Workbench Article Overview:
I should state immediately that the instructions for my workbench project are based on my own woodworking requirements, and others if they wish to follow, could build some design alterations into the instructions to suit their own project requirements.
In order to gain some inspiration and design ideas, I purchased the Workbench Design book written by Christopher Schwarz. This is a comprehensive and excellent publication and although I did not read it cover to cover, it provided me with numerous intelligent and useful features.
There are no formal plans for this particular workbench. After determining the outside dimensions, I will be designing as I move along, and attempting to build a robust workbench structure, and maintain a level of simplicity.
This article begins with the development of the overall design of the workbench including the dimensions, size and type of wood used, and strength and mobility considerations. The article continues with with a series of 10 instruction steps detailing how to build the workbench components, in order to complete the overall design.
Step 1: Development of the Workbench Design
At the outset I would like to point out that I may be missing something, however it seems that most people building this type of project begin with the concept that the workbench has to support a centurion tank. I intend using Douglas fir and the compression strength of same is approximately 7,230 lbs. per square inch. In my opinion, the leg should be designed to support reasonable weight and to prevent racking whilst planing etc. A simple experiment showed that planing exerts a horizontal force of approx. 15 lbs. The wood in my design is 1 ¾ inches thick, and the failure test conducted about 2 years ago, using 4 dowels in 1 ¾ inch stock, failed at 2,000 lbs. per square inch. I may be proved wrong, however I could see no reason, if someone wishes to save money and materials, why a good solid bench could not be constructed from good quality 2 inch by 4 inch stock, with a laminate or 1 ½ inch thick hard wood work top. Incorporating a reasonable factor for safety and using the figures for Douglas fir, 4 – 2 inch by 4 inch legs would theoretically support approximately 30,000 lbs.
My work shop is neither large nor small, but falls somewhere in between, therefore all my heavy tools run on casters, so I have decided that the outside dimensions of my workbench will be 34 inches high, 5 ft. 8 in. in length and approximately 30 inches wide.
I managed to find full 2 inch Douglas fir (un-planed), these are all 15 footers and after some careful calculations, they were cut into appropriate lengths – 5 ft. 8 in, 5 ft. 4 in, 3 ft. 10 in, etc.
Lacking a jointer, I had to mill these using both my table saw and planer. The planer was somewhat light weight for this particular application, however it eventually did the job.
As previously stated, the boards were all un-planed, so I began skimming both faces of each board on the table saw, to attempt to get parallel surfaces. Next, I milled the board edges, turning the boards after each cut, initially taking off 1/16 and eventually reducing that to 1/32. The final face cuts were done using the planer, the width slightly over 1-3/4.
ALWAYS THINK SAFETY! Drill bits can shatter during use. Always wear safety glasses when operating power tools. Always disconnect power before changing drill bits.
Table Saw: 1/ Maintain concentration! 2/ Use a Riving Blade 3/ Use push sticks or feather boards 4/ Never place hands behind blade 5/ Wear goggles
Router or Radial Arm Saw:Always follow manufacturers safety guidelines.
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At this point I would like to relate a short story about an incident that occurred approximately 2 months ago. I have mentioned before about the gentleman who turned up at my office in North Vancouver to purchase the quarter inch Dowelmax kit, and he had shown me two fingers that had been severed and reattached surgically following a saw mishap. That factor later made me give considerable thought to buying the Sawstop table saw. At that time only the large model was available and the cost was approximately $5,000. I purchased the Sawstop about 4 years ago, just as we were moving to Kelowna and quite frankly I have always had some doubts about the validity of their claims. But obviously there was no way to test their claims without destroying the solenoid brake and a blade.
To continue the story, about two months ago, I was making a deep cut in a cherry work piece and something of an absolutely surreal nature occurred. It happened at lightening speed. Without fully realizing what was happening, in an instant the blade dropped and the saw stopped. What appeared like a millisecond later, I felt a mild sensation on my left index finger. There was no blood, all I could see was a minor surface nick. In other words, the whole process was over before the message was transmitted to my grey matter! As far as I was concerned that was the best $5,000 I ever spent!! For anyone interested, I think Sawstop has a cheaper model ranging around the $2,500 mark. By the way, I have no other interest in, or connection to Sawstop other than to convey the message that their system is first class.
Step 2: Building the Leg to Longitudinal Skirt Rail Half Lap Joint
I began with the 4 legs. These are cut 1 3/4 inch x 5 1/2 inch x 29 5/8 inch.
