Monthly Archives: February 2010

RepRat main controler

I mistyped the name Reprap in the firmware code. Happy accident, I now have a name for my Repstap/Mendle project. This fits in well with the ratsnest of wires on the SDK500 mega168 project lashup.

As I do not care for the bloat of Arduino, I am writing my own firmware in assembly. Much of this I borrowed from one of the MIDI compact flash projects. This way I can use my already small footprint FAT12/16/32 code.

SD uses a serial interface for comms, so much of the low level code for initializing the card and reading blocks needs to be re-written. Using an AVR freaks tutorial, for butterfly SD card connectivity is a good way to test the code.

The supplier makerbot had a few remaining v1.2 controllers. This enabled me to not make a board from scratch. Since the SD card socket is in place I swiched over from the rats nest to the v1.2 board.

Weirdstuff, a surplus store in the silicon valley has some SD/MMC adapter cards for about 20 cents [USD] at this price I bought a couple dozen. With a heatgun and a thermocouple poping the connector off is a simple process. Provided one does not melt the plastic.

The makerbot/reprap “motherboard” controler v1.2 board has the pads and holes in the right place for these sockets. The shield on the cheap sockets is a bit smaller. Removing solder mask in these places allows for the MMC card to be attached to the board. Image 1 in the gallery below details where the solder mask was removed.

The board can be assembled either for use with an ATX supply or with a power brick. The 3.3 volt regulator I got from jameco has a different footprint than the recommended one. It is not a good idea to power a 3.3v regulator off of a 5v regulator. There is not enough headroom for the regulator to work. Looking at the ATX connector, it seemed the most efficient way to get power would be to tap the 12v line and add a standard 5v regulator. It worked out nicely to make a little bridge using the leads on the filter caps. This also gives some points where the bench supply can inject power.

The schematic indicates that the 12V is sent through the RJ45 connectors to the external controller boards. I like to recycle/reuse stuff, so I got some block of RJ45 from weirdstuff, which I de-soldered. Some of these I melted the tabs as I did not have any heatsheld. I mounted one of these extra connectors in case I want to inject power through this connector.

It is a bit annoying that the power switch is a relay trip. This means the AVR must always be powered. I still need to make some usb/rs232 boards for the FTDI chips I have about. These use an odd pitch footprint, which requires at least a breakout board. Ironically, I want to get this stuff working so I can drill the boards. I guess that is the rep part of the system. The rapid part is what my (C)NC is not.

The gallery below shows some of the steps in bringing these boards online. I moved the ex at90s8515 code from the mega88/mega168 to the mega644. The mega168 to mega644 path is fairly straightforward. Some of the interrupt vectors are different. Mostly due to the second optional USART.

Now that I have a more stable less of a ratsnest prototyping setup, I expect to make more changes to the firmware. I am still considering using i2c to drive the steppers. The current layout consumes most of the pins. This makes adding multiple heads/axis a bit awkward. There are also a shortage of pins which can be used for button panels and readout displays. Of course these can be implemented through the serial coms, which would involve removing the existing code from the system.

3D printing for the rest of us, The project

Recently I have been active posting to the reprap forums. There I started a thread relating to my observations after reading the forums almost daily for a year. This thread can be read on those forums.

I have a rather macabre and dry sense of humor. Much like the mummys here in the hall of mystery.

Reprap is a bit of a mystery. Something real that has come out of what is a dream and a bit of a lie. There is still much promise to be had with the current technology. Most of the old timers must think me a bit loopy as I tend to rant against software versification. That only the newest hardware and software are worth using.

For almost 20 years from 1982 to 1998 I made my living directly off either selling or working on the design QA team of apple products. Steve Jobs was my boss’s boss. We did what Steve wanted. If not, well lets just say Apple no longer designs laser printers. At least my products were a success. The short of it is I use Apple products. I do not download revisions because I am told to. I download what I need when I need it. Because it is a better product.

This is what damaged apple in the late 1990s. I did not agree with it then and do not agree with it now. If it is not broken, there is no need to fix it for the sake the repair bill. Which is usually padded anyway.

If this is how you feel, then stop reading now and return to the facebook fad crowd, because this sheep is an Arcadian sheep, who believes in recycle and re-use. If it is not obsolete, then why bother with it, it will become obsolete soon enough.

