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Discussion Starter #1
for those that dont know, "extrude honing" aka "abrasive flow machining" is a way to smooth/polish/deburr materials by forcing a semi-solid "liquid" filled with abrasive through or around them.

there is a company called "extrude hone" that does this for you. the benefits are that can create a very nice surface and completely polish every nook and cranny.

so im wondering what it would take to do this yourself, since it sounds so simple.

patent 3521412 seems to be the origin of this technology, or very near it. its from around 1966.

to sum it what ive learned so far:

in regards to the abrasive material, the patent mentions a "combination that worked" as GE silicone putty SS-91 along with boron carbide as the abrasive, and a couple other things to grease it up and soften it a bit.

I cant find SS-91 for sale, im not sure GE even makes it anymore. But some cross referencing of searches for "silicone putty" as its called in the patent, seems to suggest that it is _literally_ Silly Putty!! If you dont believe me do some searching and I bet you'll come to the same conclusion. SS-91 gets called "bouncing putty" and also "pink commerically available putty" , it appears to be a "non newtownian" fluid that looks alot like the stuff on extrude hones site. Every physical characteristic described in the patent fits it.

It should be noted that extrude hone offers many different grades of and durometers of putty and abrasives. And even the patent mentions that there are many combinations that could work. So this may be just one, and maybe the easiest one to acquire.

It looks like silly putty is pretty expensive, or at least, you have to buy hundreds of dollars worth. I could be wrong about that, as I only did about 30 minutes of research. Ill try to see if I can get a few pounds worth somehow.

Anyways, the silly putty mixed with the abrasive (aluminum oxide, boron carbide, etc.. nothing special) gets forced through the part at 500 to 2000 psi with cylinders, presumably hydraulically activated. The patent describes all this in excruciating detail. Oh, did I mention that there are many other patents on this technology, some much more modern. So if you want to know how they do it its no secret.

So...if we can come up with the following:

-a cylinder of some kind that can hold about a milk cartons worth of the putty/abrasive slurry, and can be pressurized at at least 500 psi
-some kind of hydraulic activator or motor that can power the cylinder
-a few pounds of silly putty
-a few pounds of abrasive grit (boron carbide, aluminum oxide)
-some adapters to connect the cylinders to the intake ports and combustion chambers that can withstand 500+ psi
-some simple circuitry to operate the cylidners back and forth until we get the results we want

then weve got our own extrude hone machine! perfectly polished manifolds and heads with no effort!

i think the method to push the cylinder could be accomplished a million ways...its the cylinder itself that i cant think of a solution. i guess you could just make one out of a steel pipe and some kind of piston with a grease seal..there must be something from harbor freight that does that..what about a grease gun? dont those operate at very high pressures?

i know you can get aluminum oxide sandblasting grit from harbor freight..in fact i have a 10lb jug of it..so thats no big deal

the silly putty material _can_ be purchased..its just expensive. $80 for 5 lbs...and thats LITERALLY silly putty, the toy. its got some other stuff in it that im not sure will be good or bad for this application. its probably time to call dow corning and ge and see if the real stuff can be purchased in small quantities...

i think it would be pretty simple to weld up adapters for the ports and combustion chambers..
 

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the pressure is way up there, a lot higher than cheap materials can hold. They have a lot of money in making the jigs to use the stuff alone. Not an easy thing to reproduce corectly
 

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which would explain the expence in haveing it done - which is likely the best route to go
almost like saying your going to build an at home, home made CNC machine. A ton harder than it looks. In order for the goo to enlarge metal the pressures are unreal, making my concrete pump look like a wimp lol
 

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almost like saying your going to build an at home, home made CNC machine. A ton harder than it looks. In order for the goo to enlarge metal the pressures are unreal, making my concrete pump look like a wimp lol
your post makes me think lol i got to ask one thing and dont get mad at me, but your post makes it seem as if the pressure is actually making the mani grow not removing the rough edges or anything?:confused:
 

