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Questions about WW2 jet engine turbines - why the Brits didn't use internal cooling?
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janne.k...@seos.fi
Mar 20, 2013, 5:32:10 AM3/20/13
to
Hi all,
I'm a PhD student currently working on a project about history of innovations, with a particular interest in jet engine development. As a part of the research, I've been looking into early jet engine development, including the question why the hollow turbine blades as used by Germans in many jet engines were not used by the British, for example.
It's pretty much obvious that the reason why Germans used the hollow blades was because of lack of raw materials and also because of production advantages (a recent PhD thesis by Hermione Giffard argues that German jet engines were designed very much with fast production rather than performance in mind, as cheap and numerous ersatz weapons to counter Allied advantages). However, it seems to be less obvious why the British, for example, didn't use internally cooled turbine blades until 1950s, and when they did, they used a different design. Any ideas?
Second, if someone has data on turbine inlet and/or turbine blade temperatures of early jet engines (preferably with a source identified ;)), I'd be very grateful. In particular, I'm looking for solid info about temperatures in BMW 003 and Jumo 004 engines.
Third, can anyone confirm whether the turbine blades on BMW 109-018 turbojet were forged, cast or machined? The picture on Anthony Kay's book "German Jet Engine and Gas Turbine Development" (Fig. 2.104, p. 133) very much looks like it's forged, but I could very well do with an independent confirmation. Tried using the search, but to no avail
Many thanks,
Janne M. Korhonen
Aalto University, Helsinki, Finland
I'm a PhD student currently working on a project about history of innovations, with a particular interest in jet engine development. As a part of the research, I've been looking into early jet engine development, including the question why the hollow turbine blades as used by Germans in many jet engines were not used by the British, for example.
It's pretty much obvious that the reason why Germans used the hollow blades was because of lack of raw materials and also because of production advantages (a recent PhD thesis by Hermione Giffard argues that German jet engines were designed very much with fast production rather than performance in mind, as cheap and numerous ersatz weapons to counter Allied advantages). However, it seems to be less obvious why the British, for example, didn't use internally cooled turbine blades until 1950s, and when they did, they used a different design. Any ideas?
Second, if someone has data on turbine inlet and/or turbine blade temperatures of early jet engines (preferably with a source identified ;)), I'd be very grateful. In particular, I'm looking for solid info about temperatures in BMW 003 and Jumo 004 engines.
Third, can anyone confirm whether the turbine blades on BMW 109-018 turbojet were forged, cast or machined? The picture on Anthony Kay's book "German Jet Engine and Gas Turbine Development" (Fig. 2.104, p. 133) very much looks like it's forged, but I could very well do with an independent confirmation. Tried using the search, but to no avail
Many thanks,
Janne M. Korhonen
Aalto University, Helsinki, Finland
Jim Wilkins
Mar 20, 2013, 8:30:11 AM3/20/13
to
<janne.k...@seos.fi> wrote in message
news:9f3c4127-dd9b-41c7...@googlegroups.com...
>Janne M. Korhonen
>Aalto University, Helsinki, Finland
I'm an amateur historian and amateur machinist, with an interest and
fairly decent library on the development of machining technology and
how it paced the practical implementation of old ideas.
The only book I have that even faintly addresses your question is a
modern reprint of this one:
http://www.amazon.com/years-machines-Fred-Herbert-Colvin/dp/B0007DO8TO
On turbosuperchargers:
"The milling of the impeller blades or vanes was also a very tricky
job, for they had been designed with unusual mathematical curves
....[which he lists]...that required expensive and fragile milling
cutters....To sum it all up, it was a costly investment for the Navy
without much to show for it in the way of superchargers."
A guest lecturer from GE Engines who spoke at the New England Model
Engineering Society said that WW2 jet engine development ran right at
the limit of what was possible to manufacture. He wouldn't give us
details.
