I just got around to opening my copy of Model Engine Builder magazine.
Thought it strange that I had two in my mail box last week. Figured maybe
they got behind and got caught up.

No, there were errors in the first mailing and they sent out a new magazine
and drawing sheet to get it right.

I am impressed.

Wes

Wes wrote:

No, there were errors in the first mailing and they sent out a new
magazine and drawing sheet to get it right.

I am impressed.

Yes, they do have a high standard!
Did you destroy the mis-print? I'll keep mine and in 100 years, it will be a
rare collector's item. Like stamps. :-))

BTW MEB:
My V-twin is almost ready, but I'm *still* working on the µC-controlled
ignition I decided to build. Will have much more features than that engine
needs, but it will be my last design for all engines with spark-plugs
coming.
* 24 cylinders (or more, depending on timing of crankshaft)
* up to 60000RPM (keeping the timing to within +/- 0.5 degrees crank)
* ignition advance table (depending on load and RPM)
* adjustment of coil's charge time depending on supply voltage
* ...


Nick
--
The lowcost-DRO:
http://www.yadro.de

Nick Mueller wrote:

Yes, they do have a high standard!
Did you destroy the mis-print? I'll keep mine and in 100 years, it will be a
rare collector's item. Like stamps. :-))

I have a hard time throwing anything away and this won't be one of them.

BTW MEB:
My V-twin is almost ready, but I'm *still* working on the µC-controlled
ignition I decided to build. Will have much more features than that engine
needs, but it will be my last design for all engines with spark-plugs
coming.
* 24 cylinders (or more, depending on timing of crankshaft)
* up to 60000RPM (keeping the timing to within +/- 0.5 degrees crank)
* ignition advance table (depending on load and RPM)
* adjustment of coil's charge time depending on supply voltage
* ...

Is that the v twin if I remember correctly that was in the magazine earlier
this year or another one?

How about a link to pictures and sound when ready.

Is that ignition using coilpacks? (two plugs one coil)

Wes

Wes wrote:

Is that the v twin if I remember correctly that was in the magazine
earlier this year or another one?

The one from MEB (forgot the name; looks like a Harley, open crank case)

How about a link to pictures and sound when ready.

Sure. When completely finished. I'll make a video too.

Is that ignition using coilpacks? (two plugs one coil)

Haven't investigated in coilpacks yet. I'm using self made coils.
0.5ms charge time @ 12V (fast!!!) 23A, 50mJ. Size is about 25mm diam, 55mm
long. And it looks like a scale ignition coil. :-)


Nick
--
The lowcost-DRO:
http://www.yadro.de

Nick Mueller wrote:
Wes wrote:

Is that the v twin if I remember correctly that was in the magazine
earlier this year or another one?

The one from MEB (forgot the name; looks like a Harley, open crank case)

How about a link to pictures and sound when ready.

Sure. When completely finished. I'll make a video too.

Is that ignition using coilpacks? (two plugs one coil)

Haven't investigated in coilpacks yet. I'm using self made coils.
0.5ms charge time @ 12V (fast!!!) 23A, 50mJ. Size is about 25mm diam, 55mm
long. And it looks like a scale ignition coil. :-)


Nick


I remember reading this a while back. HTH some.

http://www.tonyfoale.com/Articles/Ignition/Ignition.htm

--
Steve Walker
(remove wallet to reply)

Steve Walker wrote:

I remember reading this a while back. HTH some.

http://www.tonyfoale.com/Articles/Ignition/Ignition.htm

Thanks. But this type of coils are made for breaker contacts. They are
current limiting by their inner resistance.
Mine has a very low R (0.05 Ohm) and it needs to be driven by electronics,
or it will simply melt if charged for too long. The short-circuit current
would be 200A. But this is the only way to make a fast coil with constant
energy up to the maximum revs.


Nick
--
The lowcost-DRO:
http://www.yadro.de

Nick Mueller wrote:

Thanks. But this type of coils are made for breaker contacts. They are
current limiting by their inner resistance.
Mine has a very low R (0.05 Ohm) and it needs to be driven by electronics,
or it will simply melt if charged for too long. The short-circuit current
would be 200A. But this is the only way to make a fast coil with constant
energy up to the maximum revs.