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Discussion Starter #6
almost like saying your going to build an at home, home made CNC machine. A ton harder than it looks. In order for the goo to enlarge metal the pressures are unreal, making my concrete pump look like a wimp lol
you guys are making this sound way harder than it is. given the DIY projects ive heard you guys talk about, this is trivial. :)

if im interpreting the patent right, the way this works is like pushing very very hard on a sanding block and then moving sideways slowly. it might not matter at all how fast you move sideways, as long as you eventually get to the end of whatever you are sanding, the abrading gets done. its not velocity based like sandblasting.

so then why not a bottle jack? common bottle jacks put out 2 to 20 tons with a 1 inch shaft...thats 1000's of psi no problem. they move slow but it shouldnt matter since speed is not really relevant here.

if you can seal the bottle jack shaft, which is already hydraulic shaft quality since it is itself a hydraulic device, to another cylinder filled with the slurry, and then seal that cylinder to the head port or whatever with a seal that can take 500 to 2000 psi, i dont see why that wouldnt work. im leaving out the details of the piston..but maybe you can just use another bottle jack in reverse...push its shaft in and fill its cylinder with the slurry with a hole that lets you pump it out. the concept seems pretty basic.

wouldnt a half inch steel plate with a hole in it bolted to all the manifold studs (all 16 or whatever, i forget) hold 500-2000 psi? doing one port at a time with an area of about 2 square inches...lets say 1000 psi operating pressure, so maybe 2000 lbs of force. 16 of those 1/4" bolts can hold that cant they? use some kind of gasket material, copper maybe, like a head gasket shim. although maybe thats not even neccessary if the heads flat.


i dont see why this isnt plausible.
 

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Discussion Starter #7
heres a fun look inside a bottle jack...

How to Make a Hydraulic Rocket Press

i think you could modify it so its just a piston and cylinder, which you fill with the slurry and weld to a thick steel plate with a hole. attach the plate to something that you want to "hone" with the hole in the port.

i.e. the shaft is the piston, and the cylinder is whatever the shaft normally rides in, with whatever seal normally gets used. it all operates at these pressures so it should be good to go i think.

then push on its shaft with another unmodified bottle jack...

hmmmmmmmmmmmmmmmm

even im wondering if it can really be this simple lol....but why not?
 

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your post makes me think lol i got to ask one thing and dont get mad at me, but your post makes it seem as if the pressure is actually making the mani grow not removing the rough edges or anything?:confused:
actualy the how extrude hone works is an explanation on how flow with boost works. In low pressure, NA air flows differently because of shape. A better shaped short turn for instance gets more flow by widening the high flow area of the port. Boost compresses air to the edges, so a perfect shaped short turn is less needed.

In this case the "boost" is so tight and abrasive it removes material lol
 

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Discussion Starter #9
actualy the how extrude hone works is an explanation on how flow with boost works. In low pressure, NA air flows differently because of shape. A better shaped short turn for instance gets more flow by widening the high flow area of the port. Boost compresses air to the edges, so a perfect shaped short turn is less needed.

In this case the "boost" is so tight and abrasive it removes material lol
omg i think im actually going to try this..or at least buy two bottle jacks on craigslist and take one apart

if only i can find a silly putty recycler..hmmm that should be in the phone book right?
 

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heres a fun look inside a bottle jack...

How to Make a Hydraulic Rocket Press

i think you could modify it so its just a piston and cylinder, which you fill with the slurry and weld to a thick steel plate with a hole. attach the plate to something that you want to "hone" with the hole in the port.

i.e. the shaft is the piston, and the cylinder is whatever the shaft normally rides in, with whatever seal normally gets used. it all operates at these pressures so it should be good to go i think.

then push on its shaft with another unmodified bottle jack...

hmmmmmmmmmmmmmmmm

even im wondering if it can really be this simple lol....but why not?
like the guy that makes a CNC machine that makes all kinds of stuff out of plastic. if you make is softer it'll work, aluminum no doubt doesn't take the pressure steel does
 

