# Corian for spark plugs



## Metal Butcher (Oct 11, 2010)

This might be a good source for those wishing to make their own spark plugs. E-Bay might be a cost effective way to get the needed material for those that are in remote locations, or don't have any local source. Below is a link to one of many sellers. The color assortment in this auction would add a quite bit of visual interest, especially if it could be incorporated in another part of the build, like columns or other structural components.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290416047718&ssPageName=STRK:MEWAX:IT

-MB


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## stevehuckss396 (Oct 11, 2010)

I bought a box about 2 years ago. It was 99 cents and $8.95 shipping. 20lbs for 10 bucks. Hard to beat.


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## Metal Butcher (Oct 11, 2010)

How ya doing Steve! Have you tried to make one of these size plugs yet?

 Look at page 93.
http://books.google.com/books?id=ji...onepage&q=world's smallest spark plug&f=false

-MB


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## kcmillin (Oct 11, 2010)

I don't know about fruity flavored spark plugs :big:

Does Corian Machine nice?, is it brittle?, what type of fit should it be in the metal part of the plug? What can be used as glue for it if the fit needs to be loose?

Sorry for the dumb questions, I am about to made a batch of tiny spark plugs and am thinking about different options aside from the acetal (Delrin) that 
I have.

Kel

PS. I just asked the seller If I can get 74 of one color. I am still awaiting a response.


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## Metal Butcher (Oct 11, 2010)

kcmillin  said:
			
		

> I don't know about fruity flavored spark plugs :big:
> 
> Does Corian Machine nice?, is it brittle?, what type of fit should it be in the metal part of the plug? What can be used as glue for it if the fit needs to be loose?
> 
> ...



Hi Kel.

If you click on 'other items' the seller does offer smaller batches.

Sorry I can't answer you questions, I'm still doing research and haven't even attempted making a plug yet.

I did buy a Rimfire VR2L 1/4-32 for my first and future build. I know its a bit of a cop-out, but that's the decision I made.

If I do make any, it will be small one's that are not commercially available.

http://sparkplugs.morrisonandmarvin.com/

-MB


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## Tin Falcon (Oct 11, 2010)

> Does Corian Machine nice?, is it brittle?,



Yes to both. I have not made any spark plugs yet but . I have made several air engines with Corian. 
It makes great bases and I have used it for standards and cylinders as well the wife made her "rosy" hearts shaped engine out of it. an I made Cory and engine made mostly of Corian the flywheel is laminated of three pieces . 
I have also made many pen and pencil sets out of Corian. 
remember do not breath the dust. 
Tin


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## gmac (Oct 11, 2010)

Most towns have someone making Corian countertops. I went to several cap in hand until I found one that simply gave me their "scraps". "How big? That small? Take what ever you want out of that garbage bin....". 

And as Tin has said - don't breath the dust. I was warned to wear a mask and that the dust will fly about.

Cheers
Garry


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## GWRdriver (Oct 11, 2010)

kcmillin  said:
			
		

> Does Corian Machine nice?, is it brittle?


Kel,
It machines nicely but yes it is quite brittle and can "pick" like wood when the saw teeth exit the kerf. It's strong in compression but quick to fracture in tension. Being a poured material it can contain a "grain" of sorts. I have used Corian almond white for a number of bases and plugs and the grain, actually subtle changes in color as the plastic cures out, can appear as you cut diagonally across a section of sheet. You won't notice it on small bits. I've only used the off-whites so I can't comment on other colors.


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## Metal Butcher (Oct 11, 2010)

I added the link below to make every one aware that reads this thread of the MSDS link I posted in the 'Safety Forum'.

Please read this carefully, even if you have no intention of working with Corian at the moment.

http://www.homemodelenginemachinist.com/index.php?topic=11063.0

-MB


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## Tin Falcon (Oct 11, 2010)

I use a shop vac with a clean stream filter to suck up most of the dust. if you vac as you machine it will eliminate most of the dust and help keep the cutting tool cool.
Tin


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## stevehuckss396 (Oct 13, 2010)

Metal Butcher  said:
			
		

> How ya doing Steve! Have you tried to make one of these size plugs yet?



Not that small but I did make a #6-56 thread plug that worked good until i droped it.


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## kcmillin (Oct 14, 2010)

I got a e-mail from the seller. He said there is no problem getting them all the same color. You must leave a note when purchasing.

Kel


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## steamer (Oct 17, 2010)

Roland Gaucher of NEMES built plugs for his Bently BR2 from Corian and they work great!

Dave


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## Kimmo (Jan 31, 2019)

Hello. I´m new in this business and I´d like to know more about Corian. Is it heat resistant enough to work as an insulator? easy to work with? How about PTFE?


