How to make these Alternative Dovetail Joints (The Knapp Joint)

from the first time I saw one of thesejoints a couple years ago I thought I'd have to have a crack at it at some point it's known as a Knapp joint and it's very strong especially for drawers it was originally a machine joint that was made in the

late 1800s as an alternative to dovetails and being machined one man could go from making around 20 drawer joints a day up to around 200 I've started experimenting and with my method I've produce these samples they aren't the best but with my very poor setup I think I

can improve on it so hopefully by the end of the video I'm producing something half decent I'm going to make the cutter first and to do that I'm going to use a cheap spade bit I'm heating it up to a cherry red then I'll let it cool down

slowly that will anneal it which means it'll be soft and I'll be able to shape it I'm using a 10mm drill bit to get thecorrect size gap and checking the width of the cutters to keep them as even as possible to harden it I'm heating it up again

and then quenching it withvegetable oil the last part of the heat treatment is tempering I'm watching the heat run through the cutter I move it further away to slow down when needed and then when the end is a deep straw color I suspend that by cooling it in

water I'm grinding a very slight bevel just by eye using a 120 grit belt and that's all it needs and it's ready to use when I made the first one I had my doubts it would work I thought the two cutters would bend but they didn't and it

worked great so let's test the new out another option is to use a plug cutter but it doesn't make a wide enough cut so you'd have to use two different sizedcutters and keep swapping them out I wasn't happy with that idea I did think about putting a plug

cutter in a holesaw and then I could have welded thosetogether I didn't want to wreck my holesaw though because it's a pretty good one and also even though that's a pretty good fit there is a bit of movement there and it would have been difficult to get a

completely centered also I don't think a holesaw would make as clean a cut and it was easy enough to make the cutter with a spade bit anyway now the cutter is finished I'll start making the jig and while I cut the plywood for that I'll take a moment

to mentionthe Makers Mob if you click the link in the description you can download sixfree sets of plans from some great makers that I'm excited and honored to be joining very soon to use the jig you clamp your workpieceto the side and then just make your cut the

only problem I have is I have too much play in my drill press to get an accurate cut on my original crude version I made a kind of bushing to keep it in place and that should work well enough but I had too much play in that as

well so this time I've got another idea because I can't find any pipe with a 1mm inside diameter I'll make a hole the correct size in a piece of mild steel instead I don't have a 19mm drill bit so I'll drill it at 18mm then using this tapered

dowel with a piece of sanding belt stapled to it I'll fine tune it to the correct size I've just set this back up and locked everything in place the edge of the spade bit needs to be 4mm away from the edge of the fence I'm going to put

this in position mark it take it back off and glue and screw it I've got a piece of cheap pine just to try it out the first thing to do is score a line with the marking gauge just to reduce any chip out and then just clamp it

in place I'm just putting this anywhere just to try it out and then I'm going to put the edge of the cutting bit below the metal guide just so the tips don't get too hot not too bad I've kept the stop very simple it's to set the workpiece

in the correct position I could've ran a T-track along there and then just locked it in place but instead I'm just going to clamp it to the jig and I've made it wide enough that the pillar if it gets in the way I can clamp it either side

now I need to make some spaces and for that I'm just going to use some strips of plywood that's ten spacers and that will allow me to make an 8-inch high draw side before I try the jig out I'll explain a little more about the joints and the

significance of the spacing if you want the scallops to be complete semi circles then the width of the spacer will be the same as the width of the cutter or the distance from the center of two of the pins and in my case that's 19mm if you put

the pins closer together then the scallops will join up here and they won't come down to the center this is the way I'm going to do it because it's a bit easier to make this cut in here rather than to make the cut all the way down towards

the center and to do this I'm going to make my spacers 18mm if you make the spaces wider then the scallops will be further apart it'll leave this little bit in the middle you'd have to square that by hand but it wouldn't be too difficult and I think

that could look really good this one is similar to the one before apart from it's not squared off between the scallops you can buy a system that uses templates with your router to make this but it looks like it's been done by a router and I don't really

like it that much the jig worked fantastic it came out really well before I make the piece that fits into it there's a couple bits need cleaning up by hand but it's very easy to do and the ends need squaring up as well these are a couple of

test pieces from when our first work the joints out they're not very good but it'll give an idea what we're trying to make so now we need to make this piece to fit the other one I thought this one was going to be the difficult joint to work

out but I had more trouble with this one and it was quite a challenge the way I did it was to attach a template and then followthat with a router bit and then I drilled the holes out and there was a little bit of work in between that

needs doing by hand but that's pretty easy to do too the tricky part is to make an accurate template it's not easy I must have made about eight or nine of these with no success I tried printing it out cutting it out with the scroll saw and then

sanding it to theline but to keep it accurate is very difficult I also tried setting out with dividers and then using the forstner bit to score the outside where to cut to there that didn't work out either but I did work out a better method so we'll try

that now I've just made another joint on the other end of the board I'm going to cut that off and that's going to be used as a guide to make the template it's not pretty but this is the original template I made and I did that by turning

dowels and then I cut slices off they fitted it into that guide and then glued it all together better than the dowel I found this piece of copper pipe that fits the guide perfectly the pipe doesn't need a center though so I'll glue in a piece of dowel

