GilesBathgate

I recently was asked to create a DVD from a .mov video file. I had already made a post about how to do this under windows using windows ports of various linux based applications. Coming back to it and this time running completely on linux, I have realised that it can be done much more simply.

The required software can be installed using

sudo apt-get install ffmpeg dvdauthor growisofs

First off the video file has to be transcoded into an dvd compatible mpeg2 file.

ffmpeg -i <input_file> -aspect 16:9 -target pal-dvd output.mpg

Then the file has to be authored into the correct VOB files using dvdauthor. To make sure that there are no errors in the process the following environment variable must be set.

export VIDEO_FORMAT=PAL

Rather than using an xml control file for simple DVD’s the following two dvdauthor commands will suffice.

dvdauthor -o DVD/ -t output.mpg &&
dvdauthor -o DVD/ -T

Finally the files are burned to DVD media using growisofs

growisofs -dvd-compat -Z /dev/dvd -dvd-video -V "<DVD_TITLE>" ./DVD

I have been progressing slowly with my reprap build, spending a little time here and there modifying the electronics so that the wiring is neater. There are some details on the reprap wiki about how hack an ATX power supply to give you a universal power supply. This is my sightly neater solution which is specifically suited to reprap only.

With minimal filing the standard ATX power supply grommet hole can be opened out to fit a standard XLR socket. I used a female socket as opposed to the male socket mounted on the reprap. This is standard practice and ensures that the pins of the socket cannot be touched if the connector is removed. In general the live end is protected and the cold end is not.

After a few helpful comments I was pointed in the right direction for drilling a hole down the middle of my hobbed M4 insert. Unfortunately I didn’t have a drill vice, so I used my trusty Block’o'Wood and a fair amount of extra caution instead.

It really is amazing how well this technique works, the drill bit doesn’t have to be perfectly centered but because the work piece is spinning around a central axis its near impossible not to get the hole dead centre. I guess this is why a metal lathe has the drill bit set-up in the tail-stock.

Here is the hobbed insert with the central hole:

I am very pleased with the result, as it runs nice and true when rotated. All I have to do now is drill the M3 grub screw hole.

RapCAD is a new script based CAD IDE especially for RepRap printers. Read more over at rapcad.org

When I get bored of waiting for someone else to do something I sometimes end up having a go at doing it myself. The hobbed insert in my previous post is no exception

Below is my setup using a drill stand. The 12mm round brass bar is held using a U-Shaped wooden clamp that mounts some 6901ZZ bearings, with an ID of 12mm and an OD of 24mm. I created some dimples on the 12mm brass bar with a punch to create an interference fit in the bearings. This stops things sliding around whilst doing the hobbing. One advantage of the drill stand (which is normally a disadvantage) is that it can swivel around the support pillar. So I was able to push the M3.5 tap closer and closer to the brass bar by pulling the handle to clockwise.

The next problem is how to drill a hole perfectly central down the middle for an m4 tap, again without a lathe. In the meantime the Conrad M4 Inserts have arrived in the worlds most ridiculously over sized box:

I have just completed a successful migration of gilesbathgate.com to a new server. Some headaches were importing the mysql data via the commandline (I gave up in the end and used phpMyAdmin) also lighttpd rewrite rules triped me up, and I forgot to install php5-gd for my wavatars support. But appart from that the migration was seemless, I am sure no one even noticed.

I will keep this short and sweet since most of you (in the reprap community) have probably already seen posts like this time and time again. So basically here is a few snapshots of my build progress

Everything went together fairly easily, there were a few minor errors in the assembly instructions which I corrected. The only trouble I had was with Adrian’s geared extruder driver. The base has countersunk holes to fit the heads of M4 bolts, however they were not big enough and reaming them out to 7mm I almost drilled right through. I also felt that the extruder design in general was a bit “bitty” and so I am re-designing the thing from scratch. Here is a sneak peek

The following view shows the lower half of my redesign of the axle mount, it fully encapsulates the bearing rather than having them floating free. (The image shows two separate parts which would be bolted together)

I am intending to also use my internal teeth gear concept with this design

I also designed a hobbed m4 insert

The hobbed insert will soon be available to buy courtesy of raysu in his ebay shop. Price is currently TBC, but he offers similar items at around $8.50

For my birthday this year Joey has bought me…

…yes its all the parts needed to build my own Mendel 3D printer! I am really excited about putting them together thanks Joey for such a great gift, how did you know?