Modern dificulty machining the WW2 British blade alloy:
http://www.practicalmachinist.com/vb/cnc-machining/nimonic-n80-machining-251257/
The Germans directed their inadequate supply of refractory alloying
metals to the hydrogen peroxide subs which promised strategic attacks,
rather than the jets which only defend. The lower performing
substitute material was easier to machine into complex shapes. Tank
armor plus gears and the high performance tools to cut them also
suffered.
http://en.wikipedia.org/wiki/Panther_tank
"At the same time, the simplified final drive became the single major
cause of breakdowns of the Panther tank, and was a problem that was
never corrected."
" Furthermore, high quality steel intended for double spur system was
not available for mass production, and was replaced by 37MnSi5
tempered steel, which was unsuitable for high-stress gear."
"As the war progressed, Germany was forced to reduce or no longer use
certain critical alloy materials in the production of armor plate,
such as nickel, tungsten, molybdenum, and manganese; this did result
in lower impact resistance levels compared to earlier armor."
http://en.wikipedia.org/wiki/High_speed_steel
"Although molybdenum rich high speed steels such as AISI M1 have been
used since the 1930s, material shortages and high costs caused by
World War II spurred development of less expensive alloys substituting
molybdenum for tungsten."
When a drill bit breaks usually the tip stays jammed in the hole,
ruining the part unless it can be removed. If a blade needs 20 holes
and the bit breaks in 5% of them the scrap rate will be very high.
jsw
news:9f3c4127-dd9b-41c7...@googlegroups.com...
>Hi all,
>I'm a PhD student currently working on a project about history of
>innovations, with a particular interest in jet engine >development.
>As a part of the research, I've been looking into early jet engine
>development, including the question why the >hollow turbine blades as
>used by Germans in many jet engines were not used by the British, for
>example. ...
>I'm a PhD student currently working on a project about history of
>innovations, with a particular interest in jet engine >development.
>As a part of the research, I've been looking into early jet engine
>development, including the question why the >hollow turbine blades as
>used by Germans in many jet engines were not used by the British, for
>Janne M. Korhonen
>Aalto University, Helsinki, Finland
fairly decent library on the development of machining technology and
how it paced the practical implementation of old ideas.
The only book I have that even faintly addresses your question is a
modern reprint of this one:
http://www.amazon.com/years-machines-Fred-Herbert-Colvin/dp/B0007DO8TO
On turbosuperchargers:
"The milling of the impeller blades or vanes was also a very tricky
job, for they had been designed with unusual mathematical curves
....[which he lists]...that required expensive and fragile milling
cutters....To sum it all up, it was a costly investment for the Navy
without much to show for it in the way of superchargers."
A guest lecturer from GE Engines who spoke at the New England Model
Engineering Society said that WW2 jet engine development ran right at
the limit of what was possible to manufacture. He wouldn't give us
details.
Modern dificulty machining the WW2 British blade alloy:
http://www.practicalmachinist.com/vb/cnc-machining/nimonic-n80-machining-251257/
The Germans directed their inadequate supply of refractory alloying
metals to the hydrogen peroxide subs which promised strategic attacks,
rather than the jets which only defend. The lower performing
substitute material was easier to machine into complex shapes. Tank
armor plus gears and the high performance tools to cut them also
suffered.
http://en.wikipedia.org/wiki/Panther_tank
"At the same time, the simplified final drive became the single major
cause of breakdowns of the Panther tank, and was a problem that was
never corrected."
" Furthermore, high quality steel intended for double spur system was
not available for mass production, and was replaced by 37MnSi5
tempered steel, which was unsuitable for high-stress gear."
"As the war progressed, Germany was forced to reduce or no longer use
certain critical alloy materials in the production of armor plate,
such as nickel, tungsten, molybdenum, and manganese; this did result
in lower impact resistance levels compared to earlier armor."
http://en.wikipedia.org/wiki/High_speed_steel
"Although molybdenum rich high speed steels such as AISI M1 have been
used since the 1930s, material shortages and high costs caused by
World War II spurred development of less expensive alloys substituting
molybdenum for tungsten."
