#21 Making a Backing on the Loom

Another post details the process of making a laid facing. Most of that information also applies to this post so it is worthwhile to review both to gain a fuller picture.

The mould is ready to receive its wire parts. A wire backing fresh off the loom is curvy but will flatten out when taped to the mould. This post will show how the backing was made.

The counting wheel of the loom must be changed from 8 pins (previously used for the laid facing) to 4 pins to make my standard laid backing. On this loom 4 pins and 9 ‘clicks’ yields a spacing of 5.78 wires per inch. (‘Clicks’ refers to the sound the pawl makes as it drops off pins as the wheel is turned.) The twin lead screws of this loom are fixed at 13 threads per inch but the number of pins and the number of clicks can be changed to produce a number of different laid facings and backings. A simple formula calculates the wire spacing: Pins x thread (fixed at 13) / clicks = wires per inch. (In this case: 4 x 13 =52. 52/9 =5.78. ) The laid facing made with the 8 pin counting wheel used 5 clicks to make 20.8 wires per inch. (8 x 13 = 104. 104/5 = 20.8.)

This is about the heaviest wire that is useful for making chain wires. It is .015″ diameter soft phosphor bronze and makes the chain wires for this laid backing. Wove backing uses a .013″ diameter wire for a narrower space between laid wires. Laid facings can use almost any size chain wire between .012″ and .008″ diameter.

These spindles have recesses on one end and can be oriented in two ways. Using them with the recesses on top narrows the angle at which the wires are twisted for more widely spaced backing wire. Turning them over flat side up widens the angle for the tightest twist, more useful for laid facings.

As many spindles as needed are put in the holes in the spindle rack. Then they are wrapped with the weighted cords that drive them to twist the wires.

The spindle holes will need aligning after all are connected to drive weights.

After all spindles are rigged with cords and weights they are aligned by turning them clockwise. They can’t be turned backwards; the cords tighten and prevent turning counter-clockwise.

The spindles are ready and the wire trough is placed above them. For now it is elevated on posts to make it easy to string up the loom with the chain wires. Lined up along the wire trough are ‘wire slides’, one for each pair of chain wires. They are used along with wire spacers to keep the wire from twisting below the spindles.

Lengths of wire have been draped over a bar at the top to form pairs. The two ends of each wire pass through a cross-wise slot in the wire trough, down through holes in the spindles, through holes in the wire slides and are twisted tightly together at the bottom. Then a one pound weight is hung on the wire slide at the end of each pair to hold the wires taut.

The posts have been removed and the trough lowered over the spindles. You can see three of the five screws that will be tightened to hold it in place.

Wire spacers are installed below the twisting mechanism and above the wire slides. They are pieces of foam board with narrow slots cut in the sides for the wires to rest in.

The laid wires are hand straightened and slightly curved so they need the help of this wire guide to slide through the row of upside down “Y” shaped openings in the wires. The wire guide is made of lead to be as heavy as possible for its small size. The guide is pushed along by the laid wire and removed after reaching the end. You can see this in the slide show sequence below.

This shows how the wire guide is employed. Halfway through the the sequence the view switches to the left to show how the guide is removed. After this step the backing is lowered onto the newly inserted laid wire (by releasing the treadle) and the chain wires are given three half-twists to bind it in place. The twisting mechanism is then lowered the prescribed distance (9 clicks), the treadle lifts the backing and the sequence repeats. Each time another laid wire is added the backing grows wider.

This sequence of photos shows how the twisting mechanism moves down as the web of wires grows wider. Notice how the (white) wire spacers slide down the wires and that a row of them is removed periodically.

Some of the parts of the loom are labeled here. The wire lifting beam lifts about 1/2″ when the treadle is stepped on. This lifts the chain wires so a new laid wire can be slid down the trough between their splayed ends. With this loom different spindle rack/wire trough sets must be substituted to change the chain wire spacing. The narrowest spacing possible for this loom is 15/16″ on center.

The chain wires are 1-1/8″ apart here and match the rib spacing of the mould.

The aluminum angle taped in place helps guide each laid wire into the small hole in the end of the wire guide.

The first step of fitting the backing.

More Information about the Loom

This drawing shows a cross section through a spindle, wire rack and wire trough. When the twisting crank is turned (in the direction shown by the curved arrow) the cord is reeled in and the spindle is turned. When the cord is pulled to the right it is tightened from two directions (as shown by the two straight arrows) so it cinches down on the spindle and turns it. This twists the pair of chain wires 1/2 turn.