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humm , I think you would need to put the compound in some sort of container you could squeeze to cause it to move out of the container

I think if you were to try to pump the compound through the hydrolic pump you would have a pump that did not work anymore in short order as the compound would prob eat the pump's seals piston and cylinder walls real quick
 

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Discussion Starter #12
humm , I think you would need to put the compound in some sort of container you could squeeze to cause it to move out of the container

I think if you were to try to pump the compound through the hydrolic pump you would have a pump that did not work anymore in short order as the compound would prob eat the pump's seals piston and cylinder walls real quick
think of a bottle jack. a shaft that has a seal that moves in a cylinder inside the jack. (see the link on the previous post for a picture inside a bottle jack).

now imagine you replace all the hydraulic oil in the bottle jack with the abrasive slurry. now when you push on the shaft, the slurry squirts out of a hole in the bottle jack (modified).

everything was already designed for high pressure so it can handle it.

maybe yer right about the abrasive eating away the seal...it looks like its just an oring. but then again maybe it wouldnt do that or you could add a ring or something before the oring so the abrasive cant get past it? im not sure what would happen to it. the abrasive probably wouldnt get past it since its so thick, but maybe it would eat away at it. maybe you could use a sacrificial o-ring in front of the real oring that gets eaten away or something.

or maybe it would eat away at it but it would last a few times..and that would be worth it..

or maybe you could use a better seal instead of the oring, like an actual shaft seal that wouldnt let the abrasive in..

or maybe it wouldnt eat away at it at all.

etc..

this sounds really easy to try out if we could just round up a bunch of silly putty and a couple bottle jacks.

i dont want to spend $80 for 5lbs worth..and buying the silly putty eggs ends up being $60 a pound i think..ill see what i can get from dow corning and report back
 

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If you used a reversing bottle jack, like the ones used in manual log splitters, you could use the vacuum force of the reverse pumping action to "pump out" the material you pump into the object being extruded. But at that rate, you could always seal each runner to a collector, and blow sand through it. May not get you the best result, but would still "port" the part. Then work up to higher andf finer degrees of medium, till its smooth.
 

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Neato DIY idea. However i think it needs another element to make it work. In order for the extrusion to work, the pressure must be built within the port itself. The analogy above was perfect about the heavy pressure on a sanding block moving slowly. So if we are going to go the slow route of using a bottle jack, there ill have to be a pressure regulating devine on the other end of the port. U could use a nozzle of some sort (steel plate with say an 1/8" hole drilled in it), then pressure would be reg'd with the speed of....jacking. If there wont be anything on the outlet side of the port, then u would need to move the material at high volumes to build ure pressure.

In the end if u just bolted said contraption to the head and started jacking the bottle jack with nothing on the other side of the port, the material would just poop out of the port with nothing achieved accept a mess.
 

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Discussion Starter #17
Neato DIY idea. However i think it needs another element to make it work. In order for the extrusion to work, the pressure must be built within the port itself. The analogy above was perfect about the heavy pressure on a sanding block moving slowly. So if we are going to go the slow route of using a bottle jack, there ill have to be a pressure regulating devine on the other end of the port. U could use a nozzle of some sort (steel plate with say an 1/8" hole drilled in it), then pressure would be reg'd with the speed of....jacking. If there wont be anything on the outlet side of the port, then u would need to move the material at high volumes to build ure pressure.

In the end if u just bolted said contraption to the head and started jacking the bottle jack with nothing on the other side of the port, the material would just poop out of the port with nothing achieved accept a mess.
I hadn't thought of that issue at all..interesting..I assumed that the pressure came due to the force required to push the semisolid putty....but like u say a small hole on the other end could regulate it...damn this is getting interesting...time to get some of the putty and try this out! I didn't call dow this week but I will next week..
 

