mhackney's 3D Printers

[timothy svec]

Greetings Michael, I just finished up soldering both of the mk138 boards for the hot bed and the hot end. Could you please help me with exactly what wires go where. (from the power supply to the mk138 control. (just a picture with arrow's if you have one) LoL... And from the mk138 control to the hot end) I understand the thermistor to the sensor part on the mk138. Also I'm using a 12V DC 30A 360W Regulated Power Supply. I see 24v/3a max on the mk138 board. Will I be OK with this set up? Also, This was my first soldering job. I took lesson's on you tube. It was good fun!!

[timothy svec]

Just found this drawing.
http://seemecnc.org/assembly/25925%2...c%20rev1_2.pdf

so my question is. Why do you put a jumper across from com to 12v+?

[mhackney]

Hi Timothy, I don't have any photos of the thermostat (mk-138) wiring yet. I just got another kit yesterday so I can photograph it as I assemble it for the electronics manual.

The PDF file you found is a good wiring diagram though so you should follow it.

Which jumper are you referring to? If you mean the one between black and green on the power supply, that only applies to using a PC ATX power supply. Your supply does not need this.

cheers,
Michael

[timothy svec]

picture with red wire

[mhackney]

Ah, of that jumper goes from +12V to the COM pin on the thermostat. This voltage will be output through the NO (normally open) pin when the relay closes - powering the heating resistors.

cheers,
Michael

[timothy svec]

Thank You M.
I'm thinking of cutting a my own pcb board. I have a taig cnc. Just wanted to ask how your nichrome wire hot bed project was comming along?
cheers,
tim

[timothy svec]

http://www.ecemiami.com/shopdisplayp...age=3&sppp=10#

link to the pcb board I'm thinking of cutting for the hot bed.

[mhackney]

Hi Timothy, your link is broken. However, all of the boards I found on this site are 1oz copper. You need 3 or 4oz copper to make a heater from a PCB. It is not easy to find the right material.

cheers,
Michael

[mhackney]

For this who don't know, SeeMeCNC has created their own user form: SeeMeCNC Forums - Index page Lot's of good stuff!

I've now completed my homebrew hotbed and am just about to test it out. It gets to 200°F in less than 10 minutes and stabilizes nicely. Powered by a 2nd Velleman thermostat.

Here is the nichrome layout:



This was put in a fiberglass sleeve and sandwiched between a 1/8" phenolic board on the bottom and .1" aluminum on top with 1/4" standoffs between/ Here is the power on test:



The bed will be screwed to the H-1's table through holes drilled and countersunk in the corners.

[eaglezsoar]

What is the size of nichrome wire did you use and how many amps
does this draw? Thanks for sharing this with us.

[mhackney]

16 gauge, draws a little over 6 amps. Google NichromeCalc and you will find a great interactive calculator to help design a nichrome wire heater.

cheers,
Michael

[mhackney]

Ok, firstly, the home brew hot bed works great. Heats up quick and nice even temp edge to edge. Minimal Z loss too.

Now the bad news, I mounted the hot bed to the stock H-1 table - which is ABS. Even with insulation and standoffs, it got hot enough to warp:



And I was seeing a backward (Y) lean on one of my prints. Turned out to be the belt mounting post on the table bending! See the post on the left, it is tilted backwards. Apparently, as I was printing, it got hot and started bending back. The effect was a net lean backward on the Y axis.



So I dismantled the table and made an ally cross brace to mount the hot bed on:



Here is the underside of the cross brace with the new all-steel post to mount the Y belt and tensioner:



This won't warp! I'm printing now and it seems to be working well. Another advantage of this arrangement is that it's a lot easier to level the table now too.

cheers,
Michael

[mhackney]

Here's a whistle I printed for my 10 y/o nephew this weekend. It has a bit of a slant on the Y - the precursor to the bent belt post I showed in the previous post. Print order: green, blue, yellow and orange. That green and yellow ABS extrudes like butter. By far the easiest colors I have to work with. Looks good too.



I mistimed the color change from green to blue a little, but it came out pretty good for a first effort.



cheers,
Michael

[Rescue35]

Looking good. I need to delve back into mine and get her running.

[mhackney]

I have to say that this little H-1 is a fun little machine. It does nice work and looks good to boot. Not as big as a Prusa. I was originally attracted to the Mach control aspect but it turns out that any of these machines could be controlled by Mach and the H-1 by any of the Arduino-based controllers. The biggest limitation of Mach control is that the hot end and hot bed are not controlled. They are managed manually with separate thermostats. Another gent (Steve Wander) and I are working on an Arduino based temp, fan and other goody controller that will interfaces to Mach via MODBUS. My version will control two heaters, 2 fans and have a few auxiliary relays for LED lighting, etc.

Cheers,
Michael

[jerbro]

My version will control two heaters, 2 fans and have a few auxiliary relays for LED lighting, etc.

We're looking forward to it!

Jeremy

[maker of things]

Does the printer make the same size "bead" for both 1.75 and 3mm hot end? I am a little unclear how this part of the machine works.

[mhackney]

The size of the extruded "bead" is determined by the orifice in the nozzle not by the filament diameter. The easiest to get started with orifice is .050" and you can use either 1.75mm or 3mm filament if your extruder is set up for it.

cheers,
Michael

[LeeWay]

Also the extruded plastic is a bit larger than the hole and it will tend to lay flatter on the print, so becomes wider with a thinner layer.
These variables are so..........um.........fun to play around with to finally get some good prints.

If you have a good setup for PLA, throw out all the settings when you go to ABS. Behaves totally different. Different colors may also need a different fine tuning. I just label my ini files according to plastic type and color and sometimes part types. Different type parts can benefit from different settings too.
I have my ini setups on the desktop, but I can see that was a bad place to store them. Will be moving all of the soon.

[mhackney]

Good point Lee! Also, as I learned the hard way, squirting out the bead under too high pressure will also make it sell on exit. Make sure to calibrate your extruder.

I've found more variation between ABS colors than PLA colors. Not sure why that is. I do the same thing with my Slic3r ini files - set them up for a specific color or colors and even parts if it needs something special.

Where are you thinking about saving your setups Lee? I keep mine on a Dropbox account so I can access them from all my machines.

cheers,
Michael