Problems with the Porter Cable 4212 Dovetail Jig

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Forum topic by Ayoung posted 02-25-2013 08:10 AM 5270 views 2 times favorited 4 replies Add to Favorites Watch
View Ayoung's profile


5 posts in 2431 days

02-25-2013 08:10 AM

Topic tags/keywords: porter cable dovetail offset misallignment jig 4200 4212

I purchased a Porter Cable 4212 Dovetail jig for making drawers. the half blind template produced a flawless joint. The thru dovetail template however produced a joint where the front of the drawer was misaligned with the side by roughly 3/64”. This may be acceptable, but for a machinist turned wood worker, this was unacceptable, and the drawers would catch, sanding made them slide funny. searching the forums helped, some found the stamped steel side gauges to be out of spec. mine were slightly out, but only by ~0.005. Using a variety of Starrett precision measuring tools I checked all the parts of the jig, and found out what was accurate, and what was not. everything was off a small amount, but the most significant problems were:
1-side play in the mounting slot that attaches the template
2-allignment of the tails slot to the pins slot (almost 0.030”!)
3-and tolerances in the stamped steel side stops.

with this in mind, there is procedure to correct for all these problems at once. You will need a cheep dial calipers, and a set of feeler gauges. it will take about an hour.
1-use the dial caliper to center the bit in the collar. it should be within 0.005 to get a good joint.

2-set up the jig so it makes a tight (hammer together) through dovetail joint. when flipping the template, make a habit of pushing it to the right when tightening the knobs

3-Reset the jig to cut tails, and center a piece of scrap wood, so there is an equal gap between the fingers and the edge of the wood on both sides

4-route the tails, and leave the board clamped in place vertically.

5-Flip the gauge to the pins side, release the vertical board with tails cut, and push up until the tops of the tails are = to the top of the template (the fingers should be in the tails gap.) and the edge is still against the side stop.

6-there will be a gap between the back of the tail, and the finger of the template. measure this gap with the feeler gauges. take the difference between the left and right sides, and divide by two, and select the corresponding feeler gauge (for example mine was off by 0.015. divide by 2 and get 0.0075 rounded to 0.008. I selected the 0.008” feeler gauge for my correction).

7-depending on which side the gap was the largest, you will have to place the feeler gauge between the side stop and the pin board or the tail board, when you cut either the pins or tails.

if you follow these steps, it will account for loose tolerances in machining all parts of the jig, and you will have a perfect joint.

Good Luck

4 replies so far

View RogerInColorado's profile


321 posts in 2468 days

#1 posted 02-28-2013 02:16 AM

Excellent points, all. Precision set up is half the battle. Given your background, I think you would enjoy some of the videos over at He does some really nice videos using dial indicators, etc., to set up tools.

Do you have a centering pin for your router? It’s easier to use for getting your plate centered on the base than a dial caliper, less iterative. Actually, I have an inlay set that includes the centering pin. It was less expensive than buying the Porter-Cable cone.

P-C put out a supplemental manual for the 4200 that is useful for expanding the capability of the jig. It’s available at but have not been able to find it on their site. Actually, I’m not sure it is possible to find anything on their site. They need to test it using actual people.

View Ayoung's profile


5 posts in 2431 days

#2 posted 02-28-2013 01:33 PM

Thanks, I will have to check that out. I do not have a centering pin, and that would be an easier way to go. I have the stock centering cone that came with my Milwaukee router, which is fine for most operations, but for doing inlay or dovetails, it is not accurate enough. A pin would certainly be easier.

I have read the supplementary manual, but they do not mention how to adjust for offset of the boards.

a machinist turned wood worker is a dangerous thing…

View RogerInColorado's profile


321 posts in 2468 days

#3 posted 03-01-2013 12:49 AM

I have the 4210, it is just for half blind dovetails. The manual for the 4210-4212 that is on line ( )
covers this on page 10 (Positioning the Wood) in step 3 – 5. I think they expect you to extrapolate doing it to the right side as well.

I don’t think the person who wrote the manual ever had to make the jig work using the instructions in the manual or even have someone off the street make it work from the manual.

View Ayoung's profile


5 posts in 2431 days

#4 posted 03-01-2013 01:04 AM

yes, they cover positioning the wood, but they make no reference about what to do if when the joint is complete, the two boards are misaligned. By that I am referring to the having the pins and tails flush with the outside of the joint as they should be, but the top and bottom edges are misaligned. to word it differently, if you are looking down at a drawer from the top, the top of the front board is higher/lower than the sides.

hope this is helps

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