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Need some help w/box joint jig

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Forum topic by phathead posted 04-03-2017 11:49 AM 466 views 0 times favorited 5 replies Add to Favorites Watch
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phathead

8 posts in 284 days


04-03-2017 11:49 AM

As the title suggests I can’t get this right. I made this jig from a plan over 10 yrs ago as I was fooling with wood some. Never used it. Got 3 girls I’ve coached with daughter for 8 yrs graduating this yr so since finding this site buying my saw and seeing some of the projects on here I thought why not make them something as these 3 are good friends of my daughter and have spent a lot time at my house. I thought keepsake box with box joints. All thread is 16 thread per inch. Everything is tight, oak keys in miter slots are tight. Dado set up 1/2”. I tried 5 times. Crank handle pushing part to non turning blade touch. Pull jig back. Start motor, crank handle continuing same direction 8 turns with note to handle position. Make first cut. Seems right on the money as I might have paper thin piece of wood on edge. Pull back crank 16 turns. Reapeat. 4 cuts cutting 2 pc’s at a time also tried one pice at a time. Everytime joint does not fit. Females are 1/2 everytime. Males seem to come up 32nd two wide or they don’t align. Have yet to get a joint that will go together. Any suggestions. I am going to tighten handle after work just to make sure no slippage. Any other ideas welcome. I am a novice at best and some of the projects on here make me feel plain stupid, lots of talent on here. I’ve seen the simple jig of cut, move jig attach to miter, and make cuts by pushing against block then set female on male bock and “walking” part each cut. Wanted to use my jig but if I can’t figure this out may have to go to simple box jig.


5 replies so far

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OnhillWW

112 posts in 1065 days


#1 posted 04-03-2017 12:50 PM

I made roughly the same jig, albeit a bit more elaborate. Things to watch:

Make sure everything is as “slop free” as can be. Stacking of errors will occur, i.e. every error will only add to the next compounding the situation.

I cut two pieces at a time. Use painters tape applied to opposite edges to hold or clamp the pieces together so they do not shift during cutting.

I had to add shims between my dado blades, to get the fingers to form a less tight fit. Use trial and error on scrap pieces to determine the best shim combination for each finger width. I want parts to slip together fairly easily when dry fitting as once glue is added the wood will swell making parts fit much tighter and potentially starving joints of glue.

I cut fingers a hair long and sand flush once assembled.

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phathead

8 posts in 284 days


#2 posted 04-03-2017 01:31 PM



I made roughly the same jig, albeit a bit more elaborate. Things to watch:

Make sure everything is as “slop free” as can be. Stacking of errors will occur, i.e. every error will only add to the next compounding the situation.

I checked and while I can’t find enough play that I think would cause the problems I have been wrong before.

I cut two pieces at a time. Use painters tape applied to opposite edges to hold or clamp the pieces together so they do not shift during cutting.

I will try this.

I had to add shims between my dado blades, to get the fingers to form a less tight fit. Use trial and error on scrap pieces to determine the best shim combination for each finger width. I want parts to slip together fairly easily when dry fitting as once glue is added the wood will swell making parts fit much tighter and potentially starving joints of glue.

I will try this also.

- OnhillWW


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OnhillWW

112 posts in 1065 days


#3 posted 04-03-2017 02:17 PM

Also, I added this to the end of the drive screw opposite the handle to help locate and hold each single turn. It offers tactile feedback every time one rotation of the handle is made and holds the position.

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phathead

8 posts in 284 days


#4 posted 04-03-2017 02:37 PM

That looks slick. Do you “zero” the cam each time you start a new piece? I can definitely add something like that.

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OnhillWW

112 posts in 1065 days


#5 posted 04-03-2017 03:24 PM

I have it set up so that I start @ a zero with the cam/arm engaged as seen in the photo. I have an adjustable foot or locator that I set at the zero position. I shave a hair off it each time I do a box to get a good fresh zero
position.

Here is a front on view of the whole jig:

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