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Does anyone make tenons on their XYZ machine. It's easy to do one side of a tenon, But if you can't hang your board off the end of a machine how do you do both sides. You can fixture it, but then you need to ensure that your board is always the exact same thickness.
So is there a way to modify an XYZ machine so that you can do both sides and ensure the correct thickness?
If the tenon's are centered in the board both left to right and in the thickness, just butt up against a right angle stop and hold it down.
After the first operation, flip it and go again. If starting at the corner and the height is the same, it will reproduce the same thing the second time. You could always have it go lower to go past the center to make up for any onion skin if going exactly to center.
Same thing if you zero at the center of the tenon. You wouldn't need to touch for zero after the first op. As long as you have a place that's stationary for that time. You could make a board with holes to mount to the table at the same place each time. Have your machine make the right angle to butt up against. Attach some clamps or add some t tracks to slide toggle clamps for different stock sizes. Then create gcode for several sizes that you would use normally and run them when you need them. I think that if you were to do it from the center of the tenon, then you could mark it and move your tool to that marking. If you know the distance from the corner of the room angle, then you could zero there and move the position over the measured amount you need to center the tenon and set, let's say, x zero location.
Lots of ways, you just have to decide how fancy to get
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Is it reasonable to think if you were to reference to the top of stock and cut the first, upper surface of the tenon and then flip the part and reference to top of fixture/machine bed and cut the opposite surface, you would referencing to a common plane and would be reasonably close? No need to try to center thickness of anything then. You are programming 2 different operations though.
I was thinking that thickness is the only thing needed as a variable. Center is easy because it's half the thickness. Reference the top, cut the top. Flip, cut the same again. It should not need locating unless the tenon is offset from the sides.
I thought that extending the tool path beyond the center depth would make sure there isn't material missed.
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Its been my experience that an offset tenon is more common in the trade than not. But, as you are suggesting, with a centered tenon, you would have programmed one operation for both sides. You are also doubling the error if there is one.
Most of the work that I did over time involved a mortice milled with a single cutting tool, one pass. A proper fit, tenon to mortice, then mandates a close tolerance tenon (the only part in the assembly that might have a variable). An approach that wasn't dependent on an exact milling of the thickness of part was often the more acceptable path. And with using a common reference surface, you side step that issue.
Some routers have a hole in them through which which a board can be inserted so that it's supported and clamped vertically, which makes it a lot easier to cut a tenon. Of course, you're limited in the length of board that can be done this way. I'm not sure how your XYZ machine is set up, but this would only work on one that's driven from both sides; any member that travels underneath the table would interfere with the board.
I see what you mean. I was thinking that I would know the thickness of my stock and if tenoning on a CNC, I would have it dimensioned already or cut it with the CNC completelyQuote:
Originally Posted by MARV
I definitely always measure and adjust my tool paths accordingly. In a production environment, this wouldn't work quick enough. But, when I touch off the top of my material, it's well within tolerance. My corner should will be the same position. Flipping would mean that the board would have to be symmetric. Even then, if that's the worry, machine the stock to the correct dimensions and then cut the tenon. Flip that and it should be fine.
If that isn't enough you could use the pin method by machining pin holes in the spoilboard and the stock. Dimension everything within that frame and then tenon.
There are a bunch of ways to do it. I would use a jig and dimension my stock well and use the jig to reference as a fence.
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Wouldn't it be simpler and faster to buy a dedicated tenoner?Each tenon would be done in seconds and they would all be consistent.A hobbyist might derive some amusement from programming a CNC machine to do the job,but a handsaw and chisel would also do the job.
Is this a production setup?
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Routalot, once set up, yes a traditional tenoner would be much faster then a conventional CNC in a production setting. There was a machine offered years ago that would do both mortices and tenons and was CNC. It was before its time and the company is out of business now. With the option of buying modified kit parts, I believe someone could build a machine with a horizontal spindle now and fairly inexpensively. It might require a bit of tweaking mechanically/digitally, but could be done.
I'd be tempted to build a floating tenon machine - then you only have to cut mortises on the cnc machine. Though the Festool Domino might be a faster way to go.
Hey so I would like to input here as I have a commercial workshop and make timber doors. I have a two cutter spindle tennon machine that I put a ball-screw powered by a single nema 23 and a programmable controller onto so I would be able to pull the timber through and climb cut the tennon on the sliding carriage. Trying that by hand and the 200mm cutter will just pull the timber through and well, you can guess the result. So the timber is well clamped with a pneumatic ram. This vastly improves any breakout with conventional tennoning and I was stoked with the result. Infact I programmed it to peck through the cut.
I use a CNC router for the mortise operation and my joins are perfect. Absolutely perfect. I can build a full size door and only need to hand sand the joins.
But back to your question. I also needed a way to mortise out a full size door for locks. I hate doing it the old way, it is a job I despise. So I built a new plate for my Z axis, and mounted the spindle horizontally to enter the side of a door. Also, another fantastic result. I have setup a different Mach 3 profile though for this operation. And basically what it doers is changes the X axis to Z allowing the tool to enter the side. Took a bit to workout and get it perfect, but I can rotate, and mortise a full depth lock out in 20min with CNC results. This instead of drilling and chiseling etc etc.
You could do this with your machine if you want to cut tennons out. The CNC tenon machines I have seen, just cut around the outside of a piece of timber leaving the perfect bottom of the cut and a perfect dimension tenon.
Anyways. My two cents. If you want to do it in one op you can. Will just need a bit of setup is all. Personally I dont like flipping timber in the machine
Sorry I didn't respond sooner. This is for a low production environment. I have designed a desk and my goal is to slap a piece of wood on the machine and have a finished part come off. I have been asked to build about 20 since all of the schools in my area have some level of remote learning. So there is a shortage of desks in my area! So for the desks there are 2 each of 2 different apron parts so I need to make 40 of each part, plus I'm making 5 extra desks and a few extra parts if I screw one up. so I am making ~53 of each part. With 4 legs per desk I need to make 100! But I have been doing these on my 4th axis, and they are done already.
I've actually started doing this already so I'll probably be done building them before before I get this worked out.:rolleyes:
But my plan for the apron piece was to surface 4 sides of the wood, then put a slightly over sized piece on the machine and have a finished part come off. The part has a decorative curve and groove for the parts that hold the top on.
What I am doing now is putting an over sized piece in the machine face down and letting it cut the curve, the groove, and the back half of the tenon. I am working on these parts now. My machine is big enough to hold 4 at a time so while one is being cut I can swap out a part.
Once I am done with these I plan to make a jig to hold the part on my table saw, referencing off the cut face of the tenon to cut the other tenon face. I think that will go pretty fast once set up.