiring you NEED to do so!! This is even more true on 12V, do it now, do not wait. I like 14ga silicon. With the setting at 165 the bed does heat up a little slower than the hot end, but not by much. All my wires are cool to the touch now too.

Speaking of 24V, I finally got some time to swap out the other parts (hot end and fans) to the 24v parts I got off reprapchampion.com. Did a hot end calibration, put the numbers in the firmware, then retested. BAM, almost exactly the same results, never had that before, always different even back to back. The PS is a 24v 15A that is having zero issue keeping up with the system. I've switched to a glass bed taped on with a layer of PEI taped to it, also working super well (now have to use a putty knife to get ABS models off the bed even after cooling)
Anyway, now that I've given up many hours of my life, and more money than just buying a printer that works, I have one!

[www.ebay.com]
[www.amazon.com]
[www.amazon.com]
[reprapchampion.com]
[reprapchampion.com]
[reprapchampion.com]
[www.hobbyking.com]

Does someone have a drawing of how to hook up an SSR-25DD relay to the heat bed and the reprap board? I'm not electrically inclined (even if I fly electric RC planes). A hand drawn picture will do. Even on a napkin.

Thanks in advance,
Jeff

Nevermind. I found what I was looking for. Amazing what a google search can do.

Edited 1 time(s). Last edit at 03/21/2016 05:42PM by Canadian Geek.

I got my kit with the "upgrade" MK8 extruder, all metal.
Would a hobbed gear be an improvement over the brass spur gear?

The brass has already rounded so I ordered a hobbed gear made of stainless. Just unsure if moving away from the spur was a good idea. Cannot see how it could be less effective, but someone here is likely to have real info and experience. I was disappointed to not find any offerings made from a hardened steel. If someone knows a best thing ever let me know where to find it, really tired of stripping out filament.

On a tangent, I noticed the feed surges much more than I would have suspected. I was laying a bead down on the first layer with the bed a little too far away(getting kisslicer tuned in). The ABS was sticking, but not being pressed flat... So I watched it go around for a bit, figured I could see how level it was. Guess as it goes over each tooth on the spur it would pump a little faster. Left a very obvious pattern on the bed, every few millimeters along the bed, thin with a little lump, thin with a little lump.

Quote
IBaz
As I'm getting sick of waiting over 20 minutes for my heat bed to get to 90 degrees has anyone successfully added a relay to the bed getting power straight from the power supply?
I see that people are using solid state relays but having absolutely no experience can anyone suggest what to look for and how to wire this in?

yup same here. i run my beds with 24v 2-3mins to hit 110c almost as fast as the hotend.
The main thing to be careful with is making sure the 24v power supply has enough amps to push the bad, and all that amounts to is what the bed ohm's at.
(ohm's law) I am even running 24v thru the 12v side. my 12v side ohmed at 1.6ohm so at 24v it needs 15amps. but dont get a 15amp power supply tho.. youll want 20-25amp I have a hard time finding anything over 25amp cause the price seems to go way up once you hit 30amp 24v

Oh and you can run 24v on the 24v side, it is faster heating then 12v on the 12v side but its still takes 10 mins or so... again that all depends on what your bed ohms at. they are all close but different.. a .2 to .5 ohm change can make a huge difference especially when dealing with 24v

Sorry, been a bit on the quiet side, been concentrating on the FB2020 CoreXY, however, I can validly say that the stock PSU without a relay is actually faster than with. I can start all 3 heating and the one without the relay will be at 80c (for ColorFabb NGEN), from around 15c before the others. A 24v PSU and rewire will be allow you to heat up quicker, and is actually better in the long run but there is really no point if you're running off the same PSU. You're better off dumping the ally plate and putting a Glass plate directly on the heater. I've done exactly that on the Migbot I have at home and it'll hit 80c in about 5-10 mins. The only thing you need to be aware of is the Glass is more sensitive to temperature changes and cause a thermal runaway if it drops too low (happens frequently to me as I keep forgetting to spray the bed with hairspray, cools it off too much).

Additionally, I'm going to enable Mesh Bed Levelling in the non-auto level firmware. What this does is runs an assisted levelling sequence, which will then compensate like an auto level probe, which for the Aluminium plates that are supplied with the Migbots, is a perfect solution.

