Try This

If the circle you want to cut is smaller than the diameter of your router base, don't bother with the trammel. Drill a pivot hole in the factory baseplate. Then the baseplate is the trammel. Fit the router over the pin in the work, and turn it. Not flashy, but it works.

ADJUSTABLE. TRAMMEL OFFERS CONTINUOUS ADJUSTMENT, FROM I INCU ON UP

^-PLASTIC KNOB WITH 1*" BUND THREADED HOLE

-fr WITH TIP GROUND TO POINT \

'A'PCVWOOD PIVOT BASE

PIVOT STRIP

ROUTER /

MOUNTING- SCREW U0LE

10-52MAOUMC. SCREW

ita'xtVl' CARRIAGE. BOLTj UE.AD IN COUNTER BORE BENEATH PIVOT BASE

INDICATES

The procedure for making the smaller trammel is basically the same. The pans arc smaller, and all of them arc cut from hardwood. When you glue the parts of the pivot together, be sure you cross the grain in the two layers. The grain direction of each pan of Phil's prototype is shown in Adjustable Trammel.

No-Mar Trammel

What if. you ask now, I don't want to have a pilot hole? What if, you propose, a pilot hole is going to mar my tabletop?

The solution is a trammel that uses my favorite shop tape—the so-

To get the phot point "inside" the router Intse, as shown here,you have to remove the thumbscrew. Slide the pivot base into position, then reinsert the thumbscrew. Adjust the trammel to the radius of the circle to be routed. If the pivot point must actually be under the base itself, grind a point on the tip of a flathead screw and substitute it for the thumbscrew.

Arcs and circles larger than wheels for toys can be routed with a laminate trimmer, but something larger than the trimmer trammel will probably be needed. The adjustable trammel is just the ticket.

called double-stick stuff—carpet tape. Actually, there arc two models. One is designed for use with routers that use two rods for the edge guide. The other, designed for diosc routers that can't use the double-rod model, incorporates a baseplate on which you mount the router.

In both models the critical part is the acrylic plastic pivot plate, which you stick to the work—temporarily— with carpet tape. The square plate has a hole at dead center. The pivot bolt in the trammel block projects just enough to catch in this pivot hole, but not enough to bottom in that hole and scratch the workpicce.

The plastic plate is durable and bonds well to the tape. I tried using hardboard initially, but the pivot hole got defonned pretty quickly, and the tape didn't stick to it very reliably. With the plastic plate, the tape sticks almost too well—I have to work a putty knife under a corner to pry the plate off the work.

One negative to this trammel is that you can work from only one side of the blank. You do have a deep cut to make.

With the double-rod trammel, you adjust the radius of the circle at the router or at the trammel block. With the wooden-bar trammel, you adjust the radius at the trammel block only.

To make the double-rod trammel:

1. Fit the trammel rods into the holes for them in the router base, then measure the distance between them (labeled ' D"on Double-Bar No-Mar Trammel). Measure the length of the

This pivot plate is the key to the no-mar trammel's no-mar alteration. Apply carpet tape to the plate, then stick the plate to the work. If the centerpoint is critical, mark the point with extended crosshairs, then align the corners of the plate with those lines. That's why it's a square—so you can do that.

This pivot plate is the key to the no-mar trammel's no-mar alteration. Apply carpet tape to the plate, then stick the plate to the work. If the centerpoint is critical, mark the point with extended crosshairs, then align the corners of the plate with those lines. That's why it's a square—so you can do that.

CIRCLES WITHOUT * PILOT UOLC.

machine

DOUBLE-ftfcR MO-MAR TRAMMEL CUTS

UARDWOOO

TRAMMEL

trammel rod}. sized to fit your router

edge guide's rods. If you need longer rods, buy them. (One hitch we discovered in this regard is that not all router makers use standard-diameter rods. The Elu—made in Switzerland—uses Winch rods. The Porter-Cable—made in the U.SA—seems to use metric rods. Quarter-inch rods were too small. Mo-inch were too big, and getting %*-inch rods at the corner hardware store—I don't think so. I ended up using the Winch rods on the Porter-Cable and just cinching the setscrcws as tight as I could. I fretted about it at first, but the trammel has worked fine.)

