# Finger joint jig cuts progressively less deep = Why?



## Dodgy_wood_butcher (Mar 31, 2021)

After watching my 47th U-tube on ‘make your finger-joint jig’
I finally made one.
Yay. !

Works great.
Until I notice each cut gets less and less deep.

Got me beat. Why?
I am using the blade the saw came with. Not a dado set ovbiously.
Bit not the ‘flat bottom’ cut blade either ( unsure the correct name ).

Any suggestions / questions / comments welcomed.

see photos



http://imgur.com/a/Ck1vjpJ


the jig and cut parts


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## epicfail48 (Mar 27, 2014)

Got your blade height locked? Could be the blade is progressively lowering


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## Dodgy_wood_butcher (Mar 31, 2021)

epicfail48 said:


> Got your blade height locked? Could be the blade is progressively lowering


sorry, ‘no’ - blade is staying at same height.
I wonder if I ought swap in a ‘flat top grind’ blade ?
( that I don’t have )


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## difalkner (Nov 27, 2011)

Are you pushing the board all the way through on each pass? 

David


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## Dave McCann (Jun 21, 2020)

Dodgy_wood_butcher said:


> sorry, ‘no’ - blade is staying at same height.
> I wonder if I ought swap in a ‘flat top grind’ blade ?
> ( that I don’t have )


If the blade is staying at the same height, then the board is not, only possible explanation. 
I suspect the indexing finger is causing the board to be raised slightly for each successive cut.
The indexing finger does not need to be the full height of the cut.
Remove an 1/8 inch off the height of the exposed portion of the indexing finger and see if you get the desired results.


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## Tool Agnostic (Aug 13, 2017)

@Dave McCann is correct.

The indexing finger is higher than the blade height. Even though the previous cut is pressed down fully on the finger, the blade is not as high as the finger, so the next cut comes up short. Press that cut on the finger, and the next cut is even shorter, and so forth.

When you make box joints, the entire edge of the board should be "flat" on the table as you make the cut. That is equally true if you use a router table and a jig. If the finger on your box joint jig prevents the full edge of the board from staying in contact with the table throughout the cut, then something is wrong.

All is not lost. You can easily fix the board in the photo. Fix the problem by cutting the finger down as Dave suggests, and then you can re-cut the notches in that board. They will all have matching heights.


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## FrankC (Aug 24, 2012)

Looking at the photo the last cuts appear to angled which would mean the outer end of the board is rising, shorten the key and clamp the piece to the backer board for each cut, this will give you an indication of your spacing. If two pieces fit together you are good to go, with fingers that narrow spacing becomes even more critical.


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