what's up I'm Jonathan and I'm walking to maker tales where I'm sharing my
maker journey to help you go further in yours so don't forget subscribe and
hit that little Bell icon to never miss an opportunity to keep making in this
video we're going to be working off the knowledge from the first video which is
how to design a laser cut finger joint box accurately in this video I'll be
showing you how to make a mechanical lid lock this mini mechanism will be using
for individual sliding lock pins which we will develop in future videos to be
able to move all four pins with one rotational movement plus we're going to
be keeping to the no glue theme for now this is going to be a great video for
the very basics and fundamentals of puzzle box design and if you haven't
seen the first finger joint box video I strongly suggest that you watch that
them first as I am NOT going to go over how to find the perfect joint parameters
in this video the link to that video is down the description once again I'll be
using Rhino 3d but feel free to use your own preferred vector editing program
just remember to stay laser accurate before we go any further I would like to
explain what I like to call layered design and sandwich mechanisms honestly
I don't know if there are any actual words for these concepts to me the
concept of layered design is the idea of slicing a 3d design into layers of
assembly for example the lid of the first box already had a form of layered
design we had two pieces which we joined together to make one solid slightly more
complicated part a sandwich mechanism plays off the same idea except there are
usually four or more layers involved along with moving and usually
mechanically interacting parts sandwiched in between the top and bottom
layers to make the next coming steps a little easier to understand here is a
visual explaining the layer names that I use starting from the top down we begin
with the user interface layer which I also call the UI layer this is the very
outer layer of the sandwich mechanism this is usually the layer that has all
the switches knobs buttons cogs and sliders under the UI layer you get the
top layer this layer along with the bottom layer
are solely there to keep the mechanism together in between the top and bottom
layer you have the mechanism layer or in more complicated designs the mechanism
layers now that we know the general understanding of a sandwich mechanism
let's get on to the first design here is where we left off our finger joint box
design our initial box with a simple lid to take this lid to the next level let's
start with just the internal and external dimensions of the box now with
these dimensional constraints let's reapply that 0.5 millimeter offset to
the internal part of the lid plus I'll give the corners a small Filat this will
let us have a little bit more wiggle room especially while working with wood
as zero-tolerance designing is usually not a good idea with natural materials
from here I'm going to be adding a few construction lines this will make it
easier to find the center point and other points of interest these
construction lines will be removed later on and are only there to aid the
designing process all these lines will be in red from now on as this is a
relatively simple design I'm going to jump straight into the internal
mechanism generally speaking I usually work from the UI and top layer downwards
when creating more complicated designs so getting straight to it in essence we
have one sliding lock pin mechanism which is repeated four times to work
smart and not hard we are going to just design one of these lock pins and then
copy the other three in place using my construction lines I'll place a 15
millimeter wide lock pin from the center to the outer limits which will become
the top layer outline later on from here we need to keep in mind the movement we
are wanting to achieve with this lock pin I want this pin to move a minimum of
three millimeters back to be able to unlock the box as a rule of thumb I
usually add an extra 0.5 to one millimeter of movement if I'm able to do
so adding this extra little bit means the pin will now move back four
millimeters it's pretty obvious in this design that the pins will not get in the
way of each other but it's still good practice to check
this to do this I'll add a 15 millimeter construction line box to the left of the
lock pin from here we can see that the full range of motion is not going to get
in the way of any other pin to interact with the lock pin we need a way to
interact with the UI layer to add a simple sliding button to the UI layer we
need to keep in mind that we are working in a sandwich mechanism this means we
need to go through the top layer to reach the UI layer to do this we will
add a hole through the top layer this hole will let us add a pin joint from
the sliding button to the sliding lock pin let's start this connection from the
mechanism layer adding a hole to the lock pin for the pin joint going up a
layer we are now on the top layer I'll make this layer green to make it easier
to distinguish while adding the hole to the top layer we need to keep in mind
the range of movement of the connecting pin joint this means that we need to
make the hole four millimeters longer in one direction to let the pin joint shaft
move freely lastly going up one more layer we reach
the UI layer i've colored this layer magenta personally i would like to hide
the hole in the top layer for this design meaning that I'll make my button
18 millimeters by 18 millimeters I'll also give the button a small Filat on
the corners and finish it off by adding a pin joint hole hiding the construction
lines this is what we're currently ending up with to finish off the design
we need to add all the moving parts into the mechanism layer to do this I'll
bring the construction lines back and use the center point to help place three
copies of the full mechanism rotating at 90 degrees as I go along
we're almost there only three more steps to the end staying on the MEC layer now
that everything is in place we need to add the standoffs standoffs are the part
of the mechanism layer that do not move and are there purely to keep the top and
bottom layers off the moving parts in essence there are the empty spaces in
the MEC layer to make these standoffs I'll look for the areas in
mec layer that needs support this will usually be the whole outer perimeter and
any large voids these standoffs are then held in place by pin joints and hold the
entire sandwich mechanism together keep in mind the movement of the mechanism to
make sure not to accidentally impede it with a standoff while making these
standoffs and adding all these pin joints to all the other layers let's
also check each layer to make sure it has everything it needs most notably is
the outer perimeter of the bottom and top layers fundamentally that's the
tricky part done all that's really left to do with the sandwich mechanism now is
to add all the kerf compensation a couple of fillets to make sure nothing
catches on itself and then what I like to do is add a small 0.25 margin to any
moving parts to make sure that there isn't any additional friction on any of
them moving connections
with that done you should have something that ends up looking a little like this
on to the last step you may have noticed that currently the lid would not fit on
the current finger box design this has been intentional to keep the layers in
the sandwich mechanism to a minimum what's left to do now is a small edit to
the box faces plus a small edit to the top layer of the sandwich mechanism
let's start with the top layer the outcome of these small edits is to
create an interlocking lid to do this we need to remove as much of the
overlapping lid rim but keep just enough that will still hold the lid in place to
slide the lock pins into place to do this I'll be removing all the rim
apart from 11 millimeter finger that will slot into the rim of the box now
onto the box faces we need to add a small slot to let this finger slot into
Plus we'll be adding a small hole to let the lock pins slide into I know the hole
for the lock pins is nine point five millimeters away from the edge of the
top layer and three millimeters down due to the thickness of my material I'll
also be adding a zero point five millimeter offset to this hole to give
it a little bit of wiggle room a few finishing touches such as Phillips to
the slots and that's the design done now it's a simple case of separating the
layers of the design nesting it and cutting it out
once cut I hit it with a little bit of sandpaper on all the moving and exposed
parts from here is a case of simply assembling it make sure you take care
with the orientation of the parts while putting them together as these parts can
be put on backwards or inside-out a rubber mallet come in handy to persuade
the pins to go in but make sure they go in straight because if you don't there
is a high chance of splitting the wood when they go through to the other side a
small thing I would like to mention is that all these designs have no glue this
does not mean that a small amount of glue won't help especially when it comes
to the degradation of joints after a long amount of time due to changes in
humidity and wear and tear but personally in my experience using these
finger joints I have not had a single problem with any of my puzzle boxes that
I've developed over four years ago
you've made it now you've just understood the basic fundamentals of
puzzle box design that's right technically speaking you could see this
as a very simple four-step puzzle box next up we're going to be working off
the fundamentals of that design to move all four pins with one quick little
rotation in fact from there the sky's the limit we're even going to cover a 15
step puzzle box and so much more so thanks for watching keep making and let
the quest continue