Friday, October 31, 2008

 

Exponential Growth?


Here's a nice diagonal tie bracket (Thanks to Nophead for the updated design) I made Tuesday night. It's far from perfect, but it seems to be pretty functional.

After some tweaking and a few messed up builds, I awoke to this view on my webcam Thursday morning:


Getting better! A wayward G28 code caused a minor head collision, but everything survived.

I've still got room to grow though, so here's what I saw on my webcam first thing this morning:



That I like! There's actually build room for another row and column yet, but I've got enough diagonal tie brackets for now; next up are corner brackets!

Interestingly, Skeinforge and ReplicatorG both reported build times of about 4.5 hours for the 9 part build, but the actual build took over 6.5 hrs, give or take half an hour. That would explain the discrepancy I'm seeing between 8mm/s and 16 mm/s feed rates - I actually get too much plastic (densities above 1.0) at 16mm/s. Probably something to do with the many short moves along the curves causing a bit of a slowdown in the head feedrate. At any rate, my real limiting factor is now the extrusion rate; 3 mm^3/s is about as fast as I can reliably extrude at with my current extruder.

Either way, things are working smoothly now. My parts bin now has 43 usable Darwin parts in it, and with these longer builds I'm getting more and more parts with less and less effort (on my part at least).

Unfortunately, right now my Darwin only likes my favorite dual CPU computer and it's not at all happy sharing it. So, until we get offline printing working, I have to find another computer to work on while I'm printing.

Full resolution pics are over here:
http://picasaweb.google.com/wbortz

Hopefully my next post will involve something about viral distribution. :)

Wade Bortz

 

Burning Bootloaders

Just a quickie.

If you are struggling to push a boot loader onto an arduino or sanguino or even a blank chip and don't want to load up windows to run a parallel programmer there is a solution.

http://mega-isp.googlecode.com/files/avrisp.02.zip

Download the sketch above and using your usual arduno host environment with an unmodified working arduino (I used an off the shelf Diecimila) turn it into an in-circuit serial programmer ISP. It costs about the same as a real one, works just as well and when you no longer need it you can use the Diecimila for something else.

Wire the arduino up as per the comments in the top of the source file, locate the bootloader hex file, plug into your target board/devices 6 way ISP socket and burn away using something like:-

avrdude -pm644p -b19200 -cavrisp -P/dev/ttyUSB0 -v -U flash:w:ATmegaBOOT_644.hex

As you can see I was burning a boot loader onto a Sanguino from Linux.

After flashing reset the board and it should talk to your usual arduino style host application. Mine did.

Hope this is of value to someone.

Tuesday, October 28, 2008

 

Generating PCB milling toolpaths for Tommelise 2.0

In which your narrator moves from text and pictures to a more or less podcast approach to demonstrating the performance of T2's toolpath generation system for conventional PCB traces ... do you want to know more?

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Sunday, October 26, 2008

 

PIC32 > Laser cut machine




video
Images of the finished article added in PLA & PCL

To date I have been running one of the early Bits-From-Bytes machines made up from the cast resin parts. My machine, affectionately known as “RepScrap”, due to its less than ideal start in life – Ian's scrap bin! It provided me with an inexpensive start on the project and I have to say given some very good results.
As you can see from the video, the next big thing to report is that I have moved the whole project over to one of the new laser cut machines. RepScrap was never perfect, the parts used for the Z drive let me down on more than one occasion, to add to that the stiffness of the X carriage was poor. The new Laser Cut design offers several advantages over first model. Firstly, every axis is run on ball bearings giving nice low friction motion, the Z-Axis now runs like a dream even with the anti-backlash mechanism. Extra bars are now fitted to the X axis, improving the torsional strength to a point I now think the standard machine could be used for PCB routing. The new machine also comes with a complete set of cross braces, RepScrap only had a single brace on each side.
The Laser cut machine is quite a long build, and I have to say a bit fiddly to put together. If I had any advice to prospective builders of this design, it would be to take your time, get everything perfect with the sub assembly before it is built onto the machine. There are a few areas where moving elements are clearly over restrained, the X carriage is an obvious case. To align all eight bearings is a tall order. Get things perfectly square and it will reward you with a nice smooth free running machine. Ian has uploaded some very comprehensive instructions for the build, the graphics alone are worth a look! Seriously though, time spent getting things spot on will repay dividends when you start printing.
Saturday night, listening to Katie Melua watching the new machine....does life get better than this?
OK so I need to get out more!

