Tips On Making a Delrin Folder

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In this scene from Stanley Kubrick’s classic 2001: A Space Odyssey, the ape is dissatisfied with the properties of natural bone. I suspect he wants a Delrin club. Here is a great explication of the film.

Seriously, animals do tinker with their tools, and so can you. It is an intensely satisfying experience. It gives you a lot of freedom and confidence in designing, executing and using a specific tool for your individual needs. It is interesting to see how tools you have made wear, perform and even may fail in use.

While bone can only be harvested from dead animals, Delrin is mass produced and easily obtained from many suppliers. It is a very hard plastic, originally invented by Du Pont in 1960 to bridge the gap between plastics and metal. There is a dust hazard, as there is for wood, so you should review the MSDS and wear PPE.

MAKING A DELRIN FOLDER IN FIVE EASY STEPS

1. PLANNING.  It is a good idea to think and experiment a bit with what you like, or don’t like in the folders you are currently using. Monica Holtsclaw has a great introduction to various shaped folders for various purposes. How do you hold it? Do you use both ends? Do you like sharp or rounded angles? Is it for scoring, folding, and/or burnishing? What different operations do you intend to use it for? Making a crude mockup out of binders board glued together for thickness can give a much better sense of what the actual product might feel like and fit your hand. Alternatively, full size scale diagrams are also quite informative. Here is my idea of the ideal shape.

2. ORDERING MATERIALS AND TOOLS.  Obviously, it is easiest to order the Delrin closest to the size you need for the final shape. Mc-Master Carr carries an extensive variety of sizes, but consider yourself warned; their website is more addictive than cheap baggies of high potency heroin. As far as tools, I recommend a 24 tpi hacksaw if you don’t have a bandsaw, a small vice, an 8-inch coarse bastard file with handle, a woodworkers card scraper, a burnisher for putting and keeping the hook on the scraper, and an assortment of 3M sanding sponges for final polishing.

3. ROUGHING OUT. Delrin is easily marked with a soft pencil. Cut it out using a bandsaw or 24tpi hacksaw. The more care you take in cutting evenly and accurately the less time you will need to spend cleaning it up later. A bandsaw makes the roughing out much quicker and I find it easier to get a more accurate cut. Indeed, a bandsaw makes everything — even mistakes and accidents — much quicker.

4. SHAPING. Initial shaping is most easily accomplished by filing. I prefer an 8 inch Nicholson Magicut.  It works well on wood, plastics and laminates. I find the older ones made in USA better made the the newer imported ones. Alternatively any coarse bastard file can be used. Always mount a handle, otherwise the tang can cause serious injury. Grinding or sandpaper tends to produce very deep scratches that are difficult to remove, and I would be nervous about the amount of dust generated. I have experimented a bit with a plane and spokeshave, which kind of worked, but resulted in lots of chatter, unpredictable chipping, and a difficult to clean up surface. It can also be shaped with metal working tools such as a milling machine. And who isn’t looking for a good excuse to buy a table top milling machine?

5. FINISHING.  I find hand scraping (with a woodworkers card scraper) produces the most successful surface finish after filing. You will need to learn how to sharpen it and turn the burr. Scraping is also virtually dust free, since the shavings are a couple of a thousandths of an inch thick and tend not to become airborne. There is some other good advice on finishing Delrin from this thread in the Practical Machinist. In general, the finish of Delrin reflects the tool used. Delrin is very clean and nonabrasive, consequently your tools stay sharp for a very long time. It is a great way to learn about scraping, since it doesn’t have a grain direction to worry about like wood.  A final polish with a progression of 3m sanding sponges, gives it a pretty good finish. The higher the polish the easier it is to clean, and I find the more bone-like it feels.

Delrin is not yet easily available to use in a 3d printer, though I suspect it will be in a couple of months/ years. This could be very cool: one of the most useful and intimate bookbinding tools to be customized and printed on demand. For now, stock reduction is not all that difficult. I’d be interested to hear if anyone has experimented with other plastics for folders.

If you have a bit of experience shaping metal or wood, Delrin is not that different. It is a slightly challenging, but rewarding material to work with hand tools. If making tools is not your cup of tea, you can always purchase a ready to use folder from me, and use this info to tweak it a bit to suit your personal preferences.

I’ve planned a workshop on making Delrin folders. I’ll give it a test drive in a couple of weeks on full time North Bennet Street School bookbinding students. Contact me if you are interested in hosting something similar at your location.

 

delrin in progress

The Delrin Folder

Mr. McGuire: I just want to say one word to you. Just one word.

Benjamin: Yes, sir.

Mr. McGuire: Are you listening?

Benjamin: Yes, I am.

Mr. McGuire: Plastics.

Benjamin: Exactly how do you mean?

