Sander

BY GLENN BOSTOCK

hen I opened the doors of my cabinet shop for business. I was well-equipped except for one thing —a stroke sander. It's not the sort of thing the average craftsman longs for—a good tablesaw or jointer is probably higher on the wish list. But I'd used stroke sanders in school and in shops where I'd worked and fell in love with them. These large, stationary, belt sanders are incredibly efficient for sanding everything from table-tops to cabinet frames.

Stroke sanders have a wide abrasive belt, about 20-25 feet long, running above a sliding table that holds whatever it is you're sanding. You sand the piece by pushing the belt down onto it with a pad, and sliding the table back and forth. You can sand a tabletop in minutes and a set of kitchen cabinets in a morning.

Stroke sanders may be efficient, but they are also expensive. When I was looking for a stroke sander five years ago, the cheapest one I could find cost $2,000— used. (Editors Note: Stroke sanders in the $1000 to $1,600 range have been marketed since, including several models made by Woodmaster Tools, 2908 Oak, Kansas City, MO 64108, and a model by Wilke Machinery Co., 120 Derry Court, York, PA i7042.) I built my stroke sander for $400, half of which went for the motor. For about $10 each, 1 make my own sanding belts. After five years of regular use in my shop, the sander still runs like a dream.

rage-door tracks. The table adjusts up and down on two lead screws to accommodate different thicknesses of wood.

An important difference between my machine and those made commercially is that the sanding table lies within the loop of the belt, instead of underneath the loop. The abrasive is on the inside surface of the belt. This setup lets me push the belt down onto the piece I'm sanding without reaching inside the loop of the belt as with manv commercial stroke sanders.

The Bench Assembly

The bench assembly shown in Fig. 2 is patterned after my workbench. I've added a couple of cross stretchers and some other supports to hold the sliding table. My trip to get wood for the bench resulted in my first design change: The lumberyard was out of poplar, which is cheap and serviceable, so I built the bench out of 8/4 Philippine mahogany instead. I bought the wood pre-milled and designed the bench around the wood's width of 1 '/: x 7 in. A few of the supports are made of oak for its strength, as shown in the drawing, because they directly carry the weight of the table. I made them from 2 x 4s I milled from 10/4 oak.

Note that I simply bolted the stretchers in place. I've taken a lot of heat from my artsy-craftsv friends about this. In my defense. I can say that after five years and lots of abuse, the bench is still solid as a rock.

Wooden Table Needs French Polishing

One of two lead screws Is turned to raise or lower the sanding table.

Basic Construction

I designed this machine as I went along. Until I wrote this article, the only drawings of it were some sketches on a piece of scrap wood which, like all scrap in my shop, eventually ended up in the wood stove. I encourage you to design a little as you go, loo. If you make your own belts, as I do, you can make the sander as large or small as you like, so consider your needs before you start. I underestimated mine, and had to enlarge my machine by cantilevering it off to one side as shown in the photo. Unless you do real big work, the sander in the drawings will probably meet your needs.

There are three subassemblies to my sander as shown in the drawing. The bench assembly supports the machine. The sander assembly is a 6-in. wide sand-

w ing belt, looped around two drums made of medium density fiberboard. One of the drums is mounted directly on the shaft of a 1700 rpm-, 1-H.P. motor, which powers the machine. The table assembly holds the piece being sanded and slides back and forth on ga-

One of two lead screws Is turned to raise or lower the sanding table.

FIG. 1: STROKE SANDER

EXPLODED VIEW

SUDING-TABIE SUPPORT

SUPPORT RAILS

BENCH ASSEMBLY

BENCH ASSEMBLY

Mortising Machine Exploded View

Mortise legs into trestle.

SUDING-TABIE SUPPORT

FIG. 1: STROKE SANDER

SUPPORT RAILS

Trestle Table Legs Plywood

Lead screws adjust table height

PLYWOOD BASE

Mortise legs into trestle.

Lead screws adjust table height

PLYWOOD BASE

Georgia Assembly 1700s

TRACKING ASSEMBLY Assembly pivots to control tracking.

TRACKING DRUM

FIG. 2: THE BENCH ASSEMBLY

All stock nominal 2x8 except where noted.

FIG. 2: THE BENCH ASSEMBLY

All stock nominal 2x8 except where noted.

TRACKING ASSEMBLY Assembly pivots to control tracking.

TRACKING DRUM

BOLT DETAIL Drjl| lVl-.di,.

_ hole for access.

