Penmakers And 3d Print Pen Making

Discussion in 'Interest Groups' started by Oliver_Krangle, Apr 22, 2017.

  1. Oliver_Krangle
    Oliver_Krangle Active Member
    Are there any penmakers out there? I thought I'd start a thread to discuss and collect information regarding the use of 3D design and printing to make writing instruments. This would span everything from dip pens to commercial pen/pencil kits to using Bic type pen inserts or other cartridge refills in 3D prints. Maybe this is a fading interest in the age of the iPad and electronic signatures but handwriting isn't completely obsolete yet! Some ideas to discuss:

    • selecting pen kits for use with 3D prints
    • what 3D printed materials can be used?
    • designing 3D printed tubes and other pen components
    • dealing with design rules and overcoming the review process
    • post processing prints before assembly (sanding, polishing, gluing, sealing, machining, etc.)
    • pen assembly
    • 3D printed pen cases, pocket protectors, pen holders
    • ergonomic designs for disadvantaged or elderly users
    • links to companies, blogs, and pen making organizations
    • highlighting your pen creations and shop products
    any other ideas that can be added to the list?

  2. Oliver_Krangle
    Oliver_Krangle Active Member
    • Some background on penmaking

    A good way to make a nice functional pen is to use a commercially available pen kit. These kits include all of the hardware you need to assemble a pen except for the body. Most penmakers use wood, plastics, or other strange things like deer antler for the pen bodies. If the material can be drilled, glued onto a brass tube, machined or turned on a lathe, and is rugged enough to withstand being held in a hand it's a good candidate for use.

    There are many sources for commercial pen kits. If you have a local Woodcraft or Rockler Woodworking store they carry a large assortment of models in stock or online. In addition there are a couple of other major online stores that carry a voluminous number of kits as well. Those include Penn State Industries (PSI) and Craft Supplies USA among others. Available kits are also not limited to pens or pencils. There are kits for may household items that need a handle or have a cylindrical shape such as bottle openers, fondue forks, and even duck calls.

    A nice thing about having a local store is that they often have demos or classes to help you learn how the entire process works. If taking a class you'll walk away with one or two assembled pen kits of your own. If you're planning on making your own pens using wood or plastic materials at home you'll need to machine them into the proper cylindrical shape. Generally this is done on a lathe, although using other wood working tools or hand carving and sanding are also possibilities - it all depends on your abilities and your budget. Regardless of how you deal with the outside, first you'll need to drill an appropriate hole through the center of a piece of material, also known as a "blank."

    If you're lucky you'll already have access to a machine shop facility with a good drill press and a lathe of some sort. If you need to purchase these tools be prepared to spend at least a few hundred dollars to expand your shop. On the bright side you don't need a giant lathe that can turn a piece of lumber into a baseball bat. There are small project lathes available for a little over a hundred dollars that can be used to turn pen bodies. Some people make their own light duty lathes as part of their hobby.

    But why spend all that money on machinery? 3D printing opens up new options for generating pen tubes that come from Shapeways with close to perfect dimensions, a well aligned center hole, and an optional surface pattern on the surface for less than $10 in most plastic materials. It's also difficult to generate many surface patterns on the outside of a turned tube using a lathe. The function of the lathe is to generate a smooth surface or something having radial grooves to form something like a finger grip option. To get surface patterns you'll need other machinery or carving techniques to generate patterns such as angled grooves, bumps, spirals, text and numbers, etc.

    The one thing you do need to assemble your pen kits is a pen press unless you already have a light duty press in your shop. The same companies that sell wood working or pen kits also sell a variety of pen presses that are specially designed for the task in the under $50 and up range. Basically the brass tubes that are glued inside the turned blanks are pressed together with other pen kit components using friction to hold everything together.

    For more background information there are many instructional videos that can be found on the web sites carrying pen kits and from hobbyists on Youtube.
  3. Oliver_Krangle
    Oliver_Krangle Active Member
    • selecting pen kits for use with 3D prints
    You've picked a pen kit and now you need to decide if it has a chance of working with a 3D printed tube. This depends on two main factors. 1) the minimum wall thickness of the 3D printed material you want to use, and 2) how much space is available between the inside wall of the tube and the outermost edge of the pen hardware at each end of the tube. In the simpler case both ends of the pen tube will have the same outside diameter which applies to most pen kits. ( A small percentage of pen kits have different end diameters which requires a tube with a tapered outside diameter profile.)

    Things are rather easy if you decide to use a printed tube with minimum wall thickness and emboss a pattern on the surface. In this case the wall thickness required by the pen kit, or (End Band Outside Diameter - Hole Diameter)/2 must be greater than or equal to the minimum wall thickness of the 3D printed material.