When a drill bit breaks usually the tip stays jammed in the hole,
ruining the part unless it can be removed. If a blade needs 20 holes
and the bit breaks in 5% of them the scrap rate will be very high.
jsw
Ramsman
Mar 20, 2013, 9:24:19 AM3/20/13
to
On 20/03/2013 09:32, janne.k...@seos.fi wrote:
> Hi all,
>
> I'm a PhD student currently working on a project about history of innovations, with a particular interest in jet engine development. As a part of the research, I've been looking into early jet engine development, including the question why the hollow turbine blades as used by Germans in many jet engines were not used by the British, for example.
>
> It's pretty much obvious that the reason why Germans used the hollow blades was because of lack of raw materials and also because of production advantages (a recent PhD thesis by Hermione Giffard argues that German jet engines were designed very much with fast production rather than performance in mind, as cheap and numerous ersatz weapons to counter Allied advantages). However, it seems to be less obvious why the British, for example, didn't use internally cooled turbine blades until 1950s, and when they did, they used a different design. Any ideas?
>
Could it be that the overhaul life of the blades was too short until
> Hi all,
>
> I'm a PhD student currently working on a project about history of innovations, with a particular interest in jet engine development. As a part of the research, I've been looking into early jet engine development, including the question why the hollow turbine blades as used by Germans in many jet engines were not used by the British, for example.
>
> It's pretty much obvious that the reason why Germans used the hollow blades was because of lack of raw materials and also because of production advantages (a recent PhD thesis by Hermione Giffard argues that German jet engines were designed very much with fast production rather than performance in mind, as cheap and numerous ersatz weapons to counter Allied advantages). However, it seems to be less obvious why the British, for example, didn't use internally cooled turbine blades until 1950s, and when they did, they used a different design. Any ideas?
>
better alloys and manufacturing processes were developed?
> Second, if someone has data on turbine inlet and/or turbine blade temperatures of early jet engines (preferably with a source identified ;)), I'd be very grateful. In particular, I'm looking for solid info about temperatures in BMW 003 and Jumo 004 engines.
>
> Third, can anyone confirm whether the turbine blades on BMW 109-018 turbojet were forged, cast or machined? The picture on Anthony Kay's book "German Jet Engine and Gas Turbine Development" (Fig. 2.104, p. 133) very much looks like it's forged, but I could very well do with an independent confirmation. Tried using the search, but to no avail
>
> Many thanks,
>
> Janne M. Korhonen
> Aalto University, Helsinki, Finland
>
Development of Jet and Turbine Engines', currently in its 4th edition,
as far as I can tell.
He says the Germans used tubes or tapered-thickness sheet wrapped and
welded or deep-drawn to the aerofoil profile. The British carved their
blades from austenitic steel or nickel bar stock.
By the mid-1950s improved alloys allowed entry gas temperatures to rise
from about 750 to 950 degrees C, but further progress was limited by the
creep strength of the material. Rolls-Royce were making hollow blades
(wrapped/welded) from the early fifties.
There's quite a bit more about manufacturing techniques, but I'm afraid
I haven't time to quote it all at the moment.
--
Peter
janne.k...@seos.fi
Mar 21, 2013, 4:44:42 AM3/21/13
to
Jim, Peter,
many thanks for very informative replies. I also have a gut feeling that machining and manufacturing technologies paced the development of several technologies; this might be an interesting area for further study.
Fred Colvin's book "60 years with men and machines" seems to be available at HathiTrust digital library (excellent source, BTW),
http://hdl.handle.net/2027/mdp.39015068112948
for others who may be interested. Looks very interesting, have to put some time in to digest it.