After a laid wire is added by twisting the chain wires the whole ‘web’ is lifted by the treadle (not shown). This engages the untwisted parts of the chain wires in the cross-wise slots in the wire trough. This prevents the spindles from turning backwards when the weighted cords are released by reversing the twisting crank. The cords slip on the surfaces of the spindles since the cord is only pulled from one direction (the weighted end). The spindles re-align themselves each time the cords are released.

In this cross section drawing the web is lifted and a laid wire has been slid into place beneath the twists.

The foot treadle is released and the web is lowered down onto the laid wire.

The chain wires are all given a half twist, adding one new laid wire to the facing. If a backing were being made the twisting sequence would be repeated two more times before adding another laid wire to the web. The web must be lifted each time the weights are lowered and reset since the mechanism allows only one half turn of the spindles at a time.

Logically the next post in this sequence would be “Making Laid Facings” but it will be skipped because it was posted previously and can be easily referred to.

#17 Finishing the Mould Frame

This post covers the remaining steps needed to prepare a double faced laid mould to receive its wire facing and backing. The topic of ledges and how they relate to backing wires in wove and laid moulds seems to need some explanation. It is important to understand the purpose of these structures so this post contains some additional information not directly concerned with actually ‘doing the work’.

Backing wire and the need for Ledges

Ledges aren’t essential for the single-faced laid mould, the oldest and simplest European style paper mould. I’d guess that many single faced laid paper moulds have been made without them, with the tops of ribs and mould frame made to form an unbroken flat surface. When covered with a laid facing the results can be pretty good.

But for double-faced moulds, laid or wove, this doesn’t work. In order for the upper layer of wire to be supported at the sides and the ends of the mould the lower layer of wire (backing) needs to be set down into the frame.

The solution is to lower the ribs and create recessed ledges at the ends of the mould. The ribs and ledges together support the wires of the backing so that it, in turn can support the wires of the uppermost layer, the wove or laid facing, at the proper level. The ledges have a second, perhaps incidental function. This is to trap the ends of laid wires to arrest their tendency to work out of the ends of the mould. This is the reason that I use ledges for single faced moulds even though they aren’t essential.

This represents a cross section through one end of a single faced laid mould; this part of the frame lies parallel to the ribs and perpendicular to the laid wires. A simple ledge is shown, as deep as the diameter of the laid wires resting in it. The drawing also indicates the level to which the waterbars (not shown but just off to the right) will be trimmed. Their tops should be at the same level as the ledge because the laid wires should rest on both. The tops of the ribs (which would be farther off to the right) form a plane at a slightly lower level. This is to account for the thickness of the chain wires of the laid facing. Copper edging that will be added to protect the wire ends and bind them to the top of the frame is not shown in these drawings.

The simple ledge of a single-faced laid mould. The waterbar has been leveled at the same time as the ledge was created. The ledge is recessed by the diameter of the laid wires so their top surface ends up even with the top of the wooden frame.

A double-faced laid mould needs a deeper ledge. Making it in two ‘steps’ avoids weakening the mould frame along the outer edge. Backing laid wires rest on the lower level. These, along with bridge wires, provide a firm base for the laid facing. The narrow groove along the inner edge of the deeper ledge traps the ‘loose’ chain wire at each end of the mould so it can’t shift sideways along the laid wires.

The more complicated ledge of a double-faced laid mould. The upper laid wires should be even with the top of the wooden frame so the backing wires must be set lower to make this possible.

This shows the various wires of a double faced laid mould and how they are situated in the ledge.

One does not need to be so fussy when fitting wires to a wove mould but the backing still needs to be recessed to support the wire mesh level with the wooden frame.

The ledge of a wove mould is similar to that of a single-faced laid. It is a little deeper and the margin at the outside edge is wider.

Creating the ledges and leveling the waterbars.

The ledge is created using a router table which in my shop is the wing of a tablesaw modified to allow a router to be mounted beneath.

The dial indicator was used to set the router bit to make the cut as deep as the thickness of the layer or layers of wire.

The waterbar has also been routed to the same level as the lower ledge. The table saw fence must be adjusted for the bit to reach over to the waterbar.

Straight from the router…

.. and with corners cleaned up with a chisel.

Making the Trap Groove

This pointed router bit is used to make the trap groove.

The trap groove has been routed and a notch has been chiseled, extending the bottom of the groove and making room for the ends of the chain and bridge wires.

A few more details

I route out a little area at the corners where adjoining pieces of copper strip will overlap. It is the same depth as the thickness of one strip (.015″) and will keep the strips from bulging up at the corners where there will be two layers.

The edges of the mould frame are eased off with a plane and lightly sanded.

