Biscuit Joiner

Most woodworking projectsrequire at least some assembly.This is especially true for projectssuch as tables, cabinets or book-cases where wide panels mustfirst be built up from severalnarrow boards.

Traditionally, woodworkers haveused dowels for these assemblies.As you might expect, dowels addstrength to certain types of joints,but they serve an equally impor-tant function by keeping thepieces properly aligned duringassembly and gluing. The majordrawback with doweling, how-ever, is that each hole must beperfectly positioned or the individual pieces simply won't go together. Even a slight error can cause a lotof pounding and frustration.

During the 1950's a new assembly system called biscuit joinery was developed in Europe. This systemuses flat wooden wafers or biscuits which are glued into semi-elliptical slots on each side of the joint. Dueto the shape of the biscuits, the exact location of the slot is much less critical than a dowel hole. Minoradjustments can even be made during assembly, so projects go together much more quickly and yet thereis no sacrifice in strength or overall performance. That's why biscuit joinery is rapidly becoming thepreferred assembly system for professional furniture and cabinet makers worldwide.

In addition to its advantages for panel assembly, biscuit joinery can often be used to replace more compli-cated and time consuming techniques including spline, tongue-and-groove, mortise-and-tenon and dadojoints.

BISCUIT JOINER- SETUP AND FEATURES

The biscuit joiner housing attaches to the quill and the blade arbor attaches to the main power spindle ofthe Mark V's powerplant (Figure 23-1). It may be used with either the Mark V Model 500 or Model 510.Follow the setup instructions in the Owners Manual that came with your biscuit joiner.Some of the important features (Figure 23-2) and capacities of your biscuit joiner are:

• Spring-loaded workpiece guide and safety guard help improve operator confidence and safety.• Engraved centerline on guide permits easy alignment of workpiece.• Adjustable depth stops and guide rod grooves permit easy use of three different biscuit sizes (#0,#10 and #20) for a variety of applications.• Adjustable pins in guide penetrate stock to provide more positive control and reduce kickbacks.• Carbide-tipped blade will provide years of normal service without sharpening.

Figure 23-1. The biscuit joiner is powered by the Mark V’s powerplant andcna be used with either the Model 500 or Model 510.

• Builtin dust chutefor easy attachmentof standard 2-1/2"dust collection hoses.

BISCUIT SIZES AND CONSTRUCTION

Shopsmith biscuits are produced from select grades of beech.For maximum strength, the grain is oriented at a 45° angle to thelong axis of the biscuit. During production, biscuits are exposedto many tons of pressure which compresses the fibers and pro-duces a waffle-like surface for better glue absorption and adhe-sion.

When glue is applied to the biscuits, the moisture in the gluecauses the biscuits to expand by about 15% of their originalthickness and the joint becomes tight. Since this expansionoccurs very quickly, glue should never be applied to the biscuitsuntil you are ready for final assembly. Biscuits should also beprotected against water or extremely high humidity. A coffee canwith a tight fitting lid makes a good storage container.

Biscuits are available in three different sizes to meet a variety ofapplications (Figure 23-3). All bis-cuits are 5/32" thick.

#0 biscuits are 1-3/4" x 5/8". They are best for joining smaller workpieces and for edge-to-edge assem-blies where high stress is not anticipated. They are also useful for joining narrow pieces such as cabinetframes end-to-edge.

#l0biscuits are 2-1/8" x 3/4". They are recommended for general purpose joinery on all types of projects.

#20 biscuits are 2-3/8" x 1". They are recommended for use on larger projects or joints—such as a tableskirt and leg—which will be subject to high stress or twisting forces. They also provide greater penetra-tion and a larger gluing surface, so they are well suited for plywood or particle board applications.

Figure 23-2. Familarize yourself with these important features of the Shopsmithbiscuit joiner.

Figure 23-3. The three availablebiscuits are shown here.

