AndyID

If I understand correctly, you are considering coupling four wheels one side and not using a synchronizing gear? If so, I don't think that will work. You would have to couple all wheels on both sides to prevent the mechanism from locking.

Exactly. To a great many Americans, Gibson's portrayal of William Wallace in Braveheart is seen in just the same terms as Starwars movies. The real story may never be known, but I'm willing to bet it was very complicated.

As I am Scottish it's obvious that I am a close relative of Mel Gibson. The US is a very strange place. In many respects it is still locked in 19th century thinking. But I really don't want to turn this into a political thread.

I should have mentioned - please see my blog for information on using servos in a model railway environment.

Hi Simon, Yes it would work with a standard servos, although I thought the throw adjustment by adjusting the pulse widths was supposed to be a "feature" (don't tell anyone, but personally, I think it's just a PITA!) I had thought of putting the printed bits on Ebay (without the servo) as a sort of kit, but I'm not sure about the economics. The 3D printer is not terribly fast, and, like any machine, it needs a "minder", so I might end up having to charge far too much. Mass production might also be an option, but that means starting a real business, and I feel disinclined to try that again Then there's the shipping cost. I'm on US Pacific time. Do you have a 3D printer, or do you know anyone that does? I could send you the files and you could make the bits locally. The design still needs a little refining. I tried to use the screw supplied with the servo to attach the eccentric, but I'd like to see a longer screw there so I can beef-up the eccentric in that area and put a washer under the screw-head. Also, as I mentioned already, exactly how the banjo attaches to the piano-wire is a bit of a mystery, but that should not be hard to solve. Best A

But wouldn't that imply it has a circular aperture? This thing is elongated. (Not that it really matters! Banjo works for me )

Could be worse - you could be in North Dakota! We're not even in the same time-zone as Boise. Idaho is almost two different states. I find the weather here to be very agreeable. As you say, the Pacific moderates it a lot. We are at 2000 feet - it is warm enough to swim in the lake in the summer, but not so hot that we need A/C in the house. Winters are cold enough to produce just enough snow to make it beautiful, but not so much that it becomes a pain in the neck!

Hi Ian, We've had hardly any snow here (N. Idaho) too, and it's been quite mild. There seems to be a common misconception by some people in the UK (OK, OK, I said "some") that we live in the frozen northern wastelands. I'm less that 100 miles south of the border with Canada, but I'm at the same latitude as Zurich!

This is the version with 3D printed parts. The throw is adjusted by sliding the eccentric that sits in grooves on the top of the cam. I still need modify the thing the that looks like a tennis racquet so that I can attach a piece of piano wire to poke through the baseboard. The axis of the wire will intersect the fulcrum screw at the "handle" end. I should have used a tripod to take these pics, but I can't remember where I put it!

I wouldn't be too sure of that. My wife is in NJ. She just sent me a message to let me know it's snowing

Best flight I ever had was Lydd to Le Touquet on a Bristol Freighter. Well, it was very short anyway. It would have been perfect if my brother hadn't puked!

in 1982 we moved from Paisley to Mesa, Arizona with three children ages 5, 3 and 2. (I was working for ITT in Tempe). We decided to return to Paisley for Christmas 1983 so the grandparents could see the kids. We were flying AA, Phoenix - Dallas - Gatwick. Unfortunately, the Phoenix - Dallas flight was delayed and we missed the connection to Gatwick. A very nice man at the AA desk put all five of us in FIRST on the next flight! I was telling the kids to eat that caviar stuff because they might never get it again, but they only wanted hamburgers. We took the train up to London to catch a train from Euston to Glasgow Central and we were crossing London in a cab. We were going to have a bit of a wait at Euston, so I said to my wife "Look, that's Knightsbridge! Why don't we stop off at Harrods at pick up some things for the parents?" She thought about it for a minute but decided the children were too tired after the long flight, so we decided to relax at Euston and get something to eat. Shortly after we arrived at Euston, all hell broke loose. Policemen were running all over the place. The date was December 17th, and Harrods had just been bombed.

