Making sliding dovetails on large panels.

[Brice Burrell]

  Making sliding dovetails is a great way to produce a sturdy joint, that is if you have a horizontal router table to rout the male part of the dovetail. And I don't have one, but I wasn't going to let that stop me. Even if I did have a horizontal router table the large pieces I needed to make can't be safely run through a table. My solution, the Festool UP-OF Edging Plate on my 1010 router. I'm using small scraps to make sure I've got all the bugs worked out before I get to my project with dovetails on the end of 94" shelves. I started with a dovetail bit set to 3/8".

Here are all the parts I'll be using, the UP-OF Edging Plate and that requires the WA-OF Angle Arm. I'm also going to use the SF-OF Chipguard to help collect the dust. These accessories are normally used for edge trimming laminate, but they will work for this task nicely.

This shot is with it all assembled. As you can see here the Angle Arm attaches to the router where the support foot goes, then the Edging Plate threads into the Angle Arm. The Chipguard mounts the router's base. The Edging Plate can be adjusted by loosening the black thumb screw and turning the green fine adjuster knob. This will set the depth of the bit, in relation to the Edge Plate, not the routers base. In other words, the edge plate is like the bearing on a router bit.

The piece of plywood on the left is the work piece and the one on the right is added for support of the routers base and the Edging Plate to ride on.

With the router in a horizontal position, I rout the male dovetail, surprisingly this is not a awkward as it looks. Flip it over and rout the other side next.

Here is a shot of the male DT.

With the male dovetail done, I'll turn my attention to the female dovetail. The 1010 attached to the MFT's guide rail is the easiest way to accomplish this. I set the dovetail bit 5mm deeper to account of the offset of the guide rail, this should be a good depth to start at. After the first pass hold the piece with the male dovetail up to see in the depth is right. Once the depth is correct I use the fine adjuster to move the router over to make the second pass. Test to see if the male piece will slide in without too much trouble.

Its hard to tell from this picture, but there is a little slop in the fit, that is what we want. The slop will allow room for the glue and remember the plywood will swell a little bit when we glue it.

Blind dovetails are done pretty much the same way, except you simply stop the female dovetail short of the end. I like to use the MFT's flip stop on the guide rail to act as a stop.

The blind female dovetail on the left.

Cut off part of the male piece to finish the blind dovetail joint. On the left the piece with the male dovetail is being slid into place, the shot on the right shows the complete blind dovetail joint. This technique can be used on both small and large work pieces. Remember your imagination is the only limit to what can be done with the tools you have at hand.

For the whole story, Making sliding dovetails.

 

[fidelfs]

Just curious,  first I am a novice so If this does not look safe to do it please tell me.

Won't it be easier if you hold the wood piece on the side of the MFT and hold it with the same clamps you are using (having the wood perpendicular to the table) and using the rail and router guide.  You can make one side in one pass. Then release the clamps turn the wood and don't change the setting from the router guide and run the other side and then you have the male dovetail.

The advantage will be the router is in the normal up position.

The top of the MFT to the round part of the clamps holding the wood is 1 3/8" (the top of the wood is level to the mft top) so you have enough clearance to make the dovetail cut.

 

[Eli]

In my experience any time you have a router upright on the edge of a piece of work, it won't be stable no matter what. I like the look of this accessory. I was moving not at all quickly on building a horizontal router set-up, and this looks way better to me. Thanks Brice. Surely you must be on payroll by now....

 

[Bob Marino]

  Brice,

Good job!

Bob

 

[Brice Burrell]

Just curious,  first I am a novice so If this does not look safe to do it please tell me.

Won't it be easier if you hold the wood piece on the side of the MFT and hold it with the same clamps you are using (having the wood perpendicular to the table) and using the rail and router guide.  You can make one side in one pass. Then release the clamps turn the wood and don't change the setting from the router guide and run the other side and then you have the male dovetail.

The advantage will be the router is in the normal up position.

The top of the MFT to the round part of the clamps holding the wood is 1 3/8" (the top of the wood is level to the mft top) so you have enough clearance to make the dovetail cut.

  Yes, you are right, it is easy to clamp the work to the side of the MFT and use the edge guide. But the technique I'm demonstrating here is for large work pieces, too big to be clamped to the side. I know the pieces shown here are small, I was testing the concept on scrap to make sure it was going to work. The project I did yesterday needed SDT on the ends of 5, 94" shelves, I would have needed a step ladder to reach the top if they were clamped to the MFT.  ;D

 

[Dan Clermont]

Very nicely illustrated Brice!


Dan Clermont

 

[Jerry Work]

Hi Bruce,

Nice post covering this very important joint and that unfortunately little used router accessory that I find handy for a range of things.  The only comments I would make are that it is generally easier to cut the female first and then fit the male to the female than the other way around.  By cutting the female in one pass full depth you can use the center line marks on the router to position the female slot very accurately.  When you fit the female slot to the male DT, as you indicate in your excellent write up, you need to make one slot cut and then move the router a bit to cut the second face to fit.  That requires using something other than the centerline to establish the position of those cuts.  The advantage to cutting the male first is you can leave more material in the male piece since the bit needs only clear the outside edge to form a nice point on the DT.  If you do elect to cut the female first you need a bit that is the same size or just a little smaller in overall tip width than the material thickness.  Since I work mainly with solid hard woods I like the look of the 14+mm DT bit on the 20mm normal stock thickness that I frequently employ.  When using soft woods or 20mm man made materials I use a 20mm bit to leave the male as thick as possible for strength.  

