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Occasional Table Class (Hand Tool Build) #23: Shrinkage Buttons, tapers, and glue up checks

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Blog entry by RGtools posted 02-18-2012 11:30 PM 7708 reads 0 times favorited 7 comments Add to Favorites Watch
« Part 22: Cutting the Joinery for Your Table Part 23 of Occasional Table Class (Hand Tool Build) series Part 24: Drawbore, Glue Up, and Starting on the Tabletop »

Now that you have the joints cut you are a bit closer to your glue up…but don’t be too hasty. There are three things you need to do first.

1. Do a test fit on the joints for the whole table. (well, at least the base)
2. Plane the tapers on the legs after cutting them to length.
3. Create the shrinkage buttons that are used to attach the top as well as the mortises in the rails that they join to.

Here I am just getting an idea of how the final product is going to look.

Really the order here is not super important…but I start with the test fit since I have all my joinery tools ready at this stage any way. I like to assemble the whole table and make sure that everything can be made square without the joints opening up. Check that your joints are tight, your legs parallel and that your corner measurements (diagonal from leg to leg and from top right to top left) are consistent for each dimension you check…these checks will really save your life in the glue up phase….that is not when you want to find problems. I test fit all my work this way, despite what some people say about gluing things up straight from the saw. To those people who say slap the glue on, I think you are either crazy or REALLY well practiced at cutting your joints (and I am sure that savants like Rob Cosman were test fitting their stuff when they were getting started).

Once you are satisfied with the fit of the joints go ahead and place a check mark on the ones you are happy with (on the interior of the rail is a nice way to go…that way you can leave the mark….or use chalk which cleans off easily). And make arrows pointing to the trouble spots you need to fix. Do the test fit gently as many times as you need until you are satisfied with everything (If you are doing draw-bores now is the time to get those drilled out).

Planing the tapers on the legs should be a fairly simple job if you have dog holes and a proper bench. Just make sure to cut your legs to length first so the tapers don’t look wrong (and the tapers remove your true surface), I like use tape to lay out the taper so I can see what looks right to my eye and it also helps me tell which direction is going to be the right angle to plane by the time I reach the angle I am looking for. If however you do not have a good bench set up this is where Jorgenson hand screws will be a lifesaver. Use two to prop your work up at an angle and plane the whole works against a stop.

Now on to the part of this that gave me a headache…. I have been busy and brain dead lately so bear with me…believe it or not this part is simple. The top is connected to the rails with buttons which can be purchased or can be made by the craftsman in a home shop with off-cut stock (a cheaper solution). This is because simply screwing the top to the rails would cause a serious wood movement issue (the rail does not move along the grain while the top moves across it)…you would either split the top or wear out your joints (which ever turns out to be weaker will fail). The buttons allow the top to “breath” with the seasons…there are other ways to do this, but for a small table I feel this is the best way. The buttons are hard to hold when they are finished size so it is best to produce them from larger stock that can be easily clamped to your vise, this can be done starting from either long narrow stock, or wide short stock…but these approaches require different approaches. Let’s start with what is the SAME about the two approaches…your stock should be made flat and parallel on both faces (the actual thickness not being critical…just keep it even and in the realm of a half an inch), and one edge should be planed square and true. Also you should make a point to flatten enough stock to create all your buttons at once (this prevents going back and forth with your marking gauge)…. this is where the changes start in our two methods…

For Long narrow stock:

You will want to plane your stock accurately to width so all of your buttons come out the same width (or close enough). Then you will just need a set of dividers, A marking gauge a combo square and a saw. I like to scribe one line around the whole piece so I don’t have to worry about that mark for depth of cut again. This line scribed on the edges of the work and on the end that you are cutting out first will allow you to stop your saw consistently. Basically, you are creating a Tenon with only one shoulder. For ease of cutting and marking I use the same gauge setting I used for depth of cut for the shoulder measurement. First, cut the shoulder, then the cheek from the end of our work piece to remove the waste…then drill the pilot whole in your first button chamfer both side of the pilot hole…one side to counter sink the screw that will go into the button and the other to remove any obstruction between the button and the table top. Cut this button squarely from your stock (I use dividers for consistency because I am OCD in that…but the actual length of the button does not matter.). You are at this point ready to mark the shoulder and cheek cuts again, saw out waste, drill, chamfer and cut way another button…repeat until you have enough buttons for your project (12 is usually plenty for a small table, I think I should need about 18).

Do yourself a favor and keep your marking gauge on the same setting since you will adjust it slightly to lay out the mortises in the rails that accept the buttons.