Well that explains how Steve's link didn't fit with what you are
constructing. I rather enjoyed the link though.

Did you build the coils too? Am I going to see a Nick Mueller article some
day in MEB?

I believe I'm a day late wishing you a Merry Christmas since everyone
doesn't observe it on the 25th. Considering tomorrow the 26th is the day
Americans shop for bargains with our typical 'gusto' maybe we could call it
boxing day

Merry Christmas,

Wes

Wes wrote:

Did you build the coils too?

Yes. I didn't get what I wanted and the coils available for model engines
had no technical data at all. So I wound my own. And built a coil winder.
And a counter. And vacuum impregnated them. And built a vacuum box. And
repaired a vacuum pump. And ...
http://www.peters-cnc-ecke.de/forumupload/uploadFiles/16348_111971633898_coil-2.jpg

Am I going to see a Nick Mueller article some day in MEB?

In the next issue (it is already on the way). :-)
But not about coils and ignition systems.


I believe I'm a day late wishing you a Merry Christmas since everyone
doesn't observe it on the 25th.

What!? We do have Christmas? ;-)
Same to you (and all those reading).


Nick
--
The lowcost-DRO:
http://www.yadro.de

Nick Mueller wrote:

Am I going to see a Nick Mueller article some day in MEB?

In the next issue (it is already on the way). :-)
But not about coils and ignition systems.



Well, I look forward to reading it. I just renewed the subscription a few
minutes ago.

Wes

Nick Mueller wrote:
Wes wrote:

Did you build the coils too?

Yes. I didn't get what I wanted and the coils available for model engines
had no technical data at all. So I wound my own. And built a coil winder.
And a counter. And vacuum impregnated them. And built a vacuum box. And
repaired a vacuum pump. And ...
http://www.peters-cnc-ecke.de/forumupload/uploadFiles/16348_111971633898_coil-2.jpg

That is really beautiful. Any chance we could
know turns, wire sizes and core material?

On Tue, 25 Dec 2007 13:08:41 +0100, Nick Mueller
wrote:

Wes wrote:

Did you build the coils too?

Yes. I didn't get what I wanted and the coils available for model engines
had no technical data at all. So I wound my own. And built a coil winder.
And a counter. And vacuum impregnated them. And built a vacuum box. And
repaired a vacuum pump. And ...
http://www.peters-cnc-ecke.de/forumupload/uploadFiles/16348_111971633898_coil-2.jpg

Nice!!!

Jim Stewart wrote:

That is really beautiful. Â*Any chance we could
know turns, wire sizes and core material?

Primary is 93 windings of 1.12mm, secondary is 1600 of 0.1mm.
Core is iron powder from Micrometals (43mm long IIRC).
But again, the coil needs electronics! The charge time has to be limited so
you don't exceed the 23A. That makes 0.5 ms at 12V. If you use it on a
breaker, the coil will go up in smoke. It would draw 200A from a 12V
battery.

I tried triple-isolated TEX-E wire on the secondary, but it makes you poor!
The wire is just too expensive and it is too thick. So secondary is double
isolated wire with inter-layer isolation. Takes some time to acquire the
skill of winding. :-)
I'm getting 8 kV on the secondary, but that requires high voltage through
induction on the primary. I do have about 500V on the primary (@
supply-voltage 12V) with protective switch-on of the coil to reduce the
primary voltage (happens when the secondary has no spark plug connected).

