Building an Impossible Dovetail Cutting Board



Today we're building an 
impossible dovetail cutting board i love watching puzzle box videos and 
the impossible dovetail is one that has   locking joints on all four sides so it looks like 
you can't even assemble it but i want to take that   idea and scale it up and make it look even cooler 
let's build something awesome this is a lot of   cutoffs from when i used to make cutting boards 
when i was trying to make money and a side hustle   to become a full-time content creator so excuse me 
if i shed a tear when i'm pulling these out oh yes   i remember you old friend hello black walnut my 
old friend let's make some cutting boards again   all right enough weirdness let's mill some wood so i'm going to start off with the thicker 
boards and get these glued up and i am using a   waterproof glue to make sure that it 
stands up to washing and use in the kitchen while those boards are drying i'm going to head 
inside and start setting up the computer programs   that'll let me do the cnc cutouts and all the 
3d designs at first i drew a model in sketchup   of what i thought the impossible dovetail 
would look like with the joints on all sides   but that's like beethoven and i'm still trying to 
learn chopsticks so i modeled up a small prototype   single sliding dovetail design in fusion 360.

pexels photo 4792477

Now 
i'm totally new to cutting in three dimensions   all the work on my X-carve cnc from Inventables 
has been just 2d pattern and shape cutting so far   so it took a while to figure out the cnc side 
of fusion and i was ready to start testing   now it's time to find out if i can 
actually make a dovetail work on the cnc   having one that actually fits nice and tight 
that will still move but not have enough slop   that it jiggles around so that's gonna be 
the challenge let's see if we can do it all right so working with the cnc and working 
with Fusion 360 for the first time to make my   tool path has been a bit of a challenge and i 
actually ran several different shapes and designs   or several different runs so what i've realized 
is that i needed to calibrate my machine a whole   lot better than it was because i never needed 
that level of accuracy before and also i was   being too aggressive much too aggressive i think 
i got it figured out and i think it's gonna work all now i'm going to do the test cut and it's kind 
of awkward because i have to leave this in place   in case i have to make adjustments but i have 
the male dovetail piece and i just cut the   ends off it so i can slide it in here and now 
we'll see if it uh fits into the female side that's not even close wow that is so far off so 
i'm gonna have to go into the program figure it   out and just work through it because there's a 
bunch of settings in there about what to leave   and offsets and all these things and apparently 
i messed that up so i'm gonna go in there try   to figure this out and then i'll come 
back and see if we can make it work all right so I ended up actually remodeling the 
entire thing but I think I have it right now   so i've got it to the point now where 
it will just slide in oh that is a good   fit and you can see it slides nicely but there 
is a little bit of a gap you can see some gaps   around there a little bit more than i would 
like but i'm a perfectionist so what can you do   i think we're good enough to go to the next level 
which is to make a full-sized sliding dovetail   into the cutting board of one of those ones i 
glued up earlier we'll see how that works and then   gear up to do the impossible joint so the first 
glue up is dry and i have started taking some of   these out so the next step i need to get this flat 
you can see this has a very rough surface to it   but first i'm going to get these out of the 
clamps and clean them up before i hit the planer so now each of these is nice and smooth on each 
side and it's parallel and now we can move on to   step two which is making the ingrained cutting 
board so these are long grain these would look   great just as is this could be a nice cutting 
board but if you cut it into sections and then   turn it 90 degrees that's how you make an 
end grain board so i'm gonna go do that on   the table saw and that's going to let us get 
into the next step all right let's get cutting   all right here are the blanks for the boards i 
do have these turned on in so you can kind of see   what the end grain is going to look like and with 
end grain especially with walnut it can have some   pretty crazy patterns in here and if you turn it 
certain ways you can make diamonds and different   kinds of shapes as you look at i actually did 
a video where i made a diamond cutting board if   you want to check that out but i don't want that 
here because i want the eye to go to the edges   and the dovetail feature not to the top so i'm 
going to rearrange it so that it doesn't really   draw the eye as much i've got the cherry one 
then the other walnut so i am going to go ahead   and glue these up and then we can start doing some 
prototyping for the cnc design that we did earlier   so these boards are pretty flat coming off of the 
drum sander so what i'm going to do is take these   over the cnc and actually use a surfacing bit 
on these to get each side completely parallel   with the other and that will just go through 
and basically take a little bit off of each   side i can square them up on the table saw 
and have them ready for the dovetail joinery all right it is time to do the first actual cut 
on an ingrained board i gotta be honest i am   very nervous about this i've done some practices 
and stuff and i think it's gonna go okay uh but   you never know so i'm gonna do the tool path so 
i'm gonna cut the uh the male side first actually   then we'll cut the female side on the walnut 
board and we'll see if they slide together but uh   i don't know i feel pretty good 
about it we'll see what happens   all right the first cut is done the the cnc is 
buzzing in the background because i can't turn it   off or i'll lose the position but i just wanted to 
let you guys know i did it for you all this dust   i left the dust shoe off just to get those sweet 
time lapses but i'm not going to do it again so   now i'm going to switch out to the dovetail to get 
that cut and then i'm going to switch out and go   into the next board it's looking good so far other 
than that dust this drive me crazy all right this   one turned out really nicely the lines are nice 
and crisp and the dovetail there's no tear out   there everything is flat so this went really 
well so now all i got to do is clean off the   cnc from all that dust put the dust shoe on there 
and then cut the complementary female dovetail on   the walnut board and then we can do the test 
fit but it's looking good i'm digging this all right just got done and now 
i'm going to try the dry fit   i have to leave it in place 
because if it doesn't fit then   i have to do some more machining but 