So what made Apple great, and why I like so much the work of the Disney brothers is that they produced something new. Reprap is like this a new way of looking at how one can make things.

Unlike the lie of most dreams, reprap has some truth that makes it quite likely to succeed. There are a lot of issues still to be had. One of these issues is speed. This has been a problem with my existing CNC equipment. It is too slow and the design path takes forever. I am lucky if I can scan in a part and make a 3d model in less than 16 to 18 hours.

Then comes the issue of making the part printable. There are several divergent paths for the reprap. The core team made a java applet. This does not work on the mac. Since the hardware was expensive and built to last, there is no one to test the code, so the code sits somewhere in cvs hell. The problem is that most modern programmers depend on the corporate need to upgrade early and often. Little thought is given to simplifying the code to run on the lowest common denominator.

So instead of bothering to fix the mess, a new branch went off using python. So we are in the jungle anyway. One adapts. This is an experiment anyway, with just the right amount of anarchy.

The real gating force is that my machine tools are slow. So the best place to start is with the bottleneck of the 1989 drazzi motor controller. I need to make some rollframe parts for a client, so what better than to upgrade the system and mill these parts. At the same time look into how the system can be improved.

The shop is not really a place for the latest in computer hardware, So the goal is more for an NC controller than a CNC, where the build files can be read off of a smart card. I already have the electronics for reading compact flash card MIDI, so making these changes should be quick. We will see. a days project turned into a week, and is more likely to take a month.

The real question is making the motors move. In practice we are just drawing a picture. In 1773, Swiss engineers could do this with cams, so it must be a trivial process. The Swiss even used a Z axis on the pen or pencil so the final pictures look hand drawn. The doll that draws with a pen even knows when to shake the ink from the tip. The artist doll with a pencil blows the dust away.

Of course the french kings that these toys were made for were beheaded, But that is only poor solution to the problems of management. The new managers, were quick to realize that scaled up these simple toys could be used to rivet battleships automatically. This was also a simple solution to the Irish problem. Since automation did away with labor.

As I have noted, my late friend John Grass sold me the machine to prove a point. That one needed to understand the basics first. I was the only one who could make the drazzi work. It only would run one program and draw a picture of a running horse. The reprap seems to have the same issue, it currently is designed to keep the unemployed labor occupied dreaming of change, and not of what is needed.

Make a mechanical computer

Through my computer history and horology contacts, along with some targeted searching on the net, I have collected a good deal of the designs for Babbage’s Analytical engine. The next step would be to visit the archives where the papers are stored. Doran Swade estimated that it would take his team some millions of dollars to do much of what I have done.

Of course our methods are different. Doran, is working to make it just like it would have existed in the 1850s or 1860s. Doran has good arguments as to why a mechanical computer, designed in the 1830s is not likely to have been made before about 1853. His goal is to answer the question, could it have been done then? His approach is to match the metallurgy, surface finish and make a 19th century machine in the 21st century.

My approach is more pragmatic. As far as Alan Bromly or Tim Robinson were able to learn, Babbage did not have the concept of an instruction set. This makes any modern re-construction suspect. The other issue is that the Analytical Engine was huge, about the size of a steamboat or locomotive.

Bromly left some fascinating articles written in the early computing and horology journals. These observations combined with a simple paper training computer called Cardiac, produced by Bell labs is a great entry point into making a 3 digit decimal computer using Babbage’s concepts.

By scanning in much of the publicly available information, I have made some 3D models of the adding mechinisims, These look perfect for making on a repap 3d printer. This is where I was a year ago when I discovered the world of three dee printing.

So over the course of the next few blogs, I will take a look at the reprap process, and just how practical will it be to repstrap a Mendel.

Welcome to the Egyptian Hall of Mystery

Welcome to the Egyptian Hall of Mysteries…

The yellow Drazzi …

Many years ago my late friend and mentor John Grass sold me a desktop CNC machine. John was a machinist of the old school, and could not make the machine work. I think he wanted to prove a point, that having something was not the same as wanting something.

Here is an image from the sales brochure:

What the machine looked like when new.