WASHER

TRESTLE

HEX-HEAD

BOLT

TRESTLE

HEX-HEAD

BOLT

WASHER

TOP VIEW

Hexa Plywood
PLYWOOD BASE

DRIVE DRUM

Garage Door Track Detail Drawings

DRIVE DRUM

The Sliding-table Assembly

Once the bench was complete, I built the sliding-table assembly shown in the drawing. This assembly-consists of the table and the table support. The table travels on two garage-door tracks mounted on a wooden support. The support adjusts up and down on two lead screws so I can bring varying thicknesses of wood up to the belt.

Build the support first. I built my support—which is really just an open-ended box—from 10/4 oak that I milled to 2 in. thick. Build the box to fit the opening in your bench —there should be about '/i» in. gap between the box and the stretchers on all sides, so the box can move freely up and down.

When the support box is complete, bolt two oak rails to the sides to support the garage tracks as shown. The rails overhang what will be the back of the machine more than they overhang the front. The extra length in back provides additional support.

CONTINUED

THE SLIDING TABLE

BOLT DETAIL

WASHER

Recess head in l"xl' hole.

HEX-HEAD

BOLT

SUPPORT RAILS

THE SLIDING TABLE

WASHER

Recess head in l"xl' hole.

HEX-HEAD

BOLT

SUPPORT RAILS

Stanard Spacing Roof Truss

HAROWOOD LIP

Plywood stops between garage-door track and plywood strips bump against support-rail ends to stop table. l/i" x 6* x 43 -plywood strips snug against inside edges of support rails to keep table from racking.

HAROWOOD LIP

FIG. 4: TRACKING-DRUM ASSEMBLY

Lead Screw Garage Door

Vi*x37i* HEX-HEAD BOLT Tracking'drum assembly pivots on bolt.

Base slides

TRACK

PILLOW BLOCKS

Bolt pillow block to base. Recess bolt bead in bottom.

TRACK

Lead screw adjusts belt tension.

Screw cross piece to tracks.

Lead screw adjusts tracking. -Screw support to plywood.

LEAD-SCREW SUPPORT

dovetail track.

LEAD-SCREW DETAIL

Garage Door Shaft Couplers

WASHER

WASHER

CROSS PIECE OR LEAD SCREW SUPPORT

CLEARANCE

Tighten nuts against each other to lock screw.

Block moves when handle is turned.

HANDLE

Epoxy coupling nut to wood.

Drum Roller Shaft Nut

WASHER

BUSHING PIN

MOTOR

WASHER

DRUM-SHAFT DETAIL

7«" STEPS, EXAGGERATED FOR CLARITY.

TRACKING DRUM

WASHER

Disk dia. decreases each side of center

DRIVE DRUM

bushing to drum shaft

Motor Screw Shaft Woodworking
Hie stroke sender works well on moldings as well as flat surfaces if you make a pad that matches the contour.

Garage-door rollers are mounted on the oak support rails as shown. I got my rollers from a local garage-door dealer. When 1 was picking them up, he gave me some leftover track. I wouldn't count on having the same luck again, but I'd sure try.

There are five door rollers on each side. The shaft of each roller fits into a hole drilled in the rail. Drill the holes '/m in. oversize. The shafts should slide end for end in the holes just a bit so that the wheels will automatically align with the track.

Garage-door tracks are notoriously sloppy when operating, so I staggered the wheels to eliminate play (see Roller Detail, Fig. 3). One roller runs against the bottom of the track, the next runs against the lop of the track and so on. Determine the amount of stagger by mounting the end rollers first. Slip the track over them. Stagger the wheels by the amount of vertical play in the track.

Controlling the Table Height

The sliding table adjusts up and down by means of two lead screws as shown in the photo. I made my lead screws from standard Vs-in. threaded rod. a handful of nuts and some washers as shown in the drawing. The lead screws thread into coupling nuts, which I epoxicd to the bottom of the support box as shown in Fig. 4. Coupling nuts look like regular nuts except they're about five times as long (available from MSC Industrial Supply Co., 151 Sunnyside Blvd., Plainview, NY 11803). The extra length gave me more glue surface for I he cpoxv.

The table—a piece of plywood bolted to the garage door tracks—is pretty straightforward. Determine the holes for the bolts by sliding ihe tracks over the rollers. and setting the table on top of the tracks. I used carriage bolts and recessed the heads in the plywood.

I glued and screwed a 3-in. wide lip on the front edge of the plywood, as shown, that I grab to slide the table when I'm sanding. The 5-in. wide board, glued and screwed to the botlom of the table just behind the lip, is equally important —it is a safety guard to prevent you from inadvertently reaching into the moving sanding belt. It's a lesson I learned the hard way. I added it afler a friend got a nasty cut.

