I have been experimenting with making fiberglass parts for my upcoming Kansas City Maker Faire Project. To help others who are intrested, I made this short video documenting my process.
In recent weeks I've become more interested in milling three dimensional molds Using Fusion 360. At Hammerspace I have access to two 3 axis mills, my personal 1 meter square Inventables X-Carve, and a 8 foot by 10 foot frankenstein of a machine that I've taken to calling 'The Beast'.
The Beast had a cutting area of approximately 10 feet x 8 feet x 2.5 inches deep. It is really more of what is called a 2.5D CNC machine, intended for cutting slots and tabs in sheet material like plywood and aluminum. This machine had been lobotomized and rebuilt around a Mach3 controller, so it is capable running G-Code directly from Fusion 360. I'm going to use The Beast for some of my experiments, but to mill anything more then 2.5" tall, I'll need a different tool.
The X-Carve is an inexpensive tabletop CNC carver intended for enthusiast and light duty work. It's working area is 3.2 feet x 3.2 feet x 2.75". The X-Carve has its quirks, but i've had good luck running 3 dimensional G-Code exported from Fusion 360 on it. Like The Beast, this machine is intended to be a 2.5D carver, but with a few advantages. This is my personal machine, so I can freely make modifications to it, and the X-Carve is open source, so all the files and drawings for it are available on Inventables GrabCAD page.
For the first stage of the Modifications to this machine, I'm going to add more z-clearance between the bottom of the X-Carve's gantry and its spoil board.
The easiest way to do this, is to replace the four corner brackets at that connect the Makerslide rails to the spoilboard's frame with taller one. I downloaded the drawings for the original brackets from GrabCAD, and added three inches to their height in Fusion 360. The new brackets were cut out of 1/4 inch thick aluminum plate on The Beast. If you'd like to create your own extra tall brackets, you can download the DXF files for them HERE
Until next time, when we'll adjust the reach of the Z-Axis to take advantage of all that newly added depth.
Thanks for Reading!
Long ago, there was a simple plugin for SketchUp that would make Involute Gears quickly and easily. Called 'gear.3.rb' I used it on countless simple mechanical projects.
Recently I wanted to revisit one of those projects, and found that the original download site for the plugin was gone. So I dug the script out of one of my old SketchUp installs and discovered that it won't load into SketchUp 2015. It looks like there is an error in how the plugin adds itself to the menu system.
I pulled the Ruby script open in TextWrangler, and found the UI section. It looks like the code is using and out of date function to add itself to a UI menu that doesn't exist in newer versions of SketchUp...
A quick search of the SketchUp Ruby resources led me to the documentation of the Menu Class. It looks like the class was simplified at some point, and this plugin never got rewritten to use the new tools.
The Fix to get gear.3.rb working again seemed straightforward. Rework the UI.menu items in the plugin's Ruby script to match the strucure of the updated commands. To keep things simple, i'm just going to add the two commands from the Involute Gear plugin to SketchUp 2015's 'Tools' menu, and add a menu separator to make them easier to find. Based on the Ruby documentation, the changes were straightforward.
Nothing left now but to Save the script, reload SketchUp, and check the Tools menu...
Holy Shit... It worked.
Did I mention I have never written or modified a Ruby script before in my life?
A big thanks to Doug Herrmann, the original author of this plugin. I don't know where he is now or why his site is gone, but I'm happy I've found a way to keep the tool he created running.
Sunday Night at Hammerspace, We cast an Aluminum part from 3D Printed PLA original. While it didn't go 100% as planned, I'm excited to try the process again in the future on other parts!
A Big Thanks to Dave Dalton and Hammerspace for helping me make this happen!
This Week we're to look and a 3D Fabrication technology that is a little outside of my wheelhouse. 3D Milling. We'll be using Fusion 360 to generate 3D Toolpaths and carving them from pink insulation foam on my Inventables X-Carve. It's going to be an adventure!Read More
This week we’re adding a generator to my old 3D Printed Wind Turbine. Which method will work better? A DIY built Alternator, or a repurposed 3D Printer Stepper Motor?Read More
For two years a 3D Printed axial wind turbine has been happily freewheeling on the fence outside Hammerspace. We call it our Whirlygig, and the constant Missouri wind really gets it going. Now it’s time to turn our whirlygig into a source of electrical power!Read More
Every once and awhile you have to do something completely ridiculous, like cast yourself an army of Chocolate Terracotta Warriors…Read More
This Steampunk Inspired Battery Jar has the space and voltage available to run my reproduction of an 1880's electric motor patent model.Read More
While hunting through boxes recently, I stumbled across my original 1994 vintage Simcity 2000 3.5in floppy disks. Today, we will build a unique force perspective shadow box to display them.Read More
The stock of the Pulse Rifle is, at its core, a piece of metal u-channel with a slot pattern cut into it. The stock extends forward under the rifle's body work and it's mounted to the top of the Thompson's upper receiver.
