DIY Store Foam Medieval Practice Sparring Sword


One afternoon, like many others, I found myself engaged in an intense battle with with my son on the backyard grass.  This day’s chosen weapons are blocky foam replica swords from some a slightly popular video game.  I decided I’d had enough with trying to have a entertaining battle with things – and if they break? Costly at $25 each.  A new, CHEAPER, more realistic design was necessary.

Now, when I was a kid, we rolled up newspapers as tightly as we could, wrapped them with duct tape and did battle in the middle of our street.  Builder skills varied, and so did the quality of the weapons – if you wanted durability, you had to use a good amount of newspaper. In the end, you basically had to swing these heavy things like battle axes to get them going.

While I thought about going back to this design for our duels; my 32 additional years of building experience led me to a simpler, more nimble design.

COMMON SENSE ALERT!  These swords are not toys.  They will hurt you if someone swings it hard and hits you.  I’d imagine in the right hands it could break fingers or small/thin bones.  Build and use these at your own risk!  Be cool. Don’t hurt people.  These can be super fun if used with some common sense – I designed them to be safe should there be the accidental missed block or something… but we can’t NERF the world people!  Kids need to be kids.  As the authors of The Dangerous Book for Boys [ link] said:

I think we’ve become aware that the whole “health and safety” overprotective culture isn’t doing our sons any favors. Boys need to learn about risk. They need to fall off things occasionally, or–and this is the important bit–they’ll take worse risks on their own. If we do away with challenging playgrounds and cancel school trips for fear of being sued, we don’t end up with safer boys–we end up with them walking on train tracks. In the long run, it’s not safe at all to keep our boys in the house with a Playstation.

So don’t sue me if someone gets hurt, ok?  I already told you it could happen.  Have fun, but be smart.

And with that out of the way, let’s get to building!

You’ll be able to find what you’ll need at your local big box DIY superstore:

  • 1/2″ foam pipe insluation – one 6 foot section should be good for two swords
  • 1/2″ PVC pipe (thin!  see below) – a little over 3 feet per sword
  • one (1) 1/2″ PVC four-way junction
  • three (3) 1/2″ PVC end caps
  • clear PVC cement
  • duct tape – I like the cheaper, off-brand stuff for this project – its thinner and easier to work with.
  • spray paint (optional).  You can leave your PVC uncolored if you want.  I chose to go with gold for the hilt to give it a touch of class and honor

NOTE: get the thinnest walled PVC pipe you can find.  The standard schedule-40 stuff that comes in the shorted lengths near all the fittings is way to thick.  It’ll be heavy and really hurt when someone misses a parry!  At my local store, I could only find the real thin stuff in the bulk area in 10 foot lengths.  Don’t say I didn’t warn you!

Hopefully you have something to cut PVC.  These crazy things work really well [ link].  Avoid hacksaws as they make all kids of nasty PVC dust.  You don’t need to breathe that.  Your store will cut stuff for you for a nominal fee.  They might think your cut list is crazy, but who cares… tell them what you’re making and they’ll probably think its pretty cool.

Cut the PVC into these lengths:

  • 1 piece 26 inches
  • 1 piece 5.75 inches
  • 2 pieces 1.75 inches

First, we’re going to use the three shortest pieces to make the hilt.  Dry-fit the pieces (no cement) before-hand to make sure you like the sizes you’ve cut.  Once the cement comes out, you can’t go back.

The hilt will look like the letter ‘T’.  Take the two smallest pieces and fit them into the junction opposite of each other.  Put the 5.75 inch piece of pipe in one of the remaining holes.  This will be your handle.  You can put caps on the ends of each of the pipes.  If you’re happy with the sizing, you can take it all apart and glue it together.  When I use PVC cement, I like to let the brush drain off for a bit and even wipe it along the inside edge of the can to get most of the excess, drippy glue off of the brush.  Then quickly use the brush to coat the inside of three of the holes in the junction, as well as the inside of each of the caps.  I like to swirl the brush once around to make sure I’ve evenly coated the inside of the fitting.  Quickly put all three pipes into the four-way junction first, then put the caps on the ends of the pipes.  When you’re done, it should look like this (note this one is already painted – I got too excited to finish and forgot to photo document this part of the process!)


