Head gasket

[Steamchick]

Working in Engine Design for a car maker, my colleague had a lot of development ad test work to get the Head gasket right for all conditions. More a black art than calculated design! As the gasket was clamped very securely to withstand the dynamic oscillating stresses of combustion, it poses problems for oil and water seals in the same joint. With cold start temperatures from -30°C to gasket temperature up to 150°C at the edge exposed to combustion gases, means the system needs lots of tweaking, following a series of extreme tests.
K2

 

[ninefinger]

Cylinder and head are aluminum so using silver solder is out and I have no way to weld aluminum.

deleted my response - reread and saw that the nub is already JB weld epoxied on.

 

[Gordon]

Just a wild thought but has anyone ever tried to 3D print a head gasket? ABS will withstand pretty high temperatures. I have not really investigated it but I may try it just for an experiment.

 

[a41capt]

Just a wild thought but has anyone ever tried to 3D print a head gasket? ABS will withstand pretty high temperatures. I have not really investigated it but I may try it just for an experiment.

I’ve been considering a printed head gasket (and just gaskets in general) from TPU. The problem is that II don’t have a direct drive extruder/head for the TPU!

Another option to ABS might be PETG since it has the same heat resistance/deformity properties as ABS without the poison fumes!

If I do it, I’ll let you know, but keep us posted on your own experimentation as well.

John W

 

[mrehmus]

Just a wild thought but has anyone ever tried to 3D print a head gasket? ABS will withstand pretty high temperatures. I have not really investigated it but I may try it just for an experiment.

Yes, I printed a crankcase gasket for a 2-cycle engine. It worked fine. Don't remember the name of the filament but it was about 4 years ago so they probably have better now.

 

[minh-thanh]

Just a wild thought but has anyone ever tried to 3D print a head gasket? ABS will withstand pretty high temperatures. I have not really investigated it but I may try it just for an experiment.

As a hobby, I'm a person who hates giving opinions that get in the way of others..
But your idea is too complicated

 

[windy]

With my hydroplane flash steam 14cc 129.33mph engine I used a double ground joint and used no gaskets temperatures and steam pressure was very high.
In Tuning for speed by P E Irving it mentions this method.

 

[awake]

I’ve been considering a printed head gasket (and just gaskets in general) from TPU. The problem is that II don’t have a direct drive extruder/head for the TPU!

Another option to ABS might be PETG since it has the same heat resistance/deformity properties as ABS without the poison fumes!

If I do it, I’ll let you know, but keep us posted on your own experimentation as well.

John W

John, I have printed a few gaskets (and other items) from TPU on my Bowden extruder machine. One key is to constrain the path of the filament as completely as possible - I have the PTFE tubing shaped to go right up to the extruder gear/bearing on both sides, so that the filament doesn't "squirt out" around the gear. The other key is to print slow, around 20mm/s.

I should note that the gaskets I have successfully used were for relatively low pressure, unheated applications. I would worry that in a very hot environment such as a head gasket, the plastic would eventually blow out as it gets hot enough to be squeezed out of the joint. A crankcase gasket, on the other hand, won't get nearly as hot, so I am not surprised that mrehmus reports success with it.

Of course, the only way to know for sure is to give it a try ...

 

[a41capt]

John, I have printed a few gaskets (and other items) from TPU on my Bowden extruder machine. One key is to constrain the path of the filament as completely as possible - I have the PTFE tubing shaped to go right up to the extruder gear/bearing on both sides, so that the filament doesn't "squirt out" around the gear. The other key is to print slow, around 20mm/s.

I should note that the gaskets I have successfully used were for relatively low pressure, unheated applications. I would worry that in a very hot environment such as a head gasket, the plastic would eventually blow out as it gets hot enough to be squeezed out of the joint. A crankcase gasket, on the other hand, won't get nearly as hot, so I am not surprised that mrehmus reports success with it.

Of course, the only way to know for sure is to give it a try ...

Yep, I’ll have to give it a try to see how it works out. First step will be experimenting with the TPU and my Bowden tube!

John W

 

[awake]

John, here are some 3d model views, some pictures, and the .stl file of the extruder I am using. I designed it in your favorite program (FreeCAD ) and 3d printed it. As you can hopefully see, this extruder uses PC4 connectors that allow the 4mm od / 2mm id PTFE tubing to pass through. The end of the PTFE tubing that forms the Bowden tube is cut into an \/ shape so that it can be positioned right up next to the gear/pulley that forms the driver for this type of extruder. A short piece of PTFE tubing, with the end cut into a /\ shape, leads the filament into the extruder, again positioned right up at the business end. This particular design allows the extruder to be screwed into the back of one of the upright panels that form the z-axis.

I had doubts about how well this 3d printed extruder would work. For that matter, I had doubts about how well the whole printer would work - it is a (nearly) all-wood design that I came up with many years ago - shown in the last picture. But it has been working reliably for many years now. There are some things I would do differently, and I have done some design work in view of upgrading ... maybe one day I'll get that done. In any case, when I first built the printer, I was using a cheap aluminum extruder off of eBay. It worked on the same overall principles in terms of how it applied pressure to pull the pulley against the gear, but did not have the ability to feed the PTFE tubing through. I used that cheap extruder to print two or three variants of designs before finally coming up with this one. I am pretty sure I printed this in PETG, just in case the stepper motor would get hot enough to allow PLA to deform.

