http://woodgears.ca/pantorouter/tenon_setup.html
Making tenon templates for the pantorouter I previously wrote about how to work out tenon templates in my large mortise and tenon article. tenon article. To those skilled in math, the easiest way to express the calculations is with an algebraic equation, but it appears that many people find that confusing. So I'll take another shot at explaining it, this time, without equations. I will even use inches because my router bits are all inches! "nd if you prefer not to read, r ead, #ust watch the video $!
Making tenon templates for the pantorouter I previously wrote about how to work out tenon templates in my large mortise and tenon article. tenon article. To those skilled in math, the easiest way to express the calculations is with an algebraic equation, but it appears that many people find that confusing. So I'll take another shot at explaining it, this time, without equations. I will even use inches because my router bits are all inches! "nd if you prefer not to read, #ust watch the video $! The pantorouter cuts a tenon by tracing around the shape of it with a router bit. %arge router bits work best.
To get a tenon shape that is rounded on each end, the router bit needs to trace a semicircle at each end.
The path the router bit takes needs to be offset by half the router bit's diameter on all sides. That makes the total si&e of the path that the router follows one routerbitsi&e wider than the desired tenon. (.)* + (.-)* /./-)*.
To get a tenon shape that is rounded on each end, the router bit needs to trace a semicircle at each end.
The path the router bit takes needs to be offset by half the router bit's diameter on all sides. That makes the total si&e of the path that the router follows one routerbitsi&e wider than the desired tenon. (.)* + (.-)* /./-)*.
The pantograph has a -x reduction built in, so the template needs to be twice that si&e. So the path that the guide bearing must take on the template is twice as big. /./-)* x - -.-)* To get the correct path, the template needs to be smaller b b y half the bearing si&e on each side. Subtracting half the bearing si&e twice, the thickness of the tenon template now needs to be reduced by the bearing si&e. -.-)* /* /.-)* "nd that's that's all there there is to it. it. So, in summary, we add the router bit si&e and tenon thickness together, double that, then subtract the bearing si&e to get the template thickness. 0or the width of the template and tenon! the calculations follow the exact same steps. If the guide bearing is twice the diameter of the router bit, the template ends up exactly twice the si&e of the tenon, which makes things even easier.
1aving worked out how wide the tenon template needs to be, I cut a strip of wood that width on the table saw.
2ext, I use a compass, set it to half the width of the strip of wood and mark the rounds on the ends. I run the point of the compass along the edges and end of the workpiece to mark where the center of the semicircle needs to be.
2ext, cutting the rounded end on the bandsaw. " disk sander sander is great great for getting getting right right up to the the line, but I #ust gra&e the edge with with the side of the bandsaw blade to finish up that works better with a bandsaw blade where the edge of the teeth have been stoned stoned!!
I then screw the plywood template onto another piece of plywood to mount it on the pantograph. That way, I can take it off again if I need to tweak it.
Template
mounted. 1ere, I'm screwing on the appropriate si&e guide bearing. The first tenon I cut ended up #ust 345* in si&e, not the /4-* it was supposed to be. Then I reali&ed I still had the 346* guide bearing on, not the /* one that my template is designed for. 7ops8
To line up where the tenon goes, I line the bit up to be vertically centered with the workpiece, then make sure that the guide bearing is at the same height as the center of the template.
It's definitely a bit more work to set up than a tenon #ig, but once set up, it produces tenons that have the shoulders perfectly cut, with a round on both ends, all in one step. "nd if you cut around it clockwise from the view in this photo! the bit will always cut into the wood on all sides, so there is no tearout.
The pantorouter is also capable of cutting mortises, but because I also have a slot mortising machine, I #ust use that to cut the
corresponding mortises.
If you use the same si&e bit for the mortise and the tenons, it may make sense to mount the mortise template right next to the tenon template, so you don't have to worry about realigning the templates when switching between mortising and tenoning. To calculate the track length for a mortise template, take the width of the tenon, subtract the router bit si&e, then double that, and add the guide bearing si&e.