Notches for the Twists

Laid wires will reach only to the inner edge of the mould frame but the twists must lap over it. This single-faced laid mould needs very small notches for the twists..

They are a little deeper for the backing wire twists of a wove mould.

Notches for a double faced laid mould are a different story. A bundle of wires will need to fit in each notch so it must be roomy. Each notch will accommodate the ends of the upper chain wire twist, a bridge wire, and the lower backing wire twist. If these wires are too crowded the springy bridge wire will veer off to the side making it impossible for the chain wires to lie straight on the rib.

A double-faced laid mould frame with notches completed.

Applying Finish

I’ve been using Watco oil as a finish. It dries a little more predictably than boiled linseed oil and makes the new mould look nice. Either is fine; both will wear off before too long! It is pointless to try to waterproof the wood of a paper mould. Water will inevitably get into the wood and a surface coating like urethane varnish will eventually start flaking off. I believe that untreated wood is better for forming sheets. Water flows more evenly along wet wood than over a shiny, hard surface. Wood is hydrophilic and attracts water. Water is attracted to wet surfaces and can flow smoothly there. A varnished surface is hydrophobic and repels water so water beads up and flows unevenly.

When the finish dries the mould will be ready to receive its wire facing.

#18 Definitions of some Unfamiliar Terms

Defining some terms may make these posts easier to understand. I have chosen some words when a traditional term was not known to me. The terms are in italics; accompanying text and photos are intended to define and explain their meaning.

~frame sides: The two longer parts of the mould frame parallel to the laid wires. Ribs are set perpendicular to the sides, both ends being fixed in holes drilled there.

~frame ends: The two shorter parts of the mould frame parallel to the ribs.

(above) The underside of a wove mould. This photo identifies the frame sides and frame ends along with a few other parts of a paper mould.

~chain wire / chain wires: These words are especially confusing to use. I will use the singular “chain wire” in these posts to mean a single pair of wires that spiral around each other, binding laid wires side by side to make a facing. Visually it appears as a single line of wire, resembling a miniature chain, crossing the laid wires at a right angle. I will use the plural “chain wires” to refer to more than one of these structures. Examples of the two uses might include: “Each rib has a chain wire positioned above it.” And “All of the ribs have chain wires positioned above them.” (It is awkward to write many times about “chain wire pairs”. And what is the plural of “chain wire pairs”?)

(above) An excerpt from a drawing showing the process of making a laid facing in a loom. It provides a simplified view of the structure of a laid facing including a few laid wires, a chain wire and a twist.

~laid facing: The uppermost wires of a laid mould. The porous wire surface on which macerated cellulose fibers are collected when forming sheets of paper.

(above) This photo shows a laid facing being fitted to make a ‘single faced laid’ mould. This is the simplest and oldest type of European style paper mould. Another type of mould, ‘double faced laid’, uses this same type of facing supported upon an additional layer of wires, called ‘backing’.

~wove facing: The uppermost wires of a wove mould. These are in the form of a fine screen of woven wire that collects fibers to make a sheet of wove paper.

(above) A wove facing is being trimmed and fitted to its mould. A wove mould always has two layers of wire and is sewn in two stages.

~backing: A layer of wires that lies beneath a laid or wove facing to support it from below. Backing is prepared on a loom like a laid facing but with wires spaced much further apart.

(above) Backing being fitted to what will become a double faced laid mould.

(below) The very bottom of a large backing that is finished and ready to cut off of the loom. Three half-twists in the chain wires keep the laid wires widely spaced. The last four laid wires are more closely spaced with two half-twists in the chain wires. Including a few narrow spaces along one edge makes it easier to fit the backing to the mould frame.

~facing laid wires: The long, straight wires that make up a laid facing. There are hundreds of laid wires lying close together in a typical laid facing. They are fastened together by a dozen or so widely spaced chain wires.

~backing laid wires: The long, straight wires that make up a backing; these wires are the same as facing laid wires but spaced further apart with extra twists between them.

(above) Facing laid wires and backing laid wires are shown in this extreme close-up. The red arrows show where two backing laid wires are hidden under laid wires of the facing.

~loose chain wires vs. sewn chain wires: With the exception of one chain wire at each end all of the chain wires of a mould are fastened in place, each being sewn to a rib. The two ‘loose’ chain wires at the ends can’t be sewn to a rib. To secure them they are ‘trapped’, either in a groove in the wooden frame (single faced laid and wove) or between two bridge wires (double faced laid).

(above) The chain wire running across the top of this double faced laid mould is ‘loose’ (not sewn), but it is trapped between bridge wires to keep it from ‘wandering’. The chain wire seen along the bottom of the photo is sewn to its rib.