::Edit::
Derp - had it enabled anyways.. Go use it!

Edited 1 time(s). Last edit at 03/22/2016 05:55PM by Ax.

Did all 3 bed's ohm out the same?
You will lose some power going thru the ssr tho.

The only reason I would run an ssr off the same power supply as the rest of the printer is IF the bed will require more amps Then the board can handle putting out. (200watt silicone mat) I think its about 20amps max. -for everything-

I too have dumped the alum plate with all my printers. With the glass right on the pcb. Printting on glass is the only way to go.

As far as the auto lvling, my self I went to a retractable end stop switch ran with a servo.
Works beautifully once set up.

Quote
Wes78
Did all 3 bed's ohm out the same?
You will lose some power going thru the ssr tho.

The only reason I would run an ssr off the same power supply as the rest of the printer is IF the bed will require more amps Then the board can handle putting out. (200watt silicone mat) I think its about 20amps max. -for everything-

I too have dumped the alum plate with all my printers. With the glass right on the pcb. Printting on glass is the only way to go.

As far as the auto lvling, my self I went to a retractable end stop switch ran with a servo.
Works beautifully once set up.

Pass on the Ohms, I've not checked, on average they should be around 1.1 Ohms on a 12v set up. The plan is to get silcone heaters for them all, but it's an expense I can't afford at the moment, when I do, I'll be getting the plates skimmed and going to Buildtak, which is what I'm planning on for the FB2020.

yeah should be. but i have one at 1.0ohm and another one at 1.5. so in other words 12v at 1. ohm pulls 12amps , 12v at 1.5ohm pulls 8amps ( and will seem like FOREVER to warm up) but at 24v.-> 24v @ 1. ohm pulls 24 amps. 24V @ 1.5ohm pulls 16amps

always a good idea to ohm beds before applying power to them -just- to be safe.

just want to put that info out there cause if someone new dont know... well its a good way to start a fire

Edited 3 time(s). Last edit at 03/23/2016 09:33AM by Wes78.

Evening all,

Thanks to Wes, I have a couple replacement parts!!

SO I was printing with ABS, and it ends up I smelled some hot plastic.. figuring it was the new spool of ABS I had (new brand to me) I thought.. hmm stinkey.
After the print was done, I went to print another job.. and surprise. Bed wouldn't heat. SO I spent some time troubleshooting the software, and printer.. and DOH. THe heating element of the bed mounts were MELTED. THe green plastic screw terminals.. were brown and slightly melty.
So I took the board off, and then re-soldered the two contacts. So yes it got hot. Cleaned up the contacts, and fixed the unit so it worked. Connectivity, to the board etc.
Wouldnt heat. Tried a few things.. assumed the reason for failure was the bed heater failed. (notice the word Assume)

New keenovo silicone bed heater. 200x200 12V 200W. 100K thermistor.
SSR-25DD relay. Wired per the diagram listed in the forum here earlier.
New additional 12v 30A power supply btw.. for the heat bed only. (duh.. relay)
No joy. No heat. Verified voltages etc.. and as it turns out.. the repaired contact on the board for the heat on the bed, is getting 12V intermittent. Contacts are getting voltage but the connectors will need repair it appears.

SO I swapped back to PLA. (no need for bed heat.. and I had a couple prototypes to print)
Printed one item, halfway through the Y axis stopped moving. ( I was asleep.. can you say SPAGHETTI?)

sigh.

SO my y axis pulley had a crack in the mount that I zip tied.. so that wasn't it! Blam belt laying on the floor. The mount under the Y axis failed. CRACK.. belt came loose.

Wes and Ax offered to re-print items, Since Wes is here in the US, we talked and a few days later.. NEW PARTS!

New parts arrived.. put them in.. wheeeee.

First priority. PRINT ALL PARTS FOR PRINTER.. so I have spares.

Printing replacement left Z axis... Wake up to spags. Damn left side bearing area BROKE LOOSE/OFF. (breaking out zip ties for the re-print attempt)


Ok so seriously people. Print replacement parts. I am kicking myself for NOT printing them.



SO all that stuff..

Does anyone know a good source for replacement mainboards? Or the screw terminals that hold the heating elements?
I need to investigate replacing it.. and or doing some repair on the board.

