Posts Tagged ‘911’

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Hello? Is there anybody out there? Just click if you can read me…

It has been awhile since I’ve been here. The other day when I opened the door up to this place and flicked on the cyber lights everything still looked to be in order other than the fact there was a layer of dust on everything. I fired up the virtual air compressor and blew everything off, changed the oil and filter in the hard drive, topped up the argon tanks, cranked up the heat, and went heavy on the speeds and feed to get the work grunting. After taking inventory it looks as though nothing much has changed. I guess that’s the beauty of garage life…it goes back to the beginning of time.

For those of you who are regular followers of the blog you may have noticed the postings were lacking for the past 6 months. Truth is I got busy and something had to give. The majority of the past 10 months were spent completing a major basement development. It was not what I consider to be blog material. I was still doing smaller garage projects during that time but I only had so much time to dedicate to things. The blog was not one of those things.

I receive many comments from readers. Some of you were kind enough to express some concern as to what happened to the regular postings. There are many others who are usually in need of help or request services from me. I apologize for my lack of response over this past while to all of you. I needed to make sure I was looking after things at home first and that was all I had time for. Today, though, I am feeling like my old self and ready to get back at things.

As usual there are lots of things going on in gordsgarge these days. It’ll take some time, and some blog entries, to bring you all up to speed. The main project, which many have been asking about, involves the CNC plasma table build. I am thrilled to say that after the basement work was complete I jumped back in, with both feet, to the plasma table build. Ongoing progress will not make its way onto the blog. I was building from the top of my head, it got complicated, I didn’t take pictures, it was very time consuming, and many hours were spent just performing repetitive machining sequences. I am happy to say that I have been able to make my first test cuts this past week and everything appears to be coming together. I will, at some point, feature the finished project on the blog.

This brings me to today’s blog posting. I’m starting of slow just to get things rolling. I did a project for a friend of mine that involved a custom shifter knob, which he designed, for his 911 Porsche. He wanted something unique yet vintage looking for his 1973 SC. He had taken apart an old R12 air conditioning compressor from a different 911 and salvaged the pistons out of it. They are a perfect size to build a shift knob from.

Instead of just plunking a piston down on top of the shift rod he figured a nice wood accent would lend itself well to a retro look. After we tossed some ideas around he/we settled on the following. I think it all worked out to his liking and should he wish to covert back to stock I didn’t modify anything on the vehicle side that would prevent him from doing so. Like the good ole days I’ll let the pictures do the talking.

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This is my friend Jon’s Moss Green Metallic 1981 911 SC ROW/German spec’d Porsche that is getting the shift knob retrofit.

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This is the Mad (Manual-aided design) that my friend provided to me as the official concept design and blueprint. He can draw better than I can.

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We played with different woods, and wood patterns, every time one of us was out at a store that carried project wood. This is 1/4″ maple and oak stacked as a sample.

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The wood, and pattern, that was settled upon was 1/8″ birch plywood sandwiched with 1/4″ solid oak.

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My friend supplied me the wood already glued and in blocks (yes plural, always have a back up plan). First order of business is to mill a flat surface to work from using a router bit chucked up in the mill.

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The wood was then drilled out in order to accept 4mm socket head stainless steel bolts. I use an end mill in order to counter sink the socket heads.

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Next the piston was drilled and 4mm tapped in the same pattern.

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The prepped blank and piston get hitched and are ready to go for a spin.

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The diameter was roughed down to size using a carbide cutter on the lathe.

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The profile was also roughed out using a carbide tip to where the shape was close. The fine dimensions where then cleaned up using sandpaper.

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With the top rough fabricated it was time to direct the attention to the base. The piston required some kind of mounting to the shifter rod. The understand of the piston was drilled on the pin bosses.

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Using some 6061 aluminum stock the end was faced and drilled to the same dimensions as the underside of the piston. The radius side was then drilled and tapped in order to accept a set screw which will secure the sleeve to the factory shift rod.

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Moved onto the lathe to start shaving material off and bring the profile to a clean, light, shape.

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Onto the finishing stage. The piston top received a couple of coats of a polyurethane clear coat to aid in protection, It will hopefully help add some “character” wear as the piston gets some use.

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This is the assembled piston. This photo shows some details that I didn’t cover in the previous build pictures. Mainly the fake wrist pins. The one pin you can see is actually a “nut” that allows the fabbed sleeve to bolt to the piston. The sleeve, which is blurred out, received a shot of primer and the was airbrushed black.

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Installed and ready to synchronize some constant mesh

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Title Porsche heads

So the blog has been suffering over the past few months. I challenge myself to hone my time management skills and usually I do it fairly well. However ever since spring hit it has been a struggle to juggle all the work that needs to be done. Something had to give and unfortunately it was the blog. The garage projects continue to happen however the blog postings have not.