~bridge wires: Bridge wires are physically the same as laid wires but have a different purpose and are used only in double faced laid moulds. They are straight, stiff wires that bridge the widely spaced backing laid wires to provide a smooth, firm support for the laid facing. Over each rib, a single bridge wire runs alongside and between the two chain wires (one facing, one backing) and is sewn in place as part of a ‘bundle’ of wires. Bridge wires are also used at both ends of a double faced laid mould to provide extra support for the ends of the facing laid wires. They provide a firm base for the laid wires which keeps them from distorting badly when copper edge strips are tacked in place.

(above) Above each rib a single bridge wire is inserted alongside chain wires and between the laid wires of the facing and backing. It crosses the widely spaced laid wires of the backing, providing a smooth, solid support for the upper facing to prevent it from being cinched down unevenly by the stitches that bind it to the rib.

(below). You can see both uses for bridge wires here; at “A” as one piece of the ‘bundle’ of wires sewn to a rib, and at “B” lined up in a group to support the ends of laid wires where they lap over the frame end.

twists: These are extensions of the chain wires that lap over the frame sides.

(above) Extra laid wires have been pulled out to fit a laid facing to its mould leaving this twist a bit loose.

(below) The same twist has been tightened and will be trimmed to fit in the notch. After the mould is sewn all of the twists will be covered by copper edge strips to protect them.

single faced laid: The most basic type of paper mould having a single layer of laid wires sewn directly to the ribs. Until the mid 18th century it was the only type of European style mould. Paper made on this type of mould is distinctive for having ‘shadow zones’ along the chain wires. This is a result of the rate of drainage along the ribs differing from the rate of drainage between the ribs.

(above) It is easy to see that there is only one layer of laid wires in this single faced laid mould. A laid facing is in the process of being sewn to the ribs.

double faced laid: A type of laid mould developed around the middle of the 18th century having two layers of wire. Adding the extra layer (backing) improves drainage and eliminates the uneven formation typical with single faced laid.

(above) Two layers of wire are visible here, identifying this as a double faced laid mould.

wove: Wove moulds were also devised around the middle of the 18th century. Paper made on these moulds lacks the distinctive laid pattern because the facing is a nearly featureless fine woven mesh. Wove moulds require a backing; the wires of the backing keep the relatively soft wire mesh from sagging between ribs.

(above) A wove mould with deckle in place. The support grid of the backing can be seen through the fine wire mesh of the wove facing.

wove backing: The layer of wires devised to support the facing of a wove mould. It resembles a laid facing but with laid wires spaced much further apart.

grid wires: A grid is created on top of the backing to support the wove facing evenly. The grid is made of a single wire strung back and forth between small brass or copper nails. Two rows of stitching between each pair of ribs will secure the facing to the backing.

(above) The wove backing has been completely sewn to the ribs and a grid has been created to provide an even support to which the wove facing will be stitched.

ledge: A shelf or lower level created to support laid wires where they overlap each end of the mould frame. The cut ends of the wires must be protected by a copper strip. It is difficult to keep this strip from distorting the wires when it is tacked down. This can be minimized with careful attention; aiming to support the laid wires at the same level as they are supported by the ribs.

(above) One end of a double faced laid mould with two ledges. The deeper one supports the ends of the backing laid wires. The shallow ledge supports the ends of the facing laid wires.

trap groove: A groove cut along the inner edge of a ledge to ‘trap’ the ‘loose’, unsewn chain wire so it can’t move.

copper edge strip: The narrow strip that is affixed to the top edges of the frame to protect the vulnerable ends of laid wires and twists. Along the ends it also functions to bind the laid wire ends to the mould; holding them in place to align them evenly with the rest of the facing.

(above) A copper strip has been tacked to both ends of this mould. It protects the ‘ragged’ ends of the laid wires while holding the ‘loose’ chain wires (facing and backing) and bridge wires in place. The strips along the sides do less; serving only to protect the twists. If not covered the ends of wire are vulnerable and likely to be snagged and bent. In moulds receiving hard use chain wire twists sometimes ‘escape’ from their covering and will be bent, first one way, then another. They eventually fatigue and break, most likely right at the first laid wire. The chain wire will loosen near the break and laid wires may come loose, too. The copper strips at the ends sometimes work loose, allowing laid wires to protrude and become damaged.

#16 Leveling the Ribs

The wooden structure of the mould is complete; now the tops of the ribs are scraped level in preparation for sewing down the wire facing.