I switched out to these when I went 24v

Hi, guys

I got a Migbot Large Bed printer that came without a proximity switch.

I now thinking of buying and installing a proximity switch.

The question I got is where to find or what is called the white 3 wire connector that connect the proximity switch to the MK Base?

All the switches I saw on sale come without this connector.

Many thanks.
Cheers
Ta

First thing would be to decide if you are staying aluminum bed or going glass

Quote
Taisiya
Hi, guys

I got a Migbot Large Bed printer that came without a proximity switch.

I now thinking of buying and installing a proximity switch.

The question I got is where to find or what is called the white 3 wire connector that connect the proximity switch to the MK Base?

All the switches I saw on sale come without this connector.

Many thanks.
Cheers
Ta

The connector is a 3 pin JST-XH LiPo Balance plug. Frankly, though, I'd just grab my firmware and use the Mesh levelling function. It does the same thing as the probe but with a manual intervention. You'll find yourself doing a fair bit of fiddling with the probe, whereas the mesh levelling is pretty much set and forget.

Quote
Wes78

Quote
IBaz
As I'm getting sick of waiting over 20 minutes for my heat bed to get to 90 degrees has anyone successfully added a relay to the bed getting power straight from the power supply?
I see that people are using solid state relays but having absolutely no experience can anyone suggest what to look for and how to wire this in?

yup same here. i run my beds with 24v 2-3mins to hit 110c almost as fast as the hotend.
The main thing to be careful with is making sure the 24v power supply has enough amps to push the bad, and all that amounts to is what the bed ohm's at.
(ohm's law) I am even running 24v thru the 12v side. my 12v side ohmed at 1.6ohm so at 24v it needs 15amps. but dont get a 15amp power supply tho.. youll want 20-25amp I have a hard time finding anything over 25amp cause the price seems to go way up once you hit 30amp 24v

Oh and you can run 24v on the 24v side, it is faster heating then 12v on the 12v side but its still takes 10 mins or so... again that all depends on what your bed ohms at. they are all close but different.. a .2 to .5 ohm change can make a huge difference especially when dealing with 24v

Yep, that went completely over my head.
Are you saying that you use a second 24V PSU alongside the original 12V?
How do you ohm the bed?
What do you mean by the 24V 'side' and the 12V 'side'???
I'm so confused.

The bed has two different ways it can be wired. Markings for this are screen printed on the bed.
To switch to 24v on the bed you are meant to rewire at the bed to a higher ohm circuit. His comment was that even though the wattage therefore stays the same the bed will still warm faster. Meaning the effective wattage increases due to the efficiency gains higher voltages and more headroom on the PSUs.

Edited 1 time(s). Last edit at 03/25/2016 10:12AM by gotswrv.

Lol sorry.

Yes I'm running 2 power supplies.
One 24v for the bed and a 12v for every things else.

The 12 and 24 volt side I'm referring to what's wrote on the heated beds some beds can run 12v or 24v some only 12v, the mk type of beds anyway.

The difference between the 12 and 24 voltage. Is simply the amount it ohms at. They make the beds to run with certain ohms to volts soas you can run them with common power supplies.

So if you are like me and want to run 24v thru the 12v side. You must ohm it to see where it's at soas you can pick the correct power supply that's powerful enough to run the bed but still have head room. Meaning you not running the power supply at full load.

You will need to get you a volt meter with an ohm selection. Most common volt meters can read ohms.

Edited 1 time(s). Last edit at 03/25/2016 10:24AM by Wes78.

hi.

Quote
ax

many thanks for you reply!
could you send me the link to read more about your firmware/mesh
as I am new here and didn't understand what you mean.
thanks a lot.

Edited 1 time(s). Last edit at 03/25/2016 11:06AM by Taisiya.

hi.
i got one more issue. i level the extuder and z stop switch so that only a sheet of paper can go beweeen the extrude and the bed. snd all axis home and start printing.

however, the printer starts printing about 5mm above the bed after adjusting the extuder up after bringin it home.

do I miss some settings or did anyone had a similar issues?
any suggestions will be highly appreciated and hopefully I will manage o print.

thanks
Ta

Are you storing the home position? With some versions of firmware you can do this at the machine. Other firmware a require you to put the z offset in and reflash the board.