" nice fit8 I made this tenon template to cut the shelf supports for someshelve s for my brother's basement
How the pantorouter works The *9antorouter* is a template guided router for cutting shapes in wood. The template is mounted on the frame above the router. " ball bearing on the pantograph mechanism is used to follow the template.
0or those not familiar with pantographs, the lattice pictured at left should help explain. The six pieces of wood are connected with pins at the corners. The four areas inside this lattice each form a rhombus of equal dimensions. :ith the rhombuses all the same si&e and shape, you can see that the distance between the point that I'm holding and the fixed point on the opposite corner will always be divided exactly in half.
The linkage shown previously doesn't actually
need all those pieces to work. In a pantograph, the redundant links are not present. Scalings other than -$/ are possible with most pantographs, but for the sake of simplicity, my pantorouter has the reduction fixed at -$/. :ith a pair of markers in the pantograph, a shape drawn with the red marker will be drawn at half that si&e by the green marker.
7n my pantorouter, I use a ball bearing to follow the template in place of the red marker, and mount my router where the green marker was. The router mount is an odd shape so that the router's axis goes exactly where the marker was. The pantorouter is basically the same linkage as this but built much sturdier to support the weight and cutting forces of the router.
:hen I prototyped my machine, I found that pulling up on the handle against the weight of the router was tiring over time.
So I added some springs, string, and cams to counteract the weight of the router. The cams are shaped such that the spring's tension profile is matched to the way that gravity exerts a larger moment on the router the further it is away from the pivot. There's one spring for each arm of the pantograph, one mounted behind, the other in front of the pantograph.
0or routing internal cavities such as mortises, it's also necessary to plunge with the pantorouter. I added a plunge mechanism by making the whole back half of the machine move back and forth on a sled. " lever attached to the side moves the plunge sled. The sled moves back and forth on linear glides that I made from drawer slides
I also added some depth stops to the plunge mechanism. These allow me to limit how deep the router will plunge. The second stop on the left limits how far back the router can travel. This is useful for locking the plunge position in place. It can also be used for setup. I'll often use the tip of my router as a stop for where to position the stock. I'll move the router all the way back, and slide the piece against the router until it hits the bit. Then I use the plunge mechanism to cut the desired depth. I should add that this does not involve starting the router with the bit touching the stock. I can always move the router out of the way sideways.
;aking large mortise and tenon #oints with the pantorouter
I wanted to explore making some really big mortise and tenon #oints with the pantorouter . I didn't actually have a pro#ect that needed such #oint, so I made some test #oints #ust to demonstrate. I decided to make a -) x <) mm /* x 3*! mortise and tenon. That would be a good si&ed #oint if one was using - x 6 lumber to build a traditional workbench.
I bought a /4-* /-.< mm! router bit with a cutting length of -* )/ mm! for the #ob. This was actually not the longest router bit available, but I figured it should do. 0ully inserted, the bit still stuck out of the collet quite a ways. So I cut off about /.) cm from the back of it. It was relatively easy to cut with a hacksaw.
I used a - mm guide bearing couldn't find a /* bearing!. I measured the router bit's actual cutting diameter at /-.5 mm slightly larger than specified. 9lugging my tenon, bearing and bit si&e into the formula$
Ttemplate = Ttenon + -= >cutter >bearing! 9lugging in my numbers$
Ttemplate = -) mm +-= /-.5 -! )( (.6 The term in brackets in the right worked out to (.6 mm. So basically, my template needs to be (.6 mm smaller than twice the si&e of my tenon. ?asy enough. I cut the tenon template on the table saw. I used a /* washer to trace an arc on the corners. The actual radius I needed for the corners was twice the /-.5 of the bit, minus the (.6 mm ad#ustment, or -).-mm. I figured the /* -).6 mm! of the washer was close enough. If you don't like euations click here for another e!planation.
I glued the template onto a thin piece of plywood for mounting. I also glued a few strips of wood to another piece of wood for the mortise template. The mortise template is much wider than the guide bearing so I can move all around the inside perimeter of it to cut a rounded rectangle shaped mortise. The mortise template is twice the si&e of my desired mortise plus the (.6 millimeters I worked out earlier. 0or inside templates, the ad#ustment factor goes the other way around.
