# :help: Odd gaps with Porter Cable dovetail jig



## mech-e (Jan 3, 2012)

I just purchased the Porter Cable dovetail jig. My first project involved half blind dovetails for a toy box for my kids. It is made of pine 1x12s. I checked and rechecked the setup but I kept getting weird gaps as shown in the pictures linked below (I tried uploading directly with no success) It was a Christmas present, (started too late) so I couldn't fully debug the joints before giving the pieces to the kids (it was a kit that we then assembled together) I am sure both boards in the jig were flush and against the stops and template.

I understand about lowering the bit for a tighter fit and raising it for a looser fit, but my problem is that with a tight fit, the pins and sockets did not match (as shown in the picture I hope)

Any suggestions on how to avoid this on future projects would be greatly appreciated.


----------



## jlord (Nov 16, 2009)

What bit are you using? If you are trying to make half-blind dovetails the bit that comes with the jig is a 17/32 - 7º #43776PC dovetail bit with a 3/4"od template guide. Both sides of the joint are machined at the same time in the jig. The picture looks more like a straight bit.


----------



## mech-e (Jan 3, 2012)

I was using the dovetail bit that came with the jig.


----------



## mech-e (Jan 3, 2012)

I cut both sides of the joint at the same time too. They definitely locked together.


----------



## jlord (Nov 16, 2009)

Your problem looks odd to me. Usually if there is a gap you would need to lower the bit, but the gap is usually equal on both sides of the joint. How does the inside of the corner look? You shouldn't be able to see any gap at all. It doesn't look like it is cutting each part to equal depth. Any obstructions when clamped in jig? Boards narrower on ends where joint is? Planner snipe on ends?


----------



## Chris_L (Sep 15, 2011)

I have the same issue on my first attempts with the jig. I played around a bit with bit depth and the issue was minimized to some extent. My gap is approx 1/32". See below. I thought there was supposed to be a bit of a gap for glue. I also did notice that the wood I bought varied a bit in width and thickness. It was apparent when I locked the pieces down in the jig but I ran with it. You can see the width mismatch on the bottom left in the image below where the pin/tail joint on the edge don't match up. For the thickness mismatch I wonder if you're supposed to adjust the vertical piece to match heights rather than bumping it flat to the jig fingers?


----------



## jlord (Nov 16, 2009)

The template should be flat on top of material (fronts & backs). Then the front piece (sides) brought up flush to the template capping off the top piece. Parts should meet at line eched in top of template. Parts should be milled for equal thickness across material. You can join parts of different thicknesses but each board just needs to be flat & even.

Chris your parts look like they need to be adjusted as the joint looks uneven at the bottom. How wide did you cut your material?


----------



## Chris_L (Sep 15, 2011)

James,

I used boards off the shelf as bought and didn't cut them down. 7 1/4" nominal. For my next set I'm considering buying wider boards and ripping them down to 8 1/4" so that I know they are the same width across the given length.


----------



## jlord (Nov 16, 2009)

Be careful that the boards are not cupped as this is common with wider material. Which means more machining would be needed.


----------



## KenBee (Jan 1, 2011)

jlord said:


> What bit are you using? If you are trying to make half-blind dovetails the bit that comes with the jig is a 17/32 - 7º #43776PC dovetail bit with a 3/4"od template guide. Both sides of the joint are machined at the same time in the jig. The picture looks more like a straight bit.


Look at the pic again. It looks to me like the top has the angle and the bottom is straight on both pieces. What would cause that is beyond me unless the guide didn't ride the template flush on both sides. To me it looks as if the guide didn't make contact on the right side of the template on either board.


----------



## jlord (Nov 16, 2009)

Ken Bee said:


> Look at the pic again. It looks to me like the top has the angle and the bottom is straight on both pieces. What would cause that is beyond me unless the guide didn't ride the template flush on both sides. To me it looks as if the guide didn't make contact on the right side of the template on either board.


Hard to tell with such a close up. The stain makes it hard to see in picture. I think the template guide is making contact. The tops & bottoms of the joint in the picture look tight. This would be the sides of the template fingers if you flipped the parts around. Usually with a gap the depth needs to be adjusted.


----------



## mech-e (Jan 3, 2012)

The angle is actually there on both pieces. It just doesn't show in the picture.


----------



## TedG (Jan 25, 2012)

It looks to me that your set up was not correct. The top board where the Pins(?) are routered in does not appear to be set at the correct location. The top surface of the top board in the fixture is actually the inside face when it is assembled. The depth of the tails of the vertical board should be idential to the pins of the top board because they are cut at the same time during the same pass of the bit. It almost looks like the top surface of the top board was lower then the end of the vertical board, thus giving you different depths of cut.


----------



## TedG (Jan 25, 2012)

What I meant in a long winded way is; The top surface of the top board and the end of the vertical board should be flush when cutting the tails and pins making them identical in depth.


----------



## jlord (Nov 16, 2009)

They should also line up with the marking on the template.


----------



## TedG (Jan 25, 2012)

I agree Jlord. It took me a couple tries when I did my 1st set to figure how it worked together. PC does not have the best instuction manual with thier fixtures. Doing a blind sliding dove tail was quite the learning experience figuring out how to set the thickness of the tail.


----------



## oldtimer1029 (Dec 3, 2011)

You must use flat, consistant boards, (Pine is notorious for cupping). A better choice in the same price range is poplar. Also check to make sure that all of the sawdust and shavings are off of the jig. Right bushing, right 17/32- 7degree bit, bit set at approximately 9/32 high. Good luck and I hope this helps.


----------



## Imahic (Mar 21, 2010)

I haven't tried half blind dovetails yet but the through dovetails I have done are spot on after a bit of tweeking. There is a bit of a learning curve getting started but once I got it adjusted it works like a champ. Here areti some instructieons I found that helped me. I printed them out and keep in a three ring binder in the shop.

portercable.com/jigs/dovetail/DovetailJigManual.pdf

well, it won't let me post the url because I don't have enough posts but you can put the http and the www stuff at the front of that. Or just google Porter cable . com and the instructions are there. There are several pages so be sure you have plenty of paper.


----------



## jlord (Nov 16, 2009)

Porter Cable Dovetail Jig Manuals
http://www.portercable.com/jigs/dovetail/DovetailJigManual.pdf
http://www.portercable.com/jigs/dovetail/SupplementalManual.pdf


----------