Now we are ready to work on reinforcing the foam with duct tape so that it doesn’t split when we slide it onto the 26 inch PCV “blade”.  Cut the foam to a length of 26 and one-half inches (26 1/2″) Start with a 6 inch length of duct tape and wrap around one end of of the foam.  Do not apply pressure to the point that it starts compressing the foam.  You should be able to smooth it lightly on to the foam and make sure there are no wrinkles as it wraps around the tube:


For added strength add another piece of 6 inch duct tape over the tape you just applied.

Continue this procedure down the length of the of the foam, butting each new section against the last.  You can overlap a bit between sections if you’d like.  Try not to leave any foam exposed between the tape wrappings:


Before you get to the end, we want to add a couple tape squares as a cap before we wrap the last bit of the end.  Offset two square pieces of tape on the end of the tube.  Fold down the diagonal ends and hold them down with the last 6 inch section of tape:


And an additional 6 inch wrap of tape over the end:


We are now ready to start sliding the foam on to the blade.  Now, note that in these pictures that I took, I was waiting for the painted hilt to dry – so I ended up pushing the foam on to a lone piece of PVC and pressed it against my belt.  You might find it easier to use the hilt handle with pressure against your thighs for this part.

Put the 26-1/2″ long blade PVC into the open end of the taped foam.  While it’ll be easy at first, it’ll take a considerable amount of effort once you get about half way.  I like to switch between pulling on the bottom end an about the middle of the foam section to move further on to the PVC.  Use your judgement – if you pull too hard on a stubborn section, you may rip the foam and have to start over.  Keep working it until you’ve got about all but four inches of the PVC covered with the foam/tape “blade”.


(here I’m using the open end of the PVC against my belt to push the foam on to the PVC)

As you work it down, you may find that some parts get compressed and are wrinkled.  This is ok, just apply more pulling pressure to the bottom of the foam and it should smooth out.


Wrinkles are ok, they will smooth out.

Now that the foam is mostly pulled down, you’ll add some layers of tape lengthwise to the blade.  Rip a section that is almost 26 inches and pull on both ends to keep it straight.  With this method, you should be able to smooth out the tape to run the length of the blade without wrinkles.  Repeat this two more times, slightly overlapping the last layer as you go.


Add one more width-wise 6 inch strip at the top and bottom of the sword to cover up the fact that the last three lengthwise strips didn’t make it to each end of the blade.  On the open end of the foam, I like to offset it a bit over the end so that it will cover the black part of the blade near the hilt:


If you were working like I did from the pictures, swap some PVC cement on the remaining channel of the hilt and press your blade in.  Give it a minute to set up, and pull the foam all the way to the top of the hilt.


I used a hot glue gun to wrap a small section of fake leather fabric to the handle between the end cap and the junction.  You could do the same, or use electrical tape or paint… its up to you.


Now that you’re done, you just need to build one more and you’re ready for some knight-style sword practice!  Remember: be cool, be smart, have fun!

Smoothing out 3D printed parts

3D printed parts look cool and unique, but sometimes you want them to look like something that isn’t 3D printed.  And to achieve this, you need to cover up or smooth out the ripples caused by  the FDM process.

I ran some early experiments with scratch filling primer, but it took four to five coats before getting the smooth surface I was looking for.  And this took several days between wet-sanding and waiting for the parts to dry.

Not sure why I didn’t in the first place, but I remembered using automotive Glazing Putty when I customized my Jeep’s console to fit a VGA touchscreen.

To apply the putty, make sure you wear some nitrile gloves (the purple ones are cool because you’ll be like Depp’s version of Willy Wonka!).  This stuff is petroleum based and will eat right through regular latex gloves and might do nasty stuff to your fingers.  Anyhow… get a dab on that gloved finger and rub it into the part.  Make sure to rub against the grain so that it fills in the layer gaps.  If you get a little too much on at this stage, its ok… it just means you’ll have to do a bit more sanding at the next step.

Let the glaze dry for at least 20 minutes and then hit it with some 400 grit sandpaper until you see the high points of the layers coming back.  Then I recommend using the previously mentioned scratch filling primer as a base layer and sanding that with a 400 grit before you apply the final color.


Awesome, inexpensive 3D printer filament

I stocked up on a bunch of filament a couple years ago, but my stock is starting to run out.  In the past I’ve mainly used plastic from Ultimachine and Faberdashery – but its gotten quite expensive ($20.00 a lb) and shipping is not cheap.