I like to pre-load the mould with weights before leveling the ribs. This gives the mould a very subtle camber; an extremely shallow arch in all directions. The forces of forming sheets and couching push against the ribs. By its nature a mould is weaker and less well supported in the middle. Leveling a mould under weights gives this part a little lift to compensate. It is surely better for the top of a mould to be slightly domed than either flat or hollow.

The photos above and below show one way to support the long sides of the mould while allowing weights to be hung on the single brace rod that supports the ribs.

I cobbled together this structure by clamping some planks to my table saw. I will likely try to come up with something more convenient in the future.

This method of hanging the weights is fairly new to me; earlier on two brace rods and deeper ribs allowed the 12″ x 3/8″ diameter steel weights to be simply laid in place between the ribs. As shown below, a mould could be placed on any flat surface while leveling the ribs. The smaller mould shown above uses 5/8″ ribs and there isn’t enough space above the brace rod for the weights (even if there were two brace rods). The weights must be hung from the single brace rod to pull down on the ribs.

This larger mould had 3/4″ deep ribs and two brace rods passing through the ribs. Two rods allowed the weights to lie horizontally between the ribs and below the surfaces to be scraped.

The weights are hung in pairs from the single brace rod. These are leftovers from an unrelated project. Some have set screws which make it easy to attach the wires. A simple hole or even tape would also work.

Here’s what they look like from below. The two weights on the left have been attached to the wire with strapping tape.

The blade for this scraper plane is a narrow strip hacksawed from a woodworker’s card scraper, sometimes called a cabinet scraper. The arrow shows the direction that the plane is pushed. It may seem backwards when looking at the angle of the blade. This is because a sharp, forward facing burr has been formed on the backwards facing blade.

A cross-section drawing of the scraper plane and enlarged views of the blade. The burr at ‘b’ is much exaggerated and the blade shown wedged in the plane would normally be set a little lower.

The long wooden body of the plane rides on top of the long sides of the mould frame. The blade is advanced by small increments for as many passes as it takes to completely level all of the ribs.

The scraper blade needs to stick out quite a lot to reach the ribs that are recessed below the top of the mould frame.

The scraper is ground and honed at about 45 degrees. Then a ‘burr’ or ‘hook’ is turned on the sharp edge with a burnisher. You can see the burr in this photo. This allows a scraping action which is safer than the cutting action of a normal plane.

The iron or blade of a woodworking plane protrudes from a narrow mouth in the sole, the flat bottom surface of the tool. The sole normally rests on the wood right next to the blade and keeps slivers of wood from rising up when caught by the sharp edge, particularly when the grain runs the wrong way. Since ribs must be recessed below the sides of a mould it is not possible for the sole of the plane to serve this function. A cabinet scraper is slower and less efficient but a safer cutting device. I have found that a narrow piece of one mounted in a wooden plane body makes a workable tool for leveling mould ribs. The sharp burr on the scraper blade turns and breaks the shavings as it cuts so fibers can’t rise up and splinter off.

The total amount of wood that is scraped off the tops of the ribs is very small; about .010″-.015″ (.25mm-.4mm) around the edges and less toward the middle of the mould.

A block of graphite has been rubbed on the top edges of the ribs to make the leveling process more visible in the photos.

Working from the center outward, one rib at a time is scraped with a couple strokes of the plane. After finishing the ribs on one side (each rib having been be scraped for half of its length) one must walk around to scrape them from the other side. Then the cutter is advanced with a light tap and the process repeated. This is done a number of times until the tops of all the ribs have been reached by the blade and scraped to the same level. When the proper level is reached the ribs are given a few extra strokes each (without changing the blade setting) to leave them extra smooth and level.

The shavings left at the ends of the ribs look like this.

The first areas that the blade reaches are along the ends and edges; the brighter parts show where the graphite has been scraped away. The weights cause the middle to sag so it will be the last part to be reached by the blade.

A smaller unleveled area remains here.

The last unleveled bits are circled.

When no unscraped areas remain the ribs are checked to see if they are low enough. The top layer of laid wires should end up with at least 2/3 of their diameter sunk into the frame so that they can be trapped against a ledge at each end to prevent them from working out at the ends of the mould. The depth that the ribs need to be recessed depends on the type of mould; wove, single-faced laid, or double-faced laid each being a little different.

After the ribs have been scraped clean and level the weights are removed and the mould structure will relax and lift, creating a slight camber.

This drawing illustrates the relationship between the top of the ribs and the upper surface of the mould frame. The ribs are recessed by the combined dimensions of the wires that will rest on them. This topic will be covered more fully in the next post.