When I'm operating the sander. I often pull on the table from one of the corners. To prevent it from rack ing in the tracks, I glued and screwed two strips of plywood to the underside of the table so that they snug up against the oak rails as shown in the drawing.

The Drum Assemblies

This is the part of the machine thai takes its inspiration from a belt sander. The belt is looped around two drums. One drum is driven directiv bv a moior. The second drum, which I call the tracking drum, is shown in the photo. One lead-screw assembly keeps the belt taut; another makes it track correctly.

I built the drums first. Each drum is reallv a stack of eight disks of /4-in. medium density fiberboard. The disks are friction lit on the shaft, and sandwiched between a nut and a stop on the machine shaft as shown. The disks fit quite tightly on the shaft. I found it easier to mount the disks on the shaft one at a time.

Belts track best on a slightly barrel-shaped drum. I made my drums barrel shaped by making the disks slightly different diameters. The center two disks are a full 6 inches; the two on either side of them are 'A: in. smaller and next two are '/» in. smaller vet. The two outermost disks are the smallest and measure 5;'Vm in. You can turn the disks on the lathe or band-saw them and true them up with a disk-sander jig as shown in Fig. 5.

Cut the drum shafts from Vj-in. dia. bar slock lo the dimensions shown and thread the ends (1 had a machinist make mine). Drill Vj-in. dia. holes in the disks, but don't mount the disks on the shafts until after the shafts are mounted on the machine. Until then, the drums make the shafts awkward to handle.

My sander is direct drive—a bushing on one of the

FIG 5: MAKING DRUMS ON THE DISK SANDER

3. Rotate disk with sander running to form true circle.

1. Distance from dowel center to abrasive determines radius of disk.

Circle Sanding Jig

3. Rotate disk with sander running to form true circle.

tyT PLY

Bandsaw disk from *U mdf.

2. Hold jig against stop block.

tyT PLY

Bandsaw disk from *U mdf.

1. Distance from dowel center to abrasive determines radius of disk.

2. Hold jig against stop block.

The tracking-dram assembly controls the belt The lead screw to the left adjusts belt tension and the screw to the right adjusts tracking.

drum shafts slips over the shaft of the motor. Two set screws fasten the bushing to the shaft as shown in the Shaft Detail of Fig. 4. I haven't had any trouble with this arrangement, but direct drive puts a lot of stress on the motor bearings. If I had it to do over again, I'd mount the drum shaft in pillow blocks, mount a pulley on the end and drive the shaft with a belt.

However you choose to connect your motor, I recommend 1-HP, 1700-rpm, totally enclosed fan cooled (TEFC) motor. (Electric motors are available from Surplus Center, P.O. Box 82209, Lincoln, NE 68501.) TEFC motors are sealed to protect them from dust, and one thing this machine generates is dust. There's often enough dust to clog an unsealed motor and keep it from working—another lesson I learned the hard way.

Screw a piece of plywood to the bench, as shown in Fig. 1, and mount the motor on the plywood. To determine the exact location of the motor, push the sliding table back until the safety guard bumps against the

The tracking-dram assembly controls the belt The lead screw to the left adjusts belt tension and the screw to the right adjusts tracking.

FIG. 6: MAKING BELTS

1. Loop belt around drums with grit against drams.

2. Hold belt in place with weight

3. Cut through both layers on angle with straightedge and knife.

4. Tape beH together with packing tape.

ends of the support rails. The front edge of the belt should travel directly above this point as indicated in Fig. 1, so you don't accidentally flay your fingers while sanding. Screw two plywood stops to the underside of the table as shown in the drawing. The stops will bump into the support rails and keep the table from going back too far.

The Tracking-drum Assembly

The tracking-drum assembly, shown in Fig. 4, controls the belt tension and tracking. The drum is adjustable in two directions by means of lead screws: It moves back and forth in line with the belt to keep it taut. To control tracking, the entire tracking-drum assembly pivots on a boll. (The length of even the best sanding belt varies from one edge to the other. Pivoting the drum compensates for this.)

A drum that can be adjusted in two directions is not as complicated as it may sound. The drum and its shaft are mounted in Browning VPLE 212pillow-block bearings. The pillow blocks are mounted on a base with a dovetailed strip on the bottom that slides between two dovetailed tracks. A single bolt holds the entire tracking-drum assembly to a piece of plywood screwed to the bench. To tighten the belt, a lead screw moves the base on the dovetailed track. A second lead screw pivots the track around the mounting bolt to control tracking.