"ligning the template for
a cut I added a *setup bar* to reference from. This bar represents the level of the table on the template side of the pantograph. I worked out the position of that by placing a /46* shaft in my router and a /4-* guide bearing on the pantograph. :ith the shaft in the router on the table, the bottom edge of the bearing corresponds to that exact position on the template side. I made some pencil marks on the template frame for where the bar goes so next time I only need to line up the bar with the pencil marks. The setup bar can get in the way of the router, so I take it off after finishing the setup. ;y stock for the tenon is 3 mm wide, and I want the tenon to be centered. So the center line of the tenon needs to be /5 mm from the edge. 7n the pantograph side, that dimension doubles, so the template's center line needs to be 3 mm above the setup bar.
1ere's my cut tenon. The tenon is cm long - 345*!, which is longer than the cutter length of the router bit. I started the cut with the plunge carriage
pulled back, cut all the way around, and then plunged all the way in to finish the cut. That way I can cut tenons longer than the actual cutter length of the bit. If I hadn't shortened my bit, I could have made a tenon about a centimeter longer. "nd if I had bought the longest bit available, I could have made a tenon 5 cm long8
The chips sure go flying while making the cut there's quite a bit of material to be
removed. The router motor blows air out the front, which really spreads the chips around. 7n the plus side, at least this gets the chips out of the way.
That previous shot is a still frame from the video I shot. I set up my camera a meter away, but it still got a fair bit of dust on it. It's of the reasons I try to use cheap cameras in the workshop. I haven't had a camera die of dust exposure yet. @ut what can happen is that dust gets in between the lens groups inside the &oom lens. That dust is impossible to get out.
The finished tenon. I always make all the cuts around the edge with a *climb cut*, basically with the cutter moving into, not out of the wood. This eliminates any sort of tearout.
I made some through mortises on much thinner stock to test the fit with. ;y initial fit was too tight, so I sanded the edge of the tenon template down #ust a bit. I also found my mortise a little too wide, so I put a strip of (.-) mm thick A1;: tape to one of the inside edges of the template.
This photo shows the fit after ad#ustments.
2ow cutting the big mortise. Blearing out chips for a cut this deep is a challenge. @ut fortunately, with a mortise this wide there's plenty of room. 0or a mortise that's #ust the width of the bit, it would be more of a problem. If I was making a lot of deep and narrow mortises, I'd probably invest in a spiral bit.
The finished mortise
The tenon fits quite nicely, with #ust a bit of friction going in. :hen I pull the tenon out rapidly, it actually makes a loud *plop* from the partial vacuum in the mortise because air couldn't get past the tenon fast enough as I pulled it out see end of video!. Cou know your mortise and tenon #oint makes a good fit if it goes *plop* when you pull it out8
#ee also:
;ore about the 9antorouter
;aking a box on the pantorouter
;aking tenon templates without equations
;ortise and tenon #oint accuracy
ortising machine
You can buy for the slot
memade slot mortising machine for my mortise and tenon #oints. ;y previous slot mortising machine was made p ut I had always wanted to be able to build a mortising machine from scratch using readily available materials. I hav , and this article describes how it works.
Building the horizontal sliders mechanism
Building the router mount and vertical adjustments
Building a stand for the slot mortiser
ble for the slot mortiser
y %'s slot mortiser n %umberDocks. ion on flickr.
lso available in &erman
ave $enney on making pantorouter templates "fter building the pantorouter I decided that it would be really sweet if I had templates premade to make a wide range of tenons and m ortises. I like the way the template system works on the metal pantorouter , so this is the direction that I went in. Eather than milling a slot in the template the way that ;atthi as did, I glued the template together. I had used this idea last year when I made a template for my tenoning #ig and figured it would work well here. "ll of my templates are made for using a /4-* straight bit to cut the tenons. I #ust change the bearing on the follower to make 345F and /46F tenons. The first thing to do is make up a batch of template stock. I am using /Gmm birch plywood for mineH its fairly hard and very stable. :e need some /46F stock for the slot spacer.
Then we need some slightly oversi&ed 345* stock with a ) degree bevel on one side. ;y stock measures about .6() I need better calipers8! which is .(3( over on the fat end.
2ow we need to lay out the si&e of mortise and tenon we want to make. 7ur slot length is double the intended mortise si&e minus 346F. In this example I am making a 346F mortise. So doubling that would be / /4-F and taking away 346F would leave a slot si&e on 346F. 0or another example, if I wanted to make a 3 /46F mortise my slot would be ) 346F.
2ext we will glue in the spacers. ;ake sure the bevels are on the
outside.
7nce the glue has dried we can lay out the ends of the template. I am laying mine out on the back so the radius of my circle is going to be .)) or so. I made a pattern for this that you can see above the template. I use the caliper to check that the distance from the slot to the outside of the arc is about .6()
"fter cutting it out on the bandsaw and sanding it to the line I glued it onto a piece of %uan as a backer board.
So how does it workJ 9erfect fit on the first try8 7f course it helps that I had already made a couple of test templates working out all these
dimensionK
"nd of course, if youre going to make one you might as well make a tree full.
The 9antorouter
I call this machine the *pantorouter* because it's essentially a big pantograph mechanism with a router in it. It's used to route shapes from -x si&ed templates. I originally designed it for cutting tenons, but the machine is very versatile and can be used for all kinds of wood #oints. This version is optimi&ed for use with routers with cylindrical bodies only. ;y larger 9antorouter L% is designed to accomodate plunge routers.
(sing the pantorouter to make )oints
How it works
%oming up with the design
%utting through dovetail )oints
$enon templates for the pantorouter
How to align templates
%utting a large )oint.
ave $enney on making tenon templates
Making plantation shutters
Making a finger )oint
%ube in a cube in a cube
*antorouter plans
+ou can also buy a *re,built all,metal pantorouter
%onstruction of the machine:
-uilding the pantorouter
outer mount for a palm router
inear glides from drawer slides
Holddown clamp
Improved pantorotuer followers
#pecifications
-uy plans for the pantorouter
More pro)ects where I used the pantorouter:
Boat hooks
9aper towel holder
:ooden hings
Scaffold build
@uilding a large mirror stand
Muickie workbench
Akulele neck mortise
Eolling under bed storage drawer
Scarf splice #oint to fix broken chair legs
2eedlessly complicated axe handle repair
1alfblind dovetail #oints
Blever 3way #oint Nawai Tsugite!
>ouble tenon with the metal pantorouter
;aking pantorouter followers
:hen I did my pantorouter comparison with the allmetal version thatNuldeep builds, I mentioned that I liked how Nuldeep made the followers with a bearing on a shaft, but didn't have a way to attach a bearing myself, so I'm keeping with the old system of mounting follower bearings on my wooden
pantorouter. I received many suggestions, such as using %ocktite to mount the bearing on the shaft. @ut my real problem is actually that shaft si&e and bearing holes in the bearings I have don't match. @ut with so many suggestions, I started thinking about how to make round followers on shafts for m y pantorouter.
If I cut a thread on the end of the shaft, I could then mount various nuts on it, like this knock down nut with a nice wide circular flange, so it already forms a round follower. Cou can buy nuts like that at The 1ome >epot.
7r I could put a hex nut on the end of the shaft and grind that round on my bench grinder. :ith a bit of sanding and polishing, that makes for a fairly easily sliding round follower, and it turned out quite precise too.
/4-* bearings have smaller holes in them, but using the same technique on the bench grinder I was able to grind the shaft down so it fit in the bearing, though not tightly. @ut some shims, cut from aluminium cans, made for a tight fit.
:henever I take something apart, I always keep the washers and other small hardware that might be useful. So I have a whole drawer full of round bushings and spacers, and I started to dig through those to see what might work.
