Member postings for Doubletop

Dean

Try these guys **LINK** plenty to choose from in stock, good prices and they'll ship here. It's where I got my belts and pulleys for the Lynx

Pete

With new posts to this thread I've started thinking about the subject again. I had used one of these and thought I had problems with it that's why I went down the DIY route. However, that diversion has helped my understanding of how these thing work

These ignition systems are designed to have the sensor on the crankshaft so they can measure the time/rev and work out the proper timing for the to fire the spark. As the Lynx is a four stroke with the sensor on the cam the rev interval is twice what it should be and the timing will be wrong. However, putting two magnets at 180deg on the timing disc will ensure the correct time/rev is input and the firing point correctly calculated. OK you'll be firing at on all the revs with a wasted spark but any car ignition systems run wasted spark these days.

You'll see them on Ebay for $75 but the best source is HobbyKing, this one is only $35

**LINK**

The plug cap is the wrong one for 1/4x32 plugs but the proper caps can be obtained from Ebay for $8

**LINK**

HobbyKing do many different versions other than RCeXl, I also Have two Phoenix units from them. I've purchased from both sources without any problems. (well there is one problem with HobbyKing, once you've found them you keep going back for more toys! Take a look around at the amazing stuff they do at unbelievable prices)

Its all in the box 2.5"x1.5"x1.25" and by far the cheapest and most compact solution to get you running.

A further thought, I saw quoted somewhere "Most ignition problems can be traced to the carburetor"

Pete

Neil

Reflecting on my post last night it occurred to me that some might wish to make their own coils. A was aware John had done a thread on making a magneto a few years back. The peril of late night posting after a few Pinot's

I also realised I had forgotten to add that there are also pitfalls with using these 'pencil' coils from modern ignition systems. Although they can be triggered by a TTL signal they need a 2-3ms pulse and fire on the falling edge. That means the triggering circuit needs to preempt when to fire the trigger pulse and it will be at a different point depending on the revs. So it needs a 'smart' trigger circuit which these days means a micro controller.

For those interested in going that route there's a whole saga over here that also includes home made micro controlled CDI HV circuit that uses the igniter coils from gas stoves. Although appearing to be a solution those coils can’t be used independently as the primary requires 240v pulse. The CDI design includes a 400v inverter.

There is probably a series of ME articles that could be produced on this subject but my experience is limited to the Chinese CDI and the DIY micro controlled systems. I have no experience a TIM6, Minimag coils, Magnetos, distributors or the Megasquirt that some have used on multi cylinder engines.

As I said many ways of skinning this cat.

Pete

Neil

Coil winding? there is no need do that at all these days, for a quick easy and cheap way just get hold of an ignition coil for most modern cars. The Subaru coil I used has drive circuity inbuilt that can be driven by a TTL chip. Albeit it needs 12V supply. The bit that needs a little thought is the interface between the hall sensor and the coil unit.

Duncan

Depending on what you plan to do with your Lynx the Chinese 1/4x32 plugs on Ebay will be fine. If like me this is a new area for you I can't imagine you plan to stick your engine in an aircraft and trust it to fate so it will spend most of its life on a shelf looking good.

While you are on Ebay be aware the Chinese ignition systems, although very good and cheap they are designed to have the sensor on the crank and not the camshaft as the timing will be wrong for a four stroke, So something like a minimag (which costs more than twice as much as a complete Chinese CDI) and a Gerry Howell TIM6 will probably be the easiest way to get yourself up and running.

There are many ways of skinning this Lynx

Pete

Rob

I occasionally get odds and ends locally but without wishing to knock the local guys the market is too small here to support a major supplier. I order direct from the UK, in no particular order. Reeves, ARC Euro, Polly Model, RGD, Blackgates, BA Bolts etc and at times have had stuff delivered quicker and cheaper than from there, including the postage. As Ian says Little Metal Co for sheet cut to size, as Mico will only sell full sheets.

Ullirich for Aluminum, Atlas Specialty metals for stainless, some brass, Steel and tube for steel. Kendalls for silver solder, flux etc Look up your local engineering company and go and talk to them. Everyone I've approached have been more than accommodating and will sell short lengths by weight. Some of the smaller scrap dealers will still allow a bit of a rummage for useful items.

