Member postings for Doubletop

Or

**LINK**

Pete

Sean

Maybe but the overall principles of the design will be similar. Here is another link with various posts of circuit diagrams for MightyMig variants

**LINK**

Maybe different models but in all the cases the relay switches on the primary to the transformer. The variation is the way the voltage control taps on the transformer are selected.

One other thought is the state of the transformer and whether you've got a short between the coils and it is overloading the relay. Give it a visual check to see if there is any obvious arcing. There was a time I could do the maths on transformers and possibly advise a method of checking with a meter. Unfortunately those days are long gone.

Otherwise I'd suggest you jump on the mig welding forum in the link I've given you and ask the same question there.

Pete

Here is the parts list with the circuit diagram **LINK**

The only thing the relay does is switch the power transformer, maybe the back emf of a lot of repeated heavy current welding (switch setting on MAX 1)  has finally killed the relay. Just a case of component mortality?

Pete

Edited By Doubletop on 16/04/2018 12:15:39

It looks like it is one of these

**LINK**

Data Sheet here

http://www.hongfa.com/pro/pdf/HF102F_en.pdf

Beware when searching Ebay. You want a 24v version and they all seem to be selling the 12V version which appears to be JQX 102F. However some are advertising the HF 102F but as 12v which you don't want.

Pete

Edited By Doubletop on 15/04/2018 09:28:33

Edited By Doubletop on 15/04/2018 09:49:53

As the relay is completely stuffed. Take a note of all the markings to help you search for a replacement. Then carefully break off the outer case and using snips cut away as much as the relay as you can. You are trying to get it down to 4 separate connections coming out of the board.

Using pliers grip the connection on the component side and unsolder on the solder side and pull the connection free. Repeat for the other three.

It may seem a bit drastic at first but it is far easier than trying to wrestle out 4 connections at the same time.

Pete

Werner

You have it running very well

Pete

Link to streetview and the location of the plaque below.

**LINK**

Have a 'drive' around

Apparently the railcar was stored in the shed now used by the timber yard.

https://www.urbanghostsmedia.com/2016/01/abandoned-monorails-suspension-railways-railplanes-hovertrains/

Edited By Doubletop on 13/04/2018 11:24:12

Edited By Doubletop on 13/04/2018 11:24:59

We're in the tea room having a tea break...

One of our local club members has built a 'proper' diesel electric. Rather than plagiarise the article please open this link and read the whole thing.

www.tmmec.org.nz/downloads/349Feb-Mar2016.pdf

But a quote to whet your appetite.

He uses the 3 cylinder diesel engines from small Kabota tractor lawn mowers

Since then Tony has now built the second example and runs them double headed. They sound absolutely fantastic.

Also NZ uses 3' 6" guage so a larger loco when scaled to 7.25"

Pete

Edited By Doubletop on 25/03/2018 11:02:17

Edited By Doubletop on 25/03/2018 11:06:13

Edited By Doubletop on 25/03/2018 11:06:32

Gary

I see references to Sandy Campbells 3" boiler. There are plenty of refernces to it if you Google and build logs on some of the other forums.

Drawings (but not the originals) here **LINK**

Pete

Edited By Doubletop on 24/03/2018 07:31:26

That Boley looks nice and the collets and step chucks etc all look like they would nicely complement my Lorch.

Pete

After I was advised to use the Harris Stay Silv black flux I've never had an issue with silver soldering copper to copper, copper to stainless or stainless to stainless. As part of my rebuild I remade the copper headers for my Dart superheaters that had stainless tubes and spears (not concentric).

To add to the mix of the discussion one of our club members has been warning about the copper to stainless joints being susceptible to failure. The advice was:

• Wherever possible avoid a copper to stainless joints.
• If you have to do copper to stainless ensure adequate overlap of the joint, e.g. a swage the end of the copper tube and insert the stainless tube (or use a smaller bore copper tube that inserts into the ID of the stainless; but why would you?)
• Never do joint that is a stainless tube into a hole in the side of a copper tube e.g the stainless super heater tube T’d into the copper header cross pipe.
• Never use a copper and stainless super heater when it is to be upstream of the regulator, which would mean it is always at boiler pressure. Ensure the superheater is after the regulator.

The reason for these warnings were some failures recently. One was a failure of the stainless superheaters that were T’d into the copper header. Another case, apparently, was a loco with the superheaters ‘upstream’ and the copper stainless joint failed. The fire door was open and hot coals were ejected. Fortunately, the driver wasn’t on the driving seat.

The upstream/downstream scenario comes about with the use of ball valves as regulators. Something that doesn’t occur with LBSC or Martin Evans designs. I’ve replaced the Stroudley regulator on my Dart with a ball valve but the super heaters are still downstream, but when a ball valve is located in the smokebox it most likely results in the super heaters being upstream of the regulator.

The industrial engineers no doubt will have something to add….

Pete

.

The boiler looks remarkably similar the Sandy Campbell design.

http://www.modelengineeringwebsite.com/3%22_vertical_boiler.html

The holes in the side ar to allow the ceramic gas burner to draw in the secondary air. It would not be possible for the ~ 92% air required for combustion of the ~8% gas to be soley drawn through the holes in the jet assembly of the burner.

Pete

Edited By Doubletop on 23/03/2018 06:33:10

I'm glad to see that my limited experience with slitting saws reflects those of the experts. I've tended to avoid using them as much as I could becuase I wasn't sure I was using them correctly. Jasons video, with sound effects, was spot on with my efforts. I've resoured to making ny own arbours in an attempt to deal with eccentricity.

Maybe I'll give them another go armed with the info in this thread, at least I was using the right speed...

Pete

Werner

We need to catch up. There are items of yours I could use and there's stuff I can share with you. I'll send you a PM

Pete

Werner

**LINK**

Déjà vu? I'm looking forward to seeing what you have done

Although theres not much constuctional detail in the zip file Neil posted for me (scroll down to his post). You'd need to read the ME article

I'm currently working on a steam indicator using the same hardware

Pete

I had a quick look at the site and some of their fittings look very nice. I noticed reference to 1/4x40 MTP and found this on their site

**LINK**

So maybe not as much a problem but as Harry suggest be carefull

Pete

P.S. I've just ordered some of thelr globe valve kits. At $15 for 4 they've got to be worth a try, and no problems with thread sizing

Edited By Doubletop on 25/02/2018 06:55:08

A late arrival at this discussion. For many years now, I've had a Technics deck on standby waiting for a preamp so I could connect it in to my home entertainment system. Over Christmas the Jaycar pre-amp kit was acquired and assembled. With a new cartridge it was all systems go. After the earthing was sorted, no hint of hum.

The box of LPs from the 60's through 80's was dug out from the back of the garage and a day spent reminiscing. I grew up with those albums and they are ingrained in my brain. However, after such a long time it was now clear how production standards had improved over the years. Sgt Peppers from the 60’s was good but nowhere as good as Relax from the 80’s. The Pink Floyd and James Gang albums had noticeably different production standards as the years progressed.

I spent years working with Jet engines, and the compulsory rifle firing as well as attending many F1 races pre and post turbos. Technically I’m deaf but not at the hearing aid stage yet. Music is in the ear of the beholder, that’s the variable that can’t be tweaked.

Pete

Edited By Doubletop on 23/01/2018 22:50:44

A further thought on this. Under certain conditions the use of PWM could result in the striker progressing slowly towards the bell as the power level increases. So basically you are reducing the acceleration rate of the striker when actually you want it to be at a maximum.

Pete