# Cutting open a spark plug?  No way.



## Bill Kahn (Apr 10, 2018)

Yes, I like to try to make stuff.  I also have a great time trying to take things apart.  An old laserjet.  An old washing machine (simply amazing main motor deep in there. ) And recently an old lawn mower.  So, what's inside the spark plug?  I mean, seems simple enough to imagine.  But it is always a blast to cut things open.  So, throw it on the 4x6 HF and...whoa...this is not like cutting other stuff.  That porcelain (or whatever that insulator is) is way harder than my bi-metal saw blade.  OK, throw it into the lathe with a carbide tool.  Crack.  Must have been a weak insert.  Put in the other side.  And, crack again.  Some lessons just have to be learned empirically.  OK, enough is enough.  Put onto the floor, faceshield, and hammer it.  Yup, that works.  Not sure I really saw the beauty of the insides, but that spark plug, while not being "taken" a part has certainly ended up in parts (well, maybe pieces would be a more accurate description.

So, how do folks with smarts or talent slice open a spark plug?  What tooling/equipment does that?

In taking stuff apart I am simply amazed at how smart mass production is.  A million times smarter/more efficient than I could ever be. 

-Bill


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## kd4gij (Apr 10, 2018)

Diamond saw blade like a tile saw


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## FOMOGO (Apr 10, 2018)

X2, get a cheap Walmart diamond blade for a 4" angle grinder. Should cut like butter. Mike


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## Old junk (Apr 10, 2018)

Diamond blade.


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## benmychree (Apr 10, 2018)

The metal part that is crimped over to retain the core can be turned back in a lathe and the porcelain pulled out.


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## whitmore (Apr 11, 2018)

Diamond or other abrasive should work; zirconia and aluminum oxide are both common abrasives, and
are candidate minerals for the ceramic in a spark plug.   Hardness is difficult to quantify, but the (old,
traditional) Mohs scale calls 'em hardness 8 for Zirconia, 9 for aluminum oxide.   Diamond is 10.


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## Dave Smith (Apr 11, 2018)

diamond blade is fine for the ceramic but won't last long cutting the metal--benmychree has the way I do it--funny why so many of us just love to take weird items apart for reuse or just curiosity---Dave


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## cathead (Apr 11, 2018)

Some of the very early spark plugs you actually can actually disassemble.  They have a second hex at the base of the porcelain and allow one to take it apart.  










https://www.hobby-machinist.com/threads/cutting-open-a-spark-plug-no-way.68721/#top
This one you can take apart AND put it back together.


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## ultrapan (Apr 11, 2018)

My motorcycle plugs can be disassembled and cleaned


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## Manderioli (Apr 11, 2018)

Are you trying to literally split a spark plug in half?


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## JPMacG (Apr 11, 2018)

Interesting about the disassemble-able plugs.  I thought the porcelain and metal parts had to form a hermetic seal.

It might be possible to cut through the ceramic by water jet.  I know that ferrites (another ceramic) can be water jet machined.   I would think that any saw would chip the porcelain.


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## BenW (Apr 12, 2018)

Water jet can cut just about anything, but if you go careful a diamond saw should work just fine and is a lot more accessible. 

Sent from my SM-G930F using Tapatalk


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