Minimag, another way to get your ignition sorted.

[Bogstandard]

I started a post over on HMEM a while ago, of which there seemed very little interest, so much for that being a dedicated model engine site. They have no idea what a good thing these are for the larger models, it makes them completely self contained

http://www.homemodelenginemachinist.com/index.php?topic=9150

So when this little unit gets here, I will see if the build on here will get a better response.


Bogs

[John Swift]

Hi Bogstandard ,

I don't understand why there's little or no interest in it

I'm not an engine builder my self  , and at the moment would find it easier to build an electronic ignition

but the magneto is more in keeping with the engine

and if designed for the job and not the price can be more reliable (less to go wrong)

 John

[MikeA]

Hello,

Being a neophyte in machining, I'm just completing my first engine, a Duclos Fire Eater but already am thinking of the next! Likely a hit & miss such as the Kerzel or one of the Upshur designs and the availability of this MiniMag will be perfect in my opinion (FWIW!)

Thanks for this information.

Best,
Mike

[NickG]

Bogs,

I missed that on HMEM. I haven't built an i.c. engine yet but have always intended to once I have built up my skills enough.

The ignition was always a stumbling block. There are a few options, motorbike coils, points, battery etc but that is very bulky. Then these transistor electronic circuits seem to be popular. The problems I saw was they aren't self contained and are still quite expensive.

I agree the magneto is a much neater unit, more authentic and comparable cost but they are only really suitable as you say for larger model engines due to the physical size and power it takes to drive them. A lot of people do smaller engines to keep material costs down and to suit their equipment I guess.

I think for a large ish engine like you are talking about, the magneto has to be the only choice.

I am considering trying glow plugs when I make my i.c. engine because they are neat (although not authentic they can be made to look authentic) and cost effective.

I've never had one to bits but how do the ignition systems work on stuff like strimmer engines (about 20 odd cc) but they are self contained?

I will be looking out for your build when the unit arrives, very interesting. I will have to read up on them in Model Petrol Engines by Edgar T Westbury. Strange that my grandad should have that book (he wasn't really a model engineer) not knowing that years later I would become a model engineer!

[John Stevenson]

I have often wondered about why they can't be split up and hidden away more to get a scale feeling.

Take Malcolm Strides Nemit engine, built from bar stock with a square lump or rather cube of alloy for a crankcase. If the magnets were fastened on the crankshaft, coil inside the crankcase and them a dummy magneto that looks like an original bolted to the outside of the crankcase.

The dummy is run from the crank and contains the contact breakers and the HT lead runs thru it and 'appears' to exit from where it should ??

Comment's, flames, bricks etc ?

John S.

[raynerd]

This is something I need to look into for my Webster build..... thanks for posting. 

Chris

[Jasonb]

I didn't have time this morning to reply to your update (did to your first post).

It certainly looks useful and should be just the job for your R&B, As I said I have a 1/2" scale Domestic to make and the mag would suit that well, not to mention they are only about 15mins from me.

Look forward to your trial build.

I wonder if its the fact you posted it in the "Links" section, I get the feeling a lot of people there just look at the work in progress etc, certainly don't get that much feedback from the IHC build in the "engines from castings" section but the Traction engine in WIP gets more replies.

Jason

[Bogstandard]

I don't think so Jason,

The site has gone completely away from it's original conception, that of building engines from barstock, and now everyone and his dog with a question posts on there.

There are very few experts left on there now, most, who would have understood magnetos and their uses have gone to other sites or just don't post there any more, maybe because it has got too diversified and watered down with garbage and idiotic postings.


John

[Sorekiwi]

Now that little thing is just plain COOL!

I'm gonna follow this one with interest.

[Bogstandard]

Just a little update on this.

The kit will be here sometime next week. I already have the prototype build instructions and things look to be very straight forwards. I will be trialling that sequence, only 'doing my own thing' where it is nessessary for me to do. It 'should' only be a couple or three day build at most, but you know what I am like, that could easily be stretched to a week. So everything else in my shop will be put on hold until it is built and tested, I don't want any more projects clogging things up for me.

