Sunday, February 16, 2014

One More Step

G'day,

I thought it was about time to update the old blog. I hope everyone had a good Christmas and the new year has started on a positive note.

I do not really have much to show, even after having a five week break over Christmas. Layout progress has been non existent over the past few months as the weather has been just a little too hot and has kept me out of the shed.

During my holidays I was lucky enough to hitch a ride on the cement train out of Berrima. It was a great day and I really miss the train driving gig. Sometimes I wonder wether I made the right decision to go back and deal with unreliable flying machines? I guess everything happens for a reason. I really like machines of all sorts but the train is still one that amazes me, if only I could drive a steam loco.

I am still working on the MMM LFX kit and have the running boards complete ready for attaching to the underframe. I lost one of the double step brackets but with a quick email to Mike that was all fixed up.

I have still been plodding away with creating more ESU NSWGR steam sound projects. I have replaced the recording of 3801s whistle in my 3818 with that of 3830s. Since my earlier post with the 3818 video, much information in regards to 38 class whistles has come flooding in. There is a pronounced pitch variation between 3801 and the other 38 class whistles. I was amazed at how well a few people can pick sound variations. Phil one of the club members amazed me with his audio prowess! As soon as the video was seen by him I had an email questioning the whistle. With Phil's comment came a more accurate whistle.

I have lost a fair bit of hair recently. I had to vacuum the keyboard before writing this post. Templot is to blame. If anybody has used Templot you may know what I am talking about. I have slowly got my head around the track template design program and now have my layout fully drawn with NSWGR sleeper spacing and point design. The problem I am having now is getting the layout printed in one full 10 meter long sheet. I can print the layout off using A3 sheets and then sticky taping the whole lot together however this annoys me. When I took the PDF to Office Works the track gauge was printed at around 25mm rather than 16.5mm. Not sure what is going on with it? I am about to begin my first hand laid crossover and after that will be the two cross over formations including a single slip. Should be great fun........NOT ha. One thing that I must say about Templot is that it is very versatile and with versatility comes complication. One saving grace is that the Templot user group is very, very helpful. The bloke that wrote it is always there to answer questions and the user knowledge base is great. I was recommended this program by a club member and I also recommend Templot if your wanting to build custom track work. Its free, do I need to say anymore!

Also on the work bench is my turntable. This thing has had more make overs than Michael Jackson but unlike Jacko the TT can still spin. I am in the middle of building the ultimate bridge and a new drive line. I say ultimate as I will not be liable to show you any photos and it will ultimately be inaccurate. I have learnt a lot from a certain manufacturers business model. It seems if you say it's the best everyone will just believe it, sight unseen. This is the best sellers turntable you will never see.

That was a bit of a low blow. Of course I have a photo, I even have another crappy video!

The turntable drive is now just a bipolar stepper motor directly coupled to the bridge. I am using a micro step driver which allows for tiny angular displacement values. One improvement over having gearing is that there is no need to compensate for driveline slack. Another is that the motor is quite quiet during operation. It makes some funny noises, almost sounds like it is driven by high pressure water.

The drive line includes an optical isolator for power up calibration. At this point I am using a blank CD with a notch cut out to trigger the optical Isolator. Like my previous stepper drive the brains behind it is a programmable controller that memorises step positions and all motor pulse frequency commands. I am limited to only two inputs with this controller so multi tracked turntable indexing is a no go at the moment.

I cannot fault its indexing ability. Time and time again it aligns perfectly. On the negative side the motor does not run as smooth as I would like. Every now and again it will react sharply. I am considering buying a precision geared bipolar motor and seeing if running it at a higher speed will smooth things out. The beauty of this set up is that it is very simple and the bearings used in the motor are highly accurate resulting in no motor shaft play.

Bipolar stepper motor and calibration optical isolator

I still need to finish the bridge and the stepper motor mount needs building out of something more accurate than wood. I really enjoy playing around with this stuff. A multi input controller would make it very interesting however for Picton this set up is more than adequate. One avenue I would like to explore is having the TT well constructed out of acrylic. I think this material would offer more accuracy and more environmental stability.

In the video you can see that the TT bridge is not aligned to start with. On power up the calibration move aligns it to the track. Once the bridge completes 180 degrees a relay is energised switching the bridge polarity.



On other fronts I have just added sound to a Trainorama 42 class, but still have a few things to sort out in regards to the lighting. I have separated the markers from the headlight however the markers illuminate the headlight quite a bit due to there being no separation. Another little problem to solve is how to add a screw link coupler to the front of the 42. I could just glue it on as it will never be actually used however I am not a fan of just gluing things on. If any one has achieved this simply, I would love to hear how you did it.

Well that about it.

Thanks,

Linton