In order to maintain the full length of the front and rear longitudinal rails, I decided to build half lap joints at the upper section of all 4 legs.
I used an 8 inch dado blade to cut the recess slots in the skirts and upper legs. Considerable care has to be taken particularly with respect to the recessed slot on the forward and rear skirts, since it is essential to get a snug if not a tight fit between the legs and the skirt recess.
The depth of the half lap joint is 7/8 of an inch, which is one half of the thickness of the 1-3/4 inch leg and rail.
Step 3: Design of the Lower Leg to Transverse Castor Support Rail Joint
With the dado blade in, I also cut slots at the inner face of the lower legs, in order to insert 2 – 2 inch x 5 ½ inch x 28 inch transverse rails to support the castors (I designed the lower legs in this manner in order to avoid external protrusions which could impede the workbench user.)
Step 4: How To Build the Top
It could be noticed from the photographs that I have installed a 3/8 inch x 1 3/4 x 68 inch length of batten along the edge of the 2 upper longitudinal rails. This is probably adding an unnecessary complication, however I did it for a good reason. When this wood was milled at the yard, the grain was noted to be fine and very attractive. However the edge grain was gaudy, and this would show around the complete periphery of the workbench. A secondary consideration was that the termination of the 4 half laps would also be visible on the top of the bench. However we have to remember that it is a "work" bench and a beginner may want to ignore those minor cosmetic drawbacks.
The workbench top design is built from 5 – 1 ¾ x 5 ½ x 64 ½ inch boards, all milled and marked edge to edge to ensure no gaps following joint assembly. The design also incorporates 4 skirts, i.e. 2 x longitudinals, and 2 transverse, measuring 1 ¾ x 5 ½ x 64 1/2, and 1 ¾ x 5 ½ x 29 ½, all with mitred corners.
Video Instruction Part 1. How to Join the Top Boards
The following video shows the procedure for joining 2 of the 5 boards required for the workbench top. The video duration is approximately 10 minutes and is fairly repetitive. I would therefore suggest viewing the instructions for the initial set up, including use of extended distance gauge, and then fast forward to final set up.
Refer to photograph below for glue up and clamping instructions for the first two workbench top boards.
Once all 5 workbench top boards have been joined and clamped, the next step is to dress the 2 ends. I use an aluminum straight edge extrusion in conjunction with a router with twin parallel carbide tipped bit.
When setting up, it is essential to ensure that both longitudinal edges of the workbench top are absolutely at right angles to the straight edge. I do a fairly accurate cross cut using a good quality circular saw, then reset the aluminum square, and refinish the edge using a 2 inch long carbide router bit, taking off approximately 1/16 inch at a time.
Step 5: Joining the Lower Longitudinal Rail to the Front and Rear Framework Sections
Cut, drill and dry fit the lower longitudinal forward and rear. As stated the half lap joints were a snug fit and since these were cut using the table saw and sled, they were close to perfect. However these half laps were fitted together and the legs were checked for square using the Universal Tape Gauge as shown in the photograph below.
The reading gave an exact size required for the length of the forward and rear lower longitudinal rails. These ends were again cut using the sled and table saw. The design of these components measured 1-3/4 x 5 1/2 x 30 inches.
Video Instruction Part 2. Joining the Lower Longitudinal Rail to the Front and Rear Framework Sections
Step 6: How To Build the Mitered Skirt for the Top
Once the two top ends were neatly trimmed and absolutely square to the longitudinals, the next step for the top was to mill 2 longitudinal and 2 transverse skirts. As previously mentioned the design for these measured 1 3/4 inch x 5 1/2 inch x 64 1/2 inch (to ensure that I could use my longest clamps with jaws which can open to 72 inches).
In designing and building the skirt, I decided to miter the 4 corners, this certainly looked better, but entailed a lot of care and precision, and for a workbench, in all probability bread board ends would have been sufficient. The procedure for all 4 skirt pieces is virtually identical. With the transverse member, lay it alongside one end, and lay out the check marks and X’s as normal (note the skirt is a face joint and will require transferring the Dowelmax to the second configuration). The 4 skirts are 1 ¾ inches thick, therefore I left approx. 2 inches overlap at each end to allow for the mitre. Mark a line, say, on the left hand side, corresponding to the corner of the work bench top, down the inside of the transverse skirt. This is a guide for Dowelmax placement.
