Even Distance Divider Tool

Ruh-ruh-ruh Remix!

So sometimes I want to be lazy and don't want to math when laying out a project. Judge away, but you know you've been there too...

An then... I found out there is a tool that can evenly space things 4 you! I must have one of these...

Woah, they cost how much ?! (affiliate link) That's ridiculous... They don't look that hard to build, it's like 3 different parts and some bolts?! I'd even bet someone else has already done it. To the internets!

Score! Turns out Mikeasaurus has an Instructable for a similar version of the tool I'm after! https://www.instructables.com/id/Equidistant-Layou...

So I built one (Thanks Mike!).

And then I broke it (I know, I know, this is why I can't have nice things...)

Getting the rivet tension right is tough. That's my excuse and I'm sticking to it.

However, it was a really useful tool to have before I broke it. I still want one! So I took the basic geometry from Mike's tool and made my own, replacing the rivets with chicago screws. (affiliate link)

OK, intro over, onto step two!

Post contains affiliate links to the products I used to create this instructable:

Tools

1) Laser cutter

2) Digital calipers

3) Computer with design programs (I used Fusion 360 and Inkscape)

4) Some way to hold the material to the laser cutter bed (I use magnets covered in tape)

5) Screw driver

6) Medium grit sandpaper (Side tangent - Is sandpaper a tool or material or both?!)

7) Hobby knife or razor knife

Materials

1) Cardboard (for the prototypes)

2) 1/8" plywood or MDF (Make sure it's laser safe. 3mm thick wood works too)

3) Polyurethane spray (Not required, but protects the wood and gives it a nice finished look)

4) Chicago screws (Common in leather working)

1/4" (6-7mm) length for the 2 part stack

3/8" (9-10mm) length for the 3 part stack

5) Blue Loctite (I like blue over red Loctite for this in case we need to adjust the tension or change the design)

Safety stuff

1) Laser glasses (Or whatever safety precautions the laser you're using requires)

2) Respirator (or a well ventilated area to paint)

Use the right filter cartridges for painting with the polyurethane.

I also usually use a prefilter, but you also need a retainer to hold it onto the cartridge.

You can get a combo cartridge and filter.

3) Patience (This is tough for me sometimes, as the project gets closer to being finished I want to work faster to see the final product! This is usually when I start making stupid mistakes... )

*Note: My posts may contain affiliate links to products I use and feel comfortable sharing. Which means when you click the marked product links in my post nothing changes on your end, and I earn a small % on qualifying purchases. Thank you for your support!)

In case you were wondering, that is the official metric spelling of "laser." Trust me, I'm an engineer...

Right, time to burninate and iterate!

Version 1 was cut using cardboard. It mostly worked... The chicago screws fit correctly and the tool articulation was smooth, but the tool wouldn't close all the way due to the chicago screws hitting the indent on the pointer leg.

V2 eliminated the clash, but the divider body ended up a little weaker than I'd like in the indent area.

V3 beefed everything up a little bit by making the legs wider.

V4 accounted for me not adjusting the indent when I made the legs wider in V3...

V4 was successfully tested without cutting a full set of components.

V5 added some personalization with the gear wheel option for the handle area.

V6 cleaned up the file and nested the parts neatly for laser cutting.

This is the version was fully assembled to test.

(V6 is not the final version, see next step for digital file)

Proof of concept complete, time to graduate from cardboard to wood!

I used 1/8" laser safe MDF for the first wood prototype.

Assembly is "fiddly" the first time, but you get the hang of it pretty quick.

1. Start with the pointer legs on the bottom.


2. Attach a connector piece to the top hole of one pointer leg and the slot of the next leg


3. Stack another connector piece on the top, lining up the slot of the first divider leg and the top hole of the next divider.


4. Insert chicago screws into all the holes.


5. Loctite the chicago screws once you're happy with everything. This will keep them from loosening as you open and close the tool. (A dab will do, go easy on the loctite!)