Did I describe the electronics before?
It's µC driven. 8 processors working parallel, each processor having 20 MIPS
3 (maybe I'll change that to 4) processors do handle the position sensor of
the crank, calculate the timing, switch on and off the coils. Other
processors do handle reading the supply voltage, read the RS232, etc.
I do have a theory, that I can calculate (no throttle sensor required) the
load of the engine if there are less than 4 or such cylinders. I still have
to prove that (or fail to do so).
The core of the software is working, I'm finishing the setup-stuff today and
plan to have a working beta tomorrow.
Technical data:
* max RPM 60000, at 40000 RPM timing is accurate to +/- 0.5° crank degrees.
That are about +/- 0.75µs! I could get more RPM out of it, but you'd
have to show me that engine before. :-)
* Minimum RPM is something around 20 RPM
* mapped timing. Parameters are load (external sensor) and RPM.
* mapping table is bi-linear interpolated to about 0.5 million points
* configurable via RS232. Laptop (any terminal does it) can be used as
online display for several (configurable) parameters like
RPM, V_supp, load etc.
* up to 24 cylinders (and even more under certain circumstances)
* Multi-spark: Spark sequences for lower RPM or starting. Number of sparks
configurable (I'm using 3; tried it with seven). RPM where it switches
to single-spark configurable.
I do have a software-issue with multi-sparks at high RPM with
many cylinders ( 16) and many sparks (overlapping). Shouldn't
be noticeable under normal conditions and I'll fix that later.
* Charge time of coil adjusted in realtime
* Rev-span (where the +/- 0.5° are kept) is 1:20 (idle to max RPM)
Normal engines do have a span of about 1:10
* Rev-limiter
* Max current for coils is 40A constant, 120A peak. That should
make possible a coil with 0.2ms charge time that is good for 50000 RPM.
I know, that's a bit on the high end.
* other things that I forgot now :-)

I *hope* to fire the V-twin first time at new year's eve, when others do
waste their time drinking Champagne and firing fireflies. :-)


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Sat, 29 Dec 2007 12:23:44 +0100, Nick Mueller
wrote:

Jim Stewart wrote:

That is really beautiful. *Any chance we could
know turns, wire sizes and core material?

Primary is 93 windings of 1.12mm, secondary is 1600 of 0.1mm.
Core is iron powder from Micrometals (43mm long IIRC).

This gives enough spark under compression?

Don Foreman wrote:

This gives enough spark under compression?

Until now, yes. :-)
There are several factors for a spark to initially jump:
* compression
* condition of spark plug electrodes
* ratio of the mixture (rich, lean; a lean one needs higher voltage)
* dU/dT of the voltage
* and of course the voltage (having 8 kV with this coil, limited by the
protection on the primary)

I have tested this one with an engine that has quite a low CR, but a spark
plug that is oiled beyond belief.

Don't forget that I do have 500 V on the primary side and a dU/dT at the
primary that is by magnitudes higher than required (forgot the numbers I
once calculated), and also higher than a conventional system. It more
resembles a CDI (but it ain't).

The energy stored is 50 mJ (cars do have something at 120 mJ to 180 mJ). But
literature says that 0.5 ... 10 mJ are enough to ignite the mixture. I'll
try that as soon as everything is up and running.

Spark duration was measured to be about 4µs with a clean spark plug. A oily
one will dramatically reduce the duration.


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Sat, 29 Dec 2007 23:11:40 +0100, Nick Mueller
wrote:

Don Foreman wrote:

This gives enough spark under compression?

Until now, yes. :-)
There are several factors for a spark to initially jump:
* compression
* condition of spark plug electrodes
* ratio of the mixture (rich, lean; a lean one needs higher voltage)
* dU/dT of the voltage
* and of course the voltage (having 8 kV with this coil, limited by the
protection on the primary)

I have tested this one with an engine that has quite a low CR, but a spark
plug that is oiled beyond belief.

Don't forget that I do have 500 V on the primary side and a dU/dT at the
primary that is by magnitudes higher than required (forgot the numbers I
once calculated), and also higher than a conventional system. It more
resembles a CDI (but it ain't).

The energy stored is 50 mJ (cars do have something at 120 mJ to 180 mJ). But
literature says that 0.5 ... 10 mJ are enough to ignite the mixture. I'll
try that as soon as everything is up and running.

Spark duration was measured to be about 4µs with a clean spark plug. A oily
one will dramatically reduce the duration.


Nick

Working is what counts!