Of course, you will include at least two motors and a differential. The low gear mode should be good for shunting

Yes, the elk here are more like red deer, but the deer don't look familiar at all. Poor things must be having a serious identity crisis. No wonder they just stare into headlights. The moose are not scared of anything - including the huge (and extremely fast) freight trains heading up to Marias Pass. Speaking of freight trains, I assume the "Boeing fuselages falling into the river incident" was well publicized in the UK. I've rafted down that part of the river. The trains really have to crawl there because of the gradient and the curves. One hot axle box, or a broken rail, and you're toast. I considered nipping over and trying to get a few pics, but the media had the incident very well covered. I wonder if anyone has incorporated it into their layout yet?

I should have asked if she was really Anne Elk.

Another soaker rolling in from the Pacific today. Undeterred, I took the dogs for their daily 1.5 miles, but it turned out to be a bit more than that as is was necessary to avoid a moose that was happily chomping on a bush at the side of the road Of course, Torri (the Cairn) went nuts as soon as he saw it. I think it was a lady moose (moosette?) but you don't want to mess with any sort of moose, so we executed a swift U-turn. Somebody ran into a moose on the highway near here last week. Their car was destroyed and they were lucky to survive the crash.

Your photos are bringing back nostalgic memories of a time when you could go anywhere in the Glasgow area by tram.

That's a good way of explaining it. Thanks!

Jock, The infamous Shona and Torri at (this was several years ago) If you have not seen this, it's worth a look Andy

Hi Gordon, The throw is determined by the "length" of the constant radius bit of the cam. To increase the throw, you increase the angle between the low and high bits of the cam. A bit more explanation: The cam has three "levels". At the low point (smallest radius) the "normally closed" contact must be connected to the common terminal. At the high point (greatest radius) the "normally open" contact must be connected to the common terminal. When the actuator is pressing against the "middle level" (a constant radius section of the cam that can be as long or short as you like) thanks to the hysteresis, the microswitch contacts remain in whatever state they were in before the motor started turning the cam. If I'm not explaining this very well, let me know and I'll post some drawings or something. I'd like this to be well understood because I think lots of people would be able to build inexpensive and very reliable point motors based on this principle. Andy

Hi Simon, You have it right. The electronic bits are discarded. The bits of the servo that are retained are the motor and the gear train. The lack of sophistication is, I think, a major advantage! (Please see my blog for more info. on servos) The only tricky bit is positioning the microswitch actuator relative to the cam, but that can be done either by bending the actuator arm slightly, or adjusting the mounting of the microswitch. I'll try to post some photos of the "production" version next week, after I take care of my tax return. I also have some ideas about how to construct a much simpler version that many people would be able to construct quite easily, but that still needs a bit of testing and explaining. Best Andy

Hi Jock, Ah yes - that's Torri (short for Torridon no less) and although he does look a lot like a Westie he is a wheaten Cairn Terrier. He's usually on the receiving end of it from Shona! As I understand it, Cairns were the original breed. I think Westies and Scotties came later. The story is that Cairns get their name because they caught rats that lived in the stone cairns the crofters created when they dug rocks out of their fields. Best Andy

Yeah! It finally stopped raining, but now I'm getting the "evil eye" from Shona. I think she wants to go for a walk. (Shona is a Scottie, and a bossy little so-and-so she is too.)

I was beginning to wonder if I had invented the thing about trains on Weetabix boxes until I found this http://www.cerealoffers.com/Weetabix_Ltd/Weetabix/Weetabix_Workshop/Trains/Railway_Models_Series_17_Set_3/railway_models_series_17_set_3.html

I was wondering about that too. I'm pretty sure I could get it over with my little tractor/backhoe and a winch. Unfortunately, the tractor is in Idaho.