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What's wrong with my dovetails?

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Forum topic by bluplanet posted 04-17-2012 01:09 AM 1329 views 0 times favorited 7 replies Add to Favorites Watch
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bluplanet

37 posts in 2130 days


04-17-2012 01:09 AM

I’m trying out my recently purchased dovetail jig with some kitchen drawers. I’ve got a Porter Cable 2112 dovetail jig and a dovetail router bit with a half inch major diameter. I purchased the bit separately from the jig and I’m not sure they’re compatible.

This jig is supposed to only make half-blind dovetails and finger joints, not through-dovetails.

My stock is 1/2” thick. I made all adjustments according to the manual (unless I missed something) and ended up with a joint that was way too loose, so I increased the bit depth by half the amount of slop in the joint.

That gave me a perfect fitting joint, but now its a through-joint and the bottom of the router bit skimmed the paint off the top of my jig.

What happened? Am I using the wrong bit?


7 replies so far

View TrBlu's profile

TrBlu

379 posts in 2093 days


#1 posted 04-17-2012 01:37 AM

1/2” stock is probably going to give you a through dovetail. Most half-blind dovetails are 1/2” deep.

To protect your jig, place a sacrificial piece below your pins piece. That effective raise the jig by the size of the sacrificial piece you use.

-- The more I work with wood the more I recognize only God can make something as beautiful as a tree. I hope my humble attempts at this craft do justice by His masterpiece. -- Tim

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a1Jim

115207 posts in 3045 days


#2 posted 04-17-2012 01:58 AM

Do you mean Porter Cable 4212 ? If so I believe the instructions are printed right on the end.

-- http://artisticwoodstudio.com Custom furniture

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bluplanet

37 posts in 2130 days


#3 posted 04-17-2012 02:07 AM

Thanks, TrBlu.
I just tried that. Works fine but the side stop is only .160 thick so my stock now hovers above it. ...takes a bit of care to get the wood to line up with it.

a1Jim…
Nope. Its an old 4112. Doesn’t have the slide-out instructions and just has a couple of big thumb screws instead of the cam-clamp.

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TrBlu

379 posts in 2093 days


#4 posted 04-17-2012 11:25 AM

bluplanet: I have an old 5008. It is very similar. I make sure my sacrificial piece has a squared corner from the front to the side stop. Then line my project piece with that edge. I use the flat side of a narrow steel rule to make sure both are flush.

My 5008 is about 30 years old. I think the 4112 is a generation or two newer. There were two versions of the 4112 sold by PC, one with plastic guides and one with aluminum. Which do you have?

-- The more I work with wood the more I recognize only God can make something as beautiful as a tree. I hope my humble attempts at this craft do justice by His masterpiece. -- Tim

View bondogaposis's profile

bondogaposis

4037 posts in 1819 days


#5 posted 04-17-2012 02:06 PM

Generally half blind dovetails are made w/ 1/2” stock for the sides and 3/4” stock for the fronts.

-- Bondo Gaposis

View Bill White's profile

Bill White

4459 posts in 3428 days


#6 posted 04-17-2012 02:29 PM

My 4210 has a specific bit, #43776PC, for half blind DTs. It is used with a specific guide for the jig. THis cuts 3/8” lond tails. Works just fine in 1/2” sides with 3/4” fronts.
Bill

-- bill@magraphics.us

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bluplanet

37 posts in 2130 days


#7 posted 04-18-2012 12:55 AM

TrBlu:
Mine is all steel with an aluminum template.

bonbogaposis:
I’m using stock that’s about 13/16” thick for the front and I have 1/2” stock for the sides and back.

Bill White:
I just ordered a 1/2” 14 degree bit. I’ve drawn this all in CAD and this seems to be the bit to use for this comb template with a 7/8” tooth spacing.

All:
I’ve taken another measurement of the router bit I’m using and I think I’ve found the problem. The bottom of it is about .572” across at the widest point, not 1/2” as I said in my top post. It’s the wrong diameter for the comb template I’m using. In order to get a good snug joint with this bit and template combination, I have to set the router depth so deep that the smallest diameter of the cutter is below the top of the wood and the bit shank is burning through about .050” of wood without actually cutting it.

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