I have Gunston's book and a load of contemporary and post-war reports, e.g. from NACA archives, back issues of Flight, etc., but I haven't found anything explicit about the reasons why the Brits didn't utilize blade cooling in production engines (although according to Donald Eyre's memoirs, at least one test engine designed by Dr. Griffiths for RR did have internally cooled turbine blades in early 1942). The strong inference and my personal opinion are that's because solid blades did the job and Nimonic was readily available, but I'd like to have a bit more than inference :).
Eyre's book is this: Eyre, D. 2005. 50 Years with Rolls-royce: My Reminiscences. Derby: Rolls-Royce Heritage Trust.
The way I've understood the development of blade cooling is that Rolls-Royce experimented with wrapped/welded blades in early 1950 (1952 if memory serves correctly) but production engines eventually used forged blades. Are there any examples of wrapped, welded or drawn turbine blades in post-war production jet/turbojet engines, by the way?
Thanks again,
Janne
On Wednesday, March 20, 2013 3:24:19 PM UTC+2, Ramsman wrote:
many thanks for very informative replies. I also have a gut feeling that machining and manufacturing technologies paced the development of several technologies; this might be an interesting area for further study.
Fred Colvin's book "60 years with men and machines" seems to be available at HathiTrust digital library (excellent source, BTW),
http://hdl.handle.net/2027/mdp.39015068112948
for others who may be interested. Looks very interesting, have to put some time in to digest it.
I have Gunston's book and a load of contemporary and post-war reports, e.g. from NACA archives, back issues of Flight, etc., but I haven't found anything explicit about the reasons why the Brits didn't utilize blade cooling in production engines (although according to Donald Eyre's memoirs, at least one test engine designed by Dr. Griffiths for RR did have internally cooled turbine blades in early 1942). The strong inference and my personal opinion are that's because solid blades did the job and Nimonic was readily available, but I'd like to have a bit more than inference :).
Eyre's book is this: Eyre, D. 2005. 50 Years with Rolls-royce: My Reminiscences. Derby: Rolls-Royce Heritage Trust.
The way I've understood the development of blade cooling is that Rolls-Royce experimented with wrapped/welded blades in early 1950 (1952 if memory serves correctly) but production engines eventually used forged blades. Are there any examples of wrapped, welded or drawn turbine blades in post-war production jet/turbojet engines, by the way?
Thanks again,
Janne
On Wednesday, March 20, 2013 3:24:19 PM UTC+2, Ramsman wrote:
Jim Wilkins
Mar 21, 2013, 8:09:31 AM3/21/13
to
<janne.k...@seos.fi> wrote in message
news:86d3f961-4af6-4003...@googlegroups.com...
>Jim, Peter,
>many thanks for very informative replies. I also have a gut feeling
>that machining and manufacturing technologies paced the development
>of several technologies; this might be an interesting area for
>further study.
Fred Colvin's book "60 years with men and machines"
>seems to be available at HathiTrust digital library
>(excellent source, BTW),
>http://hdl.handle.net/2027/mdp.39015068112948
That book contains an interesting overview of how the US transitioned
>many thanks for very informative replies. I also have a gut feeling
>that machining and manufacturing technologies paced the development
>of several technologies; this might be an interesting area for
>further study.
Fred Colvin's book "60 years with men and machines"
>seems to be available at HathiTrust digital library
>(excellent source, BTW),
>http://hdl.handle.net/2027/mdp.39015068112948
to war production during WW1 and 2 but lacks the technical details of
machining, which he thoroughly covered in his other books. None of the
ones I have mentions jet engines. His milling machine book came out in
1941 and just missed them, though the critical processes for jets were
(and still are)secret.
Another tidbit he mentions is that most modern Japanese factories had
been built with US help so we had detailed blueprints which we used to
construct models to train bombadiers.
Advances in machining and invention fed each other. A firearms
inventor like Sam Colt might develop new machine tools to manufacture
his product, and they then enabled the realization of several other
old ideas.
http://cr4.globalspec.com/blogentry/114/Elisha-K-Root
"It was while working for Colt that Root perfected the Lincoln miller
milling machine, 150,000 of which were sold in the late 19th century,
making it the most important American machine tool of the era."