So I asked a good friend what he’s been buying lately.  He’s quite happy with the filament from Hatchbox. Its almost half the price of the other guys, comes on a spool and is available via Amazon Prime!


Link: Hatchbox filament @

Building the Avonos Classic Stormtrooper Kit [Part 2]

In this installment, I thought I would highlight some of my methods for to allow easier snapping of the parts that have bends and curves.

For items like the arm and leg pieces, there are large curved areas that are tough to get bends started on the score lines. For these areas, as well as corners, I use the snips to create long flat areas that are free for bending and snapping.

Most parts have areas where two edges come together to form a square corner. I like to use the snips to make a cut from the bottom of the formed part right up to the score line. When we do this to both sides, we are left with a straight snap line for easy removal of the excess ABS.

Here I have made two vertical cuts up from the bottom and to the score line at a corner.  This allows for an easier bending of the long strip on the right.


For parts that have multiple angular shifts along a single side, make a cut up from the bottom towards the horizontal score line at each vertical angle line.  Then simply bend and snap each small piece.


On some of the larger pieces, it helps to clear away some of the material from the center to create several separately bendable sections.  You’ll notice on this part of the thigh piece I’ve added additional scoring that will allow me to make very accurate cuts with the snips.


After snipping and removing the corners, use the snips to cut up and near the score lines.  Now you should be able to easily split the sectional score lines up to the horizontal score lines with a light touch of the snips.  Then you can access each new section independently to snap out the excess!



And today I finally finished trimming all the parts!  If you’re observant you’ll notice that I didn’t realize one of the inner upper arm halves was stuck under another piece and didn’t get pictured…

Coming in my next post, I’ll cover test fitting and glueing the arm and leg pieces….

Building the Avonos Classic Stormtrooper kit [Part 1]

So I got my Anovos Classic Stormtrooper kit on Friday.

I’m so happy the helmet was a completed part, as that would most certainly be the most challenging part of the costume to build. The painted details are excellent and I’m quite glad I didn’t have to do it myself.

IMG_1454 helmet approval!


Trimming the parts:

The parts came fresh off the vacuu-form and need to be trimmed and sanded.  With the rare exception, the cut guides were sufficiently  impressed in the part.  Because the parts are covered with a clear protective film, I decided to use a sharpie instead of a pencil to mark the lines that I would be scoring with a utility knife.  This allowed me to easily see that I was scoring accurately, as the cut would expose the white beneath the black line.

IMG_1473  tracing the score path

Using a utility knife (I happen to have this one and I am quite happy with it) I scored the cut line 2-3 times – be extra careful to make sure your repeat cuts are on the same groove of the first score cut.  If not, your parts may not snap as expected.  On the thinner pieces, 2-3 scores,  would sometimes achieve a cut through the entirety of the material.  On the thicker pieces (like the thigh and calf parts), I would recommend 4-5 score runs.  These parts wouldn’t snap and free themselves as nicely at the others without the additional score depth.

IMG_1469 scoring the material

After scoring, I decided some parts with more solid corners need some help before I could bend them enough to let them snap free.  I used a small pair of metal shears to remove the tough corners.

If you’ve properly scored your cut lines, you should be able to bend the material at your cut line, bend both ways a couple times and the parts should snap free.

IMG_1474  bendingIMG_1476 and snap!

Sanding the part edges:

I happened to have some 230 grit GP sandpaper on hand and decided to give it a shot.  It works quickly to smooth the ABS and it turned out to be a good balance between the amount of material it is able to remove and still leave a smooth finish.

If you don’t have any on hand, a pack of assorted grit sandpapers may be a good idea to get you started.  That will give you the options of quick material removal and the ability for a fine grained smoother finish.

Hold the sandpaper in your hand and run then against the cut edge to smooth the edge down to remove any material left on the underside of the score line.  The instruction manual has an excellent illustration of how it should look before and after.

Fastening the parts:

I’m using the fantastic Gorilla Glue CA Gel as my bonding material.  The gel stays put and allows plenty of time to work the parts before the glue sets up.

