One Day Builds: Ginkgo Prints for the Holidays

 

    These prints were a fun distraction from my normal technical pursuits. A career as a mechanical engineer and a lot of hobbies and projects involving engineering means I spend a lot of time with numbers and dimensions. Tweaking millimeters on a design so it looks just right, fits perfectly, and has the correct balance of weight and strength. Its fun, don't get me wrong; I'm lucky to make a living doing something I enjoy and that comes easily to me. It can be exhausting though when even your artistic expression involves chasing dimensions and tolerances (see my posts about the necklace build or spoon build).

    I've been having some technical burnout in my life recently. It just adds up. So, spur of the moment I decided to do a wood block print as part of the holiday gifts I'm making this year. A future post will cover the rest of the gift, but I wanted to write a bit about these prints.

    Nothing about these prints were really planned or ideal. The wood block is a scrap of plywood from furniture making. I don't have any chisels so I carved it with an X-Acto knife. The shape of the stem was determined by the need to fit it on the wooden block I had. No ink or ink pad, so I just used a Sharpie to ink the block. I thought I might get some nicer paper to print on, but instead I decided to reuse some paint samples I had from painting my apartment, trimming them square. 

    In some ways it reminds me of the engineering adage 'a good solution comes from a well defined problem.' Often it can be the easiest to work under strong limitations; it really narrows down what you can do and you don't waste time with all the 'what ifs' or 'we coulds'

    My home office is my dining room table which I share with my Ginkgo tree, Ola. As the seasons progress she has been dropping her leaves and it reminds me of walking in Oberlin, Ohio; a town a grew up near. I have fond memories of walking the Ginkgo lined downtown streets in fall, the air filled with the smell of rain and wet leaves, stepping into Ginkgo Gallery to look at the works of local artists.

    Tracing a fallen, golden leaf, a loose sketch guided my carving. Having a leaf to study was immensely beneficial to get the vein structure looking right; they curve differently than I really expected. Though I suppose this is part of the exercise; to learn about the little details you thought you knew and therefore overlooked. Carving random veins with no particular patterns is not trivial. I look at these prints and see the order I carved the veins in, and the subtle patterns those create. Thinking you're being clever by alternating the sides you branch new veins from and trying to be random and unplanned, only to see the distinct areas you worked in order. It reminds of the shading and crosshatching of artist Mary Azarian, or of the detailed hair of traditional Japanese wood cuts. It is doubtful any of my family and friends receiving these prints as gifts will notice, but it tells a story.

    A lot of the time I can get stuck in the analysis paralysis. A simple idea can turn into a complex project and before you know, you are never going to finish and its never going to be perfect. I liked this project because I really gave myself permission to not be perfect. To not over analyze and to not have a plan. I feel it really adds to the artistic expression; you're driven by instinct and intuition, rather than logic or experience or facts.

    Of course this approach isn't always appropriate, but here it was very relaxing. 

One Day Builds: Micro Tripod

    Growing up I had one of the little, flexible "Gorilla" tripods. It worked alright but after a year of light use, some of the ball sockets cracked (made of ABS) and the legs no longer held their shape. The unit was also very bulky given what it could do. This past year at work, I was setting up a coolant manifold on a milling machine and the LocLine I was using reminded me of that old tripod. I had a planned a hiking trip to Vermont coming up and had been thinking about buying or making a tripod to shoot some time lapses.

    I threw together this little tripod in maybe an hour. It's printed on a FormLabs Form 2 in their Durable resin. I had wanted the LocLine to snap into the printed hub, which it does, but the printed material creeps too much over time and the LocLine flops around in the socket; it doesn't stay in position. I solved this by epoxying the first section of LocLine to the printed part. The screw on top is just screwed into the printed part, into printed thread. The short legs work well for most situations, and can always be extended if I feel the need for longer legs. Made of delrin, the LocLine shouldn't see any degradation over time, even if used in the Sun a lot. It's also easy to buy anywhere in the world. As it turns out my phone is much better at taking time lapses than my camera, but luckily the tripod is versatile.

One Day Build: Strong Indicator Arm

For a while now I have been using one of these ubiquitous Swiss made indicator arms. It works okay but I've never been fully happy with it. They have too many joints and too much wiggle for precision work. Even on the best units I have seen problems with the indicator alignment when indicating small holes. The dovetail isn't perfectly radial with the stem and it side loads the contact point.

I wanted a better, simpler solution. I came up with this single pivot arm inspired by some cheap indicator arms I've seen. The clamp plates are hardened A2 and the shank is 60 case Thomson rod. The spherical surface on the clamp plates were surfaced on a CNC and match the spherical indents on the shank.