Wednesday, October 22, 2008

 

PCB supplies arrive


The PCB supplies from North Bay Technical arrived this afternoon... read more

Tuesday, October 21, 2008

 

Life imitates art far more than art imitates Life - Oscar Wilde


In which the narrator tries to solve a practical problem and finds the solution to be esthetically pleasing as well... read more

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Friday, October 17, 2008

 

Some good advice about milling PCBs from Fred


Fred, at North Bay Technical, give some good advice and demystifies the problem of wear on milling bits... read more

 

PIC32 Printing





As promised a couple of pictures of the last parts I have printed.
The complete screw holder is straight off the board without any trimming, the thin section is more a test to see if the text could be improved.
Material: PCL, 210DegC, 7.5mm/s, 27.5mm/s fast move.
Extrusion rate 9mm/s using 0.5 nozzle

Printed onto MDF.


Dimensional accuracy of the part varies from zero to +0.3mm

Thursday, October 16, 2008

 

Sort of like designing with 2D strip board


In which your narrator overestimates the difficulty in knocking his PCB layout app into shape... read more

Wednesday, October 15, 2008

 

PIC32 Printing > SDCard


As you see from the title, a lot of changes have been made since my last update. I purchased a PIC32 chip some time ago and have been itching to see what it can do.
The new chip runs so fast!
My first attempt at running a G-Code file just resulted in a loud one second buzz from the machine. It took me far longer to realise that what I had just seen was a few thousand lines of G-Code converted and run in about a second!

Most of the issues with porting the code from the PIC24 was to rescale all the timers and processes. Don't get me wrong, the PIC24 is am awesome bit of kit, it was managing to run the machine very well. The only issue I ever had with it was that it would not run a standard G code file straight from the disk without a small amount of segment pausing. I got round this by post processing the G code files to a binary format and this cured the problem.
With the PIC32 any hint of segment pausing went away, I can now take the standard G code exactly as produced by Enrique's tool suite, complete with all the comment lines and run seamless movements straight from the SD Card.

I have been asked what my connection is to the PC. The answer is : there is none. For the record my machine development has been done entirely without any direct connection to a computer. The only cable link has been via an ICD2 programmer when flashing the chip.

To run the machine, I switch on, then use the joystick buttons to scroll through the files on the SD Card, select the file to run with another button push. After file selection the machine drops into “manual mode” I am then able to position the tool using the joystick. When happy with the setup I push the button again and it switches into “Auto mode” to run the selected G code file.
Once in Auto, the machine can be flipped in and out of manual in case of emergency.

Its worth pointing out the small add on card used with the Explorer 16 development board. This card is all I have added to make the bot move, the circuit is very simple.
As you can see the chip is 100 pin, I am using a fraction of the resources and a small corner of the programme and data memory available, so plenty of room for development.
Quality of the printed parts has taken a step forward with the adoption of the new processor, I will take a few pictures in the next couple of days

Finally an apology, I have been very slow in blogging details of the machine, I did promise some time ago that I would post a circuit, unfortunately real life gets in the way of hobbies sometimes. When I do get time I like to play with the machine not sit about writing endless blogs about it! To make amends I have passed all the designs over to Bits-From-Bytes, Ian has been my mentor on both the PIC stuff and electrics. He has offered to take my unfinished circuit and sort it out with a view to having some boards made. This way it will actually get finished and to be honest he will do a better job of it. The intention is still to post the circuit independently from Bits-From-Bytes so anybody out there that feels like having a go can do so. In the mean time, anybody wanting the circuit as it is, just e-mail me, and I will send what I have, note though it is a design based on the 44 PIN PIC24 not the PIC32
Watch out for more news on the machine plus pictures of the latest output!
Tony

Tuesday, October 14, 2008

 

MultiMachine video

I'm not sure how many people here will be interested, but since it involves another open-source machine, here goes.

Pat Delany, who founded the MultiMachine project, with which I am also (minimally) involved, has produced a 59 minute video demonstrating his machine, and how it's constructed. It's now online, available for download.

Some hosting has been provided by the Includipedia project - a friendly fork of Wikipedia, aiming for inclusion of all knowledge, not just that suitable for a traditional encyclopedia. All video download links (including one for direct download) can be found at the Includipedia's mirror of Wikipedia's MultiMachine page: here.

For convience, here are direct links to the torrents:

Compressed 289MB AVI
Full resolution 3.9Gb DVD

 

J'en ai marre!


In which your narrator shares one of the better known sentiments of the French chanteuse, Alizée.

I had what was either a late night yesterdayor an early morning today, depending on how you want to look at it. By about 1830 yesterday, I was, like Alizée, ... fed up ... pissed off ... tired. For the past several weeks I have been diligently working my way through the tutorials for Eagle, KiCad and, finally, FreePCB. Voicing a few of the more pungent Afrikaans explicatives under my breath, I shut down FreePCB and opened Visual Studio in Visual Basic .NET mode. By 0130 the next morning, there was this...



