Special Topics in DIY Design and Fabrication

So just as a quick update, I am taking a class at CMU that’s sort of just for fun. The class basically covers some pretty basic sketching skills, design, and fab. It’s sort of a quick (one semester) and dirty course for people to get their hands dirty and toy around with the ideation, design, iteration, and fabrication processes.

Those single-picture posts from earlier will get better well-documented design steps and walkthrough-esque posts of their own.


Just another assignment…

This is also for completing a homework assignment. This one is much more interesting, but in keeping with my previous post, I will provide no explanation for now.


Removing Onstar Antenna and Rerouting Radio Antenna

This is a pretty simple modification I did on my Saab. I read that a couple of other people did this modification, but I was not able to find any picture instructions, so here’s a sort of how-to.

To give some background, when Saab got purchased by GM, some of them came with OnStar. As a result, there are two antennae on Saabs of that period (1999 to 2002 9-3s). The one one top is the Onstar antenna, while the extendable mast in the back is for the radio. The rubber used to seal the Onstar antenna, unfortunately, hasn’t weathered well, and most of them are pretty cracked and ugly. The nylon rack gear in my aerial also snapped, and they’re sort of a pain to replace, so I decided to remove the Onstar antenna and install a radio antenna in its place.

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Removed Onstar antenna and replacement antenna

The skirt on the Onstar antenna clearly wasn’t doing a great job of keeping stuff out. Years of dirt got under the antenna. Fortunately, the smaller grommet seemed to seal well against the car, so nothing got into the roof.

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Cheap antenna means low quality

I paid $11 for this Universal Shark Fin Antenna off Amazon. I definitely got what I paid for. The wire for the antenna ran out the back of the housing, which I didn’t really like, and the “antenna” part of the device wasn’t really much more than just a little wire sticking out. I might pick out a Windshield Antenna and stick it inside the housing if it proves to not have enough reception in the future.

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Rerouted wire in antenna housing

I drilled a a 1/2″ hole in the bottom of the antenna housing to pass the wire through the bottom instead of the back. This way, I could use the entire antenna housing to cover up the hole in the top of the car. I’m not really one for car washes, so I just spot cleaned the area using paper towels and break cleaner.

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Steel fish tape

One of these tools makes running the wire down to the rear quarter panel a little easier. They’re available for pretty cheap from Home Depot or really any hardware store.

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Fish tape got stuck

I couldn’t really feed the fish tape all the way up the rear strut, so I pulled of some of the housing to see what was going on.

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Antenna connector

I just had to unplug the antenna connector from the old assembly and link it to the new antenna connector. Pretty straightforward.

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Antenna stuck down

Tidy everything up, make sure the new antenna is properly aligned, and stick it down!

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It’s a little more bulky, but it’s not super noticeable.

Making Walled Scales

So this is going to be a pretty long, sort of how-to post about how I make knife scales that have walls. Basically all scales come in two different forms. The easier scales to make are flat scales. The name is pretty self-explanatory. A flat scale is shaped to the knife, and just has the proper through holes and countersinks for the screws. The more difficult scales to make, however, are the walled scales. One method of making these scales is to start with a thicker piece of wood and to mill out or pocket the inside of the scale, but without a CNC mill, doing it by hand it both tedious and very time consuming. With the tools I have available to me, I decided to try and makes walled scales using a combination of a 3D printer and the rest of the handle-making equipment that I already have.

To start off, it’s always nice to have the project knife on hand. This allows me to check fitment every step of the way and also allows me to create a CAD model for the walls.

Cropper Scan
Scanner image of pocket side of scale

Just for reference, the knife I am working on in this write-up is a Boker Plus Nano. It’s a pretty unique, compact knife that’s really quite affordable.

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Edited scanner image

I am really only interested in the walls of the scale and not so much the scale itself. Since on this particular scale, the screw holes don’t intersect with the wall, my task is a little simpler. The images was edited using GIMP.

Vectorize in Inkscape

After editing the original scanned image, the image is then imported into Inkscape. Using the “Trace Bitmap” toll under the “Path” menu item, I created a vector of the inner and outer edges of the wall. Taking a set of calipers to measure the vertical dimension of the physical scale, I make sure that the vector in Inkscape has the same vertical dimension. Afterwards, I export the vector as a DXF.