Another option for cutting the male in awkward pieces is to fabricate a saddle and mount the router on a swing arm attached to the top of that saddle.  The swing arm allows very small adjustments in the side to side positioning of the router bit while the saddle slides snugly along both faces of the piece into which the male DT is to be cut.  Position the bit to cut a nice sharp edge on one side, then reverse the saddle to cut the other side.  A couple of adjustment/trial passes and you can get a very accurate fit.  If you commonly work with standard material thicknesses, the settings will be very close piece to piece depending only on your ability to set depth the same time after time.  If you do a lot of sliding DT work, it is not a bad idea to keep a router with a DT bit already set up this way so long as you have two identical DT router bits.

Hope this is a helpful addition to your already most helpful post and pics.

Jerry

 

[Brice Burrell]

Jerry, you are right, doing the female first is a good idea. In this project I cut the male first because I wanted to remove as little material from the edge of the male DT as possible. However, the small DT bit I have would have meant removing more material from male DT than I was comfortable with. If I had a larger DT bit to make one pass for the female DT, I may have done it as you suggest. I'll be adding a few more DT bits to my collection, thanks Jerry.

 

[Overtime]

Another great descriptive of the some of the "mysterious" accessories available for the router line. And the price is getting better - only $99.00 for all 3 components. And only a mere $330.00 more if you don't already have an OF 1010  ;D

Brice, you are going to need your own Festool part ID # (BB 489###) soon,  as your work is like an Interactive Festool catalog !
   

 

[enderw88]

I understand this was mocking up the tooling to try an idea, but, in general, is it good practice to do this joint on plywood? This is a real question, I really don't know if it should be done with plywood.

 

[Brice Burrell]

I understand this was mocking up the tooling to try an idea, but, in general, is it good practice to do this joint on plywood? This is a real question, I really don't know if it should be done with plywood.

The joint is stronger with solid wood, but plywood can be used too.

Jerry, you are right, doing the female first is a good idea. In this project I cut the male first because I wanted to remove as little material from the edge of the male DT as possible. However, the small DT bit I have would have meant removing more material from male DT than I was comfortable with. If I had a larger DT bit to make one pass for the female DT, I may have done it as you suggest. I'll be adding a few more DT bits to my collection, thanks Jerry.

Because plywood was being used is why I didn't want to remove too much material from the male DT, I was afraid it might weaken the joint. I did use plywood for the real unit and I would use it again.

 

[enderw88]

Thanks!

 

[Dave Ronyak]

Great job, Brice.  I don't own any of the accessories that you used, or a 1010 router - mine is the 1400.  I like your idea of cutting the male dovetail referencing off the local surface of the plywood because I have yet to experience a flat piece of plywood.  If you clamp the plywood to the side rail of the MFT, it may bow and thus using a guide rail sitting on top of the MFT to guide the router when forming the male dovetail may be more problematic than using an edge guide.  I also see no reason why Brice's technique for forming the male dovetail cannot be accomplished with a edge guide to which you have added an auxiliary fence to provide a stable hand-hold-down to be applied against the top surface of the (large) piece of (ply)wood to be formed with a male dovetail.

Dave R.

 

[gkeas]

Digging up an old post here, but it seems like the MFK700 could do this pretty easily, too, if the bit isn't too large.  Am I correct on this?

 

[mwhafner]

Digging up an old post here, but it seems like the MFK700 could do this pretty easily, too, if the bit isn't too large.  Am I correct on this?

Garry,

Jerry Work has a tutorial for using the MFK700 to make sliding dovetails. 

You could probably also use the 0* horizontal base to route the male portion, and the vertical base to route the female portion.  You just have to be careful with your depth of cut. 

 

[Brice Burrell]

Digging up an old post here, but it seems like the MFK700 could do this pretty easily, too, if the bit isn't too large.  Am I correct on this?

No, the MFK uses a bearing to act as a stop when routing with the horizontal base. The bearing doesn't allow the MFK to be held perfectly perpendicular to edge being routed so the DT bit could wander side to side making a mess of the cut. 

 

[butzla]

Brice, I missed this post the first time around.  Actually I don't think I was a member in 07.  I've only seen Jerry's method of attaching the router fixed to an MFT3.  I gotta try your method.  I already have all the parts so why not. 
Question,  What dovetail bit are you using and you obviously have no trouble making the female slot in one pass?  I would think a straight bit would be necessary for a first pass, to hog out the bulk of the material.  ...particularly in hardwoods.

 

[Brice Burrell]

Brice, I missed this post the first time around.  Actually I don't think I was a member in 07.  I've only seen Jerry's method of attaching the router fixed to an MFT3.  I gotta try your method.  I already have all the parts so why not. 
Question,  What dovetail bit are you using and you obviously have no trouble making the female slot in one pass?  I would think a straight bit would be necessary for a first pass, to hog out the bulk of the material.  ...particularly in hardwoods.

I have a Festool DT bit, very nice. I just go for it in one pass, hasn't been a problem but I've only worked with ply.

 

[chrisrosenb]

Digging up an old post here, but it seems like the MFK700 could do this pretty easily, too, if the bit isn't too large.  Am I correct on this?

No, the MFK uses a bearing to act as a stop when routing with the horizontal base. The bearing doesn't allow the MFK to be held perfectly perpendicular to edge being routed so the DT bit could wander side to side making a mess of the cut.   

I do not have an MFK 700 at this time so I am just thinking.
Could some type of edge custom guide be used in place of the bearing?

 

[Brice Burrell]

I do not have an MFK 700 at this time so I am just thinking.
Could some type of edge custom guide be used in place of the bearing?

Chris, possibly, I given this some thought in the past but didn't come up with anything that was practical to make. I like the idea of using the MFK for the application, I'm just not sure I have the means to pull it off.