I'd decided some time ago that Tommelise 2.0 was, as part of it's ability to print parts, going to be able to mill the printed circuit boards (PCBs) for Tommelise 3.0. One of my long-standing goals for the whole Tommelise Reprap project has been that a reasonably bright twelve-year-old should be able to build one from printed parts received from another Tommelise owner.

read more


Monday, October 13, 2008

 

first success with bfb repstrap

Hey Reprappers- finally got to the point where I can say "I'm a fellow reprapper!"- I printed a minimug on my BFB repstrap system. Not quite at the point where I can make the parts, but getting much closer. Read on for some details of what I went through to get to this point, pics of the system and end results, and what's up next. Cheers!

Read more...

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Sunday, October 12, 2008

 

A new use for J-B Weld


...and other adventures on the way to debugging T2's controller board... read more

Wednesday, October 08, 2008

 

Notes on the operation of T2


Now that I've been running Tommelise 2.0 for a while, I've begun to see a few pressing matters that want fixing... read more

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Tuesday, October 07, 2008

 

Brave New World the making of cube

Hello Reprapper's

My repstrap aka The cube has started to take shape (pictures to follow shortly)

The main parts today are 12 lengths of angle iron, which are 1 meter and in a L shape, The L shape is 50mm by 50mm 8mm thick. which i can tell you is pretty stroung, (they use this thickness angle iron to hold cars up) and 8 of the peices have had 45 degrees cut of each end. (so they make two squares on the ground) (pictures will illustrate). I only got as far as cutting (with a angle grinder) today , as in the process i managed to catch my t-shirt alight which put me off welding.

So at this point im basicly making a 1mtr square cube that can take the weight of a car. I would try to explane the more intricate details of how its all going to work, but i only have a rough idea which could change at any time and what parts i can mannage to get ahold of , but the general idea is to make a repstrap thats capable of producing roughtly 1mX1mX1m objects which can also take alot of tourque and pressure (as i hope to be able to mill as well)

Hopefully the next update will be more intreasting

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Sunday, October 05, 2008

 

Notes on the Sarrus linkage

During the 18th and much of the 19th centuries accurate guide rails for machinery were simply not available. For that reason, the machines of the First Industrial Revolution tended to rely on linkages rather than guide rails. James Watt of the Watt steam engine fame, designed one of the first practical linkages for providing straight line guidance for his engines. Watt's linkage was followed by a succession of other, different approaches. In my opinion, the Peaucellier linkage is easily the most elegant.

It has seemed to me that a self-replicating 3D printer might well utilise linkages, which are easier to construct, rather than accurate guide rails

The problem with most of the linkages is, however, that they are 2D. By the time you either reinforce them to provide guidance in three dimensions they become either complex or bulky. For that reason, I've long been enchanted by the Sarrus linkage.



I've found watching it move is positively hypnotic. Since commissioning Tommelise 2.0 and carrying it over to production work I've had some time to consider what sorts of concepts belong in a third generation Tommelise. Of course, the Sarrus linkage came up almost immediately.

read more

Thursday, October 02, 2008

 

Tommelise 2.0 goes into production

You won't be hearing too much about Tommelise 2.0 after this. It went into regular production last night making parts for other projects. There are a few things that want sorting out about it, viz,


All that said T2 is doing very good work right now. Last night I started proving the preliminary design for the electromagnet spools for the linear stepper motors that I hope to use in Tommelise 3.0. Here you can see one of the two halves for a spool being milled out of 3/8ths inch HDPE.


Milling electromagnet spools on Tommelise 2.0 from Forrest Higgs on Vimeo.

read more


Wednesday, October 01, 2008

 

RepRap Builder's Wiki


Today we launch the RepRap Builder's Wiki. Here anyone can post any RepRap information that will be helpful to the RepRap community.

Don't be frightened to tidy, to re-organize, to correct and to clarify the work of others, but don't delete anything without good reason (good reasons are things like the post is offensive, is spam, or is scientifically incorrect).

By all means include lasting information that has previously appeared in the Main Blog, the Builder's Blog or the Forums - we want to systematize that in a chronologically-independent way on the Builder's Wiki. But please don't post questions (they belong on the Forums) or information that is transient. Indeed, if all you do is to take some nugget from one of those sources that you personally have found usefuland post it on the new Wiki, you will be doing everyone else a great service.

If you post, please include as many pictures and diagrams as you can; these really help understanding. Remember that you can freely copy any images and text from any other part of the RepRap website - it's all covered by the GPL.

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