Tooling try CTC in Hong Kong, but I've now started using Alibaba and going direct to Chinese suppliers (e.g. ER32 collets US$2 each, with shipping US$5, whereas locally they want NZ$35) Shipping is always the hard part when going direct to China but still cheaper, even if you go over the threshold for GST and have to pay.

Pete

PS Where are you? one of us may be local to you.

Edited By Doubletop on 04/03/2014 10:01:42

Edited By Doubletop on 04/03/2014 10:02:50

Me to; here **LINK**

Same answer as Roy

Pete

Dean

The size of this wonderful creation has been coming clearer in the past few posts. Any chance of a shot of it in the palm of your hand?

Did you say what the CC will be?

I can also see the ME109 connection.

Pete

Here's a brief video of my Lynx running under the control of the software that originated on the RCGroups forum and I've had a hand in getting to work.

Its a development system to enable engines to be tuned and the advance curve set for the engine.The main features

• Console control of the software on a running engine
• Running display of RPM, Ignition advance, Throttle setting, HV trigger pulse width, Hall switch position
• Two selectable advance curves and one fixed advance setting.
• Adjustable advance curve, pulse width throttle setting.
• The advance curves can be saved and will remain in memory to be available on a restart. The intention being the software can be used without the console once the optimal setup is achieved

The forum where the work has been progressing is here. This version of the software is still work in progress but there are previous working versions available. Another part of the build is a CDI ignition module to compliment the Digital part. However I'm using a Subaru ignition coil which I have found triggers very well with just a 5V signal from a TTL driver chip. (The Subaru unit does require a 12V power supply)

Pete

Jason

Thanks for clearing up the offset.

David

Thank you. To answer your question, Yes and no; If the crankcase is over filled the oil comes out everywhere. It then settles down. That worried me at first thinking I'd run out of oil completely so I opened up the engine to see if there was any oil left. There was plenty enough for the crank web to dip into and splash around the inside of the crankcase and bore. I therefore assumed all was well, but before each run I do top up again, and then the excess is then gets discharged until it settles down. The oil breather feed to the cam box doesn't seem to do much so I put a sguirt on there to.

This engine is never going to be run for long periods or go into anything that needs a reliable power source so I'm not too fused about the oil situation.

Hope that helps

Pete

Alan

I agree the full set of drawings will be fine, I doubt if they would have been changed since 2006. The problem is a transcription error from the drawings to the magazine article in 2006. The cam box dimensions are all wrong. I only noticed it when a club member showed me the engine he had made from the 2006 articles. Something didn't seem right so I checked. There are also errors in the text that have been carried over to the 'Best of ME' edition.

Just a case of builder be aware, and check when working on this part depending on your source of information.

Pete

Yes but will work with 4 strokes albeit with wasted spark

Pete

An additional note while its still front of mind. For the Lynx, and the Bobcat I built previuosly I used an RCexel ignition system They are self contained and cheap

The ignition seemed to work fine but I had starting problems on the Bobcat which I put down to being a first timer. Once I got it started it wouldn't rev as high as expected and the engine cut out. I put that down to the home made carb. On the Lynx I used a Walbro carb so didn't expect any running problems. I was wrong the performance was much the same.

In order to understand the problem I hooked up with a group on the RCgroups.com forum who are in the process of producing a similar system to the RCexel but more flexible and with more features. To cut a long story short I've got involved in helping write the code for the PIC micro controller used in the system.

These ignitions use a micro controller to measure the time for each engine revolution and then apply the necessary advance to the spark dependent on the current RPM. I have realised that all the systems rely on the the hall switch being on the crankshaft, Both the Bobcat and Lynx have the sensor on the camshaft so the microcontoller always thinks the engine is going half the actual speed and applies the wrong advance for the revs the engine is doing.. Although the hall switch is set at the right firing point before TDC, it calculates the wrong delay and fires the engine late. So although its possible to get the engine to fire (with difficulty as I found) the engine is never running at its optimum and at some point in the rev range it just stops.

If it works as planned the system we are doing on the RCgroups forum will be aware of the location of the hall switch (crank or cam) as well as enabling the user to configure their own advance curve for their engine.