Video Instruction Part 3. How to Join the Skirt to the Top
The alignment line for Dowelmax placement can now be erased. 6 dowels are dry fitted into the skirt and work bench end, the joint is then closed and accurate lines are finely scribed on the skirt at the 2 corners. These fine lines are an accurate guide for the inside of the mitre. All 4 skirts are aligned and doweled in a similar manner.
Step 7: How to Join the Mitered Skirts
Once all the dowel holes have been bored in the 4 skirts, the miters can now be cut. Again I used the sled in conjunction with the table saw, and before proceeding with the work pieces, it is prudent to check, and adjust if necessary, the 45 degree setting on the table saw blade. Considerable care has to be taken when cutting the mitres, to achieve a snug fitting at each corner, and while this proved relatively straight forward with respect to the 2 ½ foot long transverse skirts, cutting the miters on the longitudinal skirts proved a little more problematic. Even with the snug fitting accurate sled, the long overhang could cause the work piece to rock, and after several tries, this proved unsatisfactory. At that point I knew I had to become somewhat inventive, and after several ideas failed, I eventually rigged up a system which worked almost perfectly. I rigged up a pulley on the trailing side of the table saw, with a small approximately 2 lb. weight on a line attached to the work piece. This in effect acted as a kind of damper, and although it may seem somewhat Heath Robinson-ish, it actually worked perfectly!
As noted, the damper system used was a complete success, however improvements could be made by extending the fence on the cross cut sled (to add additional support to the lengthy heavy board being cut). Spray Bostik guide coat lubricant to the table saw cast iron table top and employ the pulley damper as original.
Interestingly enough, the triangular segments cut from the various skirts, were perfect for a filler piece when gluing the mitre joints. See photo below.
Step 8: How to Join the Transverse Rail to the Leg
With the top of the workbench complete, I began the process of sizing and fitting the 4 transverse rails (between front and rear legs) into the build up of the frame. Invert the top, insert and lightly clamp the 4 legs into the half laps and again using the UTG, ensure that the 4 legs are straight and square. Read off a measurement on the UTG to provide the exact length of each transverse rail. These rails measure 1 1/4 x 5 1/2 x 25- 7/8 inches. The ends of these components are again cut using the sled and table saw.
Video Instruction Part 4. Joining the Tranverse Rail to the Leg
Dowelmax Wood Joint Destructive Testing:
Size for size, I would virtually guarantee that this is one of the strongest structures of this type. Several years ago, after building a 1 3/4 inch thick alder front door for our new house (see pictures on our web site), we decided to test one joint to destruction, and at the same time, compare the failure point of a mortise. We were pleasantly surprised, both joints failed at exactly 2,000 lbs. per square inch. One thing I would like to point out though, in that test, the dowels were 3/8 inch in diameter, whereas the mortise was 5/8 inch (please refer to photograph). I would suggest that this again proves that the multi dowel joint is stronger than a comparable mortise and tenon.
Relating back to the work bench: There are 12 multiple dowel joints in the frame assembly and 4 snug fitting lap joints. The strength and rigidity of the assembly should be second to none.
Step 9: Dry Fitting the Framework Assembly Joints
The next step is the dry fitted installation of the 4 transverse rails, measuring 1 ¼ x 5 ½ x 25 7/8 inch. Initially I began by up-ending the workbench top, inserting and clamping all 4 half laps, then assuring all legs are square and perpendicular, using both a machinist’s square and the UTG. In that manner the final length of 28-7/8th was determined. These 4 joints again entailed 6 dowels on each, and it should be noted that a face joint exists where the rails butt against the inside of the 4 legs. So the Dowelmax, for those particular joints will have to be converted to the second configuration. Additionally, when drilling the legs. I decided on a ¾ inch relief, therefore when using Dowelmax to drill the legs, a ¾ inch spacer is used between the guide block and reference bracket.
Another point of interest, the lower transverse rails, right and left, provide additional support for the transverse boards supporting the 4 castors. Hence to ensure the lower transverse rail butts directly on top of the castor support rails, Dowelmax is aligned with the edge of the lower lap joint. See photo
The two - 2 x 5 1/2 x 28 inch transverse castor supports are now fitted between the dados on the lower section of the front and rear legs. While I am usually averse to using screws, especially in long grain applications, I am aware these joints are in compression so screws are acceptable in this case. The castors are then screw attached to the underside of these supports.
Step 10: Selection and Installation of the Workbench Vise
For the vise I used the Lee Valley Veritas Quick Release Front Vise. This vise comes with a template for straightforward installation and functions extremely well.