DXF imported into Solidworks

Upon importing the DXF of the scale wall into Solidworks, I again check the vertical dimension, making sure that nothing has changed between the two different programs. Once verified, I simply leave the sketch underdefined and extrude the sketch to the appropriate thickness of the wall. Finally, with a solid model in Solidworks, I can export the file as an STL and print it on my 3D printer.

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Scale wall glued onto scale

After the print completed, I glued the scale onto a rather thin piece of wood. Using the metal liner, I was able to transfer the hole pattern using two different sized drill bits that closely matched the clearance hole diameters on the original scale. Unfortunately, when I was drilling the more centrally located small screw clearance hole, the drill bit walked quite a bit. I had to use a small file to “fix” the hole and elongate it such that the screw would still fit through. The wood is Myrtlewood Burl. It’s not a very dense or strong wood, but as a sort of decorative part, it suffices.

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Countersinking the screw clearance holes

Using a belt grinder and Dremel, I was able to easily remove the extra wood that was outside of the scale walls. In order to size the counterbores, I first assembled the knife. The impressions left in the wood by over-tightening the screws that held the knife together gave me a good sense of how and I should make the counterbores and exactly where to place them. Using a mill end in a Dremel, I carefully enlarged the screw clearance holes. This process involves a lot of stepping down small increments and checking to see how far down the screw sat in the scale.

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Test fit before coating and sealing

Before sealing up the scale in acrylic spray, I had a quick test fit to make sure nothing was sticking out, everything was smoothed, and the knife still can open and close properly. With a couple passes of acrylic spray, the outside of the scale is sealed. I usually leave the inside of the scale untreated.


That’s it! I hope this walkthrough was useful.


Second Camping Knife

To give some quick background, my unnamed roommate from my previous post happens to actually have a name, Micah. Here’s a plug to his WordPress! He was working on a camping knife about the same time that I was working on my first chef knife.

DSC_1165There he is cutting out his blank with an angle grinder designed to deafen on a cold, dark, Worcester night

With all these knife posts, I think people are still interested in just seeing pictures first, so here’s a picture of the final product.


Micah had designed the blade shape, cut it all out, and placed the bevels with the “defiling jig” that I mentioned in the Chef Knife Complete post from earlier. Because that was about all he could do while we were still in Worcester, it was sort of up to me to complete the heat-treating and handle-making parts. Post heat-treatment, I decided to acid stonewash the blade, giving it a more rustic appearance. Micah selected the stained layered wood handle material long ago, but while I was working on the knife, he also requested a plaid-inspired pattern. In order to make the already flashy handles even more decorative, I decided to mill out a sort of plaid pattern and fill it with glow-in-the-dark resin.


There’s the pattern! The room was actually quite dimly lit, but the 3200 ISO and 5 second exposure helped to really capture the glow resin, but unfortunately also made the rest of the room look quite well-lit.


Somehow I failed to get any sort of progress pictures of this knife, except for the one 100% scaling scan just after putting on the bevels the first time around. Anyways, this custom is for my mother, who has a really old, cheap Nakiri from quite a while ago. The Usuba and Nakiri are both pretty much just for vegetables, with the notable difference that an Usuba has a single bevel on one side of the knife. For right handed people, the beveled side is on the right, and the flat side is on the left. This allows for cut parts to be more easily peeled off the right side of the knife and also helps with making sure the knife cuts straight up and down instead of gliding at an angle.

Well, the wall of text is uninteresting to most as always, so here are the completed pictures.

Usuba Nakiri Right

Above is a scanned image of the knife, as usual. The depth of the right hand bevel is quite obvious. The opposite side is flat. At 11.5″ total and with an edge length of just under 6.5″, the knife isn’t all that large, but it serves its purpose fine.


The knife is made of 440C stainless steel, since my mom didn’t want to deal with the awesomeness of plain carbon steel. The handle is a pretty plain Bocote, since my mother asked for a lighter colored wood instead of the dark Cocobolo that I often prefer.


I decided to put a pretty shallow edge on the knife, in keeping with higher quality Japanese knives. The sharp right angle of the heel help with delicate small tasks, like cutting out little eyes in ginger roots.


The wide, near-mirror finish edge makes all the surface smoothness imperfections very obvious. The parts of the blade that are just a couple mils thicker result in a much wider mirror finished edge. The edge on this knife is extraordinarily sharp, regardless, but it really makes me appreciate the craftsmanship of Japanese master blacksmiths who hand make their knives.

