Fine drawer making, part 3
Words and photos: Neil Erasmus
Since I last wrote about drawer making I have noticed there are still many pitfalls for the occasional maker of traditionally constructed, solid wood drawers. Among them, the process of fitting drawer slips. I used to only do this on my very best pieces, but several years ago I came up with a much faster ‘flush slip’ method.
Why drawer slips?
A drawer slip is a rectangular section of wood that is grooved to house the base, and then glued flush with the bottom inside the drawer side. On wider drawers they are accompanied by an evenly spaced, dividing muntin or two, screwed under the back. Both slip and muntin fea- ture a bare-faced tenon that is housed in the groove in the front, which also serves to house the front edge of the base. Using them because ‘it’s the way it was done around the turn of last century’ does not wash with smart people who can see no reason not to groove their drawer sides to accommodate their bases.
Here are five good reasons for using them:
1. The base is supported by the slip. Because of this, the base can be much thinner, lighter and more elegant.
2. A thin drawer side means less material has to be removed when cutting the dovetail sockets in the drawer front— an arduous task with deeper half-blind dovetails.
3. It also means less material to remove when cutting the pin sockets—very quick work.
4. The combined surface area.
of the side and slip offer greater support on a traditional wooden runner, meaning less wear over the years.
5. The extra support the slip offers the side helps prevent bowing, a potential problem that can cause binding.
Back to base
I deviate from the tradition of slotting the screw clearance holes in the back of the drawer base where it fixes to the underside of the drawer back. These slots were designed to allow for the expansion and contraction of the base, but, having seen one too many turn-of-the-century drawers with an unsightly void at the front, I use another strategy.
This problem is caused by tight screws that result in shrinkage at the front, rather than the back. Fixing the base in the drawer back, allows the wood movement to take place in a deeper than normal groove in the drawer front— a little like a solid panel in a frame. This also explains the long, slender nature of the half blind dovetails at the front that makes space for the deeper groove. A nicer alternative, I think.
Another little feature I have adopted from masters past, is the setting forward, by 3mm or so, of the drawer back from the ends of the sides, slips and base. This gives a better position for the screw clearance hole in the base, and also means that the back can be completely finished before assembly—no flushing of dovetails.
Making a drawer
1. Machine all components according to the cutting list, using the FEWTL (Face, Edge, Width, Thickness, Length) sequence. Join up boards (if necessary) to make the drawer base, but keep the lat- ter oversize at this stage. Use a sharp, crosscut sawblade and sacrificial wood to crisply cut components to length.
2. Orient all components and ‘triangle’ mark on top edges . Sides should have concave faces facing out to prevent binding in the completed drawer. Even seasoned wood when newly machined can develop a small amount of bow.
3. Hand plane or sand (use a hard block) to final finish inside front and side faces, both back faces and top face and inside edge/s to slips and muntin.
4. Set up a sharp cutting gauge to the desired dovetail size and cut clean lines across the ends of the fronts and matching sides. A deeper cut may be made on the inside faces of the sides.
5. Set the cutting gauge precisely to the drawer side thickness, and cut lines across the inside face of the drawer front, and both faces and top edge of the back.
6. Set the cutting gauge to the thickness of the drawer back, plus 2 or 3mm, and mark across both faces of the rear end of the drawer sides, again cutting deeper on the inside faces.
7. Mark pins to front. Remember that half pins at top and bottom of drawer front are sized to fit within the (anticipated) material that is left at the bottom of the groove for the base. Put simply, the half pin can be no bigger than the slip height less a saw-kerf width.
8. Mark pins to back. Remember the back has one half pin at the bottom edge, and as many pins as are desirable with the top full pin placed close to the top edge.
9. Cut, cope and chisel pins to both front and back.
10. Transfer pins to the sides with a needle-point sharp pencil, and cut, cope and chisel. Don’t forget that the drawer back is positioned one drawer slip thickness up from the bottom edge of the sides. Tip: if it is too hard to see the pencil lines, stick some white veneer tape over the tails and mark. Wet and remove once all cutting has been done. This is a great trick if your eyesight is not as good as it used to be!
11. Groove the drawer front to take the drawer base. This groove depth is 0.5–1mm shy of the base of the dovetail pins, and is positioned with its upper edge flush with the height of the slip, and is 3.2mm, or one sawblade kerf wide. Place the top face of a slip against the saw’s rip fence, and using a steel rule as a probe, set a saw tooth flush with it, before dropping the blade and sawing the groove in the front.
12. Sand the top edge of the drawer back and remove the arises with a block plane.
13. Check all steps mentioned have been completed , then assemble the drawer using PVA glue. Clamp if necessary, but ensure the drawer is square, and parallel.
Wash any excess glue from the insides with a toothbrush and clean, warm water.
14. Sand to final finish the top face of the drawer base, which is still oversize.
15. Set up the router table with the special slot cutter assembly (see bottom of this page). Set the top edge of the lower (5mm) cutter just below the surface of the router table. The distance between the top edge of the top cutter and the router table top must be less than the thickness of the drawer base.