Some friendly observations from an old ignitor designer:

dV/dt isn't relevant except where parasitic capacitance is an issue. d
(flux)/dt is what counts, which boils down to dI/dt. Your secondary
open-circuit voltage will be N * v1 * k where N is the turns ration,
v1 is the primary voltage and k is the coupling coefficient between
primary and secondary -- typically between 0.4 and 0.8 in a design
like this though it appears that you're getting rather good coupling.
v1 will be L1 * dI/dT where I is the primary current.
I designed high-voltage ignitors for oil and gas burners, not engines.
I don't pretend to know much about automotive ignition. I'd guess
(pure conjecture) that automotive ignitions may have far more energy
and OCV than are necessary in order to get acceptable ignition for
very cold starts and at higher speeds as efficiency drops due to
shorter dwells. You won't have sub-zero ( -18C) cold start issues,
and your elex will maintain efficiency at high speeds.

"Don Foreman" wrote in message
...
On Sat, 29 Dec 2007 23:11:40 +0100, Nick Mueller
wrote:

Don Foreman wrote:

This gives enough spark under compression?

Until now, yes. :-)
There are several factors for a spark to initially jump:
* compression
* condition of spark plug electrodes
* ratio of the mixture (rich, lean; a lean one needs higher voltage)
* dU/dT of the voltage
* and of course the voltage (having 8 kV with this coil, limited by the
protection on the primary)

I have tested this one with an engine that has quite a low CR, but a spark
plug that is oiled beyond belief.

Don't forget that I do have 500 V on the primary side and a dU/dT at the
primary that is by magnitudes higher than required (forgot the numbers I
once calculated), and also higher than a conventional system. It more
resembles a CDI (but it ain't).

The energy stored is 50 mJ (cars do have something at 120 mJ to 180 mJ).
But
literature says that 0.5 ... 10 mJ are enough to ignite the mixture. I'll
try that as soon as everything is up and running.

Spark duration was measured to be about 4µs with a clean spark plug. A
oily
one will dramatically reduce the duration.


Nick

Working is what counts!

Some friendly observations from an old ignitor designer:

dV/dt isn't relevant except where parasitic capacitance is an issue. d
(flux)/dt is what counts, which boils down to dI/dt. Your secondary
open-circuit voltage will be N * v1 * k where N is the turns ration,
v1 is the primary voltage and k is the coupling coefficient between
primary and secondary -- typically between 0.4 and 0.8 in a design
like this though it appears that you're getting rather good coupling.
v1 will be L1 * dI/dT where I is the primary current.
I designed high-voltage ignitors for oil and gas burners, not engines.
I don't pretend to know much about automotive ignition. I'd guess
(pure conjecture) that automotive ignitions may have far more energy
and OCV than are necessary in order to get acceptable ignition for
very cold starts and at higher speeds as efficiency drops due to
shorter dwells.

(and ignition in the higher compression environment of an engine)

You won't have sub-zero ( -18C) cold start issues,
and your elex will maintain efficiency at high speeds.

Don Foreman wrote:

dV/dt isn't relevant except where parasitic capacitance is an issue.

My picture is:
dV/dt counts on the secondary to start the spark. If there is stray capacity
it also has some R. A fast rise will prevent energy to be charged into that
capacity. As soon as the gas is ionized, the spark's burning voltage drops
by magnitudes.
At least this is the argument for CDI. They do have a higher dV/dt. That's
what I have read, but also I never found a very good explanation.
I *think* the reason that the classical transistor-ignition being not as
good as the CDI of those days was the lack of suitable transistors. Things
changed some years ago with the IGBT. There are also dedicated IGBTs
available for ignition systems that do have an integrated anti-parallel
Zener. I'm using an IGBT (U_gs 600V) and so it resembles more a CDI that
works with about 400V. Classical transistor ignitions work with about
100 .. 150V.


(flux)/dt is what counts, which boils down to dI/dt.

That's right, my fault.

typically between 0.4 and 0.8 in a design
like this though it appears that you're getting rather good coupling.

Yes, it looks like. I have measured the voltage on the secondary (with a
self-built HV-probe; capacitive divider).


I'd guess
(pure conjecture) that automotive ignitions may have Â*far more energy
and OCV than are necessary in order to get acceptable ignition for
very cold starts and Â*at higher speeds as efficiency drops due to
shorter dwells.