Adjusting the scraper plane

The wedge is given a tap now and then with a drill rod to keep the blade tight. This mould is not actually being leveled; these photos just show the method of adjusting the cutter.

The cutter is advanced by small taps with the same drill rod.

If you press a fingertip into the place where wood and steel come together while tapping you can feel the cutter’s advance even though it may be by only one or two thousandths of an inch.

#15 Pinning Ribs, Corners and Brace Rods

Metal pins are used to improve the connection between the parts of the mould. Holes are drilled and pins are driven down through the frame and rib pegs. These are made of 1/16″ unfluxed brazing rod that I bought from a welding supply house. Ribs are not glued and the pins make certain that the sides of the mould don’t spread.

A piece of rod is pointed on a grinding belt and pieces trimmed off to length with these flush cutters. I grind the other ends flat to make them drive better when they are hammered in.

Slightly undersized holes are drilled so the pins fit tightly.

I twist the ends on a block of beeswax before driving them in.

Every third rib is fastened this way. The other side will match so each of these five ribs will be secured at both ends.

A hole is drilled off-center through the brace rod end. This way the pin will pass through the plastic part while missing the brass rod.

These corner pins are started near the inside of the corner and slanted outward. This will leave room for hammering in the nails that will be used later to fasten the copper edge strips at the corners.

#14 Fitting Corner Braces

For these moulds both the braces and rub strips are made from polycarbonate sheet.

To make rub strips narrow pieces are sawed and cut to length. Like the braces they are made slightly oversized and trimmed off later.

Rub strips are attached with brass escutcheon pins. They are drilled in the same way that the braces were in the last post. First with a #00 center drill…

…then with a small number drill.

The strips are nailed on with 1/2″ long #18 escutcheon pins.

After they are attached the strips are rounded off with a router. This machines off the overhanging material so the ends can be accurately trimmed to fit the braces.

This is how the ends of the rub strips are trimmed square. Once again, the hollow ground planer blade is used.

Now the braces can be nailed in place. The heads of the brass pins are driven down into the recesses with a carpenter’s nail set.

This white plastic guide fits into the countersunk holes to guide the drill so the pilot holes for the screws are centered.

A larger hole is drilled a little way into the wood to accommodate the unthreaded part of the screws.

This tool is just a ‘stop’ to keep the hole from being drilled too deep.

I use these oval head brass screws because I think they look nice though flat head ones would also be fine.

Now the bottoms of the braces are rounded to match the rub strips.

Corner braces strengthen the mould and protect it from shocks. Both rub strips and braces reduce wear on the bottom edges.

#13 Making Corner Braces

The bottom edges of paper moulds are often protected by the addition of corner braces and rub strips. Here is an ‘old style’ brace made of brass. You can see that this one was made by soldering two pieces together.

The moulds I’m working on for this series of posts have braces and rub strips made of polycarbonate. This is a very tough material. It is used for glazing storm doors and such, shields on machine tools and, lately, for covid shields in stores and supermarkets. Narrow off-cuts (scrap) are usually big enough for making the parts needed for moulds. This plastic can be machined with ordinary woodworking tools. It tends to be very flat and fairly stiff, both good qualities for making moulds.

A strip is cut to a suitable width and the center line is marked to show where to stop the cuts when sawing out the L shaped pieces.

The pieces are sawn slightly oversize so their edges will hang off the sides of the mould frame a little. The rough edges will be removed when the bottom of the mould is rounded.

I make enough for several moulds at the same time. The burrs left from sawing need to be filed off before the next step.

Using the hollow ground planer blade to saw the ends square. These brackets measure two inches on a side.

A couple of special tools make things easier. The drill on the top makes a countersunk hole for a standard #6 screw. The #00 center drill on the bottom starts a tiny hole for the #18 escutcheon pins that will be used to tack the brace to the bottom of the mould. The wider part leaves recesses for the head of the escutcheon pins to fit into. Center drills are used by machinists to prepare material to be held between centers on a lathe.

A fence is clamped to the drill press table to keep the holes centered. A stop is set to drill the first hole in all of the parts and then moved to determine the locations of succeeding holes.

These burrs must be removed before moving to the next hole. This can be done by hand using this countersink.

Drilling the last of the four holes. Larger moulds sometimes have larger braces with six holes and screws.

I start drilling for escutcheon pins using the center drill. The pins make it easy to install the braces and, in theory at least, add a bit of grip between the braces and the mould.

The center drill doesn’t reach all the way through. To drill the rest of the way I choose a number drill that leaves a tight fitting hole to drive the pins through. The tight hole keeps the pins from working out. (Number drills are a series of 60 small drills that range in size from .040″ (#60) to .228″ (#1). )

All the braces needed for the five moulds being made.