 

[a41capt]

John, here are some 3d model views, some pictures, and the .stl file of the extruder I am using. I designed it in your favorite program (FreeCAD ) and 3d printed it. As you can hopefully see, this extruder uses PC4 connectors that allow the 4mm od / 2mm id PTFE tubing to pass through. The end of the PTFE tubing that forms the Bowden tube is cut into an \/ shape so that it can be positioned right up next to the gear/pulley that forms the driver for this type of extruder. A short piece of PTFE tubing, with the end cut into a /\ shape, leads the filament into the extruder, again positioned right up at the business end. This particular design allows the extruder to be screwed into the back of one of the upright panels that form the z-axis.

I had doubts about how well this 3d printed extruder would work. For that matter, I had doubts about how well the whole printer would work - it is a (nearly) all-wood design that I came up with many years ago - shown in the last picture. But it has been working reliably for many years now. There are some things I would do differently, and I have done some design work in view of upgrading ... maybe one day I'll get that done. In any case, when I first built the printer, I was using a cheap aluminum extruder off of eBay. It worked on the same overall principles in terms of how it applied pressure to pull the pulley against the gear, but did not have the ability to feed the PTFE tubing through. I used that cheap extruder to print two or three variants of designs before finally coming up with this one. I am pretty sure I printed this in PETG, just in case the stepper motor would get hot enough to allow PLA to deform.

Nice work Andy, and thanks for the files! I’m currently on an Ender 3 V2 using Capricorn PTFE for my Bowden, and love the way it fits. I’ve run the Capricorn Bowden into the bottom of the hot end, and haven’t had a problem with any more clogs or failures since. Since doing that, I have become a big fan of PETG for most of my projects, especially since I live in the Arizona desert!

As far as your printer goes, Wow! Excellent craftsmanship as always, and if it works, it doesn’t need fixin’!

John W

 

[awake]

Thanks! The key for me was making a 3d printer *without* having access to a 3d printer - hence, nearly all wood. This was years before the inexpensive Ender 3s and similar printers came out; nowadays it would not be any cheaper to build one, but back then it was.

 

[Longboy]

I would address the shortfall in the two head bolt design and add a third bolt around the cylinder and a couple of #6 socket heads each side of the valve cutout. That will end the issue of spreading the torque an inch away from the fastener.

 

[Rocket Man]

If you machine the gasket seal area so it has a ruff surface it seals much better. My chevy V8 engine kept blowing head gaskets, the speed shop said, machine the head so it has a ruff surface. Ruff surface solved the problem.

 

[Gordon]

If you machine the gasket seal area so it has a ruff surface it seals much better. My chevy V8 engine kept blowing head gaskets, the speed shop said, machine the head so it has a ruff surface. Ruff surface solved the problem.

Obviously there are different theories on this, In this thread it has been pointed out that the surface finish on the head must be mirror smooth or rough to embed into the gasket. My thoughts are that it has to be smooth if no gasket is used but slightly rough if a gasket is used. On the engine I am having a sealing problem with it is more of a design problem than a gasket problem. I do wonder what would happen if the head was made of steel or cast iron instead of aluminum. Less deflection?

 

[Zeb]

It'd be interesting to see a compression test with the cylinder oiled and warmed up to operating temperature. It might be worse, but worth the try. The aluminum might expand more than the hold down bolts will.

 

[zman92020]

For a perfect trouble free head seal I use a Square rubber oring. I cut a groove to leave a couple of thous to compress the oring.

 

[Longboy]

On the engine I am having a sealing problem with it is more of a design problem than a gasket problem. I do wonder what would happen if the head was made of steel or cast iron instead of aluminum. Less deflection?

I would say no based on the total flat surface area of a scale model where a change in material would not mater. An O-ring would have been a success between two head bolts and cylinder but for the open valve port pathway. The solution is still a more fasteners mod.

 

[Steamchick]

Gordon, I believe you are unable to get adequate compression pressure on the gasket because of the "glued" side-piece... component the 2-bolt sssembly. If you cannot get adequate joint pressure, I.E. greater than the gas pressure when firing, then you will never be able to seal this.
Do a simple test. Make a length of multi-core solder into the shape of the gasket line around the joint. Bolt the head in place to the correct torque. Then disantle, and remove the squidged solder CAREFULLY and measure the thickness wth a micrometer. If not within 0.001" all the way around, then the assembly is not applying uniform pressure on the joint. You will see how the pressure compresses the joint where adequate, and where you have some flexibility of the assembly permitting relaxation of joint pressure, because the metal simply cannot withstand that pressure. Solder should certainly show you what is happening inside the joint.
This is not an answer, but some way of understanding where the weakness lies in the design.

K2

 

[Steamchick]

Hi Gordon, perhaps this is the answer to securing the side piece onto the cylinder? Then you will have reduced deflection of the side piece, and it will be able to seal?
All you need is a bucket load of skill, and a drawer full of Oxy-Propane torch...
(I use a butane blowlamp to the same effect of joining 2 bits of aluminium with the proprietary "aluminium solder").

Just a thought...
K2