Tuesday, July 29, 2008
A design charette for a printed linear stepper motor, part 2
In which the narrator possibly figures out a few things... or not... read more
Making CAPA Filament
I created this:
It's basically the high pressure screw driven syringe with changeable nozzles. A nut is soldered into one end of a piece of plumbing pipe, and a pipe connector to the other. The wood contains a captive nut, a washer is soldered to the threaded rod to form a plunger, and the handle at the top is turned to force the plunger down.
The pipe is then dipped in boiling water for a few minuites so the CAPA melts, then the handle can be turned and this happens:
The nozzle I'm using has a 3mm hole in it, which created a filament of 3.4-3.5mm (pretty good consistency). I'm going to try making a nozzle between 2mm and 2.5mm tomorrow and see if I can get a 3mm filament.
See more pics on flickr
Monday, July 28, 2008
A design charette for a printed linear stepper motor, part 1
In which your narrator tools up to design a printable linear stepper motor, however clumsily... read more
Sunday, July 27, 2008
First steps towards printing a stepper motor
Printing stepping motors, or parts of them at least, may be the next step to reducing the "vitamins" required to grow self-replicating 3D printers... read more
Saturday, July 26, 2008
Stepping with interrupts
The rough test model for running the xy positioning table is being evolved into firmware which will ultimately run Tommelise 2.0... read more
Friday, July 25, 2008
Off to the races
It appears that the the faster you run the Tommelise 2.0 xy table the quieter it is... read more
Thursday, July 24, 2008
Tommelise 2.0 x and y axes operating in concert
Both the x and y axis of Tommelise 2.0 are not running in concert with a stand alone firmware test program... read more
Using (or not) telephone coil wire
Save yourself some grief. Don't try to do connections with moving electronics on your positioning system with coiled telephone connectors... read more
Wednesday, July 23, 2008
Tommelise 2.0 x-axis operational
A used Haydon 26000 series linear stepper has been installed on the x-axis of Tommelise 2.0 and connected to the controller board and tested... read more
I found out that regular threaded rod doesn't have much of a straightness tolerance on it, the hard way. I'm using pre-made pulleys instead of making my own out of Polymorph, so they have a rim that doesn't allow me to use the belt tight minus one tooth method outlined in the instructions. I pulled the belt as tight as me and a friend could get it and glued it together. Things were looking pretty good until I tried turning the stepper motor by hand. As I turned the pulleys went from their "out" position to their "in" position and the belt slipped. Upon further inspection, I could visibly see each pulley's runout error. I'm going to search for more expensive threaded rod to replace the bent rods.
In the mean time, I'm going to finish the electrical assembly and continue work on the extruder head. I might just design a ball point pen holder, manually move the table in place and draw stuff just for the fun of it. I'm going to take a week or two off of the project, so you won't be hearing from me for a while.
Labels: Threaded Rod
Monday, July 21, 2008
Tommelise 2.0 y-axis operational
The new Haydon 36000 series linear stepper has been installed on the y-axis of Tommelise 2.0 and connected to the controller board and tested... read more
I also forgot to buy superglue, so my Z-belt drive will have to wait until tomorrow.
I was trying to get finished by July 23rd. I will have to settle for a working Cartesian Robot by that date. There is no way I could get the Extruder done and installed by then. Thanks for any words of encouragement or advice!
Visit my current build at http://htc_engc_bpc.axiscam.net/view/index.shtml
By the way, I left the light on for your enjoyment.
Sunday, July 20, 2008
Group-Think Stepper Motor Problem Fixed
When i sent a signal from the reprap-host program to run one stepper motor, two boards would light up and start trying to move their motors. At one point, when I told my extruder to move along the +x axis, I got a 45 degree +x and +y movement instead.
Vik Oliver saw the post and kindly commented on it, predicting spot-on that the problem was a faulty sync connection. Indeed it was. I had tried to use two jumpers (like the ones on a motherboard) to make a removable connection that would short the three blue sync wires together, and two more jumpers for the white/blue sync wires. Apparently, this isn't a very robust approach, because a couple of the wires pulled free. After soldering the wires together instead (if I need to take them apart, I'll just cut the wires... no biggie), all three axis did what they were told and each no longer caved to peer pressure.
