PopularFX
Home Help Search Login Register
Welcome,Guest. Please login or register.
2017-04-29, 00:38:59
News: Check out the Benches; a place for people to moderate their own thread and document their builds and data.
If you would like your own Bench, please PM an Admin.
Most Benches are visible only to members.

Pages: [1] 2
Author Topic: " Old hands "  (Read 827 times)

Group: Moderator
Hero Member
*****

Posts: 1412
After a recent phone call from Chet he persuaded me to start a thread.

Many members of OUR are " Old hands " knowledge and techniques learned from different careers span decades. Tricks of the trade will be welcomed here.   O0

To business......

Chet is trying to remove the cylinder head from a "Flat head " engine or " Side valve " over here. Getting things hot is what's needed. Induction or direct high current low voltage, any ideas?

Here is a video of mine on how to remove the top off a microwave oven transformer, neatly !!

  https://www.youtube.com/watch?v=6MdCkLMEv2E

This video shows how two cores and some very heavy wire can make a hefty high current transformer.

 https://www.youtube.com/watch?v=yHkqn2cG-no

Anyone else got ideas ?

Cheers Graham.


---------------------------
Nanny state ? Left at the gate !! :)
   
Hero Member
*****

Posts: 739
So what's the problem?  Undoing the bolts or unsticking the head?

Smudge
   
Hero Member
*****

Posts: 2362
thanks Grum
@Smudge
actually its a case of stuck valves on an old continental 4cyl flat head attached to  an oil bath rotary screw air compressor

previous owner did an over rev --- floated the valves ,  jamming  a half dozen of them ...a big mess .

I unstuck all but the last two   which ring solid in the guides ,  just for reference these engines last forever but don,t like to come apart .
I had to literally jackhammer the exhaust /intake manifold off in pieces ,the head will undoubtedly be the same if I try to remove it.
so I asked some of the fellows here about "pinpoint" induction heating with a few Probes , either around the guide [which I can just get to in the Port]
or heating the valve stem by clipping high current wire top and bottom of the seized guides , which I can do thru the tappet cover and intake/exhaust ports .

Grum had some thoughts, and here we are
I am going to build the recommended unit and perhaps attach some management circuits to it for safety and quality control [arduino ?]
and share the whole process here , these engines are also notorious for stuck spark plugs which seize inplace due to a taper interface

I have two forklifts which have this same engine and all the plugs are seized in place , which annoys the heck out of me ,and I am hoping to experiment with this "induction gizmo on these plugs ..

it really should work , and if it does ..it will be a very useful tool for the fellows here that bring old machines back to life [eco friendly]
and the build should come in from Zilch to 20 bucs or so ?
??

thx
Chet
PS
and yes I am very aware it could be [IS] dangerous .



   
Hero Member
*****

Posts: 2362
some pics of the "job"

and equipment ,an inline ammeter and temp probe will be a part of the initial "dialing in"
also will monitor input power to variac

ultimately once successful  all data will be used for reference in arduino build .

Round Variac input 120 V ... output 0-140V ... amps 10  ....KVA 1.4
square Variac  ""   ""                    ""  ""           amps 4.5  ..KVA  6.3
« Last Edit: 2017-01-06, 19:58:32 by Chet K »
   
Group: Elite
Hero Member
******

Posts: 2909
It's turtles all the way down
http://www.instructables.com/id/How-to-High-current-Microwave-oven-Transformer/

http://mad-science.wonderhowto.com/how-to/turn-microwave-oven-transformer-into-high-amperage-metal-melter-0140772/

https://www.youtube.com/watch?v=KQYFII5ESME

https://www.youtube.com/watch?v=6EYxS3WW6dY

There are lots of videos available  following these.

I don't think you need to rip apart the core, just remove the secondary and put your low turns count secondary in it's place. You can hacksaw off the secondary, of course being very careful not to damage the primary.

Just be sure to turn your Variac up very slowly while monitoring the valve stem temperature.

For those with too much time on their hands:

https://www.youtube.com/watch?v=uXEPy6Za6cI



---------------------------
Just because it has a patent application or is patented does not always mean it really works.
   
