Geiger Counter Resuscitation

My son and I found this geiger counter at a surplus store, and I just could not resist.  It was pretty rough as the batteries had leaked some years back and caused much internal damage.


Rust and corrosion put holes in the case and destroyed the battery terminals.

geigercounter02-sm geigercounter03-sm

But when it was rigged up to bypass the destroyed battery contacts and tested, the unit functioned like a trooper.  It has a small radiation source for testing on the side in a foil sticker.  (don’t sleep with one of these next to your head by the way.)



And here is the indicator showing the readings.

geigercounter06-sm geigercounter04-sm

The audio plug even works when you plug in a headset or powered speaker.

I would attach a movie file, but it seems like a lot of data just to see the dial move and hear a bunch of clicks.

So it is off to the electronics store to see what new battery contacts can be found to work with these existing plastic battery brackets.  The only real question is what category to file this under since I don’t have a NBC category (Nuclear, Biological, Chemical).  It hardly qualifies under home improvement.  Well, why not label it just what it is…a new category.


First hot end duct parts

These are my first cut at printing extruder cooling duct for the aluhotend right hand and left hand parts to assemble to or remove from an installed hot end.

extruderduct01  Along with some extra test parts while I fine tune the settings on the new hot end.

fanbkt01   Like the X-stage 40mm fan bracket half.

Time to try them for fit…

temporary hot end duct

I rigged up another temporary duct in order to be able to print a hot end cooling duct for my newly installed aluhotend this time.  A little paper, scissors and scotch tape to get a reasonable shape.  It should work fine as a recursive fix.


Then I can install the plastic cooling duct… sweet.

igus new iglide tribo-filament

I just received an evaluation package from igus for their new dry-tech tribo-filament.  The impressive kit included a sample of FDM filament to try.  They released two material filaments I170-PF and I180-PF.  The processing details for I170-PF are extrude at 200C, bed temp 95C on kapton or perforated plate.  I180-PF extrudes at 220C.  See the attached files.



iglidur I180-PF Processing Instructions FDM_eng iglidur I170-PF Processing Instructions FDM_eng

Delta Printer tribofilament-linear wear tests tribofilament-oscillating wear tests




Commercial 3D Printer Quality

I got my hands on some demo parts made on a production FDM printer using ULTEM 9085.  Strangely the nozzle diameter, layer height and filament width are the same as my $350 DIY REPRAP Mendel system which uses .016 inch nozzle, .010 layer height, .020 filament width (my settings are actually in millimeters .41mm, .25mm, .50mm).  The ULTEM is a polyetherimide mixed with a little polycarbonate so it holds up to high temp ~300C heat deflection temp and is rugged stuff.  The machine uses a heated chamber, humidity controlled filament containers, a frequent nozzle replacement schedule, proprietary software and mass produced parts make for a pretty consistent part.  The commercial machine ~$150k produces nice parts, but still not flawless.  A couple of pics show the usual FDM limitations.

duct03sm slight bridging of holes,

duct07sm still a few steam blow-outs,

duct08sm high contour top/bottom edge roughness,

ductsm more of the same- with support contact in the same areas,

duct05sm support material contact artifacts,

duct11sm infill to perimeter gaps as is usual due to the filament width rasters at curve intersections,

duct02sm and ooze at z move or start/stop blob at perimeter start create a ridge.

All in all, nice parts with no real defects and really consistent, but the process produces similar manufacturing induced features as the lower priced relatives.  Although I would not leave my machine running overnight unattended as the commercial machine does typically.  My machine also cannot use a plastic as high temp or as strong as this either.  But I am still happy with my own printer.

Interior Screen Door

In order to keep our cat off the kitchen counter and dining table I made a couple of interior doors which let the air move through the house, but keep the critter in check.


So I inset the screen by cutting a channel. Used 3 inch wood screws counterbored to depth to join the corners.  Made a jig to mark the screw hole locations.


The tricky bit was where the doorknob goes and how to transition. I did not have a dado blade, so I made do with repeated cuts instead.  I just marked the boards and put a mark on the table saw for where to stop, then adjusted the fence in between cuts.


The screw plugs were painted on a strip of packing tape to hold them still.


Very happy with the results.

New hot end heater block

I made a new hot end heater block to try to increase the q (heat flow) into the melt chamber.


Reworked my hot end to remove the flange on the fitting to match a through hole in my new heater block and repaired the resistor to go into the block.  I applied high temp silicone to both leads so I could apply silver thermal paste to the resistor in the heater block without shorting the resistor.  Here is how I did that:

1) Took drill bit I used to drill out the resistor hole (just larger than the resistor maximum diameter dimension, and spiral wrapped it with masking tape along the smooth end away from the flutes with the sticky side out.  The spiral tube then slides off the drill bit.  Trim the tube with scissors to the desired length which leaves the resistor leads exposed at their ends.

2) Cut a masking tape strip to match the width of the resistor and wrap the resistor until it is just under the diameter of the inside of the spiral tape tube.  The taped resistor must slide easily inside the tube.

3) Apply silicone into one end of the tape tube to fill about a third.

4) Push resistor from silicone filled end into tape tube until the resistor is just inside the tube.

5) Start applying silicone to the opposite end to fill the tube following the resistor in as you slide the resistor in more and more.

6) Finish up when the resistor is centered in the tape tube with silicone to the trailing end, and top up the opposite end also.

7) Wait until the silicone cures.  Water vapor cured silicone can be accelerated by wrapping the tape tube resistor assembly in a damp paper towel and placing it in a warm (not hot) location.

8) After cure, gently remove the tape tube then the resistor masking.  No resistor leads should be visible between resistor and silicone plugs.

9) Voids can be filled with more silicone before touching with your hands (hand oil can reduce bond strength).

heater-block02sm heater-block03sm heater-block04sm

Insert the resistor into the heater block while applying silver base thermal paste.  A little silver paste smeared into the hole bore will help the resistor slide in easier.

heater-block05sm heater-block06sm heater-block07sm

One more thing- as the thermal paste has volatiles that evaporate at elevated temperatures you should provide a path for the vapors to escape for the first full temperature heating of the heater block.  Insert a dulled push pin or another resistor wire from one end into the top of the center cavity surrounding the power resistor.  I did not do this on my first run and the pressure ended up opening up a path from around the resistor to a resistor wire and allowed the thermal paste to electrify the heater block.  Apparently only one side was compromised, so it ended up not shorting out.  The other thing you could do is to mold a vent port into one side of the silicone seal.