Here’s a video I made of one of my mules (a 2006 vintage Kato F7) traversing an N gauge turnout built with Proto:120 flangeways some .016″ wide. The locomotive has Proto:160 wheels near enough to scale to call them that and thus designed to interact with Proto:160 track and its .0115″ flangeways. Anyways they play well enough together in this instance.
And another video showing how the loco traverses the diverging track.
After a lot of fumbling around with some redesigns I’ve gone back over the axle muffs and opted against raiding more of my limited supply of delrin rod in favour of epoxy-filled steel gear muffs. The idea for the latter came from Tom Hammond, 2mm aficionado and model engineer, in the hours I spent watching his Jacobs gear hobber last year at the Portland, Oregon GEARS show. Space, as ever, is tight but .100″ mild steel can be bored for enough epoxy to isolate .0625″ W-1 drill rod. The first op doesn’t require any more precision than a 3 jaw will grant but for the second I needed something better. My four jaws don’t hold down that small and I don’t have a .100″ WW collet yet. In any event I wanted an interior shoulder to act as a stop until I work out which method of mounting the gears to the muff I intend to use. The work holding answer was the ubiquitous ring collet turned up from what ever steel was to hand and slit to collapse around the loco axle under pressure of the scroll chuck jaws . Once I’m satisfied that steel muffs are the way forward I guess I’ll consider a home made WW collet.
To make the collet I had two options as I saw it: I could set the hole with a D-bit hoping that the D-bit could be set true in the tailstock (or modify one of the tool holders for my under construction bed turret to do the job) or I could bore to a moderate depth and call it a day. Having just made up some small silver steel boring bars I went with the path of least resistance. The photo below shows a George H Thomas designed eccentric tool holder with a boring bar that’s good to about .05″ diameter and scaled down to fit my Taig and Sherline tool posts. GHT knurled and drilled his for tommy bars on the “top” of the eccentric to set tool height but I don’t always get my tools the right way round when machining them and decided to leave the tommy bar holes off until I play around with the setup a bit more. Eventually I’ll probably put four equidistant holes around the circumference to allow for all eventualities – finger pressure for now! The tool is W-1 drill rod roasted a tad too long – it should be a light straw at the tip.
GHT pattern 1/8″ tooling holder with easily adjustable height eccentric for Taig and similar style tool posts. I tried to make both the holder and eccentric out of hot-rolled A36 but I didn’t get much of a finish on it. Regardless of the finish, the tool works very well and I wouldn’t be modelling without it.
Boring collet to hold axle muff for facing and reaming
And here is the collet being bored. With the help of an appropriately sized piece of stock to use as a plug gauge it came out dead on. The collet was then marked for No.1 jaw (the jaw was also marked) and the collet removed from the chuck to be slit.
L to R: modified syringe body with nail, home made pipe cleaner, Manifold for holding axle muffs during epoxying (six axle muffs already inserted), Metal infused J-B Weld.
With the collet ready .125″ stock was turned down, drilled and parted to rough length before insertion in the above manifold. I didn’t have any pipe cleaners small enough to fit the axle muff so I made one of floral wire and some alpaca wool. It works. Once cleaned thoroughly epoxy was mixed and injected with a broken syringe of the type I use for cementing styrene together. I gave it a day before cleaning up the ends and loading them into the collet for finish boring/reaming facing.
For quite some time now I’ve fancied getting into injection moulding. A couple of years back I bought Vince Gingery’s books on DIY injection moulding and had a go but the build fell off and I used the parts for other things. (1,2) The addition of pantograph and CNC capability in the shop has caused the project to resurface of late.
That’s a Bluenose on the clear plastic box to lend some sense of scale.
I based my build off of Vince’s drill press attachment but changed almost all of the dimensions to suit my own requirements and shop limitations. My initial foray was smaller than in the book to accommodate a short throw bench drill press but the subsequent purchase of a larger machine meant that I could have a stroke common to the Gingery plans. The bore was also enlarged to suit stock I had to hand. Originally I intend to use a nice precision ground rod for the ram but during machining I ended up scoring the bottom of the bore where the taper meets the side wall and on cleaning this up I had to enlarge the ram diameter which meant turning the ram out of 1.125″ CRS. Before preparing the new bore I saved myself further heartache by adding a combined micrometer/hard stop and a George H Thomas designed flat bottom boring bar and eccentric holder. Both have immediately found a place amongst my most used tools. Without them it was very hard to know when the bore ended and the taper to the nozzle started. At any rate, it worked, and I am the happy new owner of an injection moulder.
How the machine will be employed is yet to be seen but I have drawn up some mould cavities and made some tooling to help with cutting them. Surface area is the big enemy on such a small machine and I’ll be doing my best to learn how temperature, and injecting pressure affect clamping requirements which at time of writing are distinctly minimalist. My long range plan is to learn the most basic parts of the process and then, if possible, use the moulder as the core of a purpose made machine with part ejection. We’ll see… In the mean time a special collar needs to be made for the drill press I intend to test the moulder on in order to ensure the bearings take none of the injecting strain. It is just a simple collar that fits in place of the depth micrometer attachment on the end of the quill. There will still be some strain on the rack but a little protection is better than none at all.
1. Gingery, Vincent R. The Secrets of Building a Plastic Injection Molding Machine. Rogersville: David J Gingery Publishing, 1997.
2. Gingery, Vincent R. How to build a Plastic injection Molding Attachment for a Drill Press. Rogersville: David J Gingery Publishing, 2007.