That's absolutely right! The safety-margin is by magnitudes. But also -with
environmental regulations- they are running on the lean side and thus need
more energy.
Ignition coils of modestly modern cars are still partially self limiting (by
current) but not as much as the coils we know from out first VW-Beetle. :-)
The most advanced coils that are integrated into spark-plugs should resemble
my design. But I didn't get my hands on one until now.


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Dec 29, 6:23*am, Nick Mueller wrote:
...
Did I describe the electronics before?
It's µC driven. 8 processors working parallel, each processor having 20 MIPS
3 (maybe I'll change that to 4) processors do handle the position sensor of
the crank, calculate the timing, switch on and off the coils. ...
Nick

Would a knock sensor possibly help?
http://www.wellsmfgcorp.com/pdf/counterp_v4_i4_2000.pdf

The sensor is a ceramic microphone tuned or filtered to the
fundamental resonance frequency of the engine block. Knock causes a
large jump in the output signal level. In a closed-loop engine control
the uC slowly advances timing until knock begins, then quickly retards
until it stops. You could initially leave that out and use the sensor
to light a warning light, or show the level on a meter.

On Sun, 30 Dec 2007 13:48:13 +0100, Nick Mueller
wrote:

Don Foreman wrote:

dV/dt isn't relevant except where parasitic capacitance is an issue.

My picture is:
dV/dt counts on the secondary to start the spark. If there is stray capacity
it also has some R. A fast rise will prevent energy to be charged into that
capacity.

Right conclusion, anyway. Parasitic capacitance and secondary
self-inductance combine to form a resonant frequency. The
self-resonant frequency limits risetime to given peak voltage.

As soon as the gas is ionized, the spark's burning voltage drops
by magnitudes.

Yes.

At least this is the argument for CDI. They do have a higher dV/dt. That's
what I have read, but also I never found a very good explanation.

With older flyback (Kettering-type)ignition there was usually a
capacitor across the primary to preserve the points. This formed a
resonant circuit with the primary inductance to limit peak primary
voltage, which was still much higher than battery voltage.

More modern solid-state ignitions used a transistor to interupt
primary current, and a zener to limit primary voltage to around 400
volts. One such transistor was MJ10012.
http://www.jaycar.com.au/images_uploaded/MJ100122.PDF

In this case the secondary dV/dt was limited by secondary
self-resonance.

CDI drives the primary to high voltage by dumping a charged capacitor
into the relatively low primary inductance. This produces much higher
primary dV/dt, but more importantly also higher dI/dt.

I *think* the reason that the classical transistor-ignition being not as
good as the CDI of those days was the lack of suitable transistors.

Partially. The early CDI's used SCR's on the primary side. 600 volt
SCR's have been available for decades. Bipolar transistors capable of
800 volts and more have been readily available since the 70's.
Transistors, MOSFETs and IGBT's can be used in a flyback ignition
because they are capable of being turned off -- SCR's can't be turned
off once fired. SCR's also have limited dV/dt capability.

Things changed some years ago with the IGBT. There are also dedicated IGBTs
available for ignition systems that do have an integrated anti-parallel
Zener. I'm using an IGBT (U_gs 600V) and so it resembles more a CDI that
works with about 400V. Classical transistor ignitions work with about
100 .. 150V.

I don't know what a "classical" transistor ignition is, but the
MJ10012 (400 to 600 volts) was specifically intended for automotive
ignition in conjunction with a 400-volt zener. They were sometimes
used in conjuction with a chip that maintained essentially constant
dwell time over varying speeds. This wasn't a microcontroller, just a
simple bipolar ignition control IC, MC????.

(flux)/dt is what counts, which boils down to dI/dt.

That's right, my fault.

typically between 0.4 and 0.8 in a design
like this though it appears that you're getting rather good coupling.

Yes, it looks like. I have measured the voltage on the secondary (with a
self-built HV-probe; capacitive divider).


I'd guess
(pure conjecture) that automotive ignitions may have *far more energy
and OCV than are necessary in order to get acceptable ignition for
very cold starts and *at higher speeds as efficiency drops due to
shorter dwells.

That's absolutely right! The safety-margin is by magnitudes. But also -with
environmental regulations- they are running on the lean side and thus need
more energy.
Ignition coils of modestly modern cars are still partially self limiting (by
current) but not as much as the coils we know from out first VW-Beetle. :-)
The most advanced coils that are integrated into spark-plugs should resemble
my design. But I didn't get my hands on one until now.