Even though I am still feeling the pressures I figured I better just suck it up and post something. So here it is. I had spent the last couple months catching up on summer yard projects. With the completion of the outdoor fireplace last year it was time to pick up a load of birch for burning. I had a temporary firewood holder made from 2×4 lumber and decided it was time to rework it and build it out of metal.

Wood holder

About 4 summers ago I had built a “built in” BBQ with a full stone surround and tile top. Over the past years the tile has taken a beating. With the constant freezing and thawing over the winter the tiles started lifting and the top was in need of a rebuild. So this spring I stripped the tile top off and built a steel one out of 10 gauge. I bent all 4 sides, built a couple accent handles, and then powder coated it matte black.

BBQ top

Next was onto the deck skirting. The deck was built about 5 years ago and I had always planned closing up the lower section. I stash my spare aluminum under the deck and my better half was tired of looking at it. So the deck skirting got done, no metal, all lumber in order to match the rest.

Deck skirting

One of the garage projects I got side tracked on was some cylinder head machining for a friend’s 1973 Porsche 911. He acquired the car about a year ago and it needed a top end rebuilt so he stripped it down and upon inspection all the heads requires some repair. On the air cooled Porsche 911 engines it is common for the cylinder head sealing ring the wear a groove into the head itself. Typically this happens on the exhaust port side. The fix is to machine off about .010” on sealing surface of the head. Since the head is stepped machining of the step is also required as the same amount needs to be removed from the head surface and the step.

Gasket ridge

Here you can see the groove that gets worn into the cylinder head sealing surface. Always on the exhaust side.

When he approached me my initial reaction is that I am not set up to do this kind of machining. But as I pondered the details a little more I figured I may be able to pull it off. It was a challenge so I was game. I had warned him that he will be on the hook for any “money” mistakes I make. He already had another set of heads lined up for $2500 just in case my risky venture didn’t turn out.

In the end the heads turned out great. It took a lot of time, careful set up, and repeated measuring but I was fairly pleased with the results. I’ll work you through the process using the visual format. Let’s continue…

Combustion chamber center

The project began by having to build an adapter in order to mount the heads to the lathe. I started off by finding the center of the combustion chamber. I was just barely able to grab the edges of the combustion chamber step in the jaws of my lathe chuck. Now I was able to spin the head up and mark the center on the opposite side.

Milling machine center

With the center marked I transferred the head over to the milling machine in order to continue measuring for an adapter.

Stud centers

I machined an aluminum center finder in order to locate the exact center of the studs. using my DRO I was able to measure, within .0001″, the spacing between the center of the combustion chamber and the 2 studs that straddles it.

Lathe head adapter

With all the dimensions calculate the rest was simple. Using a 3.5 inch chunk of 1014 steel I machined up a precision adapter that would bolt to the studs on the head and, in turn, allow me to center the combustion chamber on the lathe.

Heads blasted

With the adapter built it was time to clean the heads up. Before machining they all got run through the bead blaster to get pulverized with #80 Aluminum Oxide

Ready to cut

Heads are clean and ready to cut!

Here goes nothin'

The heads just barely fit on my little Craftex B227 lathe. I set up a dial indicator in order to monitor my cuts a bit more closely.

The following is a video I shot cutting the heads. To many of you it may seem kinda boring but for me I think it’s pretty cool. Unfortunately YouTube cuts the quality down therefore the video is a bit choppy. I spun the heads up to just over 1600 RPM in order to perform the cutting.

Dial indicator adapter

I built a dial indicator holder in order to mount the tool into the 1/2″ collet of my milling machine.

Measuring step

Here is where the time consuming part comes in. I needed to perform 2 careful measurements. First one was the step. I was shooting for .100″ as that is what the factory spec was. I didn’t use the dial indicator as the measuring tool, I simple used it as a zero point and then performed all my readings using the DRO.

DRO head measuring

The Z axis of my DRO was the scale that did the measuring. All I did was use the Z axis of the milling machine to adjust my dial indicator to zero. then I was able to read my measurement off from the DRO. Here my machined step is well within spec.

Measuring head width

My second measurement involved having to measure the over head height. I built a crude gauge block seen in this picture sitting on top of the vise. I would zero my dial indicator and DRO Z axis to the gauge block. Then I had a base point in order to reference all my other heads to. This dimension is incredibly crucial as a one piece cam housing sits across three of the heads. If the head dimensions aren’t equal then stresses will be placed on the cam and cam housing.

Head dimensions

Lots and lots of measuring, here is 2 of 5 pages worth.

Completed head machining

And here is the finished product. .010″ shaved of cylinder head gasket surface as well as the deck. Just enough to clean up the groove.

6 completed heads

Happy to say I got all 6 heads done and dimensioned with no “money” mistakes.