-The Graduate (1967)

 

Bookbinders have used a variety of materials for folders. Wood, bone, and ivory are common traditional materials. The Excelsior metal folder, made from aluminum bronze, is an oddball patent from 1889. Nylon, bakelite, carbon fiber, Teflon and sometimes even steel have been used more recently.   Today, most bookbinders and book conservators use bone and Teflon. Each material has its advantages.

Earlier this summer, senior rare book conservator at Harvard Library, Alan Puglia, showed me a small spatula for pigment consolidation, which he made out of Delrin. Delrin is a plastic which was invented by Du Pont in 1960. Alan mentioned several advantages of this material, including its low coefficient of friction and rigidity. The material seemed ideal not only for spatulas, but folders.

After making a folder and test driving it for a while, I became a devotee. It is a great material for a folder ( apologies Jim Croft ) combining advantages of both bone and teflon, while not feeling plasticky and soft like Teflon. It can be shaped with hand tools. It is food compliant and impact resistant.  It is used for the stock of the M16 rifle. Du Pont’s informational Delrin booklet.

Delrin is much stiffer than Teflon, and twice as hard, yet has about the same coefficient of friction.  The hardness of Delrin is 120 on the Rockwell R scale, Teflon is 58.  Delrin has a dynamic coefficient of friction of .35, and Teflon about  .2.  More technical specifications of Delrin and Teflon. I had a lot of trouble finding technical specifications on dried bone, possibly because they can vary so much, but this article, “The Mechanical Properties of Bone” , is somewhat useful.  There is a dust hazard in working Delrin, MSDS here. Because of its slipperiness, all adhesives I’ve tried are easily wiped off, even if dried. Delrin is not quite as dense as Teflon. Teflon is 2.2 grams per cubic centimeter, Delrin 1.41 grams per cubic centimeter. Searching for “Bone Density” leads to entirely different results.

Plastics, unlike natural bone, can be made in almost any shape or size. This gives the maker a wide range of possibilities in designing a folder, since there are essentially no limitations on the shape.  I decided on this shape began by examining how I use folders and the various ways I hold them. I notice I often used a Teflon folder flat, as a burnisher, so needed it to be fairly thick and have smoothly rounded corners. Unlike Teflon, Delrin is that a folder can have large gently rounded, non-marring areas and fairly thin, knife like sharp areas that don’t distort like Teflon.

I am a firm believer in the importance of learning how to make and modify your own tools. Next week I will share some DIY tips for making Delrin folders. I’m almost embarrassed how much I enjoy working it by using hand tools. It has no grain, so can be attacked from any angle, and it is very clean, so tools stay sharp a very long time. Like most plastics, it doesn’t have a “mind” of its own but is consistently compliant with the tools and wishes of the maker. Benjamin?

 

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DELRIN FOLDER

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This folder is carefully designed to accomplish all the general uses a bookbinder or conservator has: scoring, folding, turning-in, applying non-marring local pressure, large scale smoothing. The small rounded tip area is shipped slightly blunt, but it can be sharpened if you prefer. Delrin is hard and stiff like bone, but has a coefficient of friction similar to Teflon. It can hold a much thinner and sharper edge than Teflon. It has a nice, non-plasticy feel. I saw, file, scrape and polish these from a solid block of Delrin.

Delrin Folder:  6.5 x 1 x .375 inch. $65.00

Bone Folders: Our Nearest and Dearest Friend

John Farleigh, in a chapter about Sidney Cockerell from his book The Creative Craftsman, gives a particularly observant account of the relationship between a book binder and a bone folder.

“Another man is at work putting down a leather joint on the inside of a bound book, using a folder with quick, skillful movements reminiscent of the grooming of a horse.  The folder, a small ivory instrument that has to the ordinary eye the appearance of a paper-knife, is in fact a most important tool to the binder. Its shape is fashioned with great care and according to the habits of the craftsman himself. Every facet of its surface, every curve and subtlety of its edge, is known and used for a purpose, and no craftsman will readily part with this tool. This particular craftsman tells us, as he would talk of the loss of his nearest and dearest friend, that he has just broken his folder—an extra thick piece of vellum needing rather more pressure than usual found a weakness in the ivory—and we are shown the sad remains”

The finest bone folders on earth are being made today by Jim Croft, pictured below.  He processes wild deer and elk bones with his teeth and hands.  He also offers intensive workshops on making books from raw materials: toolmaking, processing fiber, papermaking, and wooden board binding with clasps. Below he is wearing his signature bone folder vest.  Check out his website, traditionalhand.com, or email him to purchase raw or finished folders: traditionalhand AT gmail.com

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John Farleigh  The Creative Craftsman (London: G Bell and Sons, 1950) 92.