New site

I am not updating this site any more.

All new content will be posted on the blog. Please point your browsers there for current updates and new content.

This site has grown a lot over the years, but it’s all very disorganized and I wanted a clean sheet start at a new blog.

FormFutura HDglass

A project I’m working on required some clear pieces, so I purchased some HDglass from FormFutura as I heard good things about the plastic’s transparency. This is a PETG plastic so use appropriate guidelines when printing it.

The recommended printing temperature range is 195-225 deg C. The box says nothing about bed temperature or fan setting, so I modified my PLA setting to adjust the temperature and went on printing.

First part I printed at 235 deg C. The detail was great, but the part felt very fragile. The inter-layer bonding was so weak that I could break apart the 3d printed part in my hands.

Thinking I went too high with the temp,  I next tried 205 degC. Same fragility. Part would disintegrate in my hands with very little force.

It turns out that PETG doesn’t like a fan (unlike PLA) so I proceeded to make another print at 225 deg C (the upper end of the recommended temp range) with a 10% fan setting however there was no noticeable difference in print

Next I decided to go much higher in temp and printed the part at 255 deg C, and the results were impressive. The clarity and transparency is much better then at the lower temperatures, and the part is now strong. It will not delaminate when it’s bent.

converting video with FFMPEG

Needing to convert some avi files to a format that After Effects could read. Settled on converting the avi file to a x264 format in a mov container using the following syntax:

ffmpeg -i input-file.avi -c:v libx264 -crf 0 -preset ultrafast

This creates large x264 files with a minimum compression setting. As close to lossless as it can get with x264 format. It’s also a very quick conversion.

DIY optical lenses

For my AF Assist tool, I decided to make my own optical lenses to focus the light from the IR LED. I experimented with a few lenses I had kicking around (from other flash systems that I took apart) and looked online to see what I could purchase. The lenses I had kicking around did the trick in giving me a direction to follow, but were not prctical for several reasons. Sourcing is a big issue (these are custom lenses) and second they don’t quite fit my application constraints; too big, or need to be too far away from the light source.

After a brief search online (ebay, aliexpress, etc) I decided that I didn’t want to wait a month for some lens that was chosen just on a photo and scant technical info.  It’s too much trial an error for my taste. I’ve always been intimidated by optics. It felt like this black art/science that I knew next to nothing about. Having done some reading, I now feel a little more comfortable attempting to make my own optics.
Besides, learning something new is always great.

I’m approaching this from a couple different angles. 3d printing of a master (and then resin cast using optically clear resin) as well as cnc machining a mold and try to form some acrylic plastic sheet into the shape i want. I don’t quite know which will give better results which is why I’ll take both paths.


DIY Plastic lenses
– 3D Printing and CNCing Weird Freeform Lenses
– Bike pump Vacuum pump




A quick CAD sketch for a mold, and then a 3d print resulted in a


Crashplan memory problems

I updated to the latest version of UnRaid (v6.2.1) and Crashplan that runs ina docker container started misbehaving.

At first it kept cycling through “Syncronizing block information” and would not actually do a backup. It was stuck in a loop doing the sync operation.

I then changed the frequency of when the backup runs, by telling crashplan to run the backup between a specified time and days for all the backup sets.
That stopped the repeated sync operation, but now while doing backups, the Crashplan application (and engine) would crash and restart every minute.

I tried changing the -Xmx parameter in the run.conf file, but the restarting behaviour persisted.

I can monitor the docker container memory usage using the “cadvison” container, and I can see that as memory usage gets close to 2 GB, the system would restart that container. I bumped the -Xmx parameter all the way up to 4096MB, but it seems like it’s stuck at 2gb…

The next way I came across to increase the allowed memory usage is entering the CrashPlan console from within the app, ans issue the command “java mx 4096, restart”.  (SEE LINK)

This successfully increased the allowed memory usage of CrashPlan to 4GB. Looking in the “cadvisor” app, I can see that crashplan now uses 3.5GB of ram, and everything is stable.

What tool to use for CNC mill or router?

Excellent three part series of articles talking about the right tools required along with many side articles providing more details.




Strength degradation in webbing and cord with introduction of knot

I’ve always used webbing for setting up top rope anchors, but recently I’ve investigated using cord instead of webbing. For one thing, knots are easier to undo in cord then in webbing after being loaded. But is there any difference in strength between knots in cord and knots in webbing?

Interesting to see that a knot (Bowline of figure 8) will introduce a weakening to 73% of cord tensile strength.

Maybe more interesting is that in webbing, a water (overhand) knot degrades the strength much more then a figure 8 knot. Water (overhand) Knot gives a 57% of webbing tensile strength, while a figure 8 gives similar to a cord figure 8, at 71% of webbing tensile strength.


Find and change quality setting on image files

The webserver I was working on was running out of space only to find people had been uploading anywhere from 3Mb to 9MB jpeg images. Nobody needs that kind of image size and quality on the wordpress site.

Put together a script to for find and re-encode jpeg images over a certain size, to a lower quality setting.

find . -type f -size +1000k -name “*.jpg” -exec mogrify -quality 50 {} \;