Quote
gotswrv
Are you storing the home position? With some versions of firmware you can do this at the machine. Other firmware a require you to put the z offset in and reflash the board.

I measured so the extruder is 1-2 mm up the board. then press on lcd screen prepare and home all axis. but when i send file to print it seems to adjust z axis like 5 mm above the board, which doesn't make sence

where I can check this settings?

Many thanks

Hoping someone else can jump in. I'm pretty tied up with holiday stuff to have fun.

Quote
Taisiya

I measured so the extruder is 1-2 mm up the board. then press on lcd screen prepare and home all axis. but when i send file to print it seems to adjust z axis like 5 mm above the board, which doesn't make sence

where I can check this settings?

Many thanks

I see you not running auto lvling. Ive never messed with just using an end stop switch, i didnt see the point when auto lvling is available.
anyway I cant be to much help,,,, but it sounds like there is a seting in the FW giving you fits, to be honest ive never had any luck using homing from the LCD, y and x do fine but z seems to not do right. Ive always used a command line if i ever need to manual move the printer

Edited 4 time(s). Last edit at 03/29/2016 08:01AM by Wes78.

You need to heat the bed, level the bed while hot, and while still hot drive to the desired home position (including z zero) and press set home positions. Sounds like you may be pressing the one that finds home rather than teaches.
This will not work if the home Z in your FW is above the taught Z. Anymore I'll just fix the FW position rather than mess with the LCD settings. Too easy to not just make it right.

Hello! I stumbled on this thread while building my printer and it has been a great help. Thanks to those involved.

Can anyone tell me why my all my axes crash when homing? It seems like all 3 steppers are moving in the opposite direction of the endstops. All kinds of belt grinding and clicking. It is wired per the diagram.

I was able to get the Migbot connect over usb, but unable to update the firmware. I looked back through the install process noticed I had only installed 1 of the 2 drivers. Does anyone know what device to install the 2nd (port?) driver for? I have been getting a load of comm errors in the logs when trying to upload Marlin.

I truly appreciate any help getting this printer printing! Thank you all!

My guess would be you've got your limit switches in the "+" instead of the "-" slots. If you look closely at the board, they're labeled.

I don't remember more than one driver, but it's been awhile. I'm sure one of the experts will chime in.

Quote
Adam304
Hello! I stumbled on this thread while building my printer and it has been a great help. Thanks to those involved.

Can anyone tell me why my all my axes crash when homing? It seems like all 3 steppers are moving in the opposite direction of the endstops. All kinds of belt grinding and clicking. It is wired per the diagram.

I was able to get the Migbot connect over usb, but unable to update the firmware. I looked back through the install process noticed I had only installed 1 of the 2 drivers. Does anyone know what device to install the 2nd (port?) driver for? I have been getting a load of comm errors in the logs when trying to upload Marlin.

I truly appreciate any help getting this printer printing! Thank you all!

As Nick says, check your connections.If you're trying to upload new firmware, make sure you have no other programs connected.

Quote
jazzbassNick
My guess would be you've got your limit switches in the "+" instead of the "-" slots. If you look closely at the board, they're labeled.

I don't remember more than one driver, but it's been awhile. I'm sure one of the experts will chime in.

Appreciated the quick reply, thank you. I checked and even reversed the endstop connections, still the same. The bed crashes front, x to the right, z straight up.

The driver i was was questioning is ftdiport from CDM v2.08.

Quote
Adam304

Quote
jazzbassNick
My guess would be you've got your limit switches in the "+" instead of the "-" slots. If you look closely at the board, they're labeled.

I don't remember more than one driver, but it's been awhile. I'm sure one of the experts will chime in.

Appreciated the quick reply, thank you. I checked and even reversed the endstop connections, still the same. The bed crashes front, x to the right, z straight up.

The driver i was was questioning is ftdiport from CDM v2.08.

Doesn't hurt to install both. It can only help if you're getting com errors. If you take a look at my Marlin 1.1 firmware, and can get it uploaded it should work. Sounds like the directions are set wrong in the firmware and should be as follows:

// Invert the stepper direction. Change (or reverse the motor connector) if an axis goes the wrong way.
#define INVERT_X_DIR true
#define INVERT_Y_DIR true
#define INVERT_Z_DIR true