It took me a little while to realize the slots in the stock are not purely ornamental. The slots on the top are close to lining up with the holes where the Thompsons rear sight use to be attached. Our Stock will be designed to be bolted to the Thompson through these holes.
To verify my measurements of the Thompson, I printed the test objects I created in the last step and fitted them onto the gun's body. I had to modify the 3d model a bit and reprint a few times to get the fit I wanted. It was time well spent, now I know my 3d model is accurate and how much allowance I need to incorporate between the Thompson and the final printed parts.
I doubled the thickness of the stock's walls in comparison to what's in the reference model. The extra thickness will add strength to the stock and make it less brittle, a critical improvement for a part 3d printed out of PLA. The cutout in the right front of the stock lets the Thompson's charging lever move freely. The inside of the stock, the part that touches the Thompson, is shaped to match the geometry of the test piece I printed earlier, so I know it will fit in place properly.
The final part is a 278mm long and will barely fit onto the 285mm x 153mm build area of my MakerBot Replicator 2. To add strength to the finished part I set it to print with 4 outer shells and 50% infill. I also turned the stock to print at a slight diagonal, so that the layer lines on the flat surfaces wouldn't be running parallel to the direction of force.
The final printed stock fits marvelously. Its not so tight that its deforming the plastic of the Thompson, but there is good surface contact on all sides. Ther charging lever can move freely into the slot without any problems and the higher print density made the part really strong.
For now, i just used two bolts to hold the stock in place. They pass through the slots, through the sight mounting holes, and into the upper receiver where nuts hold them in place. There are many advantages to this over just glueing the stock on. I can adjust its location, remove it for sanding and painting, and easily replace the stock if it gets broken.
Next up, The hard part, building the primary body components!
Before proceeding with the rest of the pulse Rifle, I'll need to spend time looking closely at the Airsoft Tommy gun I'm using as the base.
To start I'll need to remove the Thompson's stock, foregrip and rear sight.
The Stock and Foregrip are each held on by 2 screws. Unscrew them and the parts pull right off. The gun's battery is normally housed in the stock, so i'll have to reroute those wires and create a new battery holder somewhere in the rifle.
Removing the rear sight was a bit more tricky, involving removing the upper receiver and unscrewing four small interior screws. With the grenade launcher and the reference model, we can start to see the basic shape of the pulse rifle.
I need an accurate digital representation of the Thompson to work around as I model the body of the pulse rifle. With calipers and a bit of patience, I reconstructed the Tommy Gun inside sketchup.
I didn't bother measuring and modeling the pistol grip, because there is no part of the Pulse Rifle body that touches that area. No need to waste time accurately creating something I won't need.
The most important parts of my digital reconstruction are the places where the Pulse Rifle body will touch the Thompson. To confirm the accuracy of those areas, I created test geometries to 3D print and fit onto my real world Thompson. If the parts fit, my measurements are accurate, and I can get started on the hard part.
In the original Pulse Rifle the underbarrel grenade launcher is a shortened, repurposed pump action shotgun. To simplify this project, and because airsoft pump action shotguns are surprisingly expensive, we going to use the Launcher from the Thingiverse 3d Model as a substitute.
I adjusted the Pulse Rifle 3d Model to the correct scale using measurements from the Airsoft Tommy Gun and cut the launcher away from the rest of the rifle. A little clean up work later and we have the launcher as a single solid object.
To fit the 350mm long Launcher into my 150mm tall MakerBot Replicator it has to be cut into 3 parts using SketchUp. I also added attachment pegs to each section to simplify reassembly.
Front and Rear sections of the launcher are easy to print, but the center section will need support material. MakerBot Desktop’s supports are a pain in the ass, so instead I'll use Meshmixer. Meshmixer lets you create minimal supports only where you needed them. They work great, are easy to remove, and are much more efficient.
Estimated Print Time with Makerbot supports, 11 hours.
Estimated Print Time with Meshmixer supports, 6 hours.
The finished launcher looks great. A little modeling putty and some sanding will have it ready for paint in no time. Unfortunately, something is off. Look closely at the small reference model I printed on my Form 1+.
The Thomson's barrel is about 30mm too short. Damn.
After rechecking my measurements, I have to conclude the original Pulse Rifle didn't use the stock Thomson barrel. I'll have to look into ways to fix this.
There are dozens of Pulse Rifle kits available and sections of the Replica Prop Forum dedicated to building them properly. I however, being a bit of a design masochist, am going to build it my own way. I'm not breaking any new ground, every conceivable permutation of Pulse Rifle has already been done, but this project is just for fun.
From my research, I know the original Pulse Rifles were made from World War 2 era Thompson submachine guns. If you look closely at the gun Ripley is holding in the screenshot, you can see the charging handle, ejection port, upper receiver, and barrel.
Or you can just trust me... Its in there.