Chef Knife Complete

This long overdue (2 weeks) post is for the long overdue knife that I started in January of 2014 when I was still at WPI. Part of the reason is that this knife is actually the first knife I started, and many of the steps were done by hand, with some limited use of power tools.


So to kick things off, that’s how the knife project began in my apartment. I had started going at the 1080+ steel (some people apparently say it’s 1084) with a hacksaw over the course of a couple hours but ended up getting sick of the project already. I went to Harbor Freight and picked up an angle grinder. This being the first time for me really working with steel, I didn’t realize how much harder it was to work compared to aluminum.


That’s my old roommate in the picture, and he’s not roughing out my knife in the picture, but I did pretty much the same thing earlier. It was cold and dark, and that slightly off-balance angle grinder was REALLY LOUD. Now that I have a Makita angle grinder, I really appreciate how much better a quality built tool compares to a cheapo one. I don’t own that Harbor Freight one anymore, thank goodness.


After hours and hours of filing, I cleaned up all the ragged steel to line up with the original cardboard prototype and sharpie tracing. The process from initial sketch to this roughed out shape took four days.


I colored in all the steel, and my roommate built a filing jig, which we ended up renaming the “defiling jig” after a couple uses. Shout out to Aaron Gough for the design, which can be found here. I colored in the blade to make it easier to tell how far up the knife I had filed.


Done! All of two weeks later, and much to the satisfaction of our downstairs neighbors. I spent a lot of late nights filing, but I stopped after our downstairs neighbors started banging on their ceiling. The constant buzzing and rasping coming from their ceiling was probably pretty annoying. Well, after this step, there wasn’t much else I could do at the apartment, so the knife just sort of sat around for a really long time, and my capstone project at school started to really pick up.

Chef Left

There’s a scan again for those who are interested.

After driving across the country and deciding that I would actually stay in San Jose for a year, I decided to pick up some equipment, specifically a kiln. Before trying to heat treat this large knife, I wanted to make sure that I had the process correct, so I ended up finishing four other knives before getting around to this one again. I did sort of “cheat” with the handle, since I used a belt sander for most of the shaping.The blade itself, however, I cleaned up post heat treatment with more hand filing and sanding.


It’s finally done!


The handle was made with walnut scales that I had purchased from Jantz (I think?) quite a while ago. With a soak in Meguiar’s Gold Teak oil, the handle should be good to go until they show signs of wear and dryness again. Once I’ve used the knife some more, I’ll post a picture or two of what it looks like with a patina.

Second Completed Knife (Steak Knife 1)

After a couple failed attempts at heat treating the steak knives two weeks ago, I finally realized my problem. In order to fit my large yanagiba-style knife, I had dropped the lowest shelf to the bottom of my kiln. The two steak knives were resting at the bottom, so they were never reaching the temperature that the kiln thermometer was displaying. After remedying the heating problem by placing the lowest shelf on top of some kiln furniture, I managed to get things right last weekend.

Anyways… there’s not much to be said here. Text is boring, and people want pictures.

Steak Knife 1 Left

The above is the scan of the knife just after shaping and beveling. If you want to make one yourself, just print that at 100% scaling, cut it out, trace it to some steel, and get grinding. I’m assuming most of you won’t make use of that, but it’s there, because people have asked for it before.

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After getting most of the scale off with a file post heat treatment, I switched to using 220 grit sandpaper to deal with smoothing out some of the contours near the front end of the handle. A couple seconds of inattention when shaping the bevels meant a lot more hand sanding later. It took a good hour to get rid of those little lines (grooves in the metal) in the above image.

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The front edges of the wooden handles were again prepared prior to gluing. With a good soap and water cleaning of the steel parts and a quick alcohol wipe on the inner faces of the scales, the parts were ready for gluing.


And… fast forward through a lot more sanding and polishing. There’s a knife! It measures at just under 10 inches.


I was actually pretty pleased with how things turned out. I had thought out pretty much the entire knife, including the handle shape when I first sketched it, so it was good to see how my mental image so closely matched the final product. I will probably have some side by side photos of this knife and the duplicated knife next weekend if I finish the other one up.

Well, thanks again for checking this out, and let me know if you have any questions!