For Wide short stock: This requires a rabbet plane, but is in my opinion faster because you don’t have to do as much layout and sawing (one day I should time it over an average of 18 buttons…when I get some free time). Don’t bother jointing both edges since one edge will be waste, just make sure the waste edge can be on the exit side of the rabbet planes cut. Lay out the shoulder and cheek of this joint as you would on the rabbet and cut it out. I use dividers in this case to lay out the widths of the buttons (a little over and inch seems to work out). I use a second marking gauge to layout the base line of the button (since I’m OCD) but you can use a combination square to accomplish the same feat. Mark square lines from your divider marks and use a dovetail saw to cut on one side of those lines to the baseline on each button. Then drill and chamfer the pilot holes as with the other method and crosscut the buttons from your stock…rinse and repeat.

Go ahead and chamfer the edges of the bottom part of your buttons just in case someone is running their hand underneath the piece….this is a good practice exercise for the bevel you will be doing on the table top. Cut the chamfers on the ends first with a block plane and remove any blowout this causes by going with the grain for the remaining chamfers. This is done best on a planning stop of some sort. Try the cut from a few different angles and see what kind of results you get. You will find an optimal angle to skew the plane to get clean controlled cuts on the ends…try and memorize this angle…it’s going to be helpful when you create the top.

Adjust your marking gauge to create the mortices in your rails. You want to generate a little bit of pressure from the buttons to discourage any gaps from becoming evident between the top and the rails. To do this, the mortises need to be a little lower than the depth of the cheek we made before. Again out-come the playing cards; two cards set on the top of a button allow me to capture a new gauge setting from the button with just enough pull to keep everything where it should be.

Cut the mortises for the rails that go along the grain to fit…but make the ones that go across the grain a dimes’ width too long in both directions to allow for seasonal movement. The other buttons simply move in and out of the mortise so a tolerance for those will be added when we install the top later. Cutting the mortises themselves should be child’s play compared to the joints that went before it. Just take care not do dent the rails by sweeping off your bench carefully.

Next stop glue up…Unless you want to pre-finish your legs. If so the only real advice I can render is to tape off the mortises and the tenons in a way that the finishes will not interfere with your glue…but will fully finish the piece (you may have to cut special strips of tape tp accomplish this). This is a good route to go since any squeeze out will be easy to remove.

Here are some random pics for this part.

The one useful thing I have found for the bench cookie in a hand tool shop:

Tore open a hangnail. Oh well the stain is on the bottom anyway.

Masking tape is easier for that initial layout (then you just use the dimensions you captured from that on the other pieces:

Smooth crosscuts with a ripsaw? Yep.

-- Make furniture that lasts as long as the tree - Ryan



7 comments so far

View Bertha's profile

Bertha

12951 posts in 1416 days


#1 posted 02-18-2012 11:59 PM

Sweetness. Loving the grain on that apron!

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Brit's profile

Brit

5285 posts in 1566 days


#2 posted 02-19-2012 12:11 AM

Thanks Ryan. There’s some good tips there. That’s going to be a nice table. I like the proportions.

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.

View RGtools's profile

RGtools

3312 posts in 1378 days


#3 posted 02-19-2012 03:08 PM

Finally got the third video to appear. Sorry about that.

Thanks Al and Andy.

-- Make furniture that lasts as long as the tree - Ryan

View mafe's profile

mafe

9621 posts in 1812 days


#4 posted 02-19-2012 07:25 PM

Things really start to take shape now.
What a nice table.
Best thoughts,
Mads

-- Mad F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View RGtools's profile

RGtools

3312 posts in 1378 days


#5 posted 02-19-2012 10:00 PM

Thanks Mads. Taking shape is exactly the way I feel this part is.

-- Make furniture that lasts as long as the tree - Ryan

View AnthonyReed's profile

AnthonyReed

5012 posts in 1163 days


#6 posted 02-21-2012 10:02 PM

That table is really coming out beautiful.

In the still photo where you are marking up the taper layout; you would be viewing from the face that your fingers are on (face to the right in the photo) to tell if you like taper or not, correct?

A ripsaw, really? Tpi? Sorry a little bitter maybe, i cannot cut that square with my miter saw.

Thanks for a another great class Ryan.

-- ~Tony

View RGtools's profile

RGtools

3312 posts in 1378 days


#7 posted 02-22-2012 04:16 AM

Thanks Tony.

It was my dovetail saw (in the background on that pic) so the TPI is pretty fine at 15. You can still get pretty smooth cuts down to 12 or so but after that you need to do a bit of work to prevent too much tear-out (or adjust the filing on your saw).

As far as the taper. That is correct. The tape just gives you a clear visual as to how the taper looks…I start by marking my STOP line at the top of the taper (since there is not a lot of opportunity for play there) and I place one end of the tape on that….then I mess with it until I like what I see. Once that is done I use the marking gauge to make the second mark…connecting these two lines creates the taper.

-- Make furniture that lasts as long as the tree - Ryan

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