BTW, this isn't a buy and assemble jobbie. If you can build an engine, then you are expected to be able to machine to fairly good tolerances. All the basics are supplied including the prewound and potted coil (that would be the expensive bit), plus a build sequence and plans. You could, at a push, make it with a small lathe, 3 & 4 jaw chucks and a vertical slide, but really, it does need a small mill, just to keep the accuracy required in certain areas under control.

This is the latest GA drawing, showing his web address.



So how many have been put off by my talking about keeping to tight tolerances?


John

[NickG]

John,

As I said, I think it's a brilliant idea, looks great and is definitely a better method than most being self contained and more representative of the real thing.

A slight concern I'd have for others building it is that I just think for a lot of people all the ignition system bumf is an add on, usually something bought off the shelf to get the engine they've made work. I saw your post to the guy something along the lines of guaranteeing that it will work, but if features really are required to be within certain limits for it to work, then the only way he could guarantee it working is if the tolerances were on the drawing or in the instructions. I know, it's really like any other model engineering, so you'd also be expected to know what limits & fits are required and the sequence in which to make things, and as you say, if they're making an engine they should be able to machine to pretty good tolerances anyway.  If they consider it as just part of the project it'd be fine and I think the majority of people considering it will be making a bigish engine with a pretty large outlay to start with so it will be fine. The only risk is to the newbee who is trying to make his first i.c. and thinks it'd be a good idea and ends up wasting 100 squid, where as really they maybe should have bought a box of tricks off the shelf with a glue on magnet to do the trick. To me, this would be like a whole new project on its own!!!

Nick

[MrFluffy]

I've never had one to bits but how do the ignition systems work on stuff like strimmer engines (about 20 odd cc) but they are self contained?

Absolutely, they trigger off a magnet on the flywheel somewhere, and everything including pickups etc is built right onto the coil itself which is tiny. The only wire off them normally leads to the run/kill switch which just grounds the pickup out to gnd to kill the sparks. The same with briggs vertical crankshaft engines. Just a trigger spot of a magnet on the flywheel passing the coil assembly triggers the spark event. The only tolerance there is the gap between magnet and coil/pickup assembly, which also sets the timing within a narrow range. They are tiny and easily hidden and easily adapted. Another source of these is mini moto engines, chainsaw motors etc.

Incidentally, smaller motorcycles and most older enduro/trials bikes are self contained flywheel magnetos too. The honda stepthru c90 wiring loom can be disconnected completely and the engine will start up. The key just providing pickup to gnd. On my sp400 enduro, it has a igniter coil and a rotating magnet on the flywheel too with cdi ignition, and that runs batteryless happily.

[NickG]

Thanks Mr Fluffy useful info there, I have created a specific post about this and replied to avoid this going too far 

http://madmodder.net/index.php?topic=4175.0

Nick

[Bogstandard]

Nick,

Thank you, I was just about to jump on that post as this is about the Minimag, not about other ignitions systems.

But to raise your points again, if you have the experience of building a decent engine, then these should hold no terrors at all.
Also even the very experienced people have taken the easy way out, electronical gubbins all over the place. Pretty soon they will have digitachos, and blowers, on a hit & miss engine. And they are the ones who scream out loud if it doesn't look right to scale.

They didn't have many batteries and chargers on farms many years ago.

This item is for people who want to get towards having an authentic running engine from a century ago, and not having a box of bits controlling everything. Fill it up, flick a switch, start and run it, just like the originals.


I hope to prove it when my engine runs on this one.

John S raised a point with me about it not looking authentic. If you look at the youtube vid where he has one of these running a full sized Lister engine, it shows what an original was like (on the floor, next to the engine), and with a little cover, one could be made to look very authentic indeed.

John

[Rob.Wilson]

Interesting John

Just right for an R&B Engine 


Rob

[John Stevenson]

Interesting John

Just right for an R&B Engine 


Rob

Rob,
There is a design error in these magneto's.

They don't work north of Doncaster   

John S.

[NickG]

You're right John, It's the best solution for such engines and I certainly hope to build one at some point. Looking forward to the build, it's certainly working well on the lister d.