16. Place and clamp a fence over the cut- ter assembly so the cutter cuts a 5mm deep groove. Use a marker pen to mark close to one of the three teeth, then meas- ure with a height gauge the exact height position of that tooth relative to the top of the table and record.
17. Fix two featherboards in position to guide the slips through the cutter, then rout the slips, top face down, using a pushstick.
18. If a muntin is fitted, use the same setting, again face down. Reset the side feaetherboard.
19. Raise the cutter assembly by precisely the thickness of the top blade—add this to the last measurement you recorded.
20. Reset the top featherboard to fit the drawer base(s).
21. Check the dimensions of the drawer base(s) by measuring between the grooves in the slips. These must be held in place and cut to fit leaving an extra 5mm at the back edge. If a muntin is fitted, be sure to deduct the measurement between the grooves.
22. Rout the tongue onto the ends, not the front or back edges, of the drawer base(s), again face down and check its top face is flush with the top face of the slip or muntin.
23. The bare-faced tenons on the front ends of the muntins and slips can be created by carefully marking and cutting by hand. Material is removed from the bottom edge to leave a tongue whose thickness and length matches the groove in the front.
The photo above shows the muntin with a completed bare-faced tenon.
24. The cutter assembly has to be changed once more to cre- ate the tongue on the front edge of the base. Raise it so the space between the bottom of the 5mm (lower) cutter and the router tabletop is the width of the drawer front groove (usually
3.2mm). The fence too must be adjusted to cut a tongue that matches the groove depth. As before rout the base with the top face down as shown above.
25. Re-sand all the inside faces of the drawer with 320 grit, especially where water was used to clean up glue ooze.
26. Drawer slips can now be glued in place, flush with the bottom edge of the sides. The glue face may be relieved slightly with a shaped scraper to prevent glue squeeze-out.
27. Rip the sacrificial 5mm from the back of the drawer base(s).
28. Measure and drill clearance holes near the back edge of the base(s) for brass screws, and countersink.
30. Slide the base(s) in, drill pilot holes into the underside of the back, and screw down with ‘spun’ brass screws. I take standard No.3 countersunk head brass screws, chuck them in a drill press and press the screw head down gently onto 320 grit sandpaper on a softwood block to give the head a nice concentricly machined appearance. Be sure to use a close fitting screwdriver, or the nicely prepared screwhead will inevitably get damaged.
It is better to fit a drawer to its housing once the base has been fitted, as this may place some stresses on the sides. First, you finish the bottom edges of the drawer, flushing all the components to one another—this should only take a minute or two.
Slightly remove the arises from all sharp corners, then, repeat the process on the top edges. In addition, you also want to relieve the top, back corner with a chisel and guide. This serves to help the drawer into the housing without damaging the carcase.
Next, hand plane and/or scrape the outer faces of the sides and dove- tails nicely flush, taking very fine shavings. Offer the drawer up to its housing to see whether it will enter, and if it does, see how far it goes in by pushing gently. Pull it out slightly and then in again several times. This should leave some shiny pressure marks on the drawer sides, indicating where more material needs to be removed.
You may first have to dull the planed finish with some 320 grit sandpaper to see these tell-tale marks. Another indicator of tight areas is where you see a little build-up of sanding dust on the edge of the carcase. Repeat this process until the entire drawer slides easily into its housing. You should know that the task is done when you are able to give the drawer a short shove and it glides all the way home, without any side- to-side slop. Sometimes, you may hear a ‘clunk’ as the drawer front enters the carcase. In most cases, this is caused by the underside of the front hitting the bottom edge of the carcase, but, regardless of whether or not it’s a problem, I relieve, at an acute angle, the inside corner of the front with a spokeshave.
I like to finish all parts of my drawers, rather than leaving them bare. First, I remove the base to make the job easier, then I brush one coat of blonde shellac onto all surfaces, except for the front face if that is to be oiled. I usually use cedar of Lebanon for bases however camphor laurel or Huon pine are also suitable. Once dry, all surfaces are steel-wooled down and rubbed to a gentle shine with a micro-crystalline wax, before reinserting the bases. You will now be surprised at how well the drawer glides with this treatment—who needs modern, metal runners?
Neil Erasmus is a furniture designer/maker in Perth, WA and also teaches woodwork.
SLOT CUTTER ASSEMBLY IN ROUTER TABLE
The smaller the drawer, the smaller the components will be. 4mm is a standard groove width in slips and muntins but this can drop to 2mm on very small drawers. Cutter assemblies are readily available and vary in cost from $100 to $300.
The top cutter in the assembly must match this size, and the space between it and the lower cutter must be set at precisely that amount too. The lower cutter (the one closest to the shank) should be, say, 5mm thick. The 22mm bearing at the end of my setup, that comes standard with the set, simply acts as a spacer. The set comes standard with several different size spacers to finetune the positions of the cutters relative to one another. First try a combination of spacers, and measure the gap between the cutters with verniers to get it within acceptable tolerances. Final adjustment depends on making a cut or two to try the fit of the tongue in the groove. It should need a firm push, but no taps with a mallet.