Hero Member
*****

Posts: 2362
Thanks for all contributions

Ssoo

since I will be heating the heat treaded valve [very important it stays "heat treated'] and since I see it heats from the middle out ,which will be out of view/access here , a temp sensor or method to monitor the actual temp as accurately as possible is imperative .

will definitely practice on some disposable /junk valves to dial things in .

will make some copper[insulated] Hooks to sneak into the Ports and latch onto valve stem.

also one thing I am going to try before I sacrifice the secondary to the Grinder is run a few laps of 8 gauge or whatever the biggest wire
I can run in the gap between the secondary and transformer core

I have been told its possible this may work ...thereby leaving my transformer unmolested [wifey might need it for cooking Dinner later  8)

after al,l I don't need to run this up to 700 degrees in milliseconds


** Also to note ,continental made aircraft engines too and it is possible that they may have used sodium filled exhaust valves
this would need extra care as bursting at high temp could result ?

will run this by Tinsel for his opinion too,  the bursting may just be a "Hollywood" concern ?

   

Hero Member
*****

Posts: 1152
In my experience hot orthophosphoric acid and heat is effective in unstucking things like that.  Where heat is not tolerated, an ultrasonic toothbrush can be used instead.

Heat alone also promotes similar chemical reactions with steels as well as the thermal expansion, but less effectively.

I would not recommend high DC current for heating because it can lead to localized spot welding where the I2R conditions happen to be the best.
HF AC inductive heating is hard to apply in tight bores.
   

Hero Member
*****

Posts: 606
What's the theory here? I mean, how is heating the valves supposed to work to unstick them?

And yes, there could indeed be sodium-filled valves in there.



---------------------------
"The easiest person to fool is yourself" -- Richard Feynman
   
Hero Member
*****

Posts: 2362
Hmm

Verpies

I may need to try and simulate this stuck valve stem in a junk block or perhaps a fairly tight fit "mockup"
to see if this spot welding does Manifest

In your opinion would input power be able to show this [sudden drop or spike at input ?

what other observations could indicate a welding event is taking place [unbeknownst to the technician...     RF ??

I like the acid recommendation although getting it to Migrate into the  problem area may be an issue
   
Group: Elite
Hero Member
******

Posts: 2909
It's turtles all the way down
Chet said:

Quote
also one thing I am going to try before I sacrifice the secondary to the Grinder is run a few laps of 8 gauge or whatever the biggest wire
I can run in the gap between the secondary and transformer core

You can leave the secondary intact and try to sneak a few turns through the area where the filament winding is usually placed. This would mean removing the filament winding, and maybe some of the hardboard insulation. You will be limited to the number of turns, but the fewer turns, the less trouble you will get into.

Be sure to tape up the secondary wires very well as there are lethal voltages on those wires. You don't want to accidentally touch them.

If you max out the Variac and still can't get enough heat with one turn, add turns until you do get the required temperature.

Try to make very good contact with your electrodes and keep the secondary wires as short as possible, in other words, the transformer should be very close to the work. Put a clamp probe on the secondary to measure the amps and go slowly with the Variac. Happy heating.

This is high current AC resistive heating, not DC and not HF AC. Sodium filled valves, if you have them should be a very big concern.

Maybe you could just shrink the valves stem diameter down by packing with some dry ice to free it up?
i know extreme cooling is used to free up close tolerance shafts and collars etc..


---------------------------
Just because it has a patent application or is patented does not always mean it really works.
   
Hero Member
*****

Posts: 2362
@ Tinsel
I have always used heat to unstuck seized thread connections ,applying heat and then oil ...as it cools it draws in the oil
wax has also  been mentioned recently [gets drawn in during cooling

so the theory is

 cause expansion to crunch the softer corroded area and apply oil [or acid ??] to lubricate

rinse and repeat as necessary

@
I see lots of good suggestions here.

Thanks

Chet


   
Group: Elite
Hero Member
******

Posts: 2909
It's turtles all the way down
To avoid any spot welding effects be sure the current flows through the valve or through the guide seal but not from valve to seal. And keep the temperature well below red hot.

With these things it often takes a lot of patience with heating cooling cycles and repeated and distributed tapping.

I recently had to remove a faulty drill chuck from a tapered shaft on a drill press. It took quite a few gentle heating and cooling cycles and tapping before some wooden wedges popped it off. I did not have the proper removal fork on hand.


---------------------------
Just because it has a patent application or is patented does not always mean it really works.
   
