Tag Archives: tips

Wraparound Dovetails – How I Fit Them

Most of us are familiar with the techniques for fitting dovetails during construction.  You cut the pieces to size, mark your dovetails, and cut away.  Even if you machine-cut, the process is basically the same.  Everything is measured from the end of the board.  However, there are times when this approach doesn’t work.

This blanket chest is a perfect example of this.  Christopher Schwarz’s Anarchist’s Tool Chest is another.  In both cases, a base or dust seal wraps around the basic structure of the chest, and is dovetailed into place.  The problems start to arise when you realize that the pieces cannot be precut to length, but must be fitted to the existing structure to ensure a good fit.  No, measuring with rule is not a substitute for a good direct measurement.  Of course, your measurement doesn’t tell you how far past the end of the casework the board should extend for the overlap that will give a good, snug dovetail.  This is how I do it:

Dovetail Tuning 1

Start by dovetailing one corner to act as a reference, leaving the board overlong.  Then, with the assembled dovetail snugged into place, mark the corner of the casework on the other end.  A marking knife will work, but I find that a pencil will angle into the corner more easily without wandering.

Dovetail Tuning 2

Next, stand the opposing board (or an offcut of the same) on edge on this board, with the inside edge flush with your pencil line, and mark the location of the outside face.  This measurement isn’t really critical – you just don’t want to be too short.  Next, crosscut the board to just outside this last line to establish the rough length.

Dovetail Tuning 3

Now comes the trick.  Take your marking gauge, which you already set while cutting the first dovetail, and place it against the sawn end of the board.  There will probably be, as shown above, a gap between the knife/pin and the pencil line.  Simply plane away the excess with your shooting board (you do have a shooting board, don’t you?) until the marker touches the far edge of the pencil line.  If your marking gauge was set correctly in the first place, you should now have the correct amount of overlap to yield a dovetail that wraps snugly around the casework.

With a little thought and modification, this technique will also work with dovetailing jigs.  Simply set your marking gauge to the base of the first dovetails, and proceed as above.  Since all you’re doing is effectively cutting a board to length, the dovetailing method is really irrelevant.  Give it a try!

What I Screwed Up This Week – Molding Miscalculation

Welcome back for another educational issue of What I Screwed Up This Week!  This time, we take a look at a molding miscalculation from the current blanket chest project.

The Problem:

Panel Molding 2

My plan was to have the panels of the blanket chest set in 3/8″ from the front of the frame.  This would allow a 1/8″ shoulder at the top to provide a visual break between the molding and the frame.  However, there was one problem.  The above drawing reflected my thinking.  I visualized the panel as a flat surface, rather than having a raised bevel.

Panel Molding 3

The reality was far different.  The sloping bevel of the panel raised the molding upwards.  While the drawing above is exaggerated, the oversight is clear.  The shoulder at the top of the molding becomes too small, giving no real definition to the transition.

The Solution:

Panel Molding 4

I played with several ways to rectify the problem.  However, the simplest turned out to be the best, and easiest to implement.  I simply trimmed down the upper edge of the molding to recreate the shoulder.  Surprisingly, it had very little effect on the appearance of the cove – much less than I had anticipated.

Blanket Chest 30

To remove this wood, I took a page from Matthew Bickford’s blog, Musings from Big Pink, and made a small sticking board.  This allowed the small piece of molding to be held in place simply by the friction of planing it.  The taper of the side support reduced the area of contact for the plane, and acted as a sort of depth stop (or at least reference) once the first piece had been planed to the desired thickness.

Blanket Chest 31

A few strokes with the plane were all that were necessary to reduce the height of the molding enough to create a viable shoulder at the top.  Here, you see a piece coming to final thickness.

Lesson Learned:

Angles can change everything.  Even a small slope or curve can drastically affect how pieces interact with each other.  Be sure to do mock-ups of any such areas, and determine if you need to make any modifications to your design before you paint yourself into the proverbial corner.

Close At Hand Holdfast Pads

Holdfasts are wonderful devices.  Their ability to secure wood to the benchtop with a single mallet tap can seem almost magical some times.  However, they have a tendency to dent the surface of your workpiece, especially in softer woods.  I’ve tried gluing on leather pads, but found that they tended to come loose after a short period of time.  A block of wood works well, but a piece of the right size can sometimes be difficult to locate when you need it.  Plus, a scrap off the shop floor can have a chunk of “something” imbedded in it, the impression of which can be transferred to your work.

Holdfast Pad 1

My solution is a pair of dedicated holdfast pads.  You’re probably wondering what makes these different from the nearest piece of scrap.  I’m glad you asked!

Functionally, there is no real difference.  The biggest difference is in what you do with them when not in use.  These pads were cut from a piece of offcut from a pine tenon cheek, so they are basically non-mar.  The piece was thicknessed carefully to ensure that two of the pads, when placed together, would fit in a slot in the French rack on the back of my bench.  They were sized to this end, with a modified “T” shape to keep them from slipping all the way through the slot.

Holdfast Pad 2

So, when not in use, the pads reside in a slot in the back of the bench, taking up little room and not sticking up far enough to get in the way.  When needed, they are close at hand to be grabbed, used, and then replaced in their slot.

If you don’t knock them off on the floor and lose them in the shavings that you haven’t swept up, that is.

Bench Helpers

One thing about a bench – you invariably wind up with all sorts of handy-dandy things to make it more useful. Now, bear in mind, I’m a simple hobbyist woodworker.  While I like to make nice pieces, you won’t see them in my shop.  I can see no reason to use expensive woods and involved finishes on something that’s going to take a beating as part of it’s normal existence.  As a result, my shop furniture and fixtures tend to be simple and to the point.   That said, below are my solutions to various problems around the bench:

Accessory Retention System

As I mentioned in a previous post, one of my favorite bench accessories is my collection of T-spacers for my face vise.  The problem is, there are several that I use routinely.