That’s all I have for this installment.  I still have a few more parts to trim and sand… then I’ll follow up a segment about how I attached all the parts to make the final costume…


40W Chinese Laser: More upgrades

Made some upgrades over the long weekend:

Took out the stock work holder in preparation for the adjustable Z bed. It is hard to see in the first picture, but all but two of the posts were standing about 10% off of vertical. Even the allen screws securing the original work holder were at an extreme angle:



The LED strip lights got installed. If there is any upgrade that adds instant polish to your rig, its this one. The lights look amazing:




Also removed all of the original cooling system and installed fresh tubing. Added reservoir, radiator, fan and anti-freeze:




40W Chinese Laser: First cuts with open-source toolchain

Now, since I haven’t removed the stock work area, and because of the way the machine homes before the cut, I had to rest the test piece up higher than the normal work height. Outside the ideal laser focus width. Therefore the cut width is a bit thicker than if the material was a proper distance from the lens.

Still, I’m pretty happy with the performance – this is an example of a vector drawing:


Digital source:

Screen Shot 2015-09-04 at 9.17.55 PM

40W Chinese Laser: Public Service Announcement: Clean your mirrors and lenses!

Don’t trust that your mirrors and lenses will be even remotely clean.

Remember when I mentioned I saw some soot on the lens carrier? Well, today I took it out for a closer inspection:


And the mirror wasn’t in much better shape:


I cleaned them up with some alcohol imbibed lens wipes:


40W Chinese Laser: Brain Transplant!


I’m removing the stock controller board. The proprietary software is terrible. It is getting replaced with the Open Source RapRep RAMPS G-Code controller. Thanks to the customized Marlin firmware by TurnkeyTyranny, this gives us several new advantages:

  • open source software chain (thanks again to TurnkeyTyranny and the Inkscape G-Code Export Extension)
  • programmatic control over the laser output power (ditching that terrible manual pot)
  • A slick new LCD control panel
  • I’m surprised I’ve not seen this elsewhere, but I plan to use a thermistor in my coolant tank to monitor the coolant temperature. Hopefully I can hack the firmware to stop firing the laser if the tank temperature rises beyond the set threshold.

    I ordered a new ribbon connector and made a new transfer cable to connect to the RAMPS pins. I was too impatient to design and order a wiring harness board, so I just soldered the cable right to the pins on the connector. I covered the contacts with some Liquid Electrical Tape.


    Below is a diagram of the wiring. Thankfully this was my exact power supply, so I didn’t have to get creative. Now, on the RAMPS, the servo pins are marked 2B 2A 1A 1B and the diagram has A- A+ B- B+. Here is the translation:

    A- -> 2B (ribbon cable pin 9)
    A+ -> 2A (ribbon cable pin 10)
    B- -> 1A (ribbon cable pin 11)
    B+ -> 1B (ribbon cable pin 12)

    It’s also not very clear on the diagram, but the XHOME goes on the first Signal pin on the endstop header and YHOME goes to the third signal pin. Even though it shows the 5v and GND going to the AUX-3/SPI header, you can use any 5V/GND connections on the other AUX or SERVOS header blocks.

    The Y stepper cable connects the following colors to pins:

    red -> 2B
    blue -> 2A
    white > 1A
    yellow -> 1B

    I’m borrowing this photo from TurnkeyTyranny’s git repo and putting this here so I can find it later:


    This is not the greatest photo, but some of the wiring choices can been seen here:


    I made sure to test the steppers and homes before I even hooked up the laser fire and PWM controls to the RAMPS board. Once everything was moving as I expected, it was time to test the laser! Something about this screen preparing to push the button had me feeling like a mad evil genius set to take over the world: “FIRE ZEE LAZOOR!”


    As you can see by the burn, the initial tests were a success:


    Now its time to mount the board and get the wiring cleaned up to make room for more upgrades!

40W Chinese Laser: First cuts!

Today I finally wrangled a Windows XP machine back into shape so that I could run the stock software that works with the stock controller board.

I did the test cuts on 1/8″ thick hardboard.

We immediately see the value in having an air assist cutting nozzle. Without one, the exhaust fan pulls the smoke and heat up and across the work.

No problem – a couple hits with the sandpaper and its clean! Not bad for a machine out of the box with zero calibration!

The RAMPS arrives Monday. That’s when the teardown and upgrade will begin. Honestly, I can’t wait, because the stock software provided is terrible! Perhaps I’ll experiment with different power settings in the meantime.

%d bloggers like this: