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Thread: My latest jig build - this one is special

  1. #1

    My latest jig build - this one is special

    Hi all,

    Thought there might be some interest in my latest jig build. I try to explain it with pics and short words.

    It's a table saw jig for tenons and box joints. It cuts single tenons, double tenons with individual spacing and boxjoints on all mm numbers larger than 4mm. In first video I said only even mm numbers but later found out it could also cut the odd ones, also boxjoints on halv mm numbers are possible.

    Accuracy is better then 0.05mm and it's super fast to set up. The workpiece is clamped to a carriage, and the movement is acchieved by a large control driving a ball screw to which the carriage is connected. The pitch of the ballscrew is 4mm, backlash is less than 0.03mm and the control wheel is devided into 80 segments with holes at the ends. Pitch 4mm divided by 80 means there is 0.05mm movement between each segment of the control wheel and this is also the resolution of the system, in other words I can trim the thickness of a tenon or boxjoints in step of 0.05mm.

    Coloured pins are used for positions on the control wheel where to start or finish the cut, when the pins matches a reference line on the jig. The control wheel is also equipped with a scale ring that can be zeroed in any position and is used to set the distance between the coloured pins.

    The jig has customable templates/notes that keep track of the cutting process, so I don't have to count the turns of the control wheel. Coloured pins gives exact position, templates shows the bigger picture. If I made boxjoints or tenons of a certain type before, I just bring out the template and is ready to cut without test cuts or other preparations.

    Set up time once used to the system is extremely short, I cut a tenon or boxjoints better than 0.05mm accuracy with a minute set up time.

    Sounds very complicated in words but, this is actually a very easy to use jig.
    Attached Images Attached Images
    Last edited by Lee Schierer; 10-18-2022 at 8:02 AM. Reason: removed links

  2. #2
    Some pics that shows how it looks in operation. Boxjoint pieces are clamped to the large area of the carriage at both left and right position (only left side clamps shows in pic). Tenon cutting pieces are clamped to the wing of the carriage.

    Max width for a boxjoint pieces is 240mm and max for a tenon piece it's 8130mm. Super efficient built in dust extraction tunnel through the jig to the backside where a vacuum hose is attached, tunnel visible in attachment #2.
    Attached Images Attached Images
    Last edited by Ola Carmonius; 10-16-2022 at 7:02 PM.

  3. #3
    Join Date
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    It appears that some of the parts were made on a CNC, is that correct?
    Lee Schierer
    Captain USN(Ret)

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  4. #4
    No CNC involved in this, just plain woodworking (and some very basic hand tool metal working) and standard off the shelf components.

    Although the jig itself, once finished, performs on par with a CNC in terms of accuracy
    Last edited by Ola Carmonius; 10-16-2022 at 8:18 PM.

  5. #5
    Join Date
    Oct 2007
    Location
    Waterford, PA
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    305
    Good grief.

  6. #6
    This is remarkable! But I have to say CNC entry costs and DIY costs are low enough that if you go this far with precision, you might as well go the rest of the way...

    Cutting box joints with a conventional jig works well, but I always found the actual cutting really tedious, and on harder woods, annoyingly loud and gnashy. I occasionally make box joints on my CNC, and am always cutting piles of hand cut-style through dovetails on my CNC , (which was built for joinery, with a spindle that goes horizontal). Though the precision is of course the usual reason to go CNC, for someone cutting lots of joints the fact that you can clamp it and then go do something else for the 30-90 seconds it takes to cut most joints is the real kicker. Also, you don't have to be directly next to the noise of the cutting action.

    But the engineering and build quality in this jig is really something! And it makes me realize that a CNC positioner that would then slide a sled back and forth to make the cuts, making a true CNC joinery table saw device--now that would be really cool! And something the right person could perhaps design for mass production at a reasonable price. Box joints are an example of where the blade geometry of a table saw with a dado is a big advantage over a router with a spindle. The big boys have "aggregate cutters" for their massive CNC machines, but an attachment for CNC table saw joinery could easily weigh under 100 pounds.

  7. #7
    Join Date
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    Columbia MO and Howard County MO
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    1,418
    Thats excellent! It seems like that should patentable.
    Best Regards, Maurice

  8. #8
    @al ladd. Thanks and thanks for your thoughts on this jig vs cnc. For what I'm building which is typically one offs this system is faster for some operations. That's based on my cnc experience, a skilled cnc operator might have other opinion. I typically use it for cutting tenons and the set up time I would say is 1-3 minutes depending on if I've done the exact same tenon before and which blade I have in the saw. Imo very short time to acchieve a tenon within 0.05mm of target. If I cut 4 or 8 tenons which is a typical run for me, set up time is crucial. If I would cut 100 tenons same size, run time would be more crucial and there my jig would be beaten by both cnc and some other methods for cutting tenons.

    For boxjoints the set up time is pretty similar but the time to make the actual cuts cnc is way faster. The boxjoints in my second post is pretty much max width the jig can handle, 240mm, and I think the complete run time was around 15 minutes for all four parts. I ran those in stacks of two. Compared to many existing boxjoint jigs mine (again) exceels in the set up time and how easy it is to trim the fit in steps of 0.05mm, but actual run time is the same as the rest of these type of manual boxjoint jigs.

    Not really up to date on pricing for cnc's, anyway, the material cost for my jig was around 100-140$ (the lower cost corresponds to no digital readout, nice to have but not at all necessary) + wood.

    But maybe most important, although I work with CAD every day I like to keep my shop computer free
    Last edited by Ola Carmonius; 10-19-2022 at 6:18 AM.

  9. #9
    Ola, I was quite interested to see your jig.IMG_0375.JPGIMG_0347.jpgIMG_0373 (1).jpg

  10. #10
    Very nicely done! What were the rail and ballscrew diameters? I'm not sure I completely understand how the the dial and the colored pins work and would love a more in depth step-by-step explanation with photos of that part. Did you make 3D drawings first or did you just wing it from an idea in your head?

  11. #11
    Join Date
    Oct 2005
    Location
    Helensburgh, Australia
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    2,463
    Quote Originally Posted by al ladd View Post
    But the engineering and build quality in this jig is really something! And it makes me realize that a CNC positioner that would then slide a sled back and forth to make the cuts, making a true CNC joinery table saw device--now that would be really cool! And something the right person could perhaps design for mass production at a reasonable price. Box joints are an example of where the blade geometry of a table saw with a dado is a big advantage over a router with a spindle. The big boys have "aggregate cutters" for their massive CNC machines, but an attachment for CNC table saw joinery could easily weigh under 100 pounds.
    Shark CNC have just released a router table kit with pre-programmed joints coded in.
    Chris

    Everything I like is either illegal, immoral or fattening

  12. #12
    Join Date
    May 2008
    Location
    MA
    Posts
    2,016
    It is a work of art! Very much appreciate the thought and engineering that went into it. Awesome!

  13. #13
    Quote Originally Posted by Tom Dixon View Post
    Very nicely done! What were the rail and ballscrew diameters? I'm not sure I completely understand how the the dial and the colored pins work and would love a more in depth step-by-step explanation with photos of that part. Did you make 3D drawings first or did you just wing it from an idea in your head?
    Thanks Tom. Both rails and ballscrew are 12mm. This started out many years ago, inspired by Wandels with wooden gear wheels + other screw using jigs. My first version had the same layout as this latest version of my jig with rails and open construction with built in clamping. Never became friend with my first version, didn't like the backlash in the threaded rod and used it to seldom to remember the different gearing options.

    Rebuilt it last christmas when I installed the ballscrew and invented the control wheel and the templates. No 3D at that time, this jig idea has evolved in my head over the years.

    It's a bit difficult to describe in words how it works but I give it a try.

    If you look on my fourth picture in my original post, you see a coloured pin and a black line on the jig. When my coloured pins line up with that line on the jig something should happen. If only two pins green indicates start or cut#1 and red indicates finish or cut#2. Attach a pic in this post of control wheel only.

    Lets say I make a 12mm tenon and my blade kerf is 3mm wide. I rotate the control wheel to move the carriage/workpiece to where to cut the first cheek. In this position I zero the control wheel using the rotatable scale ring (the part with figures every 0.05mm on the outside of the control wheel). Here I set my green pin indicating a start cut. I should make the second tenon cut at 12mm + the blade kerf, 15mm total travel from where I made my first cut. The ballscrew pitch is 4mm so 15 mm equals 3 turns of the control wheel and then another 3mm. So, in the 3mm hole on the control wheel I set the red pin, stop cut. Then it's time to cut, I begin at my green pin, hold the control wheel steady and make cut#1. Then I crank 3 full turns + until I reach red pin. Here I make cut#2. Done.

    The pitch 4mm is divided into 80 segments, meaning 0.05mm between each hole where I can set my pins. So, if a tenon is loose or oversize, I can move one pin and trim the fit it in steps of 0.05mm, same goes for boxjoints.

    Scale ring can also be used for more advanced zeroing operations, for example setting the exact location of a tenon sideways, not only the thickness of it.

    Maybe sounds complicated but a day or two and you're really up to speed with the mindset. 4mm per turn of the control wheel is pretty much the only thing to keep in mind.

    The cardboard templates that the metal arrow is pointing on is there to keep track of the control wheel turns. So, lines on my template doesn't have to be exact, they are there only so I don't have to count the turns of the control wheel when nothing is supposed to happen, in the case of the tenon the 3 turns freewheeling.

    I only make templates once for a tenon, double tenon or a boxjoint type. Next time I do the same joint I bring out the matching template where I also have written the pin positions. That means I have minimum set up time if I have made the same joint before.

    That was for a single tenon but hope you understood a bit more. Boxjoints works the same way pretty much but there I make multiple cuts between start colour pin and end colour pin, and then some turns of freewheeling the control wheel until process starts over. Looking at pic#5 in my first post you can see a typical template for boxjoints. I start a cut at the green pin=green line on template, then widen my cut a few times until I reach the read pin/line on template, then freewheeling until next green line and start cutting again. For boxjoints the distance between my coloured pins is boxjoint pin size minus kerf, whereas for tenons it was size + kerf.

    Single tenons and boxjoints on every 2mm I run with 2 pins. Custom double tenons and boxjoints on every 1mm I run with 4 pins. Also done boxjoints on 1/2mm and that requires 8 coloured pins, went surprisingly well and wasn't much more complicated than running on 2 pins.

    The digital readout I don't use anymore, the pin system is way faster and more accurate.

    That was the short explanation but there is more to it...

    20220101_181955.jpg
    Last edited by Ola Carmonius; 11-21-2022 at 4:58 AM.

  14. #14
    Ola
    Two items:
    1. If you google pyrouterjig you will find a free program for printing templates for box joints which you may find useful.
    2. I would very much appreciate it if you would comment on my previous reply to your thread.

  15. #15
    Hi Dan,

    1. Ok thanks. I know how to do it myself though in the computer but in this case pens are quicker. It's a one minute job to make the template when I dry run my first row of boxjoints of a new type.

    2. Sorry I didn't know what to comment. It looks kind of unique but I think you should create your own thread to describe how it works, otherwise this thread will very soon be very confusing to read.

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