Bench Organizing 1

This Accessory Retention System (hey, sounds good anyway) is a simple little good piece of plywood drilled for holdfasts, notched for T-spacers, and screwed to the underside of the end of the bench.  After installation, I realized that vibration from working on the bench caused the T-spacers to jump out of their notches, so I added the lips to the end to keep them in place.

French Rack

I’ve never been fond of tool trays in a bench.  Called “hamster nests” by many (including me), the seemed to be a great way to give up bench space and lose tools at the same time.  Some time back, Christopher Schwarz wrote about employing a “French Rack” on his latest Roubo workbench.  His was, typically, made of hardwood and attached with some fantastic Roman nails.

Bench Helpers 2

My version is, typically, made of strips of 2×4 with spacers/dividers cut from matching strips and then glued and brad nailed where desired.  The entire assembly is then screwed to the back edge of my bench with not-so-fantastic drywall screws.  I liked it so much that I added a second one to span the entire back of the bench.  I realize that it is not nearly as impressive as the one The Schwarz made.  However, it performs the same basic function of holding tools out of the way for the work in progress.

Board Jacks

One of the main advantages of the Roubo bench is that the legs are flush with the front edge of the top.  This allows all sorts of holding and clamping options not available with other designs.  When I made my bench almost four years ago, I didn’t take this factor into consideration.  However, by lucky coincidence, my top overhang was almost exactly 1 1/2”.  This allowed me to install a pair of board jacks made from simple 2×4’s with 1” holes.  A pair of moveable brackets were added to support the board.  I chose this over a simple peg to prevent “ovalling” of the holes over time from the weight of boards on a single peg.  Two legs, two jacks – simple and effective.

Bench Helpers 4

As you can see, my bench helpers are lacking a certain “fit and finish.”  I simply used available materials in response to a particualr need.I’m sure there may be better ways to do things but, as Detective Rick Hunter (remember him?) used to say years ago, “It works for me.”

What I Screwed Up this Week, October 29, 2010

This is the last installment for the outfeed table.  I’m not sure what it says about my woodworking skills that I got three different screw-up articles from one project, but at least you get to learn from my mistakes.

The Problem:

IMG_6061b

The outfeed table was intended to push up flush against the back of the tablesaw, but, as the photo shows, the leg of the table lined up perfectly with the slightly-splayed leg of the saw and prevented a flush fit.  Tthe table’s overhang is kept back from the edge of the saw top about two inches.  This isn’t enough to cause problems, but is not what I intended.

The Solution:

At this point, there really isn’t one.  If I had recognized this problem sooner, I could have left the overhang of the outfeed table longer, so it could reach over the rail all the way to the table.  As it is, I’ll just have to live with it.

Lesson Learned:

Never forget to consider how your piece will interact with its surroundings.  While you can’t predict everything, repeated checks and test fittings before important glue-ups or other one-way steps will greatly reduce your grief.

That’s it for this project, but plenty more are on the way in the near future, so stay tuned to find out What I Screwed Up.

What I Screwed Up This Week – October 20, 2010

I mentioned that the outfeed table should provide plenty of food for thought for this column, and this proved true. The first problem occurred while assembling the plywood frame for the table top.
 
The Problem:
 
As I drove the first pocket screw to assemble the frame, it went through the bottom of the hole, and split the end of the plywood apart.  I was puzzled – the screw had worked just fine when I did some test joints in pine.  Obviously the torque setting was too heavy for plywood, and had spilt the plys apart rather than stopping when the screw bottomed out..
 
The Solution:
 
I backed the screw out, glued and clamped the split plys back together again, and redrove the screw with a correct torque setting.
 
Lesson Learned:

Always make a test run of joinery techniques using scraps of the same material as your project.  This will ensure that everything works correctly, and you don’t get surprised on that first connection like I did.

The second problem was noticed the morning after I had attached the frame to the top.

The Problem:

The plywood top had developed a pronounced bow during the night.  This was despite the fact that the support frame had been screwed into place. 

I had tried to save some money by using a B-C exterior plywood. I reasoned that only the legs would be visible, an the frame would provide plenty of rigidity.  I was wrong – the plywood was not stable enough for this type of light support, and bowed 3/4″ in the middle.

The Solution:

There was only one thing to do – replace the plywood top.  Accordingly, I went back to the lumberyard and got a sheet of cabinet-grade maple.  This stayed obligingly flat and allowed the project to continue.

Lesson Learned:

Construction plywood is for just that – construction.  It rarely has the degree of flatness required for furniture.  In construction, a certain amount of warp is acceptable since the plywood sheets will be firmly nailed to a sturdy frame such as a stud wall or roof rafters.  In furniture, rather than being attached to a structure, plywood often IS the structure and flatness and stability are paramount.  A sheet of cabinet-grade maple was only $11 more.  Spend it.

That’s it for this episode.  Stay tuned for more goodies in the future.

Upcoming Feature: What I Screwed Up.

A new feature is coming to the Little Good Pieces blog: What I Screwed Up this Week (or month – we’ll see). The purpose of this series, besides giving you someone to point to and laugh, is to analyze things that I did wrong in the shop and find ways to correct the situation and keep it from happening again.

This will be a great chance for all of you to post comments with possible solutions or alternate ways of working that might prevent these problems from occurring. At the very least, you might get a good laugh at my stupidity. So, be watching for the first post sometime in the next week or so.