Thanks, Vik! :)
Thanks to Wade too, who suggested that instead of turning all four of my z-axis pullies right-side-up, I should only do two. Not only is this less work for me, which makes me smile, but if I have every-other-one in a different orientation, they should keep the pulley from slipping up or down, and still allow quick removal of the belt. I will definitely try this. Thank you, Wade!
Assembling T2's xy positioning stage
With the USB/EEPROM link working properly, final assembly of the repstrapped xy positioning table for Tommelise 2.0 begins... read more
Saturday, July 19, 2008
Stepper Controller Working
I also discovered I needed some more parts to continue assembly. Shown below are the parts I created on a Stratasys Dimension 3D Printer.
If you would like to take a self-directed tour of my lab (including the current status of my RepRap build), here's a link to the Webcam in my room:
Warning! The room is undergoing some changes and no classes are being offered until late August, so it is currently messy. Furthermore, the lights are off most of the time. If it is daylight in Minnesota, you should be able to see around the room.
Thursday, July 17, 2008
RepRap Built - Z axis is stubborn
The collapsible stand below it was made from an old laundry hamper frame (the flexible mesh bag used to drape over the top like a garbage bag folds over the lip of a garbage can). Drilling holes for the four steel rods to slip into was all it took, it's structurally sound, and easy to transport. I like it.
The RepRap is not yet functional, though. Problems must pop up to allow us to conquer them and feel superior, right? :)
Well, anyway, the main problem I had was getting the Z-axis to work. The stepper motor kept skipping, not having enough torque to turn the belt.
I tried running the motor from a different driver board (the y axis one, which works fine for the y axis), and got the same result.
I took off the belt and checked how hard I had to hold the motor coupler before the motor skipped. I compared this to the y-axis motor and found that the z-axis skipped much more readily.
This suggested to me that the motor might be the problem... So, I disassembled one of the four posts that comprise the z-axis, a seemingly daunting task, but something that wasn't so bad, in order to remove the z-axis motor and coupling from the machine. I also removed the y-axis motor and coupling, and ran them both side by side, applying the same grip test. Now, the two motors were identical!
Then came my hand against my forehead. Of course they were different before, there was a different amount of friction in the z-axis posts and y-axis rod. Because the z-axis had more friction, it required less of my hand-grip to make it skip. Wow... I should have thought of that! :)
Ok... So it's not the motors, probably.
I then checked how hard it was to turn each z-post, and lubed everything I could. Two posts were still difficult to turn. One would easily turn 90 degrees or so, but on each side of that it was difficult to turn.
To make a long story short, I narrowed it down to washers and nuts at the bottom of the post. When these were loosened, the post rotated freely. When they were tight, it would rotate a certain angle (at first 90 degrees, later about 180 degrees?) and then become too difficult to turn. Rotating in the opposite direction produced the same symptoms.
Take a look at the following video (ignore the audio, though). It shows the bottom washer on the subject post as I turn it. It's hard to see, but it seems to bind at the extreme angles. At first, and when I made the video, I thought the washer was bent. It turns out the washer is sufficiently flat.
The bottom side of the corner bracket supplied to me by Bits from Bytes is not flat, however. It instead, has lower edges and a higher middle, presumably from the casting material shrinking as it cures/dries.
Yeah... That Dremel's an efficient instrument on this plastic. As you can see, I ground about twice as much out as I wanted to. :)
After putting the washer and bolts back on, the post turned quite easily.
The other stubborn post happened to fix itself while I was doing all of these troubleshooting steps. It was probably the lube that helped.
In retrospect, I'm not exactly sure what fixed the first post. I could have just been squeezing the corner bracket too hard, or I could be right on about the angled-corner-bracket-edge thing.
