making Archives - Metro Grade Goods

I recently bought a new Chinese cast aluminum slingshot called the Tiger Scorpion, while the attachment system wasn’t new (I have a few frames with the same style tip), the shape was kind of neat.

So I banded it up with some bb tubes and played around with shooting it..it was neat! I had set it up with a single tube with a ball in the tube end, then after one particular shot, the single tube slipped into the big hole as well as the small hole….bling..lightbulb. I quickly undid the bands and ‘wormed’ it through both the big and small holes, terminating at the small hole. Kind of like the Wave attachment.

Boom, instant OTT single tube attachment…this got me thinking..the Tiger Scorpion, while cool, wasn’t 100% what I liked. What I do like is my Tyton. I have practically packed up everything to send to Peppermack of Cracked Pepper Cataplts, so when the urge and inspiration hit…I was nearly devastated, BUT I have never been so happy to have found two extra cores in my shop.

I took my digital file of the plain tipped Tyton frames I got cut for modding and discovered that there would be room for a big and small hole set up like the Tiger Scorpion, but what I wanted to do was make the smaller hole, even smaller than it was on the T/S so it would be more of a friction fit with no ball in tube needed. Thus the Wormhole attachment was born, and the namesake for this slingshot, the lumbricus terrestris: an earthworm.

I started by gluing up two plain tipped Tyton frames with a blue spacer in the middle. I pinned the top two pin holes with aluminum and peened them into place before flush sanding the face.

I layed out the new hole patterns, a big 5/16 and a smaller 3/32, with connecting channels to the outside of the fork tips. This would allow for single tubes or looped tubes if I fancied it. From there, I shaped the tips till they were rounded and a divot was filed into the top of the tips to center the bands. I also shaped the finger and thumb grooves like my other Tyton mods.

You can see here how the Worm attachment works. Since the band makes a 180 degree turn before rolling over the tips, there is no way the band will slip out.

From there it was time to dress the Lumbri up! I shaped a small bit of ‘patriot’ pattern Kirinite. It was just wide enough to get to the base of the handle. After profiling it, I resawed it into to identical halves and flushed the faces. From there shaped and finsihed the front edge of the scale that touches the surface of the slingshot, like building a knife since you can’t access that area with out really damaging the surface of the slingshot.

After fitting a 1/4 brass tube a 1/8 pin, I decided to try something I’ve seen 1000’s of times on custom knives, the very popular Anso texture pattern, an intersecting series of scalloped grooves. After plunging in for my first couple of grooves, I could already tell this was going to look sweeeeeet.

The Anso pattern is named after Jens Anso, an fellow industrial designer, custom knife and gear maker. Jens first did the pattern and has since been used on many custom knives and equipment. Here he is adding this trademark texture:

Rough cut and shaped scales.

The rest are final pics, I didn’t want to ruin my work flow as the dust from the Kirinte is heavy and gets EVERYWHERE. In the end, I buffed the scales and matt finished the aluminum. I also added a Paduak makers mark and coated it in superglue to seal it up.

Thanks for stopping! See you at ECST 2015!

-Metro

This is a short tutorial and some would consider it a minor detail, but as they say, the devil is in those said details. In this Metro Made, I show you how to I cut band grooves in slingshot tips.

Band grooves are important as they aid in the attachment of bands when using the wrap and tuck method. The grooves also improve safety as they seat the band tying rubber and prevent it from slipping off the tips of the forks. Having evenly space and equally spaced band grooves improves the accuracy of the slingshot as the bands would be tied equally on the slingshot’s fork tips.

How far from the fork tips edge is completely up to you but I generally go with a minimum of 1/4″ish from the edge of the band groove to the tip. It really depends on what kind of bands you shoot, how much band attachment rubber you tend to use…but here’s what I like. I enjoy using single cuts of the thinner Therbands, blue & black, for a lighter draw and faster retraction, as such I don’t need much of a band groove, but I still need one there.

I begin by marking where my band groove’s center will be. To mark them evenly on all the sides of the fork tips with the same distance from the tips, I use my trusty drop compasses.

Here, I’ve used my blue lead to mark. Why blue? It’s the first drop compass I picked up.

I use a very fine tooth razor saw and cut down the line. With the a lot of teeth per inch, the razor saw won’t cut much but the surface of the metal or wood, but the point isn’t to cut the through the tip, just to make the blue line indelible.

The blue line is no more, but replaced with a shallow, straight cut.

I then pick up a triangle file and seat one of the tips and pull 4-5 stokes to deepen the line into a shallow groove. You want to open up the material so that a round file will have a place to sit in and not skip around. I typically use a 1/8″ diameter round file but if you want a bigger one like a 3/16 or 1/4 groove, you may want to go a bit deeper with the triangle file to ensure the larger round is placed accurately.

Remember, slow is smooth, smooth is fast. You can check your work after each stroke or two, if you mess up, you can correct it.

Now for the real magic.

Use the round file to open up the channel to a round groove. I usually don’t go past 1/2 the depth of the file, approx 2/5 of the way. Again, slow is smooth, smooth is fast. Check your work as you go, if it’s deviated left or right, you can correct it.

After about 10-12 strokes with the file. If there is any material blowing out the back side, you can run the file in the opposite direction to clean it up.

Now do this 3 more times and your band grooves are good to go!

You could also do this to the front and back of the frames, but I usually don’t.

A better look at the whole package.

In case you were wondering, the frame is a new aluminum core we have yet to release, based on our Tyton design.

With some Theraband Black tied to it, a 15mm-10mm tapered cut at 7.5″ active length, my formula for deadly fast bb bands.

So that’s it.

A quick demo of how to cut accurate band grooves on pretty much any board cut style slingshot.

Thanks for reading!

-Eric

Tag: making

Metro Made | The Wormhole Attachment (Lumbri Tyton Slingshot)

Metro Made | Cutting Band Grooves in Slingshot Forks