the test piece fits so this should fit this should fit let's measure this and see what's going on because 
this does not look like it is fitting at all   this is 5 inches and 13 thousandths and this 
is 4.98 so what is that 32 how am i 32 000 okay so i'm 32 000 off apparently missed it 
by that much uh which is significantly more   than i should be i'm just going to keep running 
this until it expands so i'll just take off a   little at a time and then test it uh but clearly 
this is a little bit too small but it's better   than the alternative all right uh since we're 
at the desk you probably already know i did   take a little uh just the beginning to 
see if it would fit and check this out this fits so nicely oh this looks 
cool so i'm super happy with how this   is working but i just had an idea and i am now 
going to do something different with the project   so i want to have some magnets to hold 
this in place so i'm going to figure   that out and then we can go start 
working on the impossible dovetail all right i got the magnet all worked out here 
and it works pretty well though it could be a   little bit stronger so i may have to go 
with a bigger magnet for the larger one   and speaking of the larger one it is now time 
to start on the impossible dovetail joint   i've got two little blocks that i have glued up 
and made square and it's important that these   are square you'll see why in just a minute 
so i definitely want to try these out as   test pieces first because there's a lot more 
complexity than with just the sliding dovetail oh yes yes yes yes yes check this out this is so 
cool i got it assembled the fit is almost exact   and i tell you what it is really tight i'll do 
some close-ups you can see the grain and how tight   it is there are not any gaps i am extremely happy 
with this and here's how the impossible joint   works you can see it looks like four separate 
joints but really it is just two that are cut at   45 degree angles so you can slide them when you 
apply the pressure diagonally pretty cool trick   but i am ready to go full scale and what i'm gonna 
do on the full-size board instead of just having   one i was gonna make it wider i'm gonna do three 
dovetails across it's gonna look crazy so it'll   look more like an actual dovetail board than what 
my original idea was which just one wide one which   i don't think would have had the same effect after 
looking at the single dovetails versus the three   i had to go with the three the modeling for this 
one was a bit intense though this is about a half   hour of modeling cut into this short clip but my 
main concern is that with three dovetails per side   any poor fit or air might just make this whole 
thing not work at all and after i finished the   modeling i just needed to do a little more work on 
those blanks while i'm prepping those boards let's   talk about the sponsor today's video Skillshare 
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to see what you can learn thanks Skillshare let's   get back to the video so the boards are prepped 
and ready for the cnc so what i did on the blanks   is i put some little trim of just uh it's just 
poplar and i used some blue tape and ca glue   to attach it there and as soon as it goes through 
there it should have support so it shouldn't blow   out this should help protect that so we'll see 
if it works or not or if it just blows it off   but now i am ready to start the machining on 
the impossible dovetail we'll see how it goes the first round of machining on the 
base is done i'm going to pull it out   but it looks like it turned out really nicely uh 
the back end did blow off the little strips but   it looks like these did a really good 
job at uh everything else stayed on and   there is no blowout so it's gonna be super 
clean in the final product so those worked   out really awesome let's throw the walnut 
top in there and we'll get to milling that   and that's where the fun comes in and 
trying to get the fit this is the easy one all right guys we are like right here this i i 
am a little nervous because this like right now   it fit just it's barely starting to fit and i 
feel like i'm just i pushed it in about like an   inch and it was just starting to bind up i'm just 
super scared if i get it in here that it's gonna   it's i'm not being gonna be able to remove it 
and not even be able to close it the right way   so i think i'm gonna err on the side of just 
getting one more pass at it i've already done like   four or five passes one more pass to hopefully 
free it up enough and not have a bunch of gaps   i hope this will be the one let's see 
if it passes this first one then um   i think i'm just gonna take 
it all off oh there we go   there we go there we go all right see if this 
goes by oh it's still catching a little bit it's past them and it's going i'm gonna take 
all the poplar strips off but leave it in   the thing and see how it works should i do 
that no um ah i'm gonna push it a little   bit more ah there's so much friction 
here i knew this was gonna be an issue all right it just hit me that uh i saw the 
rubbing is happening like i said because   there's so much more surface area but i'm 
not really concerned about the surface   in the middle all i want is the outside 
to look nice and crisp so what i can do   is come in here and relieve some of these 
edges so that there's not as much rubbing   i'm going to try to do some sanding and you know 
spend a few hours just really massaging the fit   if you will all right i just spent like an hour 
sanding everything and i think this is gonna be it come on go go go go go yes that is it oh man that is it i don't 
want to slam it all the way in there   but that is it i'm gonna clean this bad boy up and 
we'll see the final look all right guys check it   out oh man this thing turned out so amazing and 
i haven't even put the finish or the oil on it so   i will do that i'll have some beauty shots for 
you here in just a minute but it fits together   perfectly and there is so much friction in here 
i was worried it was going to slide apart like   like the sliding dovetail did it did not uh but 
i can look at it now and i'll show you how it   opens up just slides oh you gotta really put 
some pressure into it and then it slides right   open check that out that is so cool if you don't 
know how an impossible dovetail puzzle works now   you do and if you've never seen a three dovetail 
puzzle i've never seen one now you have so i'm   gonna sand this up and put some finish on it i 
am so happy how this thing turned out it looks   amazing hey if you're loving these hidden and 
secret feature videos i've got a playlist queued   up for you right there that's got a few more 
in it i think you're going to love as well   i want to give a big thank you to all those 
folks that have been joining the builders   club you can get more information down below but 
i'll catch you guys over there on the next video

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