After assembling everything again, I was able to successfully move my z-axis under computer control. Whoohoo! :) :) :)
* Last night, some weired things were happening with my stepper driver boards. When i sent a signal from the reprap-host program to run one stepper motor, two boards would light up and start trying to move their motors. At one point, when I told my extruder to move along the +x axis, I got a 45 degree +x and +y movement instead. This happened after I accidentally unplugged one of the boards with my chair, but I've since double-checked the wiring. Did I short something with the flailing wires as they were pulled loose? Did one of the stepper motor board's driver ICs overheat (the one with the big heatsink gets really hot)? Maybe I'm getting electromagnetic interference with my bundled wires? Who knows?
* My z-axis pulleys were installed upside down, I believe. The lip that is supposed to prevent the belt from falling down due to gravity is on the top instead of the bottom. The belt falls off after about 15 seconds of use.
Wednesday, July 16, 2008
PICkit 2 Cable
- Pin 1 on PICkit 2 goes to the center of the 3-pin connector.
- Pin 2 on PICkit 2 is unused. Power will come from the power supply not the PICKit 2.
- Pin 3 on PICkit 2 goes to the left pin of the 3-pin connector (left when "Max/Empty" is right-side up). This is a ground connection; follow the trace from the "-" to capacitor C4 to the empty hole by R6, flip the board over and trace it to the left pin.
- Pin 4 on PICkit 2 goes to pin 3 of 7. (Pin 1 on the board is square if your board doesn't have the numbers silkscreened on it. Pin 1 also is toward the center of the board.)
- Pin 5 on PICkit 2 goes to pin 4 of 7.
- Pin 6 on PICkit 2 is unused.
Why bother with the PICkit 2? It is a small USB device that is purchased complete. No assembly required. (Other than the in-circuit programming cable that I built above.) Why make the cable? I have a notebook computer and the USB port gives 4.75 volts not the reuired 5 volts, so I need to use my RepRap power supply. Furthermore, my notebook computer has no serial ports making a USB solution a necessity.
One more thing that I have to share with the community... Silver Sharpie markers are truely excellent for writing on PIC chips. I'm not going to recommend adding it to the miscellaneous list, but if you have one silver on black is really easy to read.
I can hear some diodes begging to be installed in some Universal Controller cards...
Greetings RepRap Builders!
Since this is my first blog (ever!), I thought I should start with a summary of what has happened so far:
- Built rapid prototyped parts in February.
- Bought structural components in March.
- Built more rapid prototyped parts in March.
- Bought electronic components in March.
- Cut steel pieces to length in April.
- Built more rapid prototyped parts in May.
- Bought miscellaneous components in June.
- Asked a co-worker to cut threaded rod to length in June.
- Soldered PowerComms board, Stepper testers, and Opto Endstop boards in June.
- Soldered Universal Controller Boards in July.
- Asked a co-worker to create the Bed in July.
This morning, I am going to create the in-circuit programming cable for my PICKit 2 programmer. I actually bought two programmers for this project and the Ramsey Electronics kit worked to program the first PIC processor, but I really want to know both programmers work. The accessories that I bought for the PICKit 2 have not worked and do not have pin 1 labeled. Therefore, I've tried programming a PIC right-side up and upside-down with no results. I at least had the foresight to buy way too many PICs. Wish me luck...
Labels: summary of events
Sunday, July 13, 2008
Cheap and dirty data compression
A simple data compression scheme achieves as much as a 70% reduction in the size of print files moved across the USB link between Tommelise 2.0 and the PC... read more
PC/USB/EEPROM link fully operational
Print files in excess of 500 KBytes are being successfully transmitted from Tommelise 2.0's PC, written into its EEPROM print buffer and verified... read more
Thursday, July 10, 2008
RepRap protoseedling: toy 2D plotter
Wednesday, July 09, 2008
Verifying data quality in T2's EEPROM buffer
Data integrity on the Tommelise 2.0 EEPROM buffer is verified... read more
Monday, July 07, 2008
Loading real print files into Tommelise 2.0's EEPROM buffer
Labels: Tommelise 2 Reprap EEPROM USB