Nick

Perhaps you did this, but just in case: secondary parasitic
capacitance can be significantly reduced by winding the secondary in
"pi" windings: several tall narrow windings in series rather than
several full-length layers. Imagine a stack of washers perhaps 0.75 to
1.5 mm thick, each separated from the next by perhaps 0.75 to 1.5mm. I
made bobbins by cutting narrow grooves (0.75 to 1.5mm wide, sometimes
as much as 20mm deep)in delrin rod. The tricky part is making the
vias from the top of one layer to the bottom of the next. Commercial
H.V. coils using this method use molded bobbins. Tooling for such
bobbins is rather expensive to make, but the bobbins themselves are
then quite cheap. I was able to make 40 KV coils with self-resonant
frequencies on the order of 50 KHz, or rise time to peak voltage of 5
uS.

Jim Wilkins wrote:

Would a knock sensor possibly help?

Thanks. I'm did think about integrating one in a next version.
Requires some spectrum-analysis and tuning to the engine. So not a simple
task!


Nick
--
The lowcost-DRO:
http://www.yadro.de

Don Foreman wrote:

More modern solid-state ignitions used a transistor to interupt
primary current, and a zener to limit primary voltage to around 400
volts. Â*One such transistor was MJ10012.

Ah, 15A peak. That were the old days.

CDI drives the primary to high voltage by dumping a charged capacitor
into the relatively low primary inductance. Â*This produces much higher
primary dV/dt, but more importantly Â*also higher dI/dt.

Certainly, the dI/dt in the moment of switching off the coil is important.
But IIRC I calculated something in the 10µs range to get the 500V on the
primary side. But I may be wrong. Anyhow, 10µs isn't that fast and I even
don't switch off as fast as I can.

Transistors, MOSFETs and IGBT's can be used in a flyback ignition
because they are capable of being turned off -- SCR's can't be turned
off once fired. SCR's also have limited Â*dV/dt capability.

Right. That's what's happening if the secondary has no spark plug connected.
Some of the cheaper ignition systems warn you of that problem. The coil's
isolation won't be good enough. With my vacuum-impregnated coil and the
voltage-limiting on the primary, that doesn't happen.

I don't know what a "classical" transistor ignition is, but the
MJ10012 (400 to 600 volts) was specifically intended for automotive
ignition in conjunction with a 400-volt zener.

Slow and "big" coils (high R_i and high L). As I said, my coil has a charge
time of 0.5ms, even "fast" coils (the big type know since decades) do have
several ms and their limit is at about 200 sparks per second with already
reduced energy.
I couldn't measure it right at the moment I tried because I lacked a
suitable power-supply (now have one). But it looks like I get about 1000
sparks/second out of that coil. I really don't know wether there is some
such thing like recovery time (for the coil), but I'll investigate on that
later.

Perhaps you did this, but just in case: Â*secondary parasitic
capacitance can be significantly reduced by winding the secondary in
"pi" windings:

Thanks for the explanation. Looks to be too complicated to do, except for
one-offs.
I can't measure the capacitance of the coil, but it *looks* like I didn't
make a bad job (looking at the rise-times on the secondary). I learned,
that the inter-layer isolation reduces capacitance too. The means is
simple: Increase the physical distance between windings with a high voltage
difference.


Thanks for your input,
Nick
--
The lowcost-DRO:
http://www.yadro.de

On Wed, 02 Jan 2008 12:06:50 +0100, Nick Mueller
wrote:


Right. That's what's happening if the secondary has no spark plug connected.
Some of the cheaper ignition systems warn you of that problem. The coil's
isolation won't be good enough. With my vacuum-impregnated coil and the
voltage-limiting on the primary, that doesn't happen.

Good HV coils are all vacuum impregnated. Climco Coil, as one
example, makes thousands or perhaps millions of them per year, mostly
for small engines and magnetos. The spark ignitors in gas stoves are
pi-wound ferrite-core fully-potted coils about the size of a large
thimble. The 25KV ionizers in the made-in-China cheapo powdercoat
guns are vacuum potted. They claim that they're 50KV. They lie!

