Heated bed not heating?

Hey Tim,

I came up with that z-stop mod because the way the stock setup came. It was just difficult to get the z height adjusted and dialed in. On top of that, the limit switch sits on an arm that is movable. If you hit the arm enough eventually its gonna move and throw your z height off again. You may not need it at the moment. It is definitely not required but I recommend it in the long run for reliable no fuss consistent prints.

This goes along with a fully leveled build surface. If you don't have a level build surface. Specifically the abs model. You will have a hard time getting that first layer to stick or come out right. My robo was not level out of the box, wiring was a mess, (by the way everyone needs to check the wiring when they get their machine, some of mine were loose or not seated correctly) hence all my changes to improve the machine. You can find them all in the mods section.

I did all these mods before I started using the printer because I knew these would be problem areas later on. I've built a couple of printers so I kinda knew what needed to be changed.

My printer has been printing reliably and consistently since I made these changes. I've not had a single problem with my printer.

another note: I highly recommend calibrating your hotend and heatbed temps before you start printing anything.

 

Whats the difference between the blue masking tape and the normal off white stuff ?

 

Most people use 3M #2090 blue painters tape. The reason being is that the texture of it creates a good surface for PLA to grip too. People have tried other tapes with some luck, but #2090 is deemed to be the best.

 

The adhesive from painter's tape is also designed to be a lower-tack, so it will remove cleaner from the bed. Which saves time in maintenance.

Though from the responses to how well the PVA glue method has been working for people with PLA I might forego tape completely, which would be nice.

 

Yeah, but hairspray is probably the highest cost of the three options. =P

I'm gonna have to hit CostCo and see if I can find a suitable one there where I can get a dozen cans cheap-ish. =)

 

Thanks for the description of your mod Cambo, and the link to the other thread. Looks like a very elegant improvement to the Z-Stop. I will look into doing that once I get everything else working! Good tip on checking the wiring too, my heated bed problem (which I started this thread for!) ended up being due to a loose wire.

What exactly do you mean by calibrating the hot end and heated bed temps though? With the hotend I did the initial 230C heat before loading my first filament, and have let it preheat to the relevant temperature every time I've tried a test print. When I've tested with the heated bed I also let it preheat to the appropriate temperature before starting the job. But I'm guessing you're talking of something over and above this.

Cheers
Tim

 

Calibrating the temperature is the process of taking the rephost measured temperature and comparing those to actual measured values from an attached thermocouple meter.

When you calibrate this temperature, your are determining what your actual print temperatures are. Rephost is only accurate by what is programmed into the temperature table of the thermistor. Those temps can be off if not checked. I've seen hot ends melt and machines catch on fire, because user assumed that the temperature in rephost was accurate. When in reality they were way off. All it takes is a +10 degree off temperature can cause a hot end meltdown.

This temperature check/calibration should be done prior to your first print. Why?
1. you will know actually how hot your printing
2. peace of mind
3. better print quality, in the long run
4. etc..

My temperature on my hot end is off +6c. so I adjust my temperature accordingly.
For instance, if Rephost says hot end temp is 230c, my actual calibrated temp is 236c. (because of the +6c offset, measured by the external calibrated thermocouple meter)

I did a little write up here to you give you guys an example:
http://forums.robo3dprinter.com/ind...nd-build-surface-temperature-calibration.848/

Now the robo machine is supposedly ready to use out of the box. To be honest, I had issues to work out before I could use it. I'm glad I inspected it before use. Some of the stuff I changed were optional some were definitely needed. On the software side, im sure their pre-configured settings are fine and you will not see any meltdowns. BUT........
......
.....
I REALLY RECOMMEND CHECKING YOUR TEMPERATURES BEFORE YOUR INITIAL PRINT. It is the best time to do it because once you run filament through your nozzle, it will be difficult to get it out. If you want to measure the inside nozzle temperature later.

my temps were only off 6c but what if yours were off +10c, +20c etc... you can imagine what could happen. If your not around watching it. Some companies go as far as, making the consumer sign a waiver that states, they are not responsible for damages from a 3d printer that they built and sold to you. Its that serious.

Since your setting it up for the first time. This extra step only takes about 15min of your time, doesn't effect operation of your printer. An Extra step for little peace of mind is well worth it in my opinion and will aid in troubleshooting issues down the road.

 

Thanks for the detailed description Cambo. Does sound like it would be useful to know how accurate the reported temperature is, although I am lacking the tools at the moment to make these calibration tests. Will definitely do this as soon as I can afford a decent digital thermometer with thermocouple.

Haven't had a chance to look at Robo last couple of days, I've had some time off for the kid's school holidays but now they're over I'm struggling to find time to tinker in between work and everything else! But my current priority is still to get a test print happening when I get back to it, as this will really motivate me for these other improvements!

Cheers
Tim

 

Pm me anytime you need help!