Making the Belts

I make the belts from a 6-in. wide roll of aluminum oxide paper (available from Econ-Abrasives, P.O. Box B865021, Piano, TX 75086 and from Kuster Mfg., P.O. Box 34, Skillman, NJ 08558). I have a collection of grits that ranges from 80 to 220, but I find I do almost all my sanding with 120- or 150-grit.

To cut the abrasive to the right length. I put one end of the roll on the sliding table and loop the roll around both drums with the grit facing the drums as shown in the drawing. Where the paper overlaps, I cut it with a knife and a straightedge. Turn the straightedge at a slight angle, cut a line through one layer and then through the next. This makes a perfect seam, which I splice together with plastic packing tape. ("Sand Aid." a belt-splicing kit. is available from Kuster Mfg.)

Tape along and across the seam, and slip the belt over the drums with the grit facing the drums. Adjust the tension until the belt is snug, and rotate the drums

Splicing Machine For Belt Sanders

slowly by hand to check the tracking. You may have to finc-tunc both the tracking and the tension while the machine is running.

Unlike a belt sander, a stroke sandcr has no sole. As a result it operates a little differently. Instead of pushing the machine onto the work, you raise the table until the work is lh to '/* in. below the belt. You then push the belt down onto the work with a special pad. My pad is nothing more than a piece of plywood with a handle on one side, and a piece of plastic laminate glued to the other side. Sand the edges of the laminate slightly so you don't have a sharp edge meeting the belt. Lubricate a new belt slightly by holding a chunk of paraffin against the back of the belt while the machine is running. Repeat when you feel the pad dragging on the belt. A

Glenn Bostock makes period furniture and does custom millwvrk in Rushland, Bucks County, PA.

THE SANDER IN ACTION

he stroke sander won't eliminate all your hand sanding. On fine pieces, I still sand lightly with 180-grit in an orbital sander and follow that up with a light hand sanding of either 180 or 220. But the stroke sander does end all that grueling 80- and 120-grit work that accounts for probably 80 percent of your sanding. The sander is very good at removing machine marks and scratches.

Sanding a flat piece, like a tabletop, is pretty straightforward. Put a 150-grit belt on your machine. You will use this throughout the entire operation. Put the tabletop on the sander's sliding table with the grain running parallel to the belt. Raise the sliding table so the top of the work piece is within in. of the belt. The exact distance will depend on the tension you've put on the belt, but I like to set up the machine so that when running, the belt just skims above the surface of whatever I'm sanding.

Start the sander. Slide the table back and forth with one hand. With the other hand, gently push the belt down onto the tabletop with the pad. Travel with the pad along the length of the belt to get to each end of the table, and as you move, slide the table back and forth to sand each side. Keep pushing with the pad. It's an awkward motion at first, but vou'll soon master it.

When you've stroke sanded the entire surface, turn off the machine, and remove the tabletop. Sand with 180-grit in an orbital sander and finish sand by hand with either 180- or 220-grit.

You'll quickly discover stroke sanders have a disconcerting tendency to grab whatever you're sanding and throw it in the direction of the belt's travel —to the right on this machine. Make sure you snug your piece against the stop at the right-hand end of the table to avoid this.

I find the stroke sander especially handy when I'm doing kitchen cabinets or bookcases. I can sand the disassembled plywood carcases on the stroke sander. When I'm done with the plywood. I sand the frames of the door, too. I glue up the door, sand with the grain along the rails, and then turn the door 90° to sand the stiles.

I also use the stroke sander to sand moldings. This doesn't work well on intricate shapes, but if I've got a large cove that I've built up in the shop, it's perfect.

Sanding moldings requires a pad that is the inverse of your molding profile—the two must mate perfectly while the belt runs between them. First, I rough out both the molding and pad on the tablesaw. To make a pad that precisely matches the molding, I take the stroke-sander belt off and put it back on with the grit facing away from the drum. I place the molding on the table and carefully push the belt into the molding with the roughed out pad. The paper side of the sanding belt conforms to the shape of the molding, and the grit side of the belt is running against the pad. In no time, the belt sands the block into the correct shape. (It will do the same thing to your fingers, so be extremely careful to keep yvur fingers away from the belt.)

I reverse the belt again to sand the molding, and when I push it into the molding with my newly made block, the two mate perfectly.

Incidentally, the machine is an excellent belt sander when the grit faces away from the drum. You can sand flat surfaces on the table and contours on either drum.

The stroke sander looks like a gentle enough machine, but it can be dangerous. Belts may break while you're sanding. Always wear safety glasses to protect yourself from the belt and from random flying grit. Wear a dust mask to protect your nose and lungs.—G.B.

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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