It could cut arbitrarily curved shapes like revolver hammers (or
turbine blades) in high volume efficiently.
Sometimes the inventor overestimates what is possible or practical to
manufacture:
http://en.wikipedia.org/wiki/Lockheed_J37
"By this point the original design proved too complex ..."
I encountered that personally during the initial development of
automotive antilock brakes. The Ph.D. inventor expected 8 digit
precision from his analog circuits because he didn't realize that
affordable commercial resistors have a tolerance range.
jsw
Ken S. Tucker
Mar 21, 2013, 1:31:31 PM3/21/13
to
at GE, P&W, RR for specialized scholarly references.
Ken
Eunometic
Mar 24, 2013, 7:42:23 AM3/24/13
to
commonly used for electrical resistance wire. It consisted of 80%
nickel and 20% chromium. An improved version of this known as nimonic
80 with an addition of 0.2% zirconium formed the basis of most jet
engines for the next 30 years. The blades of allied engines were
machined out of solid bar and attached to the turbine disk via
carefully machined fir tree roots. Nimonic machined this way did not
require cooling. frank Whittle did try a water cooled disk but found
it unnecessary.
The Germans were under extreme pressure in non ferrous metals. Nickel
could only come from Finland and Chromium from Turkey. The Germans
were also under extreme pressure to reduce manufacturing man hours and
machine tool usage.
The alloy the Germans used was a Krupp steel known as tinidur that was
0.13% carbon, 0.18% silicon, 0.7% Manganese, 2.1% Titanium, 29.2%
Nickel, 14.9% Chromium with the balance steel. The blades of the
alloy were forged in the Jumo 004B1. However in the Jumo 004B4 they
were deep drawn from sheet stock by approximately 10 stamping
opperations and these blades were hollow and allowed air cooling from
about October 1944 onwards. The Nickel situation only got worse when
Finland fell under Soviet influence. An alloy used from January 1945
onwards was Krupps Cromadur which was 18% Manganese, 12% Chromium,
0.65% Vanadium, 0.5% Silicon and only 0.2% Nickel. Cromadur blades
were bent and then seam welded at the trailing edge. It was not
possible to weld tinadur as this destroyed the austenitic grain
structure. Cromadur was nominally inferior but in practice produced a
more reliable blade due to easier quality control.
The GE I40 engine used in the P80 used inconel and hastelloy even
though it was a scaled up British dehaviland ghost engine. These
alloys came out of US turbocharger experience at GE.
The Germans simply did not have the nickel to contemplate alloys such
as nimonic. They did much promising work on ceramics and water
cooling. They were way ahead in air cooling. In fact in early 1950s
a Siemens gas turbine based on the Jumo 004 ran of blast furnace gas
using ceramic turbine guide vanes. Nevertheless they expected that
alloy improve would give them 300 hours engine life.
There was also work on two spool engines with an inter cooler to lower
inlet temperature.
I'll provide some links tomorrow.
David E. Powell
Mar 24, 2013, 7:55:15 PM3/24/13
to
Thanks Euno! Neat to see that alloy data.
tutall
Mar 25, 2013, 9:46:38 AM3/25/13
to
On Mar 24, 4:55 pm, "David E. Powell" <David_Powell3...@msn.com>
wrote:
Don't you know better by now?
wrote:
> Thanks Euno! Neat to see that alloy data.
You trust a something from Euno?
Don't you know better by now?