Nick

[Rob.Wilson]

Interesting John

Just right for an R&B Engine  


Rob

Rob,


There is a design error in these magneto's.

They don't work north of Doncaster    

John S.

I had forgot about southern engineering  John S  



Rob  

[raynerd]

John, has your Minimag arrived yet?

I have been on Julian's website - what advantage would the Minimag Kit give you over  buying coil, controller and sensor which he sells?

Chris

[Bogstandard]

None, other than these make the engine totally portable (they are permanently fixed to the engine, as part of it) and require no batteries to be recharged or any other hangy on bits, it is totally self contained, put in fuel, turn it from the crank, wire to the spark plug, job done.

As I said earlier, these are really for a scale working model, running as they used to do when the originals were made. without all the electronical wizardry.

The kit will turn up when it turns up, the postal service in this area is crap, we got a Christmas card the other day, posted on the 20th December, locally. Parcels normally take up to 14 days, when they feel like delivering them.


Bogs

[Russel]

Forgive me if I stray a little from the thread subject.

[On topic mode OFF]

Roughly 25 years ago I worked repairing all kinds of small and industrial engines. Most of the 4 and 6 cylinder engines (at that time) as well some of the 1 and 2 cylinder engines used magneto ignition. When I say magneto, I mean magneto like the original one on the ground in the Lister engine video Bogs posted.

I remember how much the customers hated those magnetos because they were not familiar with them. I also remember the very robust and reliable spark they produced. I alway admired how well they worked.

I think the minimag kit is perfect for homemade IC engines! It bring back fond memories of the Fairbanks Morse magneto.

[On topic mode ON]

[Bogstandard]

Thanks for that Russel.

That is the sort of era I am looking at, where everything had to be, basically, portable and self sufficient.

Can you imagine having to tell a farmer back in those days that he had to recharge a battery. All he was interested in was that when he dug it out from under piles of junk, it would start.


Bogs

[75Plus]

I remember how much the customers hated those magnetos because they were not familiar with them. I also remember the very robust and reliable spark they produced. I alway admired how well they worked.

I think the minimag kit is perfect for homemade IC engines! It bring back fond memories of the Fairbanks Morse magneto.

The genius of the FM mag was the impulse coupling that would deliver as robust a spark at cranking speeds as when running at 1000 RPM.

Joe

[madjackghengis]

Hi John, after watching the Lister video, I am definitely going to model a magneto for my radial engine.  Like so many others who have posted here, I've used magnetos all my life, since a boy with my first Briggs and Strattton, having to remove the flywheel to set the points and clean them, and setting timing as well.  To Joe 75 plus, I actually had to go out and charge the battery of my 53 farmall cub, because my charging system only sort of works, and it gets charged about twice a year, when it won't hand crank start.  The impulse coupling is indeed true genius, magnetos have been put on Harleys "because they're cool" for all the four decades I've worked on them, but only in the seventies were impulse coupled mags available, and they were advertised as auto-advance magnetos, and substantially ease starting.  The "Scintilla" design magneto makes it easier to have the single coil magneto, firing multiple cylinders and enables magnetos for odd number of cylinders.  I'm really looking forward to seeing how this build rolls out.    cheers, mad jack

[gbritnell]

John,
I have to admit this mag would be a fine unit for a larger engine. The key here is 'larger engine' I followed your original posting on HMEM and went to the website to gain more information about the mag. I feel it would be quite a nice addition on some engines.
Now to your sour grapes attitude about the other forum. Why didn't you just say there didn't seem to be much interest and leave it at that. Having followed this and the other forum for some time I find there are a great bunch of talented people on both but not many people build 'large engines'. I just finished a 1/3 Galloway engine and the mag would probably look just about right on something that size, (10.25 flywheels) but in the modeling community not everyone has the tooling or abilities to build something that large. Most builders work in the smaller sizes because it's much easier. I'm sure Lou Chenot (Deusenberg fame) would take great umbrage that working small is not acceptable.
One last thing, could you point out where the 'dogs' were posting. I must have missed that.
George D. Britnell