Shortly after receiving my gift I dismantled OverlapStrap. I was supprised that the sum of the assembled parts seemed so much more than the 22 bits of MDF 25 bits of aluminium angle and the box full of fixit blocks.

OverlapStrap was by necessity a much simpler design than Mendel. So maybe there is something to be learned from this, although I think designs  like the one  Josef Prusa has designed and built are even simpler still!

So, the bad news is that I have given up trying to print out all of the Mendel parts using OverlapStrap However the good news is that I now have a full set of Mendel RP Parts that materialized themselves sometime on Nophead‘s 3D printer(s) and which was then bought from him via his ebay shop. It seems a shame that I didn’t ever fully manage to bootstrap Mendel using my own repstrap, but at the end of the day it was never really my goal. I really started out on this journey because at the time no one seemed to be selling Mendel parts, and of course this is increasingly becoming untrue. I think I have learned a lot putting OverlapStrap together and proved to myself that given enough time, I could have printed out the missing parts and upgraded the machine bit by bit until it had become a Mendel. I believe I have also inspired at least one or two people to create designs that use elements of OverlapStrap, so I think will continue to document and develop OverlapStrap but it is likely only to be driven by other people taking an interest in the design. I never managed to get it running on belts, but I did have designs for how the belt driven “upgrade” would work. For example here are the Y-axis belt idler and motor mounting blocks.

And here is a photo of the x-axis fixit blocks which would have attached to the x-axis motor mounting plate.

Shortly after announcing his initial design Adrian updated his Extruder Nozzle Design. The top-hat and steel plate had been combined into a PEEK block instead. I had a few thoughts about the implications of this improvement. The first thing I realised was that getting the required materials would be expensive. Adrian suggests a crowd sourcing solution to this which is a good idea in theory, but I figured that the design could be made cheaper if we went back round PEEK bar. Also after showing my design to a few people on the reprap IRC channel one argued that my Best compromise nozzle offers no real advantage over existing hybrid thermal barriers. I decided to sketch out a few alternative approaches.

Eventually I came up with something that you are probably all quite familiar with. Its a PEEK insulator with a PTFE insert, however I came up with a slight twist on existing designs. Instead of having an insert that slides into place, my insert is M10 threaded PTFE rod, which screws into an M10 internal thread in 16mm dia PEEK. The brass barrel screws into the PEEK only, and since PEEK is much tougher than PTFE there is little chance of the barrel coming out. The PTFE basically just acts as a nice slippery surface for the filament.

I came up with a drilling methodology that I think keeps things as concentric and true as possible when using a drill stand. The first step is to drill a 16mm hole into a piece of wood, which acts as a work piece clamp. The PEEK was a tight fit in the piece of wood, since it was slightly over 16mm, I tapped into place with a hammer. Next I drilled a blind 8.5mm dia hole to a depth of 25mm. I found it was better not to drill a pilot hole as then the piece would turn in the holding jig. I tapped the hole to M10 using a taper tap followed by a plug tap, as I wanted to get the thread as close as possible to the bottom. I had already prepared a length of M10 threaded PTFE which I cut longer than needed so that I could screw it in and use the protruding part to screw it in extra tight. I cut the PTFE flush and drilled a 3.5mm hole all the way through the assembled insulator. This 3.5mm hole then acted as a centre so that when I turned the PEEK over I could drill the 5.0mm and Tap to M6.

Here is the result, I was quite pleased how central the hole turned out, before I bought a drill stand I had had a lot of difficulty getting a hole to be consentric over this length.