DIY - Small Segment Jig


Well, I finally got around to upgrading and replacing various tablesaw sleds and jigs to fit the new saw. And in addition to the mandatory crosscut box, I designed an add-on for cutting small wedge segments for turned vessels.
I looked at various designs that others pointed out, and decided to build this instead. <BFG> I will build one dedicated add-on jig for each of the common angles (12 sides, 16 sides, 18 sides).
This jig has not even been fine tuned, but this will be accomplished by gently sanding the left or right locating boss slightly - then it is forever aligned perfectly - as long as the main sled survives. I considered putting an allen head adjustment screw in one boss for tweaking, but it really wasn't necessary. KISS is my motto. You can cut through the middle of an 8 foot stick with this design.
The stop block is adjustable for differing lengths of segments. Yes, it requires a screwdriver - big deal. I guess I could put a couple of knobs on it when it starts to bother me.
The jig is retained securely to the sled by 1/4" x 20 screws and T-nuts which are marked by the blue arrows. One keeps the jig securely sandwiched to the sled, adjacent to the hold-down clamp, and the other insures that the jig is held against the rear fence so that the proper angle is maintained. You obviously don't want to torque down on this one too hard or you'll bow the 'fence' <g>
The 3/4 inch 'fence' face was jointed perfectly flat and true. It is HDF core cabinet plywood. I will lacquer the whole mess later.
The crosscut sled is shown here, with the mitre accessory alongside: (This one is for 12 sided vessels, or 15 degrees.) You can also _just_ make out the homemade table insert.
http://www.thevideodoc.com/Images/SegmentJig01.jpg
This is the assembled jig, ready for work:
http://www.thevideodoc.com/Images/SegmentJig02.jpg
And this is the result of the first test cuts: (Barreling of the camera lens doesn't do this shot justice.)
http://www.thevideodoc.com/Images/SegmentJig03.jpg
Pretty good, no? First shot, no sanding, straight off the saw. Man, I love that geared dial protractor. And the best part? No high dollar blue or red extruded aluminum. <g>
FWIW,
Greg G.
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Greg,
Thanks for doing the work of taking pictures and posting. I do not understand the fine detail of the insert piece with the hold down clamp. If your camera has a macro capability, could you make some close up shots from diffrent angles to let us see how it really works? I know its pretty simple, but since I've never seen one quite like yours, I cannot figure it all out.
Thanks, Bob
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BillyBob said:

Bob, you are SO lucky I took an extra picture yesterday. And I'm assuming that you're not being sarcastic here...
This setup is used for cutting small wedge shaped pieces of wood that are subsequently used to make segmented vessels, similar to this:
http://www.thevideodoc.com/Images/SegmentedBowl1.jpg
and this:
http://www.thevideodoc.com/Images/seals.jpg
(just checking to see if you're paying attention...)
It's not designed for cutting 2x4s or furniture stock. I guess it _could_ be used for picture frame moldings, however. If you wanted a 12 sided picture frame...
The sled is a standard crosscut box, as depicted by the first photo:
http://www.thevideodoc.com/Images/SegmentJig01.jpg
It is guided by 3/4" x 3/8" dual runners that ride in both mitre tracks of the cabinet saw.
Note that right above the flash glare, there is a small hole. It is a 1/4" hole with a recessed T-nut on the bottom side of the sled. It has no effect on the _normal_ operation of the crosscut box, and it is recessed into the bottom of the sled so that it doesn't contact the saw table and leave scratches. The bottom of the jig hold-down bolt should also be ground down so that it also doesn't contact the saw table - for the same reason.
This is what holds the add-on jig flat to the sled with the screw depicted by the blue arrow in the second picture:
http://www.thevideodoc.com/Images/SegmentJig02.jpg
Without this screw, the jig would not stay flat when actuating the hold-down clamp to hold the cut-off stock. It's position is important. Be careful not to apply too much pressure with the clamp, or it will move anyway. Only light pressure is needed to keep the wedge in place.
You can't see the second screw (blue line), but there is an embedded barrel nut in the edge of the jig 'fence'. A second screw goes through the crosscut box's rear fence into this nut to hold the jig firmly against the crosscut sled's fence.
Here is your new picture:
http://www.thevideodoc.com/Images/SegmentJig04.jpg
The hold-down clamp holds the cut stock tightly so that it doesn't wander back into the blade when withdrawing the sled after the cut. The green line represents the saw kerf, if you were to allow the blade to cut that far (which you shouldn't.) Keep all fastener hardware and the clamp base clear of this line so that you don't have a disaster should 'someone' mistakenly cut too far into the jig.
The yellow arrow is the stop block assembly. It is simply a long piece of stock with a matching (but flipped) angle cut on it. It attaches to the jig with a 3/16" piece of tempered hardboard with slots cut on the router, so that it may be adjusted to allow for different face lengths of segment stock.
The Cyan arrow indicates a relief cut into the back side of the jig fence, only 1/8" or so. This relief cut only extends to within an inch or so of BOTH jig back edges. The red +/- signs indicate the locating bosses that are sanded lightly to adjust the jig for a PERFECT angle. Sanding the + side results in a greater angle, sanding the - side results in a smaller angle. When you have adjusted the jig for _perfect_ circles, you're done. Each time this plate is attached, it should result in perfect mitres at the desired angle.
Repeat the jig building process for each desired angle - with a totally new jig plate. 10 and 15 degrees are very common angles. 7.5, 8.181818, 11.25 and 22.5 are less commonly used. Make as many plates as you need, as you need them. It takes far longer to explain it than to build one. <g>
If you decide to build this contraption and send it flying through your garage wall at 120 MPH when you first use it, don't call me. Instead, consider cooking or gardening as your new hobby... <g>
HTH,
Greg G.
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Beauty.
--
"I'm a man, but I can change... If I have to... I guess." -- Red Green

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Greg G. said:

And this one is for 18 segment rings - or 10 degrees. Took about a half-hour to build - again, made from scrap.
This is the assembled jig, ready for work:
http://www.thevideodoc.com/Images/SegmentJig05.jpg
The 15 degree jig is sitting to the right - clampless. (I ran out of hold-downs...)
This is the result of the first test cuts: (And again, barreling of the lens effects the image somewhat.)
http://www.thevideodoc.com/Images/SegmentJig06.jpg
No sanding, straight off the saw. Another good thing? No high dollar gold extruded aluminum, either. <g>
FWIW,
Greg G.
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Hey Greg!
Do everyone on the woodturning side a favor and post this on the woodturning NG. Shame on you for not posting it there. Just copy your original post and send it on. I am sure the guys will like it!
BTW, it is pretty damn nice! More important, the quality of the cuts look great.
Robert
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snipped-for-privacy@aol.com said:

Thanks! have already done so. There is a thread going there...
FWIW,
Greg G.
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