    If you decide to use an engraved pattern in the body of the pen the wall thickness must be greater than the minimum wall thickness of the process to allow the engraving pattern to be printed and see. Two figures are attached below to highlight this scenario. The first shows a side profile of the engraved pen tube case. The second is an example using the data sheet of the 8MM Metallo pen kit which has been obsoleted by the manufacturer. But the same principles apply to most pen kits. I liked using the 8MM Metallo pen kit in the past because of its relatively thick walls and the fact that it was a single tube pen with no hardware (such as a clip) touching the 3D printed portion after assembly.

    pen kit key dimensions.jpg 8mm metallo data sheet.jpg
    Last edited: May 10, 2017
  4. Oliver_Krangle
    Oliver_Krangle Active Member
    • what 3D printed materials can be used?
    I think the answer to this question may be just about any material, although some materials will be better than others when used as part of a pen. The main concerns might be for appearance or manufacturing capability, considering design rules such as minimum wall thickness and detail capability. I collected some of the pens in my possession that I haven't given away yet as gifts so they may not be the most stellar examples of finished pens, but here they are. Most are the obsolete 8MM Metallo pen except for the last which is a Slimline Pro model.
    3D pen assortment.jpg

    A) White strong and flexible material coated with a brushed on wood sealer. I can't remember if this was polished or not from the factory.
    B) Red strong and flexible material with no sealer.
    C) Black strong and flexible material coated with a brushed on wood sealer.
    D) Metallic plastic unpolished with an engraved pattern.
    E) Metallic plastic unpolished with an embossed pattern.
    F) Metallic plastic oversized tube with an engraved pattern filled with a colored resin. The pen body was then turned down to final size on a lathe, polished, and sealed with several layers of CA glue applied while on the lathe.
    G) Full color sandstone oversized tube turned on a lathe for improved color rendition, polished, and sealed with several layers of CA glue applied while on the lathe.
    H) Elasto plastic material.

    Also attached is a magnified view from the above image which shows each pen tube body in finer detail.

    A big take away from the images is that sealing the prints with hard layers of CA glue can lead to cracking, particularly for materials such as full color sandstone that might contract or expand over time with moisture absorption or drying. A lighter and thinner sealant will help to keep hand dirt and oils from staining a porous blank without the serious cracking issues. While I haven't tried acrylic or frosted detail materials yet they probably have improved resistance to getting dirty. The problem with acrylic materials is the requirement for thicker walls and coarser details. Frosted detail materials have thinner wall requirements and better detail resolution but the level of transparency may be sufficient to reveal glue and the underlying brass tube.

    I have some other tubes laying around that I have not yet assembled onto pen bodies. These include brass, full color plastic (obsoleted print process), and the high definition acrylate which as I recall looks horrible because of the required supports. Once I get around to assembling those pens I'll post the photos in this thread.

    We can certainly look forward to more print materials to arrive in the future that may be better suited for use with pens. Maybe you already have a home printer that can print a material having exceptional material properties!

    3D pen assortment closeup.jpg
  5. Oliver_Krangle
    Oliver_Krangle Active Member
    • designing 3D printed tubes
    In principle designing a tube for a pen kit is rather simple. A basic tube can be designed using the most basic versions of 3D design software including embossing, engraving, or other surface shape variations. In addition a tube printed with a larger diameter could also be machined with tooling to add patterns or to achieve the final dimensions for the most perfect fit possible. In this post I will summarize the process of generating a pen tube design for a simple pen kit requiring a minimal amount of sanding, if any. In later posts, after I order and receive the tubes, assembly steps will be covered.

    For the design process I will be using a ShapeJS creator I have written to generate tube designs. This makes it a bit easier for you to follow along at home if you wish to assemble a trial pen of your very own or aren't a 3D design guru. At present I have written two creators to generate two basic types of tubes. For the first creator the end diameters can be individually set which is required for some pen kits. With this creator the shape of the tube will taper linearly from one end to the other. With the second creator the body of the tube can be slightly bowed outwards but the end diameters must be the same. In time I may combine the creators and add more pattern capabilities but these two creators give us a good starting point. These creators may be found at the temporary ShapeJS site being used to develop the capability at Shapeways at the following link:

    I have selected a very simple and cheap pen for this example from Craft Supplies USA which sells pen kits, lathe turning supplies, and pen assembly tools. It is called the Artisan Mini Key Ring Pen and is pictured below. Our goal is to design a tube so the pen will function well. The nice thing about this kit is that the tube walls are very thick, making it easy to produce tubes that don't tempt the Shapeways rule checkers to reject the design. When rejection happens much sadness can result.