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## aka9950202 (Jan 31, 2019)

Does anyone know where to buy corian in Melbourne? 

Cheers, 
Andrew in Melbourne


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## ozzie46 (Jan 31, 2019)

yes corian is ok for spark plug insulators. It machines much better than ptfe.

ozzie46


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## Cogsy (Jan 31, 2019)

Try countertop/cabinet installers for scrap corian. The sink cut-outs are good sources, as well as the little bits of scrap as thy fit them. I did buy some pen blanks from the US on eBay but I have tracked down local installers here in Perth (tho I haven't contacted any yet). I imagine Melbourne should be similar to Perth.


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## Brian Lawson (Jan 31, 2019)

stevehuckss396 said:


> Not that small but I did make a #6-56 thread plug that worked good until i droped it.



Hey Steve, 
Your note didn't make it clear as to what occurred or meant when you "dropped it". As I recall, it was so small that it wouldn't have had enough energy from gravitational pull to actually "break" if it hit the floor unless you then stepped on it.  So I for one am going to suggest that it got "lost" rather than broken.  I could supply a really large magnifier to hunt for it if that helps.  Hey, on the other hand you made it sound so easy to do, just spend another week and make a new one !! hahaha


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## Brian Rupnow (Jan 31, 2019)

I made a sparkplug using Corian. I found it to be quite brittle and rather miserable stuff to work with.


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## stevehuckss396 (Jan 31, 2019)

Brian Lawson . .  When I dropped it the corian cracked right at the base. It still looked good but it would short internally when under power.

Brian Rupnow  . . . I don't have a lot of trouble with it. I use very sharp, very thin inserts for grooving to machine it. .032 is typical. Don't rush and don't take too deep a cut and they come out pretty good. It's probably the best thing to use that is affordable. I just purchased some for 10 bucks a square foot and I'm guessing I can make about 1000 insulators for #10-40 plugs with a square foot.


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## aka9950202 (Feb 1, 2019)

Cogsy said:


> Try countertop/cabinet installers for scrap corian. The sink cut-outs are good sources, as well as the little bits of scrap as thy fit them. I did buy some pen blanks from the US on eBay but I have tracked down local installers here in Perth (tho I haven't contacted any yet). I imagine Melbourne should be similar to Perth.


What do they call in here in Australia ? When I asked about corian they did not know what I was talking about .

Cheers, 
Andrew in Melbourne


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## Cogsy (Feb 1, 2019)

aka9950202 said:


> What do they call in here in Australia ? When I asked about corian they did not know what I was talking about .


Possibly just something generic like 'acrylic counter top' but here in Perth I've seen local counter top suppliers websites with the name 'Corian' on them. I didn't find much on Google when I searched 'Corian Perth' but instead I just searched for counter top businesses and browsed their websites.


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## karlw144 (Feb 1, 2019)

Steve, those are looking good.


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## Kimmo (Feb 1, 2019)

karlw144 said:


> Steve, those are looking good.


Yhteystiedot


karlw144 said:


> Steve, those are looking good.


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## Kimmo (Feb 1, 2019)

Plugs looks fine. What about heath resistance .


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## kquiggle (Feb 1, 2019)

Corian is made from acrylic and alumina and is heat resistant to 100°C (per Wikipedia). On the one hand, numerous people have successfully made spark-plugs with on, but on the other hand it does not sound like an ideal material to me. I have not (yet) tried to make any spark-plugs, but I would be more inclined to use teflon, which in my experience machines well with sharp HSS tools.

The ideal material would probably be machinable ceramic, but hold onto your hat when you look at the price!


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## TonyM (Feb 1, 2019)

I have a local guy who does SLA printing. He is doing some patterns for my Gardner. He says he can hold tolerances in microns. Would anyone be interested in printed spark plug insulators.


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## stevehuckss396 (Feb 1, 2019)

kquiggle said:


> Corian is made from acrylic and alumina and is heat resistant to 100°C (per Wikipedia). On the one hand, numerous people have successfully made spark-plugs with on, but on the other hand it does not sound like an ideal material to me.



Nothing in our price range is ideal but it's the best cheap material out there. As an insulator it will out perform most materials we use in this hobby. I have the same plugs in the peewee that were put in in 2010 and I run it more than any other engine I own.


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## cheepo45 (Feb 1, 2019)

I have 3 engines running homemade corian plugs. They have run all day at the shows for years on the same plugs.
The only issue I have had is that the insulator is easy to crack during machining.