I’m going to start my build from an Airsoft replica of a WWII M1A1 Thompson. Starting here will simplify my build by giving me something with known dimensions to work around. As a bonus, the final creation will fire Airsoft BB's. I'm also going to use this 3d model of a Pulse Rifle from Thingiverse as a guide. It’s the same 3d model Freeside used to print their rifle, and it will save me a lot of time working out the weapon’s proportions.
I recently had the pleasure of hanging out with the awesome people at Freeside, Atlanta’s Hackerspace. We were lucky enough to be in town for one of Freeside’s ongoing cosplay group build nights, where they are building equipment of a squad of Colonial Marines from the Aliens. I got to help sand their pulse rifle master…
Which reminded me…
Long ago, during high school in Alabama, I wanted to build a Pulse Rifle. At the time I was interested in so many things and didn't have a clue how to do them. I also didn't have any money, and was a little worried how my parents, dyed into wool anti-gun new englanders, would respond to their son building a sci-fi machine gun in the basement.
But now I'm an Adult, with an income, and a bunch of 3D Printers…
So I'm going to build my own very own Pulse Rifle.
I'll post updates and files as I work, so you can come along for the ride.
In HG Wells ‘War of the Worlds’ the HMS Thunderchild is only human creation to defeat a trio of Martian Tripods. The ship, described as an ‘iron clad torpedo ram’, charges three Tripods attacking a of fleet London evacuees at the mouth of the River Blackwater. Thunderchild rams one Tripod, destroys another with her guns, and consumes the third when her boilers explode.
The story of the Thunderchild is romantically British. A brave Royal Navy ship sacrificing itself for King and Country. What makes the story even more intreseting is that the ship is a Torpedo Ram, which is something of a historical fluke.
Torpedo Rams where an extremely short lived class of small warship in the 1880’s. They were small heavily armoured ships intended to attack enemy battleships at high speed with torpedoes and, if that failed, ramming. Like most novel weapons, they were great at capturing the public's attention and not much else. Only one was ever build, the HMS Polyphemus, and War of the Worlds is the only depictions of a torpedo ram in action.
For my version of Thunderchild I drew inspiration from the SMS Beowulf, a German ship and really life contemporary of Thunderchild. Launched in 1890, she would have been in the prime of her career during the 1899 War of the Worlds. The ship had a sloped hull and a bow with a reversed rake, broadly matching a torpedo ram’s shape. Beowulf’s artillery was mounted in twin side by side turrets, an anachronistic features that places the design firmly in another time.
Modeling the Thunderchild
Most of the ship is simple polygonal shapes, easy to model in Sketchup, but the hull presented a some special challenges.
The center section is a simple extrusion. I used Fredo 6’s ‘Round Corners’ plug-in to start the curvature of the bow and stern, then stretched the resulting geometry into shape with Fredo 6’s ‘Scale Tools’.
To create the reverse rake of the bow, I drew the basic curve and used Eneroth’s ‘Upright Extrude’ plugin to extrude it along a path while keeping the direction of the curvature constant. I intersected the resulting shape with the hull, and cut away the excess.
The ships stern proved to be more challenging. I made a section of the hull into a separate group and squashed it with Sketchup’s scale tool to create the bottom of the aft deck. (blue in the illustration) The transition between the hull and propeller is an extrusion of the hull profile along a path using ‘Upright Extrude’. (Teal) The final part is the proper shaft tunnel, which brings the two sides of the hull together and hides some of the less optimal parts of other shapes. (Magenta) Once I had all the geometry, I intersected the shapes and cut away the excess.
The rest of the modeling was straightforward. I used the basic sketchup tools to create the upper decks, superstructure, armaments, and lifeboats. The only exceptions are the three large turrets. They started as cylinders that I used Fredo 6’s ‘Round Corners’ and ‘Scale Tools’ to bend into shape. Everything was build as components, then exploded and attached together to make a single unified mesh.
Printing the Thunderchild
For this project I used a Formlabs Form 1+ desktop SLA 3D Printer. Desktop SLA printing is great for small highly detailed models, but is limited to smaller build sizes. The Thunderchild model is 200mm long, which puts it at the upper limit of what is possible with a Form 1+. I had to position it runing corner to corner at about 45 degrees to fit it into the build volume.
I used Meshmixer to hollow out the interior of the ship add drain holes in the stern. Hollowing the ship makes it more efficient to print on the Form 1+, and the drain holes let excess air and resin escape. The support structure was created by Formlabs Preform software. Print time at 100 microns is about 6 hours.
Removing the support structure was tricky, some of the supports where larger than the parts of the model they were supporting.
I gave the ship a quick coat of gray primer to even out the color and bring out the details. What amazes me about SLA printing is the level of detail you can get. The small cannon barrels are less than 1 mm in diameter. The little detail like stair treads, ventilators, and lifeboat dericks really bring the ship to life. Its not hard to picture a tiny crew running to get the Thunderchild ready of battle.
Download the Thunderchild from Thingiverse and print your own!
Thingiverse Link: www.thingiverse.com/thing:775961