Hero Member
*****

Posts: 1164
... .-.. .. -.. . .-.
What i'm picturing here, is a device with 2 probe holes on the front.
You could fit the right gauge of wire and right design to the front, to do the needed job.
If something is smaller but needs to be done quickly for safety or other concerns, you'd pick a thinner wire and plug that in.
Stepping out further with that thinking, you could have a ready made guide chart on a screen based system, working like those examples that microwave ovens themselves always have on them.
The point of that, would also be to have the 'machine' set the correct current flow and timings.
PWM through capable MOSFET's would work instead of a variac ?
If so, the code would entail quite a simple PWM pulsing routine, based on the selected outline of job.
Such a thing could also have a temperature sensor plugged in, for monitoring purposes, while also displaying that info on the screen. If you know the job needs 420F for 3 minutes, it can be checked via the screen.

Hope i'm on the right lines !


---------------------------
ʎɐqǝ ɯoɹɟ pɹɐoqʎǝʞ ɐ ʎnq ɹǝʌǝu
   
Jr. Member
**

Posts: 76
I found this worked miracles on a steel stud broken off in a cast iron exhaust manifold on my truck. The nut was so rusted onto the stud that trying to take it off broke the stud. There was only a small nub of the stud sticking out of the flange of the exhaust manifold.

I heated it with a torch to quite hot (not red but getting there) and touched a wax candle to it to melt the wax which mostly burned off but I guess some wax ran down into the threads.

The stud came out very easily with a pair of pliers on the nub sticking out. I could have done it with my fingers if it wasn't so hot.
   
Hero Member
*****

Posts: 2362
Mark
in my opinion you can never get enuff data or quality control
knowing how much heat your applying as well as a frame of reference for what should be required for the Job [time to heat]

great ideas
and yes do we really need a big transformer and the variac ?
once we see the actual input requirements for certain jobs that can be sized accordingly.

think about all the small guage screws that like to snap in ferrous non ferrous applications , having a small probe tool that can be touched to the fastener for recommended on time [as you outlined[Chart]] and break it free...without all the alternative _Snap_ grind, drill, Tap .....tears !!

would be a tremendous timesaver for the shop .

thx1138
yes the paraffin method is a nice deal ...when it works

,an associate swore by this method and spent half a day under a machine with various flames and the seized Bolt ...used up all  my better halfs christmas candles
 ...he came out from under the machine with a full wax facial ....he looks nice with no eyebrows and half a mustache !!

but the bolt ended up Snapping...

took off the secondary and wound 4 gauge fine wire on

will setup a test board tomorrow and start cooking

   
Hero Member
*****

Posts: 739
Have you thought about the opposite of local heating, i.e. local cooling?  Applying dry ice to a metal part could cause rapid local cooling.  Of course you don't handle dry ice with your fingers  :).

Smudge
   

Group: Moderator
Hero Member
*****

Posts: 1412
Hi Chet.

There's talent out there !!

Looking at the pictures you posted you could easily sneak a few turns of multi stranded insulated wire around the valve guide and use one of these......

https://youtu.be/R9himdPWYQM

With regards " Sodium " filled valves I would think it highly unlikely for such a " bog standard " engine. The practice was mainly for high performance engines.

Cheers Graham.


---------------------------
Nanny state ? Left at the gate !! :)
   

Group: Moderator
Hero Member
*****

Posts: 1412
Hi Chet.

There might be a more non technical remedy....   ;)

Is the engine, otherwise free ? Does it have a cranking handle ? Another old dodge, fill the tappet gap with a suitable packer and rotate the engine to try and raise the valve a little higher. It might just crack the rust!

The valve springs aren't coil bound, quite, a couple of thou might work.

Cheers Graham. 


---------------------------
Nanny state ? Left at the gate !! :)
   
Hero Member
*****

Posts: 2362
Grum
we're getting some nasty weather ATM ,been busy sealing up the out buildings.

I have tried applying leverage to the valves , as well as forcing a flat bar between the springs and banging downward too ...even locked onto the valve stem with a vise grip [as gently as possible] and tried twisting ....all the while soaking with every manner of oil .

will be back in the shop in an hour or so to work on the "spot heater"

in the mean time have a look at what the "new hands" are up to at Honda
https://www.youtube.com/watch?v=mWsBRgq7pk8

 :o
   

Hero Member
*****

Posts: 1152
What's the theory here? I mean, how is heating the valves supposed to work to unstick them?
I think it relies on the physics of different thermal expansion across thermal gradients and some heat accelerated chemistry. 
Phosphoric acid reacts with bulky iron oxides and contracts them into thinner black phosphates, while preventing future formation of more oxides.  This contraction frees a lot of space for movement.
Also, dissimilar metals enhance the thermal expansion differential even more.