    The first thing to do is to consult the data sheet for this pen to get the important dimensions. Most sellers of pen kits include online documentation for their kits, and some are more thorough than others by including information that the 3D print designer might need. At worst you might need to purchase a pen kit to measure some dimensions yourself using a precision caliper or micrometer. Below is an edited version of the data sheet for this pen. I have highlighted the primary dimensions of import using big red arrows.

    craft supplies mini key ring data.jpg

    Pen tubes are best built from the inside out. We can see that the center hole of the tube needs to be 7mm in diameter to hold the supplied brass tube. The end diameters are determined by bushings that are designed for each specific pen kit. They match up to the diameters of the pen hardware and are used on lathe during the turning process to get to the final proper sizes of the tube ends. From the diagram we can see that the end diameters are 0.432 inches. The last critical dimension is the length of the tube. Unfortunately the data sheet does not show the expected nominal length of the tube. Fortunately I had a spare kit available and measured the length to be 2.03 inches. So lets go with that number. (My guess is that the target length is 2.00 inches but having a slightly longer tube is better than having one that is too short. More on this later...)

    So in summary these are the dimensions we know about so far:

    Center hole diameter = 7 millimeters = 0.276 inches
    End tube diameters = 0.432 inches = 10.973 millimeters
    Tube length = 2.03 inches = 51.56 millimeters

    And from these numbers we can calculate the wall thickness at the ends, or
    Wall thickness at ends = (10.973 - 7) / 2 = 1.99 millimeters.
    This thickness is sufficient for most if not all of the Shapeways common 3D printed materials which would work for a pen tube. For example the minimum wall thickness of polished metallic plastic is 1 millimeter so we could use this material. The minimum wall thickness for porcelain is 3 millimeters so it would not be a good candidate, and in addition there's the additional problem of dealing with glazed and unglazed areas of the print. Nothing is impossible but let's avoid such troubles at this point!

    But what numbers should we plug into the creator program? For the center diameter I'll use the 7 millimeter number. Practically speaking you don't want the brass tube of the kit being too loose in the 3D printed tube. Personally I like to take a small cylindrical file and carefully enlarge the center hole of the 3D print if necessary until the brass tube slides into the 3D printed tube easily but with no wiggle.

    Next up are the end diameters. I would rather have the tube ends extend outwards slightly from the pen hardware but that's just a personal preference. Hitting the diameter exactly without any machining can be a long shot unless everything in the print process is perfect and repeatable. I would say that in 2017 the technology is still slightly wishy-washy and prone to slight variations. Therefore I'm going with 11.1 millimeters. In addition a slightly larger end diameter can always be reduced with sanding performed by hand or on a lathe for the most perfect fit.

    For the tube length I'm using 52 millimeters. The tube ends are actually quite easy to sand down to make a shorter tube if necessary. The trick is to sand the ends extremely flat so they mate up to the pen hardware without any gaps around the mating circumference. After a little bit of practice I have been able to get excellent results by sanding the end of the tube on a piece of very fine grit sandpaper resting on a very flat surface. Ultimately the goal is to match the length of the brass tube supplied with the kit. If the tube assembly ends up being too short the writing tip of the pen may stick out too far. If the tube assembly is too long the writing tip may not stick out far enough. In general getting to within a millimeter or so will result in a functional pen.

    The last step of using the ShapeJS creator is to select a pattern and adjust parameters as desired to get an attractive pen surface pattern. The creator automatically places a safe tube around the center hole with a wall thickness that is set by the minimum wall thickness parameter to prevent accidental thin wall rejections. In general this minimum wall thickness value is determined by the print material you want to use. Always consult the Shapeways material rules to get the proper and most recent numbers for any material.

    I've taken some screen grabs of a pen tube generated by the 002 creator tool which has the bowed wall capability and it is shown below. Note that all dimensions entered into the tool must be in millimeters.:

    mini key ring generated tube finger grip detail.jpg

    I have put this tube and a few others in my Shapeways store
    so they are available for the play at home crowd and other mad scientists out there wanting to make their own key ring pens based on this discussion. However feel free to generate your own patterned tubes and see how the process works. Remember that this entire ShapeJS thing is still experimental at Shapeways but as long as you have a Shapeways account and are logged in while generating a pen tube you should be able to purchase your own design from within your own account. In theory that is!
    Last edited: May 10, 2017
  6. Andrewsimonthomas
    Andrewsimonthomas Shapeways Employee Community Team
  7. Oliver_Krangle
    Oliver_Krangle Active Member
    Thanks, I thought I'd collect my thoughts and tips in one place in "chapterized" posts. Looking forward to buying the new HP print materials (hint, hint) and continuing with assembly posts. Eventually I'll be upgrading the ShapeJS routines to generate more patterns and maybe do some other interesting things. It's a continuation of ShapeJS efforts I started years ago but it makes more sense now with some integration into the DIY marketplace.

    Unrelated, but if you could offer printed materials that have splotches or speckles or random streaked patterns, those could complement or replace physical surface patterns and might be more appealing to penmakers that prefer a smooth surface and the look of wood grains or swirly patterns in cast acrylic materials. Penmakers are always looking for exotic materials to use. Just a thought!