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A small hole isnt going to work, youve got to have high volume of the material flowing through the port, a small hole is just going to allow the material to find the path of least resistance wich will be nowhere near the walls.
you would need about ten big bottle jacks all being pushed consecutively just to get a few seconds of sanding, your going to expend a lot of energy for very little benefit.

ive seen video of the process in action and the material is pumped through pretty quickly and most people say the results are less than satisfactory even from extrudehone
 

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Discussion Starter #19
A small hole isnt going to work, youve got to have high volume of the material flowing through the port, a small hole is just going to allow the material to find the path of least resistance wich will be nowhere near the walls.
you would need about ten big bottle jacks all being pushed consecutively just to get a few seconds of sanding, your going to expend a lot of energy for very little benefit.

ive seen video of the process in action and the material is pumped through pretty quickly and most people say the results are less than satisfactory even from extrudehone
facts from the patent:

the patent describes the device as two cylinders "slightly less than 3 inches in diameter and 10 inches long". its a push-pull arrangement. it actually describes it in excruciating detail with drawings too, but thats the cylinder dimensions.

with a hyrdaulic pressure of 1500 psi driving the cylinder arrangement, the material was expelled at about 3/4" a second from the cylinders, and because the work piece hole was small, about 30" per second through the work piece.

one pass removed typical grinding burrs and radiused all edges 0.002 to 0.005.

i cant seem to find the diameter of the workpiece hole in the patent, from the drawing it looks to be just under an inch.

so if we extrapolate here, if our pressure source can push a 3" diameter plunger at 1500psi and move about 3/4" a second, thats in the rough realm of this device, and roughly close to the diameter of a port. if we can do better than that by a factor of 2 for displacement per second, I think we are in the head porting range of speeds..sort of a guess but it seems based on the numbers here.

so the area of a 3" diameter plunger is about 7.1". if we double that area and keep the plunger displacement rate the same (3/4" a second), in order to double the flow rate, we need to make the plunger about 4.4" in diameter. The area of a 4.4" diameter circle is about 15.2".

if we assume we need 1500 psi on our 4.4" diameter the plunger, thats 15.2 x 1500 = 22800 pounds of force on the plunger. Divided by 2000 for tons its 11.4 tons.

Assuming you can "hollow out" a bottle jack, modifying it so you can fill its cylinder with putty and push on its shaft backwards to force the putty out of a hole, I think you can do what the patent describes. The patent describes a plastic cylinder filled with the putty, so maybe thats how they protect the actual metal cylinder/plunger. A disposable plastic one inside the metal one. Since its surrounded by the metal, the plastic doesnt have to hold the pressure itself.

Even a cheap-o average bottle jack can put out that kind of pressure. And if you operate them fast enough I think 3/4" a second is possible, although apparently irrelevant to the abrading action, since its not based on velocity, anymore than pushing on the sandpaper block and moving slowly is.

To really make this DIY project shine, its going to need to be automatic. Air operated or something so you can let the cylinders push the abrasive putty back and forth for hours. Its way too much work to do by hand.

Heres an air operated harbor freight, 20 ton jack (40000 lbs):

20 Ton Air / Hydraulic Jack

Its $119, but get used one and yer in the $50-$60 range..plus, this one doesnt get modified. You use this as the force creater to push in the shaft of your putty filled modified standard bottle jack. So you get to keep this as a nice jack to have around.

This actually seems so fun to try that the part keeping me from trying this right now is $90 of putty...I just cant see myself buying that much silly putty. It'll happen, but Im gunna have to feel I have cash burning a hole in my pocket. Next month or so I bet...

Heres the patent diagram, item 39 is the workpiece.

 

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I used to have a couple samples of the actual Extrude Hone material and I can attest to the fact that it is exactly like silly putty. Though, EH has different viscocities available for use on different materials.

We used to play with it in the office just like you would silly putty. The most fun we had with it was dripping it down the monitor, or coating the desk of an engineer that was on vacation. Amazing how far that stuff will flow over the course of a week...
 
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