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## stevehuckss396 (Feb 1, 2019)

cheepo45 said:


> I have 3 engines running homemade corian plugs. They have run all day at he shows for years on the same plugs.
> The only issue I have had is that the insulator is easy to crack during machining.



Can't disagree with that. Care must be taken when you machine them but also when you press the insulator into the base. I have cracked a few during that step also. Once they are done, you cant beat them.


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## Kimmo (Feb 2, 2019)

Fish spine beads are used by some guys as insulator. Stuff is alumina. Don't know about prices. Beads are made in different sizes.


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## stevehuckss396 (Feb 2, 2019)

The beads are over a buck a piece and are too short to make an insulator. The rods I saw were 27 bucks a foot and machinable but the forum I looked there was a guy who was blowing up diamond inserts trying to machine the stuff. Being ceramic I would think they are unable to be modified. Do you have any photos of the plugs made from this stuff Kimmo?


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## Kimmo (Feb 2, 2019)

There's this chap Graham Meek  on modelengeneeringwebsite who's done these plugs. He made the ptfe insulator with the bead on the head of the plug. There's drawing on site too.


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## stevehuckss396 (Feb 2, 2019)

Found it!

http://modelengineeringwebsite.com/Miniature_spark_plugs.html

I see how it worked for him. Wouldn't work for me as the available sizes are not quite right. This latest plug i'm making only has .078 hole in the base.


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## Kimmo (Feb 3, 2019)

OK. I'ts good to have few option. I think they all works fine, corian, beads and ptfe. Ptfe's possible chemical decomposition worries some guys, don't believe it's a big issue with these engines.


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## cds4byu (Feb 3, 2019)

Some other possibilities:  Soapstone (samples often available from countertop manufacturers), hexagonal boron nitride (nice and white, machines like graphite, good to 950C), Macor (machinable ceramic).

I suspect that the first time I want to make a spark plug, I will use HBN.


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## stevehuckss396 (Feb 3, 2019)

Where do you buy HBN rod?


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## cds4byu (Feb 3, 2019)

Goodfellow chemical: http://www.goodfellow.com/E/Boron-Nitride-Rod.html -- but their price is way over the top; I've had access to some scraps from laboratory work.  I wouldn't make a plug out of HBN from Goodfellow.

There's a possibility of getting reasonable prices from vendors on alibaba.  But you have to ask for a quote.

Ebay currently has some NOS steatite rods on sale -- 1/2 inch diameter by 8 inches long for $14.o0 with free shipping.  Steatite is purified soapstone.  It is reputed to be machinable, but I've never tried it.


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## cds4byu (Feb 3, 2019)

One can also purchase 1/4inch diameter x 5 inch long white soapstone rods for $4.50 per pack of 10.  That is also possible source material for small spark plugs.

http://www.safetyequipmentdirect.com/radnorr-1-4-x-5-round-no-1-select-soapstone-10-per-card.html


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## stevehuckss396 (Feb 3, 2019)

Your right about the price being over the top. At 100 bucks an inch i'll stick with the Corian.


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## GreggA (Feb 4, 2019)

I use "ultram' from mcmaster...Great stuff. cheap and machines well. Made tons of plugs with it and i like it much more than corian. Comes in rods of different sizes. Try it!


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## cds4byu (Feb 4, 2019)

Do you mean Ultem?  I couldn't find Ultram on McMaster-Carr's website.


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## kquiggle (Feb 4, 2019)

I like the idea of using soapstone - never would have thought of it. Almost seems ideal in terms of heat resistance and insulating qualities.

Looks like it also machines well too: https://www.tormach.com/blog/soapstone-machining/


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## kquiggle (Feb 4, 2019)

Steatite also looks like an ideal insulator, but I am not sure it is machinable. I could not find anything directly, but what I could find looks like the machining is done with diamond tools and diamond grinding. Does anyone have a better answer on steatite machinability?


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## GreggA (Feb 4, 2019)

Whoops! My bad...yes...Ultem. Ultram is my pain killer pills for my foot...they come in handy too though.


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## stevehuckss396 (Feb 4, 2019)

Brian Lawson said:


> Hey Steve,
> Your note didn't make it clear as to what occurred or meant when you "dropped it". As I recall, it was so small that it wouldn't have had enough energy from gravitational pull to actually "break" if it hit the floor unless you then stepped on it.  So I for one am going to suggest that it got "lost" rather than broken.  I could supply a really large magnifier to hunt for it if that helps.  Hey, on the other hand you made it sound so easy to do, just spend another week and make a new one !! hahaha




All done Brian! I even recorded the test


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## doc1955 (Feb 4, 2019)

actually find the stuff machines nice here is a short vid being turned on my mill with a .025 wide grooving tool.


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