2. Cut the trammel block to length, which is 2 inches longer than your distance D.

trammel rod}. sized to fit your router

CIRCLES WITHOUT * PILOT UOLC.

machine

DOUBLE-ftfcR MO-MAR TRAMMEL CUTS

UARDWOOO

TRAMMEL

CUTTING LIST

Picce

Number Thickness

Width

Length

Material

Trammel bar

1 y«"

W

D + 2"*

Hardwood

Pivot base

1 W

2W

2 W

Acrylic

Hardware

1 pe. V" x 1 " bolt with nut

2 pes. 6-32 X W roundhead machine screws with

washers

2 pes. 6-32 T-nuts

2 steel rods of a size to fit your router

•See Step I to determine "D."

Don't want to leave a pivot hole in your work? Use this no-mar trammel! The trammel pivols on a small square of plastic attached to the work with carpet tape. To adjust the radius of the circle, Itwsen the screws on the tram mel bar and reposition it on the trammel rods. Adjustments can also he made at ihe router.

3. The trammel rods slide through holes in the trammel block and arc-pinched to hold them. The pinches are provided by machine screws turned into T-nuts, the pinchablc leeway by kerfs extending from the block's ends to the trammel-rod holes.

Drill holes for the rods and for the screws, then countcrborc the latter holes for the T-nuts. Drill the pivot hole equidistant from both ends of the bar; countcrborc the bottom so the nut will be partially recessed.

4. Kerf the ends of the bar. as shown. To do this on the table saw, crank up the blade to make a cut at least IV« inches deep. (The kerf should extend at least Vi inch beyond the hole for the pinch to be secure.) Set the fence so the cut will pass through the center of the hole. Stand the trammel block on end to make the cut, and use a scrap block to back it up.

5. Assemble the trammel. Insert the bolt through the pivot hole and turn the nut onto it. The nut should pro-tntde just a bit so that the whole trammel block doesn't rub on the pivot plate. Drive theT-nuts in place, and turn the machine screws into them. Insert the trammel rods and tighten the screws, pinching the rods.

6. Cut the pivot plate from a scrap of acrylic plastic. It must be square. Scribe diagonals to locate the center point, then drill a '/Vinch pivot hole there.

To make the wooden-bar trammel:

1. The size of the clear acrylic baseplate blank may need to be adjusted to accommodate your router. Cut it to the appropriate size, then attach your router's factory baseplate to it with carpet tape. Drill and countersink the mounting-screw holes. Then trim one end of the new baseplate to match the factory baseplate, using a router and a (lush-trimming bit. After separating the two baseplates, drill and countersink the mounting-screw holes for the transition block.

2. Chuck a plunge-cutting straight bit in your router. Mount the new baseplate on the router. Plug it in. switch it on, and advance the bit that's cutting the bit opening in the baseplate.

3. Cut the pivot block, the trammel arm, and the transition block. Shape the transition block, as shown in Wooden-Bar No-Mar Trammel, and attach it to the baseplate.

4. On the router table, cut the dovetail slot in the pivot block. Use the same dovetail bit to bevel the ends of the trammel arm. trimming the arm to fit the slot in the pivot block. Switch to a 'A-inch straight bit and rout the slot in the trammel arm.

If your router doesn't have the douhle-rod setup for an edge guide, or if the rods arc too big, try this model of the no-mar trammel. The trammel bar is attached to a plywood baseplate that you fit to your router.

CUTTING LIST

Piece

Number

Thickness

Width

Length

Material

Trammel arm

1

Yi"

2"

28W"

Hardwood

Transition block

1

W"

VA"

base dia.

Hardwood

Pivot block

1

w

3"

4"

Hardwood

Pivot base

1

2 K"

2K"

Acrylic

Baseplate

1

sized to fit router

I pc.'/«" plastic knob, with through threaded insen. Available from Reid Tool Supply Co.. 2265 Black Creek Road. Muskegon. Ml 49444 (800-253-0421). Pan #DK-54. I pc. '/T I.D. liar washer

2 pes. #6 X 1" roundhead wood screws

W00PEN BÄR NO-MAR TRAMMEl LLAVES NO MARKS ON YOUR WORKPlECE

H&ADWOOO PIVOT N.0CK

FLAT WASUM

HU NUT

'A" ACRYLIC PIVOT 6A5t

W00PEN BÄR NO-MAR TRAMMEl LLAVES NO MARKS ON YOUR WORKPlECE

H&ADWOOO PIVOT N.0CK

FLAT WASUM

HU NUT

'A" ACRYLIC PIVOT 6A5t

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Wood Working for Amateur Craftsman

Wood Working for Amateur Craftsman

THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.

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