Perhaps you did this, but just in case: *secondary parasitic
capacitance can be significantly reduced by winding the secondary in
"pi" windings:

Thanks for the explanation. Looks to be too complicated to do, except for
one-offs.

It's done routinely in production coils. Just a matter of getting the
molded bobbins. Production coil winding machines are almost
completely automatic. Cost is a matter of pounds of copper and number
of terminations, numbers of turns or bays are about irrelevant.

I can't measure the capacitance of the coil, but it *looks* like I didn't
make a bad job (looking at the rise-times on the secondary). I learned,
that the inter-layer isolation reduces capacitance too. The means is
simple: Increase the physical distance between windings with a high voltage
difference.

Yup, that works. Fish paper between secondary layers was used for
decades, may still be in some older-tech coils.

Don Foreman wrote:

It's done routinely in production coils. Just a matter of getting the
molded bobbins.


Cosmo used to be pretty good with samples. Nick may want to give them a try.

http://www.cosmocorp.com/en/bcat-search1.cfm

http://www.cosmocorp.com/en/reqsamp.cfm



Kevin Gallimore

Wes wrote:

Well, I look forward to reading it. I just renewed the subscription a few
minutes ago.


It came the other day. Straight forward and logical work flow. Did they
edit for space?

Btw, what is that tool post you have there?

Wes

Wes wrote:

Straight forward and logical work flow.

Thanks

Did they edit for space?

No, it was accepted almost the same way I wrote it (minus my errors).


Btw, what is that tool post Â*you have there?

It is an AXA-toolpost (AKA Multifix). The reference here in Germany since
decades. Funny enough, they are sold under at least two brands, but coming
out of the same factory (in the same cardboard box, wrapped with exactly
the same old newspaper and oiled paper).


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Mon, 14 Jan 2008 12:44:00 +0100, Nick Mueller
wrote:

Wes wrote:

Straight forward and logical work flow.

Thanks

Did they edit for space?

No, it was accepted almost the same way I wrote it (minus my errors).


Btw, what is that tool post *you have there?

It is an AXA-toolpost (AKA Multifix). The reference here in Germany since
decades. Funny enough, they are sold under at least two brands, but coming
out of the same factory (in the same cardboard box, wrapped with exactly
the same old newspaper and oiled paper).


Nick

rotfl!
when I saw this thread again that was exactly the same question I was
going to ask. whats that neat little toolpost in the photos.
good article.
Stealth pilot

Stealth Pilot wrote:

when I saw this thread again that was exactly the same question I was
going to ask. whats that neat little toolpost in the photos.

It ain't that small. The lathe is big. :-)
The toolpost has 40 positions, real fast changing of tools, repeatability of
position is 1/100mm. Different sizes available. Also available as Chinese
clones.

good article.

I wrote it while I built the Hoglet (? The cute 37ccm V-twin in one of the
later '07 issues). Last weekend, I was at a fair with that engine (and
others, unfortunately, the V not yet running) and people loved it a *lot*.
But I made some changes to the look while I converted it to metric. Changed
the push-rods to be slimmer, changed the case for the cam and used
followers (? right word) instead of the short tappets. Also made my own
carb that looks a lot like an old Harley carb. Further changed the shape of
the cylinders and the shape of the "crank case".
I'll send photos to Mike as soon as I'm finished.

Also had some issues of MEB with me to show them to the people how good that
magazine is. Hope I convinced some of them to subscribe it.


Nick
--
The lowcost-DRO:
http://www.yadro.de

On Tue, 15 Jan 2008 13:11:28 +0100, Nick Mueller wrote:

Stealth Pilot wrote:

when I saw this thread again that was exactly the same question I was
going to ask. whats that neat little toolpost in the photos.

It ain't that small. The lathe is big. :-)
The toolpost has 40 positions, real fast changing of tools, repeatability of
position is 1/100mm. Different sizes available. Also available as Chinese
clones.


Pretty well standard fitting on Hardinge lathes in the UK (the Multifix, that
is)

Mark Rand
RTFM