BISCUIT JOINER SAFETY

Read, understand and follow all safety and operating instructions in the Owners Manuals that came withthe Biscuit Joiner and with the MARK V on which it is mounted.

• Wear safety goggles, safety glasses with side shields or a full face shield.• Tuck long hair under a hat or tie it up. Do not wear ties, gloves, jewelry or loose clothing.

Roll sleeves up above your elbows. Wear nonslip footwear.• Before mounting the biscuit joiner on the Shopsmith MARK V, turn on the MARK V and

set the speed dial to SLOW. Then turn off and unplug the machine before proceeding.• When mounting the biscuit joiner on the MARK V, be certain all locking screws are tight-

ened securely before turning on the machine.• Be sure the blade is mounted in the biscuit joiner with the teeth pointing in the direction of

the arrows on top the housing. Installing the blade backwards will result in kickbacks andinjury.

• Connect a dust collection system to the biscuit joiner dust chute or wear a dust mask.• Do not allow anyone to stand directly in front of the opening of the dust chute.• Move the workpiece slowly into the blade—never force it. Feeding stock too rapidly could

cause kickbacks.• Do not stand directly in-line with the workpiece being fed. In the event of a kickback, you

will be hit.• Do not rest fingers in the miter gauge slots where they could be trapped and pinched by

kicked back stock.• Always use the push block in your right hand to feed stock into the blade. This is especially

important when working with small stock.• Use your miter gauge and/or rip fence as a stop when working with stock less than 6" long

or wide.• Always be certain the pins protrude from the guide before beginning operations. Failure to

do this could result in the workpiece being grabbed and thrown by the rotating blade.• Listen for chatter and signs of looseness at startup. If you hear, see or suspect problems,

turn off the power and unplug the machine immediately. Cor-rect any problems beforeproceeding.

• Never use the biscuit joiner for jobs it is not intended to perform such as sawing, grooving,etc.

• Never exceed speed setting "T" on the MARK V's speed dial for biscuit joiner operations.• Never attempt to use the biscuit joiner on stock less than 3/8" thick.• Never operate the biscuit joiner without the housing and guard in position.• Always keep the blade clean and sharp.• Use only Shopsmith blades and parts for your biscuit joiner. Using non-Shopsmith blades

or parts will create a hazardous condition and will void your warranty.

BASIC BISCUIT JOINERY TECHNIQUES

Marking Joints- The only marking normally required for biscuit joinery is to indicate the centerline foreach biscuit's location. These markings are usually made on the back side of the stock and may be madewith a square (Fig-ure 23-4) or freehand. Marked centerlines are then aligned with the engravedcenterline on the biscuit joiner guide while quill and worktable adjustments are then used to control thebiscuit's vertical position. Figure 23-5 shows typical markings for various types of joints.

Basic Adjustments and Cuts-After mounting the biscuit joiner on the Mark V (Figure 23-6) and es-tablishing a basic setup as shown in the biscuit joiner Owners Manual,several adjustments must be made before using the accessory. Thesebasic procedures apply to all types of joints, so review these stepsbefore each biscuit joiner operation.

Begin by selecting the size biscuit you will be using and set the depth-of-cut accordingly. This is done by unplugging the Mark V and com-pressing the spring-loaded guide until the desired grooves on the guiderods are even with the biscuit joiner housing. The three grooves in theguide rods indicate the correct settings for #0, #10 and #20 biscuitsrespectively. Adjust both depth stop setscrews (Figure 23-7), so thatthe guide cannot retract beyond the desired depth.

Next adjust the two pins in the guide face and lock them firmly inplace (Figure 23-8). These pins provide important kickback protectionand should penetrate about 1/32" in hard woods and 1/16" into softerwoods.

When using the Mark V Model 510, position the worktable so the faceof the biscuit joiner guide is above the table insert (Figure 23-6). Thiswill keep the leading edge of the stock from interfering with the ribs inthe worktable surface.