The machine came complete with all the manuals, and a Dos program called RobotMart. Many times I searched the net for more information on this. Several years after I acquired the machine in I was able to upgrade the Dos program and purchase a few more collects and accessories. I set the machine to making roll transports for Piano roll scanning. I also used it to create some parts for a mechanical doll. More recently I modified some hobby gears for use in a difference engine model.

At the time I lived in a 2 bedroom apartment, I leased the machine in exchange for shop space at a friends company. This worked out well. I was also able to make an EDM sinker machine and a watch pinion cutter. The the dot com era came to an end. My friend moved his tools into a Silicon Valley Garage, where I continued to use it for making roll-scanner parts.

We nicknamed the machine “Yellow Drazzi” as the eastern European name rhymed with an alien species on the Babylon-5 show, popular at the time. Where there were Green and Purple Drazis.

My work took me to Kentucky were I worked for piano movers designing a floppy disk MIDI playback system for pianos. This company failed after a few months and I was left with the floppy disk player to manufacture on behalf of one of the partners. This poor machine sat idle.

My workshops are in a barn like structure in my parents back yard. This is a potting shed, not water tight. I did not want the machine rusting, so left it in my friends unheated garage, Which also gave me access to the Bridgeport mill and atlas lathe. When it came time to make the feet for my Caliola Pipes, having to travel 60 miles to use it I moved the machine to my parents garage.

Over the years I have owned this machine, I have wanted to speed up the axis, which move around 5 to 10 inches per minute. When the machine sat idle, the fans developed a rattle, which was annoying. A few weeks ago I took the controller apart. Replacing the fans with new ones that glow with blue LEDs, these fans were half the price of the black ones.

While I had the machine apart I drew a schematic of the controller. The electronics were made in 1989. The stepper chips were manufactured through 2008. Searches of the network, I found better programs such as KCam and Mach3 to run the machine. The controller was compatible with these programs. It is like getting a whole new machine to play with.

For the last year I have been reading the Reprap forums and blogs Having worked with printers and scanners in the 1990s I have collected quite a few rods and steppers. Having spent so much time consuming information from these forums and blogs, It is time to start sharing my own progress under the name of sheep. Since I am simply just another sheep in the fold.

The first plan was to use the Yellow Drazzi as a repstrap. This may be a bit slow, as the old stepper controllers are resistive limited and max out around 10 inches/minute. A desire for speed improvements, has lead me to completing the reprap (now Mendel version) stepper electronics. While this will not run the coffee can steppers, I should be able to mill the Mendel parts on the Drazzi.

The ultimate goal here is to be able to replicate, not only a Jaquet-Droze style keyboard player, but the connected pieces, such as Babbages analytical computer, The mechanical calculators from Swilgue’s astronomical clocks, and the Antikeythera device. This while at the same time looking for work/contracts, speaking at conventions and working out a new act for the Dickens Christmas fair. So there may be gaps here as these project progress. No promises on updates, bit there is a lot to share and much more to come…

Bird in a box.

Somewhere I seem to have lost almost a year. Should you find it, please return it. Hopefully I can maintain a better blogging schedule. There are some exiting new things happening.

Last spring I came close to making a small 20 note organ in 1 week. Everything was completed except the pipework. Shortly after I started making and voicing the pipes, a family of birds moved in and made a nest in a box of pallets, which are for my w146 band organ.

It was difficult getting photographs of the birds. With some effort I managed to snap this picture. The birds were bold and seemed to enjoy watching me voice the pipes. Later when I took the nest apart after the young one left, I discovered that they were using the shavings from the pipes, as I made the pipes! Clever birds.

Bird who moved in

Bird in a box

Finally a I got around to downloading the photographs of the completed pipes. Here is the image.

It has taken me some months to get these items uploaded. I was called back in to complete the Theater organ I was installing. This project took until October of 2009!.

The 20 note organ was a success. I was able to take it to Several events and rallies. Below is a photograph from 2009 sutter creek.

I was also able to take the little 20 note organ to Participate in the 2009 Dickens Christmas Fair. Since the photographs were taken I added a nice top. I also made a new costume. Part of the reason I have been behind on my blogging. Of course, when one is so busy with a production like Dickens (there were 1000 performers this year) I have no photographs of me entertaining the folk entering the cow palace.

If someone did get a photograph, I would like to see it. Of course I have plenty of photographs from when I was in the Dark Garden window. That seems to be the nature of the show.