The screw is kinda cool. Its a standard SCHS with a little plastic knurled knob pressed on. I didn't know these existed until one of the toolmakers I work with bought some a job. The clamp gives just enough friction on the joint that it wont be knocked out of place, but can easily be adjusted by hand.

The little spring on the front of the clamp is just there to hold the clamp plates on the shank and the dovetail open when the indicator is not on the arm. Right from the start the radial alignment wasn't perfect. This this design, that alignment is easily adjusted by grinding the faces of the clamp plates to affect the angle the indicator is held at. With a bit of fiddling I got the contact tip to less than 0.25mm radial misalignment. 

This isn't a perfect solution for every application but it works perfect for any time you need an indicator in a mill spindle. Going forward I would make a second one of these with a 10mm reduced shank for using in my small drill chuck.

Example of the suspect indicator arm. Photo from wttool.com

One Day Build: Gale Crater Topographic Model

This project was inspired by a kick starter project I found where backers were funding large scale models of the moon (500 mm dia.). The models (which were castings of a high quality 3D print) looked stunning, especially when lit. Poking around out of curiosity, I found NASA has a substantial collection of 3D resources available here including 3D models of spacecraft, satellites, asteroids, comets, and Lunar and Martian surfaces.

I decided to carve a small model of Gale Crater, the current location of the Mars Science Laboratory. The model from NASA had a 3x vertical exaggeration, which I reduced to 2x. Made out of a scrap of PVC, the model is around 200x150 mm. It ran on a machining center overnight and took an estimated 16 hours. It was supposed to run faster, but motors on this machine are very low torque, so the feed rate is dynamically throttled to ensure the axes won't overshoot. All mesh editing and programming I did in Fusion360 and it ran on a Trak 2 Op.

As a result of mesh reducing, the model has a beautiful, faceted effect

   

Homemade Carbide Shank Boring Bar

    This project originated from a scrap find. In our carbide scrap at work, someone had blown up a long reach carbide end mill. Only the flutes were damaged and a considerable length of untouched carbide was left behind. Being a pack rat who found a large piece of his favorite material, the carbide shaft went into my tool box for a future project. At the time I didn't know what I was going to do with it.

Finished Boring Bar

   That was well over a year ago and not much happened with it. I had decided early on I wanted to make it into a carbide shank boring bar. The boring bar decision came out of a frustrating boring job on the lathe where I didn't have a good boring bar in the right size. Boring is one of my favorite operations but it can be finicky without a good bar. Work doesn't have and good boring bars. Carbide shank boring bars are the bees knees but are well outside my price range. Looking around online, many bars use odd or proprietary insert designs, or don't have a good selection of insert grades and geometries available. I do high mix work so the ability for one tool to preform well in a range of materials in critical. 

    With my first bar design ideas, I chose CCGT21.5 inserts because they are inexpensive and meet my generalist criteria. With some quick 3D models and a plastic prototype, I saw that it wasn't going to work. The clearance between bar and wall was too tight and insert pocket shape was less than ideal. I didn't save any of the models, prototypes or programs from that first design so I can't show it here.

    Shortly after this prototype, life got busy and I put away the project for a long time. Only recently, my schedule opened up and some A2 landed in my lap so I decided to give it a second shot. This time around I chose to use DCMT21.5, which are also available in a wide range of geometries, coatings and grades, and come with the added benefit that my workplace stocks them. Starting with the insert pocket and working out, I iterated through two versions to have a final design. I scrapped my first design after my modeling program broke down trying to handle blending all the curved surfaces I generated.

Model of boring bar head

    I did all design and programming in Fusion, mostly due to it being my CAM platform and an integrated CAE package is hard to pass up. Unlike my first attempt, the insert pocket walls on the final design have a 7 degree taper to match the insert walls. I had to make a decision on the joint between the steel head I was making and the carbide shank; notched or tapered. Some feature had to be made to increase the surface area for the joint. The notched joint has the benefit of simplicity, but leaves a translational axis of movement that needs to be monitored during assembly. The tapered joint restricts all axis of motion and is easier to form on the shank, but greatly complicates the machining of the head. 

    The biggest influence of the solution came from the bond type. Most bars use a brazed joint, with is preferred. I lack the experience and proper materials to effectively and cleanly braze carbide to steel and I wanted to finish this project. I decided to try something new and glue the head to the shank. Loctite 380 is well known for its high strength and impact resistance so I thought I would try it. The notched joint ends up having slightly more surface area than the tapered option I modeled. The notched also has the added benefit of a large part of the joint being subjected to high shear loading, which glue is strongest in. Some quick math suggested with my chosen geometry, the joint can support ~100kg of down force on the tip of the cutting tool. I don't expect to ever exceed. My only long term concerns with the glue joint is heat resistance. In a heavy cut with no coolant there is a chance the joint could become hot enough to fail.