Finally, adjust the height of the biscuit joiner. Press the stock againstthe joiner fence until the blade is visible and adjust the quill until theblade is at the desired height (Figure 23-9). Normally the biscuitlocation will be about midway between the top and bottom, but higheror lower positions may occasionally be desirable. The most importantfactor is that the cuts be at the same height on both pieces of stock.When making these adjustments, the quill should not be extended more

Figure 23-4. Mark centerlines onboth pieces of stock to assure properalignment.

Figure 23-5. Here you see typical centerline markings for varioustypes of joints.

Figure 23-6. Attach the biscuitjoiner to the quill and tighten thehousing collar capscrew. Don’tforget to tighten the setscrewwhich holds the blade arbor to thespindle.

Figure 23-7. Adjust the depth-of-cut setscrews to match thebiscuit size being used.

than 3" and be sure to allowclearance be-tween the biscuitjoiner arbor and the worktable inorder to prevent damage to thetable surface.

After all adjustments have beenmade, turn on the Mark V and setthe correct speed. Guide theworkpiece with your left handuntil the biscuit centerline markon the stock is aligned with theengraved centerline on the biscuitjoiner guide. With a push block inyour right hand (Figure 23-10),press the stock slowly against theguide, compressing the springs until the guide reaches the depth stops. then retract the stock. Repeat thisprocedure for each cut on both pieces of stock before changing the setup or height adjustment.

Panel Construction- Panel construction or edge-to-edge joinery is one of the most common woodwork-ing operations. For best results, place the boards face down next to each other and mark biscuitcenterlines on the back side. Then cut the biscuit slots and assemble the boards in this facedown positionto help assure a flat, smooth final surface.

Typically, allow one biscuit for each foot of length in an edge-to-edge joint, with a minimum of threebiscuits. Space the biscuits evenly and position the end biscuits at least 3" from the ends of the boards sothe boards will engage both of the pins in the guide when the biscuit slots are cut.

End Grain and High Stress Joints- Because of the wood's high porosity, end grain joints—such as T-Frame, L-Frame or End Butt-are almost impossible to make with glue alone. Using biscuits willstrengthen these joints because the biscuits are glued face-grain-to-face-grain.

Figure 23-8. Adjust and lock pinsto engage work during cuts.

Figure 23-9. Use the quill adjust-ment to position blade for cut. Allowclearance between biscuit joiner andworktable.

Figure 23-10. Align biscuit centerline with joiner guide anduse a push block in your right hand when feeding stock.

Figure 23-11. On stock morethan 1” thick, two biscuits maybe used for added strength.

For best results, use the largest biscuit available that will allow at least 1/4" of stock at each end of thebiscuit slots. On wide joints, such as a T-shelf, use multiple biscuits, allowing as little as 1/2" betweenbiscuit slots.

On stock over 1" thick—especially on high stress joints such as a table leg and skirt—two or more rowsof biscuits may be used for added strength (Figure 23-11).

When joining stock of different thicknesses—such as a 1" thick skirt being joined to a 2" square tableleg—a thin piece of scrap wood or hardboard can be used as a shim (Figure 23-12) to eliminate the needto make quill adjustments for each thickness. This assures that the setback will be exactly the same on alljoints and that the biscuit slots will be aligned correctly for easy assembly.

Short and Narrow Stock- Workpieces less than 6" in width or length must be handled with special carebecause the pins in the joiner guide will not engage the stock and a kickback or injury is possible. Forthese cuts, align the centerlines and lock the miter gauge into the worktable to serve as a guide and stop.Hold the workpiece against the miter gauge face and advance it slowly and firmly into the biscuit joiner(Figure23-13).

If you are making multiple matching components—such as door frames or rails and stiles for a cabinetfront—you can make the setup once and cut all biscuit slots quickly and accurately.

