3X Sparkplug 4X Size

[stevehuckss396]

This is a bit of a crazy project put it is something I have wanted to do for a long time. Back in the teens and twentys this would have been one of the plugs found in the old flatheads like the ford model T and model A and maybe a few of the hit miss engines that required a plug.

I'm not a big fan of the text with all the photos in a pile at the end of the post so i'm going to make a post for each photo with a description until i learn of a better way.


Bottom insulator is up first. A piece of white delrin will become the lower insulator. The top and bottom were broken up so 2 small drops could be purchased instead of a large and expensive piece. The 2-3/8 diameter piece was faced on both ends and brought to a 4 inch length.

 

[stevehuckss396]

The piece was drilled 3 inches deep with a 5/16 drill bit

 

[stevehuckss396]

Next a 1/2 inch endmill was plunged into the delrin 1-1/4 deep. This will create a counter bore where the lower electrode will settle into.

 

[stevehuckss396]

Then a boring bar was used to create a .970 counter bore an inch deep.

 

[stevehuckss396]

Next the insulator was drilled through with a 9/32 drill bit. Seems weird to do this last but the operation required that the jaws of the drill chuck go deep into the .970 bore or the drill bit wouldn't make it all the way through the piece.

 

[stevehuckss396]

Last operation was to thread the 5/16 hole with a 3/8-16 as deep as I could go. I will need the threads to secure the piece to a mandrel for doing the outside contouring.

 

[stevehuckss396]

Forgot to post a picture of the finished product. It will be almost a foot tall with a 4-1/2 inch hex

 

[Cogsy]

Steve, here's a quick picture tutorial for you. I've drag and dropped 2 images into my post (or I could have uploaded them normally) and I can see them sitting at the bottom of my post. If I do nothing more, they will show up as thumbnails at the end of my text. However, I'm now going to start a new line and click on the button next to the first one that says "Full Image" and :

Then I type some more text, start another new line and hit the button next to the second picture:

And that should be all there is to it!

Btw - this plug should be a thing of beauty. Great idea for a paper weight or decorative piece (or you're planning a truly massive build).

 

[stevehuckss396]

Thanks i'll give it a try

 

[stevehuckss396]

Today I finished up the outside of the lower insulator. Made a little what ya call it with a 3/8 thread through it. Then using the internal thread in the insulator
it was screwed to the what ya call it and that freed up the small end to be machined complete.

Just need to drill one more hole in it and it will be 100%

 

[stevehuckss396]

Thanks for the lesson cogsy!!

 

[johnmcc69]

Cool project steve!

John

 

[stevehuckss396]

Got my bottom electrode completed today. Simple part that took less than 1/2 hour.


This is 1/2 inch drill rod. Faced and then Center drilled.

Part was turned to print

After cutting it off with the band saw the piece was reversed, faced to size, center drilled, and drilled with a 1/8 inch drill bit about 1.5 inches deep.

Sorry about the bad photo. The part was reversed again. The end got a chamfer and then polished up for a nice appearance.

 

[stevehuckss396]

Little more progress today.

Chucked up a piece of 6" round and indicated it in to within .010.

Faced it off and drilled a center hole.

Inserted the tail stock center and made a 5.25 inch piece out of a 6 inch. Had to reduce it or it will not fit in the other lathe.

Then it was drilled through with a 3/4 drill bit. Spent the rest of the day making a boring bar long enough to reach 6-1/2 inches into the piece. Tomorrow we bore!

 

[stevehuckss396]

Well we managed to get a little more done today. The bore is 2 inches (2.003ish) to allow the 2 inch bottom insulator to be inserted. My boring bar was to short so a 12 long piece of 3/4 was converted into a boring bar.

Started at 750RPM and .025 deep passes. Had to stop at 4 inches deep and clear the bore of swarf and then again at 6 inches deep. About the 1.250 inch diameter mark I started getting alot of chatter so I slowed down to 450RPM and continued with the same program. About the 1.750 diameter mark the chatter was back so I had to lighten the cuts to .015 deep and 330rpm. and when finished I was down to .005 deep cuts and 150rpm but real nice finish. Took forever!! But real happy with the result.

Piece was flipped 180 degrees and indicated in. First faced to length. Had to borrow a caliper larger than 6 inches as the piece is 7.100 tall. Then bored the center hole and finally cut the counter bore.

All my buddy had was a giant, 24 inch caliper. It's 4 times bigger than a standard 6 inch caliper. 4x caliper to measure a 4x sparkplug base. Gotta love that!

 

[stevehuckss396]

More progress to report. The top insulator is complete

The piece of delrin was faced to length and drilled through.

Then the hole was counter bored for a future bolt to hold the brass cap on.

The part was bored out to remove unwanted material.

Over to the mill the part was chucked and the center of the bore found.

Holes were drilled and tapped to mount the insulator to the base.

A small mandrel was made with a matching hole pattern.

The piece was mounted in the CNC lathe using the mandrel.

The piece then was tapped in alignment and finished.

 

[stevehuckss396]

Little more progress today.

I wanted the top and bottom bolt patterns to be close in alignment. Don't need to be exact but close is good. Made a small mark in sharpie on the jaw of the vise and then marked up the piece with a square off the top of the vise jaw.

Located the center of the hole and drilled in the pattern that will hold the top insulator to the base.

Rotated the part 180 degrees and aligned my mark with the mark on the vise jaw. Then I located the center of the bore. Only needed one hole to screw the electrode into but my lathe is so small I had to make 4 to bolt on a mandrel.

A mandrel was made from a scrap piece of ally to allow the piece to be mounted into the 9X20 lathe.

Now you can see why the 6 inch round was knocked down to 5.25 inches. I think there was about .050 or less between the piece and the cross slide.

Sorry about the picture quality but the camera battery died so the phone was used. The top portion of the piece was machined to size and shape.

The CNC machine doesn't seem to care about how the swarf is coming off, how much and where it ends up. I used a pair of needle nose pliers to coax the never ending stream of swarf to go onto the floor instead of wrapping around the chuck and everything else. After making tiny parts I was not prepared for the never ending stream of aluminum but we got through it with a nice looking piece.

 

[stevehuckss396]

Camera died so I couldn't show it last time but the bottom was roughed out on the manual lathe. It was them mounted in the little lathe to be finished.

The bottom was finished up to the proper shape.

Starting to look like a sparkplug base now. Still a lot of metal to remove.

 

[stevehuckss396]

Brass showed up for the top nut so I got a start on that job. A mandrel was made with some thread sticking out.

The blank was made by facing both sides and drilling and tapping completely through the piece.

Blank was screwed onto the mandrel.

4 minutes later the piece was to shape. Still a little work to do but close to being done.

 

[stevehuckss396]

The cap was basically the same process as the nut so I decided to make a short video of the final cuts.