I've also included pictures of the layout part of the assembly process, I know pictures help me more than text sometimes.

Overall, it worked. It was just a little loose. So I fired up Fusion 360 again and made version 7.

Version 7 changed the holes to net fit (exactly the same size as the chicago screw shaft) and I undersized the slot by .15mm (Yes, .15mm, not a typo. And yes, it made a noticeable difference). Version 7 is where you might need to use sandpaper or the razor to open up the holes if you can't get the chicago screw to fit.

All those changes tightened things up, but it still just wasn't quite right. Check the last picture in this step to see what I mean.

So... yep, that means another step in this instructable!

Ever had one of those projects that you started redesigning before you even finished?

Right, of course you have. THIS is why everything takes so much longer than it should!

Soooo.... yeah...The tool works, but even after removing all the clearance in the holes and slots there's still just a bit of tolerance I can't seem to get rid of with the sliding design. And... I made the mistake of borrowing a professional version of this tool from a friend to see how it works. So this "tolerance stackup" is enough to annoy me now that I know the "real" version works better. Wiferneer also ran across a metal commercial sliding style divider tool at a sewing expo about this time and we saw the same tolerance stackup with the commercial version that is in our homebrew version.

Sigh. Back to the drawing board...

The tool I borrowed works well. There isn't noticeable or measurable (with a tape measure) slack. The main difference I see is that it uses a pivioting motion on the pointer legs instead of a sliding motion.

With this observation, I changed directions from a sliding style divider tool to a pivoting style divider tool. This doesn't look as neat, isn't as fun to use, isn't as clean to mark intervals since the tip is canted - but it removed a little more tolerance and it reduced the number of parts to assemble so we'll call it a win.

Attached to this step is the re-remix V8, a pivoting style equal distance divider tool.

This is the one I'm personally using in my shop.

Assembly of V8 is easier than V7, there's only two layers to stack and that means there's also only one size of chicago screw needed. Basically criss-cross a pointer leg and a connector leg to assemble. Insert a chicago screw and then Loctite the screws when you're done. I forgot to take pictures during the assembly so unfortunately we'll have to use the picture of the tool expanded for the assembly reference.

It works!

OK, I know you have questions, so here's some questions I asked myself while working on this re-mix.

1) Self - Why can't the tip of the divider just be a normal triangle? Answer - Dear Self, The tip has a straight edge so you can draw a straight line to mark on your workpiece. Duh...

1a) In the pivoting version this is less of a thing since the tips angle sideways instead of slide up and down.

2) (OK, I can't do third person anymore...) Why are there scallops on the divider leg of the sliding version but not on the other legs? Answer - The chicago screws need to be able to nest into this piece in order to fully collapse the tool. Checkout the picture.

3) Do you think this will be as accurate as the commercial versions? Answer - Probably not. This version is made of wood and there has to be some "tolerance" to allow the screws to rotate. However, I'd bet it's just as accurate as using a tape measure to do the same layout job and it's faster.

4) You list polyurethane in the materials section, but this tool doesn't look finished? What gives? Answer - I need to stop using it for a couple days so I can take it apart and put a coat of poly on it to make it last longer!

5) Why is the metal version so much taller? Answer - Please proceed directly to the next step. Do not pass go.

Answering the question 5 from the last step:

While making these tools it became evident that the longer/taller legs on the commercial version serves to force the center of the tool to open at the same time as the outside. This is important since it eliminates even more "tolerance stackup" and makes the tool more accurate.

Yep, that mean a re-re-remix.

Someday...

For now I can live with V8 (vroom!) so V9 might have to wait until the next instructables contest!

Or, maybe you, person reading this, will run with it and make version 9?!?! I've attached the Fusion 360 file to this step in case you want to play with the geometry (Thanks mevans12 for requesting it!).

OK, that's it for today. Thanks for reading along with me as I learned how this divider tool worked and please consider voting for this Instructable in the Remix Contest!

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