Thursday, October 20, 2011

A Quick Update

Just a short post here.  

I have discovered the source of at least one of my problems.  One of the leads on my thermistor is broken.  I think it may have burned through when I had the thermistor and the heater wired backwards.  In any rate, the thermistor reads as an open circuit and is definitely dead.  I will have to remove the extruder and dismantle the hot end to replace it.

I have also made up a ground wire to run between the main and extruder boards.  hopefully that will help to clean up the signals between the two boards and get the instructions to the extruder cleanly.

Tuesday, October 11, 2011

More progress - still no extrusion.

I didn't get as much time this weekend as I expected.  The furniture moving, along with the cooking and the Turkey Torpor, kept me out of the lab for most of it.

I did, however, get time to re-do the wiring for 12v power to the stepper controllers and the extruder board.  I had decided that poor wiring was causing some of my problems.  The issues with the steppers corelated with their distance from the power source. X and Y moved OK, Z was intermittent and the extruder didn't work at all.  This was due to my crappy job of wiring that caused more grounding problems as the power was passed down the line.  I rewired the whole thing and the problems disappeared.  I now have all 3 axis moving just fine with no squealing steppers and no pauses.

The extruder is still a problem though.  The motor doesn't do anything at all, which is odd since, last week, it was not moving but was squealing, indicating that it was getting some power when I sent a command.  Probably still a wiring issue.  Also, I noticed that the heater did not seem to shut off when I set the temperature to 0.  It seems to be getting power all the time so I guess I still have an issue with it.  I will get my IR thermometer from the garage so I can tell for sure what it is doing.

I will be logging in to the RepRap IRC chat tonight to see if someone can give me a fix for these items.  Progress is slow but at least it is progress.

Friday, October 7, 2011

Progress - in less than 10 minutes!

I only had about 10 minutes last night to work on the Mendel but I came away happy.  I had figured out that my firmware was probably not correct for my boards so I downloaded a new version specifically for the techzone hardware.  I loaded it up on both the main board and the extruder and got some great results.

All 3 axis are now working, although the Z axis seems to be intermittent. Sometimes it doesn't move when I jog it and the stepper makes a squealing sound as if it is jammed or something.  A couple of times it moved just fine though so I think that this is probably a hardware issue (something stuck in the gears etc.).  I will take a look at it tonight.  The correct commands are definitely getting to the steppers now though.  

Also, the hot end of the extruder is heating up just fine and the thermistor is passing good data back to the board.  I was using Pronterface last night and could easily track the temp as it went up.

I didn't have any filament in the machine but I hit "extrude 5 mm" a couple of times to see if the extruder stepper would rotate.  It didn't move so that is my biggest concern at the moment.  I set the desired temp to 0 and it still wouldn't move so I guess it is not something in the firmware as I had suspected.  I may have the stepper wired incorrectly but I didn't have time to check last night.

This will be a long weekend here in Canada for Thanksgiving and it is supposed to rain all weekend.  That means that I should have lots of time to work the bugs out and get something extruded.  I also have to move our entire home office down to the basement so my wife can have the spare room to set up an office for her new accounting business but what the heck, I have three whole days!

Tuesday, October 4, 2011

I'm an Idiot!

I got my old Linux tablet working again and connected to the Reprap.  Guess what I discovered?  The damn thing can't connect.  This indicated that the problem had nothing to do with my Windows workstation at all and was probably hardware related.  I pulled out the 6 conductor cable between the main board and the USB/TTY adapter and, sure enough, one of the leads was dead between the two connectors.  I made up a new cable and "voila" both Pronterface and Repsnapper can now connect with no problems.

I have the X and Y axis moving fine but my Z axis won't move anymore.  Probably more of my sloppy wiring.  The hot end is heating up but I don't seem to be getting any temp readings back from the thermistor.  Again, probably a hardware problem.

I tried to sending a command to the extruder but the motor didn't do anything.  I only thought afterward that the software may prevent it from running until the hot end reaches operating temperature to prevent damage from trying to push un-melted filament through the tip.  I will check the code for this.

So it looks like I am finally able to proceed with final debugging and getting Mendel working.  There's a lesson to be learned here - don't assume anything.  Just because things were working on the Linux tablet didn't automatically rule out hardware problems being the culprit.  It was really my tunnel vision on the ports that kept me from examining other possible issues earlier.

Oh well, Onward to Victory!!