Dean Markley
Mar 25, 2013, 10:43:16 AM3/25/13
to
Eunometic
Mar 25, 2013, 11:08:01 PM3/25/13
to
>
> Third, can anyone confirm whether the turbine blades on BMW 109-018 turbojet were forged, cast or machined? The picture on Anthony Kay's book "German Jet Engine and Gas Turbine Development" (Fig. 2.104, p. 133) very much looks like it's forged, but I could >very well do with an independent confirmation. Tried using the search, but to no avail
This is the KTB (officers war diary or "Kriegs Tagges Buch") of the
Luftwaffe's Cheif technical intelligence officer.
http://www.cdvandt.org/ktb-tlr_part_8.htm
"109 - 004 (Junkers: Jumo jet engine, AOB)
Vorschau am Monatsanfang 1000, am Monatsende 900, geliefert 876.
Mehrfache Forderung eines Einbaues eines Beschleunigungsventils,
welches die Aufgabe hat, unzulässige Überheizung des Triebwerks bei
plötzlichem Gas geben zu vermeiden. Einführung bei der Truppe und
soweit vorhanden in der Serie bis Anfang April 1945 vorgesehen."
Translated into English:
"Jumo 004: Planed to produce 1000 engines, actual production 900,
actual deliveries 876
Promotion at all points of production of an "acceleration control
valve" whose task is to prevent unacceptable overheating of the jet
engine. Series production Delivery to Troops is expected by April
1945."
Also from this diary entry:
"Werkstoffe
Schaufelfertigung für 003 und 004 (Jumo, Junkers jet engines, AOB)
Durch Kriegslage ist den Schaufelstählen empfindlicher Engpaß
entstanden.
Dagegen ist Entwicklung keramischer Schaufelwerkstoffe in
aussichtreichen Fortschreiten bei verschiedenen Firmen im z.Zt. nicht
gefährdeten Gebiet. Die bisher hergestellten Probestücke zeigen
erstaunlich gute Festigkeitswerte. Die Herstellung von Probeschaufeln
(Leitschaufeln) ist eingeleitet."
Translated into English:
"Raw materials
Turbine Inlet nozzle guide vanes fabrication for BMW 003 and Junkers
004.
Due to the war situation shortages of critical raw materials has
developed.
As a reaction the development of cermaic turbine materials is underway
at multpilte companies and that are providing astonishingly good
strength. This work is being advanced."
Also worth a look at is
http://www.cdvandt.org/BIOS-272.pdf
which indicates a small proportion of the German ceramic work.
BMW tended to use an alloy called "sicromal' from a company called
"Boehler" it was more like Krupps Cromadur as it was stamped and seam
welded as well. Sicromal was also used in German turbo chargers (eg
BMW 801TQ) but with aircooling of blades and housing.
The BMW 003 turboject had an insert inside the hollow blade to aid
cooling flow distribution.
http://www.flightglobal.com/pdfarchive/view/1945/1945%20-%202450.html
Note that BMW was considering using water cooling in the BMW 018.
(one of their Stage III engines). A stage II engine known as BMW P.
3007 (which received a letter of intent and was essentially a scaled
up BMW 003) had as an option the use of a turbine made out of simple
mild carbon steel: this had only an expected life of 2 hours, i.e. it
was disposable. Essentially quite practical since BMW had gotten the
art of a complete turbine change down to less than 2 hours with the
engine remaining on the wing.
The Jumo 004B1 had a nominal MTBO of 25 hours at which point the
turbine was to be x-rayed and allowed in place for another 12.5 hours
if in good shape, however only the Jumo 004B4 got close to this. The
Me 262 test pilot Gerd Linde got 60 hours out of one he nursed however
it is likely this would have become normal when the acceleration valve
was fitted.
http://www.enginehistory.org/German/Me-262/Me262_Engine_2.pdf
"But the Germans had made real
progress in overcoming materials
difficulties, for just after they
capitulated that development of a
new alloy of excellent heatresistant
qualities had made it possible to
get up to 150 hr. service
in actual flight tests, and up to 500
hr. on the test stand."
In "the best of wings magazine" walter j boyne makes the point that
german test pilots could get 60 hours out of the engine.