Many years ago I was inclined to copy traditional moulds more closely. I made patterns and had bronze braces cast for this reason. I believe that many braces on old moulds were castings but I now know that some were made of soldered pieces of half round brass.

In the back are cast bronze braces including one set that are finished and ready for a mould. Making braces this way is a lot of work. The white ones are made of acetal. These are much easier to make, lighter weight and very tough. They were made in the same way as the polycarbonate ones described in this post.

Here is some half round brass that I have recently purchased. At some point I’ll try mitering and soldering this material to make some corner braces.

#12 Gluing Moulds

This mould has had epoxy applied to the corner joints and is secured with spring clamps while the glue cures. The dents left by the clamps poking into the wood will be covered by brass sheathing.

Using clamping cauls eliminates the dents for moulds without sheathing. This mould is ready to glue and clamp. At the ready are spring clamps, the clamp spreader and a puddle of epoxy ready to be mixed and applied.

I buy Devcon 2 Ton epoxy at my local hardware store. I mix and apply it with a short piece of 1/16″ brass rod with ends sanded and buffed smooth.

Glue is applied to both parts for every joint.

The socket for the brace rod end.

The cauls are made of thin polycarbonate plastic with pieces of sanding belt attached with contact cement. A groove has been cut along each end to engage the points of the spring clamps.

The clamps hold the parts tightly together while the glue cures.

The mould stays in clamps until the next day.

There is always glue squeeze-out to clean up.

Excess epoxy inside a corner.

Epoxy can be pared away with a sharp chisel.

The job is finished with a file.

Squeeze out around the brace rod end is easy to clean off with a chisel.

Applying a little paste wax with a toothbrush after dry-fitting the parts but before gluing helps the excess epoxy come off a little easier.

#11 Fitting Waterbars and Brace Rods

Before the corner joints of a mould are glued one or two brace rods must be fitted. One for smaller moulds, two for larger ones. They will pass through all the ribs and be anchored in the frame at both ends. Waterbars also need to be fitted along the ends of each mould.

The waterbars are really just little ribs and have the function of helping to draw water away to help form a good deckle edge. They are made in much the same way as the regular ribs. I straighten them and cut them to size in only one sequence of steps, unlike the ribs which have been reduced and shaped in two sequences. This might make more sense after reviewing the post on making ribs.

A by-product of roughing the deckle parts to an “L” shape are small strips of wood just right to make waterbars from. The straightest of these scraps were saved to make these waterbars. The lighter colored ones are for the experimental wove mould that is being made completely of Larch.

The bottom edges are rounded just like the ribs were.

These are ready to be cut to length and fitted into notches in the mould frames. They have tapered sides and rounded bottoms like ribs but do not need pegs formed on the ends.

Instead the ends are slimmed down with a block plane to fit into shallow mortises previously routed in the frames. Here a waterbar has been fitted into place and a brad point drill is being used to mark the location of a hole that needs to be drilled for a brace rod.

The brad point drill is turned with the fingers until the wings score the wood.

The sides of the waterbars are tapered so the table of this drill press is tilted to drill the hole at an angle. Using the same brad point drill to mark and then to drill is a good idea.

Fitting a Brace Rod

1/8″ diameter brass rods are used to brace the ribs. They are threaded on both ends so larger diameter acetal plastic ends can be screwed on.

Here, a 6-32NC threading die has been embedded in a block of wood with a 1/8″ diameter guide hole drilled through to the other side. The rod is held in the lathe chuck as the die is turned by hand. The power to the lathe is disconnected.

About 1/4″ of the ends are threaded.

In old moulds these rods are often hammered flat and inserted into slots chiseled into the ends of the mould frame. A small pin at each end anchors them in place. Until recently I glued the ends into same-size holes and then drilled for a 1/16″ diameter pin after the glue was set. This works but is tricky; it’s not easy to ‘hit the target’ and the brass shavings enlarge the hole in the wood as they are carried away by the flutes of the twist drill. And it is easy to break a drill this small. Now I prefer the method described in this post.

A brad point drill is backed into the holes in the ribs and waterbar in order to mark the place where a hole needs to be drilled into the frame.

In these moulds the brace rods pass through the waterbars. This is a recent innovation of mine to accommodate the narrow ribs in these small moulds. In larger moulds with deeper ribs (and all other moulds I’ve seen) they are not drilled this way. Usually the waterbars are added after the mould frame is complete. They rest on top of the brace rod(s) and are bound to them with wraps of wire.

