Welcome to the SeeMeCNC Community

I think I read somewhere that if you use a glass top you can run the MK1 heated bed with the soldermask side down, trace side up for more consistent heating?
Can anybody confirm this? I cant find the info any more.

That's how I run my MK1 bed. Traces up and glass on top.

cool beans thanks Chris!

I run mine with letters down on my Prusa. The hot side is the circuit side, so makes more sense to have it on top and directly under the glass. Heats mine well.

Thanks Lee!

I will run mine that way as well. I think it will be easier to do the strain relief, and there is not much room under the H1 table (clearance at full travel) . How much room does the prusa have between the all thread and table at full travel?

Well, finally got all my wiring completed, and some little things buttoned up, finally got around to testing my hot end,
turned the switch on with the pot all the way down, got called out of the shop by the kids for no more than a min and
when I came back my nozzle was hanging off and all melted
Crap! 1 step forward 2 steps back. ordered some stuff from seemecnc (a bunch 'o' stuff) and will attempt again.
Why would the hot end get so hot so fast? even with the thermostat turned all the way down? I check for a short but
didn't see anything wrong

JTCUSTOMS wrote:Well, finally got all my wiring completed, and some little things buttoned up, finally got around to testing my hot end,
turned the switch on with the pot all the way down, got called out of the shop by the kids for no more than a min and
when I came back my nozzle was hanging off and all melted
Crap! 1 step forward 2 steps back. ordered some stuff from seemecnc (a bunch 'o' stuff) and will attempt again.
Why would the hot end get so hot so fast? even with the thermostat turned all the way down? I check for a short but
didn't see anything wrong

Possible causes: Thermistor was not sensing temperature because of high temp silicone in the hole before thermistor was installed, thermistor was shorted, thermistor is defective.
Other possibilites include a bad thermostat, wiring problems etc. A valuable lesson learned, if you are in the testing phase, stay with the machine and if you can't turn everything off
until you can provide your unimpeded attention. Here is wishing you better results the second time around.

Regards, Carl

JT

Welcome to the Hot End Melt down Club. I finally have all the parts to finish the rebuild of my hot end. I finally got the duel temp controller from Turkey. It uses a thermocouple for the hot end rather than a thermistor. The thermocouple bolts to the hot end so it will not fall out of a hole like my last one did.

Dave_Sohlstrom wrote:JT

Welcome to the Hot End Melt down Club. I finally have all the parts to finish the rebuild of my hot end. I finally got the duel temp controller from Turkey. It uses a thermocouple for the hot end rather than a thermistor. The thermocouple bolts to the hot end so it will not fall out of a hole like my last one did.

I assume that this is a K type thermocouple. Would it be possible to show us a picture of where and how you mounted the thermocouple to the hot end?
More details would definitely be appreciated.

Regards, Carl

Carl

I posted photos of my new hot end here http://forum.seemecnc.com/viewtopic.php ... 9&start=10 I have not heated it up yet working on another Mod right now.

I tested the hot end for any shorts, its good. I am just curious why it took off without even turning it up. Got another one on the way so will try again when it gets here.

update:
Got the new thermostat and it works....just like the first one.
Which I thought was strange that it just started ramping up right when I turned it on even after the thermistor and heating resistors were isolated, but I put it all back together and cranked it up and it maxed out about 185c w/ a 10kohm resistor at R5. Oh well now I have a backup. I ordered it from seemecnc and It came with an extra resistor just floating around in the box not in the sealed velleman package, wonder what thats about?

Also bought the new 3mm hotend as well nice 1 piece design.

JT- Did you get your printer working? I melted my first hot end before I could even get it to print. I just installed the new 3mm hot end and and turned it on and tried to watch the Velleman board to see if it would kick off and it just stayed on. So I turned it off. I'm starting to think the Velleman is bad. Do you have any advice on how to check to see if it is working?

Thanks,

Ressie

JTCUSTOMS wrote:update:
[snip]
I ordered it from seemecnc and It came with an extra resistor just floating around in the box not in the sealed velleman package, wonder what thats about?

Also bought the new 3mm hotend as well nice 1 piece design.

I'm pretty sure that the extra resistor is an 18K resistor that replaces the stock one in location R5. The new values give a pretty good heat range on the hot end for dealing with ABS and PLA.

Drew

I am with you on that one Ressie! I burned mine up before first squirt as well!!
In my case I believe it was a bad thermistor, put a new one in and away she went.
I would sure like to verify what the extra resistor is before I drop it in,which means now I have to find it, but it would be good info to know if indeed seemecnc is providing these resistors at no charge! Outstanding, if you ask me.
Saves money on separate shipping charges.

BTW how long did you wait before turning the velleman off when testing the new hot end? And double check your thermistor is going to stay put and not short out.

JT. I'm no expert but in my case I set the velleman on its lowest setting and waited a few minutes for the relay to cycle off. I had a borrowed hand held IR temperature sensor but didn't trust its results as I couldn't get consistent readings from thinkgs like hot incandescent light bulbs, etc. Maybe they were emitting IR and messing with the readings. I just pushed by hand filament into the extruder and deemed the temperature too low based on the high force and little output from the hot end. Yeah, I know, real scientific and all. I moved the velleman pot to a little past 1/2 and again waited for the relay to click off and tried pushing the filament into the extruder and began extruding (1.75 ABS BLACK) well enough to think I was about there. At the max high setting I didn't like the smells coming from the extruder and quickly lowered the temperature back down. I think I'll add an arduino with a separate thermister to provide both a digital temperature reading and a second temperatre stop for the velleman as a safety feature so I don't burn up anything (even though I don't plan on letting it run unattended.) An arduino could very accurately control the temperature working with the velleman as the velleman could set the max not to excede temperature and the Arduino could control the temperature digitally if it could get the desired temperature setting from the PC via MACH or EMC2 somehow. Best Wishes, Mark

I haven't put any abs through it yet hopefully this weekend, 13hr days but I only gotta work a half day on friday!
But got the new hot end all rtv'd last night so I could get it together in the 5min here 5min there with 2 kids under 9 and work. Would of had it buttoned up this last weekend but I had decided to install a index pulse sensor on my CNC lathe. Finally got that all sorted out and turned some real nice threads for some sort of doohickey for a friends Mtn bike, I believe it was where the pedal cranks bolt through? Anywhoo, 1.37X24tpi internal and left hand internal,worked pretty good, now on to some spare hot ends!!! Oh and I could use a new plumb bob too.

Little update, got the new hot end together, wrapped the head in kapton for easier cleaning , still have to put a small piece around the nozzle.
Pushed some 1.75 abs through it last eve, now I can button up all the electronics and get to extruder cal. and bed leveling then i can start getting my settings all nailed down, so much to do so little time...

Well, I did it! I officially turned 1.67mm black abs filament into .072 filament!! Then I made a 1" square thingy still a loong way to go with settings and such
Still have to level the bed out and calibrate ext. then I can do some official testing, I just couldn't help myself had to squirt something!!

Wow,my first print and no comment, is it that ugly?
All joking aside, I just wanted to give a plug to seemecnc as the "extra" resistor in my velleman kit was put in there by them, I know its an inexpensive part but saves a trip to cell phone shack or shipping charges
TOP NOTCH!

That is hardly the ugliest first print.

This is a front runner in the Ugly 1st print contest.

Wow! I didnt know these things can make astro turf!

It certainly isn't the solid cube I was looking for.

The dimensions were just about right though.