Planing dovetails?

[jgourlay]

I need a tip for piece of dovetailing that has been bothering for many years: the final step of planing out the dovetails on boxes.  I get a combination of three issues which tells me I don't know how to set up a plane for this particular operation.  The goal is to do what Schwartz, Cosman, etc do:  get a good final sweep that cleans it all up.

What I get is: 1) I'm planing with the grain and the entry side looks good but the exit end where the endgrain is facing straight up chips out REALLY bad. 2) I plain cross grain, and the endgrain is fine but the long grain between tails or pins is now not like the long grain on the side and finishing makes that defect 'pop' 3) I'm approaching towards the center from both sides in which case both joints look good, but 1/3 in on side is planed with the grain and 1/3 of the way into the other side has tearout from planing against the grain.  The latter is especially true in the curly swirly we like to use for boxes and other small pieces.  

I've tried using a low angle plane for problem 1, and it fixes it 1, but makes 2 and 3 terrible.  I've tried higher angle planes with super tight frogs, that fixes 3, but planing over the end grain feels like hitting the parking block with your car. Chamfering the corners helps but doesn't 'fix' unless I chamfer so far in that it looks bad.  How do I get that long shaving right across the dovetails on the exit side and make the work look easy?

[JimReed@Tallahassee]

I planed the side on the last dovetail drawer project I did. All of them came out well. It was a few years back but here is what I remember doing.

I clamped the drawer frame (without bottom) into my shoulder vise.
I used a piece of sacrificial stock butted tightly against the front.
Sharpened the blade and set for very thin shavings.
Planed from the end up to the pins on front and finished on the sacrificial stock.
Planed at a 15 degree skew.

Of course there was tearout on the sacrificial piece, but not on the drawer. The drawers came out really nice and most of my dovetail mistakes were just swept away.

Good luck on your project.

[knockknock]

Like Jim, I have been clamping sacrificial blocks flush on the sides of my boxes before planing (mainly #1), to avoid breakout at the edges. This does work.


----------
On my last box I decided to try something different. This does require using a plane with a close set cap iron, so that you can plane against the grain without tearout (the key to doing #3).

Note: When making the box with half blind dovetails. I puposefully made the baseline of the pin board a tic shallow. So that the tail board would be slightly proud.

I used a large wooden twin screw cabinet maker's clamp, to clamp the box close to flush, to avoid catastrophic breakout (just in case).

While the initial cleanup and flushing could be done using a plane with a close set cap iron. I used my small bevel up smoother with a toothing blade. I planed to the center (2/3) of the side, both against the grain and with the grain (mainly #3).

For the final smoothing passes I used a number 3 smoother (Kunz+) with a close set cap iron and set for thin shavings. I first planed against the grain to the center, then planed with the grain going almost all the way across lifting just before the edge.

Picture 1: The side of the box after glue up and ready to plane.

   

Picture 2: After cleanup and flushing the side of the box using a toothing blade.

   

Picture 3: The side of the box after the final smoothing passes.

   

[Strokes77]

I might be wrong, but I think it comes down to sharpness, and a tight chipbreaker.  You need to be able to plane in towards the box, without breaking out the end grade. Another problem I have sometimes is if the joint is gappy, not alot, but a tiny bit, i'll get more breakout there that if the joints are super tight.  


Some ideas I have had, and tried are... If you're against the grain planing in towards the box, you could clamp a sacrificial piece to outside of box and plane the other way... or you could cut a small chamfer on corner and plane normal, or potentially use a card scraper.  

None of these work though if your plane isn't sharpened well enough to cleanly plane endgrain.  Which a #4 is completely capable of doing...

[AHill]

Well, Cosman would tell you to make your tails so that they are flush with the sides in the first place.  I never, ever plane from the center toward the dovetails.  I always plane from the dovetail toward the center.  That way, the end grain is supported by itself at entry, and by the drawer side on exit.  Very sharp low angle plane with very light cuts.  If you absolutely must plane from the center toward the dovetail, then get a sacrificial board to lay up beside your drawer.

[Tony Z]

Something I never thought about until this thread! I've always planed my dovetails as Alan just described, towards the center. I also don't have much left proud that needs cleaned off. Again, low angle plane, since it is end grain and hair popping sharp.

[Strokes77]

Something I never thought about until this thread!  I've always planed my dovetails as Alan just described, towards the center.  I also don't have much left proud that needs cleaned off.  Again, low angle plane, since it is end grain and hair popping sharp.

I think OP is trying this as suggested... but he sometimes gets tearout on the face of the drawer when he does this; probably when it's against the grain, then when he tries to plane toward the dovetails, he is getting breakout on the endgrain.

[Derek Cohen]

Just two words ....

belt
sander

.... if Becksvoort does so, why argue?


Regards from Perth

Derek

[hbmcc]

Even when the edge seems sharp, an iron can skip and tear because it is dull. During blade depth adjustment, when I can't get a fine shaving and the tool is at extreme skew to get any shaving, the prognosis is "dull--sharpen it, lazy [guy]!" I've probably made that mental note a couple times, already. A dull blade wants too much exposure in order to cut. 

For my tool of choice, the LN #4, adjustment is sensitive. I feel like I must blow on the nob to get the required adjustment. Lateral adjustment is even finer. 

Second issue, likely leading to tear out in first, is those canyons the blade is spanning, between end grain and side board. Even a backer board needs to be dead flush at corner edges to prevent tear out. Be a good doctor and fill the gaps before final shaving. Obviously, this also applies to the edge-of-the-world shaving also. Use a backer board for when you get caught up in the passion of creating wooden window panes. Jumping off the edge is never a good idea.

[hbmcc]

Just two words ....

belt
sander

.... if Becksvoort does so, why argue?


Regards from Perth

Derek

Hi, Derek. Thought you were busy with work. 

You being grumpy?

I think Becksvoort has assessed the commercial requirements vs amateur snobbery, and found a sander safer. I hope his finishes are smooth rather than 'orange peel' of sprayer.