So if anybody is struggling using one of these ignitions, like i did, that's the reason

Pete

Edited By Doubletop on 20/01/2014 09:34:48

An interesting debate but to go back to my original question/observation

MEW split from ME with the express intention of providing a separate vehicle for workshop topics and keeping ME to model making. Of course prior to that time ME covered both topics, as you'd expect.

My observation was that topics that my reasonably be expected to be in one magazine are appearing in the other and asked why this was the case. I wasn't complaining about the quality of the articles or editorship and I agree with everybody else splitting the editor role has improved the quality of both magazines.

The point I was making was that if this blurring of boundaries continues the individual identity of both magazines would put in question the need for one or the other to exist.

To put it another way, if everybody had their own personal league table of magazine preference, and currently ME and MEW are at the top then if this blurring continues one or the other magazines could well slip from the second place to be replaced by some other organisations offering.

That's all really, its all down to personal choice in the end.

Pete

I didn’t intend to start a bun fight but moving on

Diane

I'm in the positive feedback camp for ME. Every month there is something new that adds to the improving quality of the magazine. The articles "Problems of combustion in small i/c engines" and "locomotive adhesion" were cases in point. However, there have been a few articles in MEW that were marginally ME territory.

The point I was making was if the two magazines don’t ensure they retain their identities through their content they could come to the position where one or the other becomes irrelevant.

I’m thinking along the lines of Ian. I imagine that some point back there was so much material available that a split was the obvious. MTM or whoever they were at the time had an opportunity increase their readership, and more importantly their advertising revenue.

Now that so much is done online on the various forums, including what could be seen as interactive build articles, I imagine that written articles are harder to come by *. There could well come a point when MTM, in order to maintain quality, may need to balance the economics of running what could become two similar magazines.

In my case on renewing my subscriptions ME is renewed without thinking about it, but with MEW I consider whether I want to do it every time. If it comes about that there is no point of difference between the two I’ll be dropping one in favour of one of the alternatives.

Pete

* (Stewart Hart has the right idea, he does both by posting builds online and then writing them up as articles.)

I subscribe to Model Engineer for articles related to the engineering aspects of making models. I subscribe to Model Engineering Workshop for articles relating to tools, equipment, workshop practice etc. I'm not really fussed what the subject areas are in each magazine as long as they relate to the general expectations of each magazine.

In ME4472 we have two articles that are clearly MEW subject matter, and they aren't one off’s they both are "to be continued". This confusion of the role of each magazine has been going on for some while now, particularly since the editor jobs were split.

Should we expect that David and Diane actually liaise on their respective magazines content? Or is it the case that the writing on the wall for MEW? If ME continue to contain MEW type articles why would I bother to subscribe to both?

Thoughts?

Pete

Anthony

Follow this thread by Stewart Hart and then the links off to other places. Plenty to chose from here, even from the man himself

**LINK**

Of course you may not be interested in the diversion to steam operated drain cocks, but then again you my be

Pete

I'd subscribe to the wobbler route, there's no better incentive to get something going the first time. This is a good design that Erik Stroetinga designed as a student project.

**LINK**

I made it on a mini lathe. After failing metalwork at school 45 years before, it was my first attempt at model engineering, only 4 years ago, The rest is history as they say.

An alternative source is the John Tom site. He also has the Elmer plans posted there

**LINK**

Plenty to choose from

I've never made a Stirlling engine but it seems there are plenty of failed attempts adorning shelves around the world.

Pete

Dean

Cambridge NZ? That means there is some chance of seeing this creation in the flesh. ME109 or just on the bench

Pete (Wellington NZ)

Likewise;

I'm guessing they have a problem with their left and right hands. They've sub contracted the subscriptions, website, digital content and nobody at MHS is assessing the impact of decisions being made with the various subcontracts. Rather than just sloppily assuming that everybody would have to have renewed their subscriptions by July 2014 they only needed to do a query on the subscriptions database to establish how many existing long term contacts would still be in place at that point.

Pete

Edited By Doubletop on 29/12/2013 22:56:43

Stew

Apparently its your birthday.? but with the time zone thing its not clear if that is today or yesterday?

Anyway congrats and a bit of a milestone as far as I can tell

Pete