Take a look how this works for this guy.
https://youtu.be/J8NdQHqKxIU?t=763
« Last Edit: 2017-01-07, 23:03:01 by verpies »
   
Hero Member
*****

Posts: 2362
Slyder [Mark] is working on putting a brain to this Job

we were discussing thermal imaging and the possibility of Arduino interface

https://www.kickstarter.com/projects/andyrawson/ir-blue-thermal-imaging-smartphone-accessory



the transformer makes crazy heat and needs some monitoring methods to prevent component damage [IE overheating of sensitive heat treated parts],   the laser therm

is not really adequate and temp probes are a nuisance [at least the ones I have .

any suggestions welcomed and appreciated
« Last Edit: 2017-01-08, 03:48:17 by Chet K »
   
Hero Member
*****

Posts: 1164
... .-.. .. -.. . .-.
What the heck ?  O0
haha, sticks on the front of a cellphone.
But, the campaign is a few years old and the link doesn't work now for buying one. That's a shame, however, we do know it can be done and there must be some kind of equivalent.
Looking for the 64 zone sensor I found this:
https://www.melexis.com/en/product/MLX90621/Far-Infrared-Sensor-Array-High-Speed-Low-Noise
The only Ebay listing is this and it's spendy at $127:
http://www.ebay.com/itm/MLX90621-Open-Source-Thermal-Imager-with-ATmega328p-MCU-/122130933690?hash=item1c6f9227ba:g:2iYAAOSwAuZX18sX
Which, mentions an ATMega328P, indeed an Arduino possibility because that is the chip on Arduino's.

The fix for such an idea then, would be to find some of those MLX90621's at least, or again an equivalent.
Which lead to their 'Where to buy"
DigiKey have them...and they're I2C, which is supported on Arduino's.
http://www.digikey.com/en/product-highlight/m/melexis/mlx90621-16-x-4-pixel-thermal-imager
$43, still spendy.


Edit -
Wait a minute, there is a crude way.
If you want to know the temperature of the transformer for example, a regular thermistor might be the way ?
Grab one from an old PC fan and hook that up to an analog read pin of an Arduino. Measure the temp at frequent intervals (based on resistance change) and even just have 3 LED's as indicators, in lieu of a screen. Green for cool, orange for heating up and red for hot.


---------------------------
ʎɐqǝ ɯoɹɟ pɹɐoqʎǝʞ ɐ ʎnq ɹǝʌǝu
   
Hero Member
*****

Posts: 2362
seems it evolved into a product at Samsung

http://www.flir.com/flirone/android/

http://www.flir.com/flirone/content/?id=81730

sooo the important Bits must be around somewhere for cheap ??
   

Full Member
***

Posts: 184
Believing something false does not make it true.
Way back in the mid 1970s I built a temperature sensor for a friend to measure the temperature at the top of a hot air balloon.  We used a diode and measured the forward voltage drop across the diode.  We used a high value resistor to limit the current so the current didn't heat the diode junction.  Then we took the voltage drop and applied that to an op-amp and added some gain and sensitivity adjustments.  The output of that was fed to an analogue to digital converter. The output of that was applied to a readout.  We calibrated it with some ice and boiling water to get our linear scale.   It worked pretty neat for old technology.  With an Arduino it should be easy now days to do that.   Just use a diode for your sensor and feed the voltage drop to the Arduino and let the software do the rest.

Here is a link about measuring the temperature of a diode using the voltage drop.  It is much more complicated in the way they are doing it but I don't think you want that kind of accuracy either.

http://electronicdesign.com/lighting/use-forward-voltage-drop-measure-junction-temperature

Carroll


---------------------------
Just because it is on YouTube does not make it real.
   
Jr. Member
**

Posts: 76
Have you thought about the opposite of local heating, i.e. local cooling?  Applying dry ice to a metal part could cause rapid local cooling.  Of course you don't handle dry ice with your fingers  :).

Smudge
Now that I think about it, that might be what makes the wax method work. I heated the cast iron manifold that the stud was in and then touched the wax to the stud. The heat makes both expand and touching the wax to the stud draws heat out of the stud so that it contracts? It was hot enough to burn the wax away immediately so the heat in the wax was expelled out to the atmosphere.
   
Pages: [1] 2
« previous next »


 

Home Help Search Login Register
Theme © PopularFX | Based on PFX Ideas! | Scripts from iScript4u 2017-04-29, 00:38:59