I've got this piece from a past project it just needs something down a bit it would have been easier to make them with just dowels but they're pretty solid and they fit well so I'm happy to have done that there's one last thing I need to do they

slightly overlap each other so I need to file a flat edge on the inside of each one this piece will be the template and the disks will get glued to it and here I'm marking where the shoulders of the joint will be on the template I'm using five

minute epoxy to glue the disks I'm wearing gloves because this is going to get messy I meant to put some furniture wax on the guide piece to stop any stray epoxy stickingto it but I forgot when it mattered I'm pushing the disks hard into the guide and holding

it there until the glue goes off and I'm also checking that the sides of the template are square with the ends I held on to it for five minutes untilit's set and then went in and had some lunch so let's see if I can prise it away and

hopefully that guide isn't stuck too bad either just stuck a little bit I'm gluing another piece of thin plywood to the first to hold everything together I'm putting a line of epoxy across the disks then using what glue for the restof it I'm using a forstner bit to

mark the center of the disks then they get drilled the holes will be a guide for marking where to drill out for the pins to locate into that side of the joint I may as well flip it over and clean up the plywood on the back of the

template I'll use a single clamp to attach the template to the workpiece and I'm eyeballing the edges to make sure that they're parallel there's easily enough grip with a single clamp you'll know if you knock it out of position you could actually glue some sandpaper to the underneath

of the template if you wanted to to make it grip even more you'll need to make sure hat the temple it's long enough that it reaches over the end ofthe router table another way is to put your trimmer router in a vise and then the template could be

a lot shorter but my trim router hasn't got any speedcontrol so I prefer to do it on the router table I'm using a 6mm orquarter inch pattern following bit it almost gets right into the pointy bits but there's a little bit left to clean up by hand a

countersink bit will relieve the edges a little and help the joint go together easier I'm using a skew chisel to clean up in between those scallops but any chisel or knife would work and it's perfectly fine to undercut the joint a little as well keep watching because after

this I figured out an easier way of doing this stage and I'll show itlater in the video I'm not super confident but we'll try it it might need some adjusting yet but we'll give it a go it was a little bit tight and I probably shouldn't have driven

at home I'm not going to take it apart now to put glue in because I think it just break I was getting some nasty tear out there using the plane so I cleaned it up on the belt sander it looks really good there's no glue in there it

looks promising now I'm going to have a go with hardwood and see how that comes out my new method to cut out the bits between the scallops is to use a gouge this is a number seven sweep and it's not exactly the same radius as these disks but

it's very close and it's closeenough so it's just a cup of taps in each one and it doesn't matter if Iundercut the joint a little bit either I can just go in between with the skew chisel again and just clean it up a little bit further down in

the joint I'm trying out different combinations ofwood and this one is silky oak and camphor laurel I reckon that turned out great and it's repeatable and it takes less than 10 minutes to make the complete joint while I was making the black wattle and the Oregon one on

the right I realized the holes for the pins were a bit tight but changing from a 10mm forstner bit to a 10mm brad point bit made the difference and now the joints go together well I did a couple of extra things to the template I glued some paper

underneath for a bit more grip I did have one slip and that's much better now I put a fence on the outside so now it's a case of just getting your workpiece putting it up against that fence and just make sure that it overhangs slightly at the end

and clamp it up and it's ready to go this template will only make a joint of this size so if you want to make it wider with more scallops you'll have to make a new template making use of the original template it's a pretty easy task to makea

new one I made this one out of 12mm plywood I haven't tested it yet but I don't see any reason why it shouldn't work if you make a template like this you'll need to test it out and make sure it's accurate and there's no reason why it shouldn't

be but I wouldn't bother trying to cut those bits out and trying to follow that instead I'd route the workpiece and then I take it off the template and I'd use the original template and it's not difficult to line that back up you really can feel when it's

in the right place and you can either clamp that down and use the gouge or just mark it with a pencil I really do think that worked great but if you have any ideas on how to improve it then share those in the comments the only thing I

would change is I think I'd make the pins slightly smaller I made it 10mm I'd make it nine it just means making a new cutter now I need to use the joints in an upcoming project I'll have to put my thinking cap on hopefully you enjoyed the video

if you did please like and subscribe thanks for watching and I'll see you on the next one