The end of the frame is removed to be drilled after the point of the drill has marked it. The inked circle makes the mark easier to see in the photo.

A 3/8″ diameter hole is drilled to fit the acetal plastic cylinders that will be threaded on to the ends of the brace rod. To start the drill I lift the wood up and feel that the point of the drill is in the small hole. (This with the drill press turned off.) Next I move the drill down with the feed handle to push the wood gently down onto the table. Then the motor is switched on to drill the hole.

A forstner bit drills a clean, flat bottomed hole; good for this purpose.

The hole is drilled about 3/4 of the way through.

The brace rod is inserted through holes previously drilled in the ribs.

A piece of plastic rod is threaded onto the end of the rod as a sort of wrench. It is used to twist the brace to even it up at the ends.

Fittings for the brace rod ends are prepared. Pieces of acetal plastic rod have been cut and surfaced at both ends to about 3/8″ length. Smooth 1/8″ diameter holes have been drilled 1/8″ deep and smaller (#36) holes have been drilled all of the way through and threaded with a 6-32 NC tap. Here the outside diameter is being reduced to fit into the 3/8″ hole drilled into the wooden frame. (The acetal rod is manufactured slightly oversized to allow for machining.) For this operation the fittings are threaded onto a scrap piece of threaded brace rod that has been chucked into the lathe.

The inner end of each is beveled. The waterbar will rest against this end. The length of the fitting and the depth of the hole in the frame are calculated so the waterbar will end up being held at the right distance from the frame.

A fitting is threaded onto the brace rod at both ends.

The plastic fitting has a couple of advantages. It strongly secures the brace rod to the frame and holds the waterbar away from the inside of the frame. Waterbars can slide along the brace rods and often shift out of place.

The ends can be adjusted by screwing or unscrewing them a little to make the overall length exactly right so the ends of the frame won’t be bowed in or out.

The frame joints and the brace rod ends are ready to be glued with epoxy. After the epoxy has set a 1/16″ diameter hole will be drilled down through the wood and plastic (slightly to one side to just miss the brass rod). A brass pin is then tapped into the hole to make the connection even more secure.

#10 Assembling the Mould Frame and Ribs

The first step in putting a mould together involves only the ribs and the four pieces of the frame. Other parts; a brass brace rod and extra ribs called waterbars will follow.

You may recall that one edge of each frame piece was intentionally left rough. This bottom edge is now smoothed by a single pass over the jointer.

Compressing the pegs by twisting them into a sized hole smooths out the facets left from the twelve sided rib peg tool. This also makes the ribs easier to fit into the holes in the sides of the mould.

Ribs are lightly sanded mainly to remove the little bits of wood that are left from drilling all the sewing holes.

The inside surfaces of the frame are also lightly sanded.

One end of each rib is inserted into a hole.

The penciled numbers are used to keep the ribs in the proper order.

Four ribs to go.

After all of the ribs are fitted in one side the whole assembly is carefully turned around so the free ends can be started into holes on the second side. One at a time, ribs are gently twisted back and forth while pushing them down. All will end up about halfway into the holes at each end. In this photo only the first and last rib (not visible here) have been moved down.

This just shows how the ribs move down as they are re-positioned. Three ribs have been moved down partway into the holes of the opposite frame piece.

When this step is completed the mould looks like this. The rib pegs are all about halfway into their holes.

Now the frame must be pushed in from both sides. This is done gradually as the sides are gently tapped together in small steps. Care is taken to tap evenly across the length of the frame, keeping the sides parallel. I turn the mould around each time so the sides get tapped from both sides equally.

After each stage of tapping all of the ribs are turned a bit in their holes. This is easy but important. Here the top five ribs have been ‘flipped’ down a little by my thumbs running down the sides. If the mould is assembled without doing this the ribs can become locked in; turned at odd angles. It can become difficult to straighten them and there is even a chance of breaking a rib.

When the pegs are all the way in their ends will be flush with the outside of the mould. Now they are aligned with the scribed marks on top. Both ends are rotated at the same time to make a rib stand nearly straight up; then each end can be individually nudged into position.

The narrow top surfaces should be centered on the scribed lines.

Now the ribs are completely inserted and aligned.

The holes drilled to receive the brass brace rod now line up perfectly.

The ends of the mould can be fitted in place.

The mould frame should be square, or very nearly so. This is the cumulative result of the care taken to make all of the pieces, ribs and frame, as straight as possible, with ends cut perfectly square; and of being certain to drill the rib peg holes into the frame at exactly 90 degrees.

This batch turned out very well!

Five assembled moulds, ready to be fitted with brace rods and waterbars.