Miter Joints- For corner miters, mount the biscuit joiner so that it faces the front of the Mark V with theguide perpendicular to the miter gauge slots (Figure 23-14). Adjust the worktable so one of the mitergauge slots is under the biscuit joiner and the quill is extended 3" to avoid interference between the safetygrip and the Mark V's powerplant. Set your miter gauge to 450 (or to match the angle of the miter), placeyour workpiece against the miter gauge with the centerlines aligned, and adjust the safety grip to hold thestock securely.

Make the cuts by advancing the miter gauge and stock into the cut together. Do not slide the stock acrossthe miter gauge and into the biscuit joiner as this will not produce an accurate cut. A piece of coarsesandpaper may also be attached to the surface of the biscuit joiner guide to keep the stock from creepingduring the cut.

Figure 23-12. When joining stockof different thicknesses a shim maybe used to eliminate adjustmentsand assure accurate alignment.

Figure 23-13. If the stock does notengage both pins, use your mitergauge to maintain control of theworkpiece.

Figure 23-14. Use your miter gaugeto hold and advance the stock onmitered cuts. Do not slide the stockacross the miter gauge face.

Edge Cuts in Wide Stock- Working with large or wide stock issimilar to other edge joining oper-ations, but additional support mustbe used to give the operator control of the stock for accuracy andsafety. This is achieved by mounting the biscuit joiner diagonally, atabout a 30° to 50° angle to the miter gauge slots (Figure 23-15). Withthe Model 510, check your setup to be sure the table height crankdoesn't interfere with the stock.

If additional support is needed, use the extension table system (Model510), a roller stand or a helper to gain control.

Surface Cuts-Surface cuts are necessary for two basic types of join-ery: edge-to-face joints, such as along the corner of a cabinet, and T-shelf joints, such as where a shelf joins the sides of a bookcase. Surfacecuts require special setups and additional care.

For edge-to-face joints, mount the biscuit joiner with the Mark V in thevertical position. Also lock the worktable vertically with the table edgeslightly below the biscuit joiner. With the Mark V unplugged, depressthe biscuit joiner guide to the desired depth stop and adjust the work-table until its surface is even with face of the guide (Figure 23-16).Finally, mount the rip fence on the table so that it supports the workpiece at the correct height for the biscuit position.

To make the cuts, tip the top edge of the work slightly away from the table and slide it along the rip fenceuntil one of your centerlines marked on the top edge of the stock is aligned with the engraved centerlineon the joiner guide. With a push block in your right hand, tilt the stock slowly back against the worktable.As you do the stock will engage the pins and compress the guide to make the cut (Figure 23-17). Pivotthe stock toward you and away from the table before attempting to advance to the next cut.

Figure 23-15. When working with large stock, mount the biscuit joinerdiagonally for maximum support of the workpiece.

Figure 23-16. For surface cuts,adjust the table so it is flush withthe biscuit joiner guide when fullydepressed.

Figure 23-17. This setup isideal for surface cuts along theedge of the workpiece.

A T-shelf or similar joint is more difficult because one side of the cut must be made "blind." The accuracyof the joint depends totally on the accuracy of your measurements and setup.

Mount the biscuit joiner with the Mark V in the horizontal position and slide the worktable close to thebiscuit joiner. With the Mark V unplugged, depress the joiner guide to the desired depth stop, set thestops, and adjust the Mark V table to match this height (Figure 23-18).

A typical setup is shown in Fig-ure 23-19. In this example, the rip fence on an extension table determinesthe position of the cut along the length of the stock and the miter gauge locked in its slot determines theposition across the width.

After all measurements have been made and checked, hold one end of the stock elevated and place itagainst the rip fence and miter gauge. With a push block in your right hand, lower the stock slowly until itengages the pins, depresses the guide and finishes the cut. Lift the stock completely before attempting tomove to the next cut.

Figure 23-18. For surface cuts,adjust the table so it is flush withthe biscuit joiner guide whenfully depressed.

Figure 23-19. The rip fence and miter gauge can be used asguides when cutting “blind” biscuits.