Checking insert fit before cutting head off from stock

    If this happens I'll just glue it back together and keep using it. This whole bar was supposed to be a fun project so why not try something totally new. All the machining was programmed in Fusion and run on a Trak 2Op. The 2Op is an interesting machine. Its sold as a VMC that can be moved on a pallet jack and it has a great, compact work envelope. While intended for secondary and finishing operations, we use it at work for primary work because its rare we do more than 6 of the same part at a time. 1000mm is great in X if you are doing mold and die work, but when 95% of your parts fit in a 300mm cube, you don't need a huge machine. I love its compact size and the fact it has a tool changer for such a small machine. Despite this, the machine steel feels a bit 'hobby-ish'. Something more professional than a Tormach, but greatly lacking in some obvious areas. A 15k spindle, 25000mm/min axes, and a more powerful control and coolant pump and I would buy one. 

Operation 1 after roughing

    Tooling selection was pretty standard; an assortment of small, carbide endmills. My design did require a 7 degree/side tapered endmill. This wasn't explicitly necessary - I probably could have gotten good insert registration on square walls - but if its worth doing its worth overdoing. I ground a single lip tapered cutter on the surface grinder. The HSS blank used was an old tap from a job several years ago that I have been carrying around with my tools ever since; good to finally put it to use. A custom tool presented a problem for CAM programming; tool tip diameter. I took the tool on the optical compactor and measured both the angle of the cutting edge, and the diameter reduction from the shank. This allowed me to model the tool in Fusion and program the contours. I started out leaving material on the walls, and then slowly cut the walls back checking the insert fit relative to the locking screw hole until there was a perfect fit.

Custom ground cutter, HSS has the advantage that I can easily sharpen it

    After machining, it piece was shined up a bit with a sanding sponge and files to give a pretty snazzy looking part. The harder part was chopping the head off of the parent stock and adding the notch. Cutting off, easy on a band saw. To cut the notch I decided to set up on the surface grinder and plunge grind it. There is barely enough flat land next to the insert pocket and before the angled wall to clamp on, but I managed it. The ground notch was just centered by eye and checked against the carbide shank.  

    The vice in vice method of compound angles is by far my favorite. Its clean and easy. To set my 45 degree angle, I clamped this little 90-45-45 square I made to the jaw. For the grinding a dressed the side of the wheel square with the face of the wheel by clamping a diamond to the side of a block and traversing across the wheel.

Grinding set up

Homemade 45 degree square setting the angle

    This wrapped up all the machining operations and it was off to hardening. I brand all tools and projects I build for myself and this was no different. I hand engraved a small version of my logo above the insert pocket. I hardened the head with a MAPP gas torch. For such small parts, naturally aspirated torches have enough Watts to heat the part evenly. Naturally aspirated torches also have the advantage of producing a neutral flame. Oxy-acetylene torches - having oxygen forced into the flame - have the possibility to be oxidizing flames, that is you can supply too much oxygen for the stoichiometry of burning acetylene. This extra oxygen reacts readily with the hot metal and causes pitting and damage to the material surface. This doesn't happen so readily with naturally aspirated torches. 

Back side of the finished bar

    Oxides still formed on the surface of the head but they were very even and didn't damage the surface. I really quite like this matte grey finish the heat treat left, and it stayed through tempering. A quick clean up on the joint surface and some glue and the project was done. Eager to know if it worked, I bolted it up in a tool post and gave it a test cut. It preformed as best as I could have expected. 1 mm radial cut in aluminium at 7 x D overhand and not chatter. Light finishing passes caused chatter but I honestly attributed that more to a old, sloppy lathe and poor tool holding.

    I don't regret working on this. It was a lot of fun and I have a great tool at the end of it. It also gave me reason to exercise some of my little used tool grinding skills. Hopefully this tool will last for years to come.    

One Day Builds: Kinetic Necklace Update

       This is somewhat of a follow up without an original so bear with me. I started making kinetic jewelry around 2012 after being unable to find any satisfactory steampunk jewelry. Everything I found was just plastic gears or old watch cogs glued onto some sort of base. As en engineer, I couldn't stand it. I have always enjoyed the work artists like Chris Fitch, Arthur Ganson, and Theo Jansen; for me, if art has gears they have to move.

The updated, machined necklace (not when I was 12)

       This was when I was 16. I had no experience with gear design, no machining or jewelry experience, and I decided I would have to make what I wanted. I used Matthias Wandel's Free Online Gear Generator to generate the involute patterns to which I added spokes to by hand. Frames and bridges were all drafted by hand. Using a my grandfather's old files and improvised tools, I cut the gears and frames out of unfolded copper water pipe and riveted the parts together with recycled building wire.   

       I only made 5 or 6 pieces, only one of which has left my possession. Looking at them again they are far less precise that I remembered them, but this combined with their recycled nature gave them a certain style. 