I found some bushings that fit snugly on the mm shafts I was using. I used mm to make it compatible with Nuldeep's. I used one bushing as a follower directly and ground another one down a little again on the bench grinder! to fit the hole of a - mm bearing I had. "gain, with a shim from an aluminium can to make it fit snug. I also found one bushing that fit perfectly between the mm shaft and the 5 mm hole for another bearing.
Cou could also make your followers out of /46* bolts, which already have threads on them. Bombined with a nut with integral washer, as shown, all you would have to do is glue the nut on and cut off the bolt head to make a follower.
Ooing through my #unk, I made quite a lot of followers of different
si&es. @ut one si&e I
didn't have was /* -).6 mm!, so I decided to make one that si&e out of wood.
I started by cutting a slightly larger circle from @altic birch plywood on the bandsaw. The hole I drilled is a bit undersi&ed for the shaft. I roughened up the end of the shaft and used some Oorilla glue in the hole and shaft, then drove the shaft in with a hammer.
"fter that, I spun the disk in a hand drill, held up to my disk sander to make it perfectly round. I'm guiding the shaft with a piece of wood, near the end to make sure it's steady. I ended up sanding that one down to #ust under /*, then applied some A1;: tape to it to bring it back up to si&e and make it slide easier. A1;: tape is also useful for upsi&ing metal followers. ?ach turn of A1;: tape adds (.3 mm to the diameter of the follower. Dust be sure to have a whole number of turns on the follower so the tape is the same thickness all around.
I ended up making a lot of followers, mostly from random bushings and round plastic parts. I have no more than / mm of si&e difference between most of them.
I made a mounting block to clamp the mm shaft on my
pantorouter. I didn't have a mm drill, but a /)46* drill made for a hole that fit the mm shaft #ust snugly. The only change I had to make to my wooden pantorouter was to drill a /<46* .< mm! hole all the way through the operating lever, then mount the new holder. The orange knob on the holder clamps the block together to lock the mm shaft in it. That knob came from a broken Eyobi circular saw.
Making tapered and slotted tenon templates 1aving figured out how to make followers like on the all metal pantorouter , the next challenge was to make the clever templates with the slot in the middle and tapered edges around the outside. The tapered edges of the tenon template allow fine ad#ustments in tenon si&e to be made.
I set my table saw to four degrees, then cut a bevel on a piece of /5 mm thick @altic birch plywood. /5 mm is perhaps a bit thick, but I figured more thickness is better, and the next thinnest @altic birch plywood I had was // mm.
:ith the wide side of the plywood facing up, I set my compass to half the width, then use it with the point on either edge to check the center of the mark, and draw an arc from there.
I tilted the bandsaw to four degrees, checking it with a speed square, because my homemade bandsaw doesn't have
any angle scale.
Butting out the
semicircles. I cut within half a millimeter to the line...
...so that I don't have to sand away very much material finishing it
up. 0or my first tapered template, I drew the semicircles on the front the narrow side!, but then reali&ed the disk sander table doesn't tilt towards the disk. 7ops8 That's why I drew the semicircles on the back this time. I was however able to tilt the strip sander table towards the belt a bit, but the disk sander is better for this #ob.
I cut the slot in the template on my pantorouter, #ust using a straight piece of wood to roll the follower bearing along to get the straight line. >espite being very careful, I got the line about / mm off center and, worse yet, about (.- mm higher on one side. "rrgh8 Sliding the template on a router table to cut the slot could be iffy, but would avoid the possibility of getting the angle wrong. I ended up *fixing* it by doing a plunge cut on the table saw with the template held down against the fence!, then finishing it with a chisel.
Oluing the template on a backer board, being very careful to keep the template exactly flush along the bottom edge to make sure it's straight.
So I hope this gives you some ideas for how to make followers and tapered templates for a wooden pantorouter .
@ut if you haven't built a pantorouter yet, I'd recommend starting out with #ust a bearing on a block and leave these fancy followers for a later upgrade. Cou probalby want to start using your pantorouter as soon as possible, and mounting a bearing on a block is much easier.
