Elyasaf Shweka's box joint jig
Elyasaf Shweka, from Israel, made a screw advance box joint jig to use with his format sliding table saw. Instead of using a miter slot, Elyasaf just clamped it to the fence on the sliding table.
I just finished my screw advance box jig.
It works amazingly well. The hardwoods are mahogany and oak.
I am attaching a photo of the jig and my first try, with ipe(!) - without any setup - got perfect results.
I would like to express my gratitude for the comprehensive and very detailed material you attached to the plans. The four videos are very clear, and go over all the important details. The spacing calculator is very easy to use. Your plans are probably one of the most worthy purchases I ever made. I have been following your work for more than 3 years now, and your work is a true inspiration for me.
I have some difficulties clamping the wood pieces firmly:
Also I noticed that making small boxes in this jig, less than 13cm in height, is problematic because of the clamping, unless I can find a very deep clamp with long jaws. I'm thinking of some kind of a clamp that will give pressure from the inner side of the box - maybe a block that would be against the piece - from the inner side of the box which is in front of the piece that needs to be clamped - to the piece itself. Any thoughts on that issue?
Elyasaf later wrote:
Ok, so there was a little surprise waiting for me today...
Since the first time that went surprisingly well, every try I did came up awful. Every piece got a strong tilt and the joints got ruined over and over again. I added clampss, tightened them firmly - but nothing helped. After 3 or 4 turns - the piece was totally off.
So I inspected the jig carefully, and then I found it. At the bottom of the jig, at the gap that was made by the saw in its first cut - there was some kind of small burning mark. I guessed that I left the jig steady on the same position with the saw running for too long. That burning made some burr on the right side of the gap. Not more than 0.2 mm thickness, but it was enough to hold the piece and prevent it from sliding. This was causing every piece to tilt. It actually never passed that line.
I sanded it quickly - and now we are back in the game.
The jig was built mainly for a project I am working on now: building a stand-alone tilting base for a 50" touch screen. For this I'm making a walnut frame, 115X75 cm, with pieces of 5X10 cm. I'm working now on the test-model, which is made from the cheapest wood that is available here (pine) - . You can see the results of one joint.
Elyasaf later wrote:
After inspecting it more, I realized that it is not a burr. Actually, the heat caused the right side of the gap plywood to expand upwards. And it was like a barrier, which prevented to move straight on the jig - and this caused the tilt.
Here are some new examples of pine and walnut. Tooth width - 4.965mm. For this tooth spacing I use the 12 and the 25-tooth gears. The cut is a turn and a half (one pass on blade, then half a turn, then another pass on the blade) - and then spacing of 2.5 turns. The problem is that it is too narrow. It's attached now with high pressure (I used a mallet to get it in) and no space left for glue. The saw blade is 3.2 mm and with the 25-tooth gear I get 3.31 for each turn. I guess that if ill make a 26 tooth gear, which will give me 3.44 mm for each turn, it would be much better.
Thanks for that, you saved me so much frustration! :)
Elyasaf later wrote:
1 I feel that making a pictorial tutorial that discuss various aspects of operating the jig (not building) would be very helpful. Only for explaining the theory basics behind it, which now i know that are very confusing.
2 i published some photos on a Hebrew amateur carpentry forum, with reference to your site. got good feedback. I know at least about one guy who plans buying your plans now...
I showed the walnut joint to 3 different professional carpenters today (I work in the contraction field, I meet professionals daily as part of my job), and all of them weren't quite sure how I got such an impressive accuracy, tightness and strength. (btw - if the joint is very tight, would you recommend not putting glue at all?) further more, they estimated that this joint requested a digital saw table or CNC, and they assumed it took couple of hours (at least) to build. They didn't believe me that I did it in my house in less then 3 minutes, until I showed them the pictures.
Shweka also sends along this link:
For a mechanical "digital" clock project he built.
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