       How does this relate to a one day build? Fast forward 4 years and I chose to make a few more, and this time all out on the technology. The involute gears I used before would jam frequently due to low their low precision, even with a very high pressure angle. The high pressure angle also resulted in pointy teeth. I designed a totally different type of gears for the new pieces, based on a ring of evenly spaced semicircles. Alternating semicircles would be peaks and valleys of the gear. These are not suitable for power transmission but mesh very smoothly and are do not pinch or poke in any way. They also can be machined easily. 

The design of the new gears in 2D CAD

       This post really contains two one day builds. The first was the machining of the original necklace. The four pieces were machined on a Tormach and programmed with Fusion360. As much as I criticise the small Tormach mills, they do get the job done for small, slow jobs. I avoid our's when possible but if its the only machine open, you make do. I had intended to make a post about machining the components at the time but I never got around to it. The final piece measures only 20mm wide and is made out of 7075 aluminium and 932 bronze.

       Finally to the actual title of the post, the update. The client this was made for enjoys fiddling with necklaces, well suited for my work. I unfortunately underestimated just how much they would twirl the gears and the loctite joints holding the cage together came loose. Thrice. I decided to drill out the integral pins and use thread to stitch the cage together. I had originally intended to drill the pins and use them as integral rivets, but didn't have the proper tools at the time. 

Indicating the integral pins. 2mm dia. 1mm tall stepped to 1.5mm dia. 0.5mm tall

1mm drill 

       While I had the necklace I cleaned up some of the corrosion and took some better photographs. Speaking to this design and project overall, I am very please with the result. The scale especially makes it attractive, but it also means I probably wont make pieces this small again. If I did this again in the same or similar size, I would use a more durable material for the cage and use a more permanent connection. 

 

One Day Builds: Center Punch

    This post is the first of what I hope is many to come. Because I am a full time student, and work 20 hours a week, my shop time has been greatly limited. This is why I have been posting articles about design work rather than shop work. I don't like being away from the shop for fun this long. While I do work there, helping students and doing job work isn't the same as fun projects.

    Most days I have an hour or two between classes that I use for studying, napping, or otherwise killing time. I hadn't previously considered using this time for shop work because it was only an hour or two; not long enough for the setups most of my main projects use. I decided to try the idea of a One Day Build, similar to what Adam Savage does for Tested. The premise is you try and build a smaller and simpler item in one shot, one day, finished product. I expanded on this idea a bit to include smaller projects with simple setups. With simple setups, I can quickly set up and clean up in the small periods of time I have.

    The idea for the first One Day Build came from a broken tool. I was at work rifling though drill bits, sorting strays and looking for dull ones to sharpen. I found a bit on the larger side with the tip absolutely destroyed. Oddly, the bit didn't have any heat damage so I can only assume someone was drilling composites with it. It turned out it wasn't just the tip that was destroyed but both margins too. Dulled, chipped or melted tips we can repair, worn margins we can't.

    I always hate throwing out tools, even when they are broken. So much time and resources went into making that special piece of metal only for it to be thrown away one day. Always seemed like such a waste. I decided to save it and find something useful to make with it. That useful thing ended up being a center punch because I didn't want to store the drill for a long time.

    I began by chopping off most of the flutes. This was a task in it's self. The abrasive chop saw did not like the HSS. It finally cut through and I was disappointed to see the web wasn't as big as I would have liked it to be up near the shank. Moving forward anyway, I roughed out the taper on the bench grinder and then moved to the surface grinder. I used a spin index tilted on a magnetic sine plate. I wasn't super concerned about the dimensions of the punch, so I eyeballed everything.

Finished center punch

     I set the sine plate with a few pieces of scrap to get it to match the rough grind I had done. The surface grinding went quick. When roughing, I use a .01 inch (0.25 mm) cut with .01 inch (0.25 mm) step overs. This is my preference, I understand there are many schools of thought with grinding, this is what I use. This is a low precision tool so I used the same 46K wheel for my finish pass at .0002 inch (0.005 mm) as I did for roughing. I didn't even bother redressing.

    For the struck end. I did some quick chamfers and a flat end. Again, no measurements were taken. The shank is relatively soft, so I don't know how it will hold up over time. I'm happy with how this project turned out. I really like the look of the remaining flutes on the taper and the drills size still visible. HSS isn't the advised material for centerpieces, but I couldn't find anything saying don't do it. I guess because there is no heat build up in center punches, no one ever tried to make out with HSS. Even if this tool only lasts for a year or two, its still worth it as I didn't have to throw something in the scrap bin.

A ghost of a previous life

    Sorry there aren't any photos of the process. Because I'm short on time when doing these things, I don't have time to take lots of photos. In the future I'll try to do better.

.David.