The Best of Wings Magazine
http://books.google.com.au/books?id=i984H9SGXGgC&dq=the+best+of+wings&hl=en&sa=X&ei=PA9RUb_sAYTdkAWmg4CICQ&ved=0CC4Q6AEwAA
I suspect that with the acceleration control valve that was to be
installed in series by April 45 would have made that normal. The Jumo
004 used a centrifugal governor to control fuel flow. However this
meant fuel could be overdosed or underdosed during changes in RPM and
throttle position. The solution was an aneroid capsule to measure the
air pressure across the compressor and use this to effective measure
airflow and 'trim' the fuel flow precisely.
Nickel is important because of its 'creep' resistance. Most metals
slowly strech when hot but nickely avoids this. I suspect the
Germans were initially more interested in cobalt alloys, which are
also good.
a425couple
Mar 26, 2013, 9:38:57 AM3/26/13
to
"Jim Wilkins" <murat...@gmail.com> wrote in message...
> <janne.k...@seos.fi> wrote in message...
>>I'm a PhD student ----
(Big snip)
What a concept to consider! (or, dismally consider!)
For whatever reason, I'm reminded of my fairly recent,,,,
I play with race cars. Last year (or was it 2 years ago?)
in trying to change a gear sprocket, had to remove a
stub axel, then in a low down ackward to get to small area,
remove bolts. One broke, of course just 'below grade'.
OK,,,, so drill a hole into the slanted/uneven 'face' of
the hidden remander of the bolt. Once done, put in an
"easy out", seat it good, torque, play, play etc. more torque.
Snap,, shit!!
The material of the "easy out" remainder tip, is very hard.
And, having been properly sized, pretty much blocks
any further effort.
Recalling one advisors opinion, "That tip (broken "easy out")
is very hard, but it's brittle, so whale away on it with
a punch & sledge, and it should shatter, and then you
should be able to drill it all out."
Hmm, easier said than done!
> <janne.k...@seos.fi> wrote in message...
>>I'm a PhD student ----
(Big snip)
> When a drill bit breaks usually the tip stays jammed in the hole,
> ruining the part unless it can be removed. If a blade needs 20 holes
> and the bit breaks in 5% of them the scrap rate will be very high.
Thanks for that!
> ruining the part unless it can be removed. If a blade needs 20 holes
> and the bit breaks in 5% of them the scrap rate will be very high.
What a concept to consider! (or, dismally consider!)
For whatever reason, I'm reminded of my fairly recent,,,,
I play with race cars. Last year (or was it 2 years ago?)
in trying to change a gear sprocket, had to remove a
stub axel, then in a low down ackward to get to small area,
remove bolts. One broke, of course just 'below grade'.
OK,,,, so drill a hole into the slanted/uneven 'face' of
the hidden remander of the bolt. Once done, put in an
"easy out", seat it good, torque, play, play etc. more torque.
Snap,, shit!!
The material of the "easy out" remainder tip, is very hard.
And, having been properly sized, pretty much blocks
any further effort.
Recalling one advisors opinion, "That tip (broken "easy out")
is very hard, but it's brittle, so whale away on it with
a punch & sledge, and it should shatter, and then you
should be able to drill it all out."
Hmm, easier said than done!
Jim Wilkins
Mar 26, 2013, 10:54:51 AM3/26/13
to
"a425couple" <a425c...@hotmail.com> wrote in message
news:kis8e...@news3.newsguy.com...
If you can manage to anneal it with welding equipment and have access
to a milling machine you may be able to bore out the hole with an end
mill, which is less likely than a drill to be deflected into the good
threads.
EDM is anotherr possibility.
http://www.brokentap.com/
jsw
news:kis8e...@news3.newsguy.com...
to a milling machine you may be able to bore out the hole with an end
mill, which is less likely than a drill to be deflected into the good
threads.
EDM is anotherr possibility.
http://www.brokentap.com/
jsw
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