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Question on Acetone/ATF use

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Old 07-11-18, 10:52 AM
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tiger1964
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Question on Acetone/ATF use

Trying to remove a seat post stuck for several decades. I bought acetone (nail polish remover, there are other ingredients) and ATF (STP general purpose, it's reddish) and mixed 50/50 in a jar. I have started dribbling it around the outside join with a syringe, and also flipped the bike and dribbled some into the seat tube via the BB shell. So far no luck, but am willing to be patient.

I've noticed that the two ingredients separate, rather like salad dressing, after about a minute. Is this normal, and will it still work? I read somewhere around plugging the hole in the end of the seat post (with what, I do not know), inverting the frame and filling the seat tube until the entire seat post is immersed (again, how to tell?); but, if the ingredients separate, I'm only going to have one of the two in contact with any part of the post or frame.

Of course, if none of this works, I am prepared to start cutting - yikes.
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Old 07-11-18, 11:08 AM
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Did you already try Zep 45, Kroil, PB Blaster or other penetrating oil products first? The Zep is supposed to be especially good with aluminum parts.

Acetone will eat your paint.
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Old 07-11-18, 01:22 PM
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tiger1964
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Thanks. Of course, I have PB Blaster handy but not Zep 45.

Paint? All gone, down to stripped frame.

Was hoping that the 50/50 mix was a magic bullet here,,,

Originally Posted by Kontact View Post
Did you already try Zep 45, Kroil, PB Blaster or other penetrating oil products first? The Zep is supposed to be especially good with aluminum parts.

Acetone will eat your paint.
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Old 07-11-18, 01:28 PM
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If its down to the bare frame then why not use a little heat? Start off with a heat gun then move onto a torch if necessary. Just don't get it hot enough to met the solder (assuming lugged construction).

But to answer the question, separation is normal. Vigorous shaking can help prolong the time before separation.
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Old 07-11-18, 02:25 PM
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tiger1964
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Originally Posted by zze86 View Post
If its down to the bare frame then why not use a little heat? Start off with a heat gun then move onto a torch if necessary. Just don't get it hot enough to met the solder (assuming lugged construction).
Hmm, I do have a plumbing torch. Also, a point-n-shoot pistol-grip thermometer, I wonder what's a "safe" temp?
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Old 07-11-18, 02:55 PM
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Yeah, like oil and vinegar, the ATF/acetone mix does separate, but I keep a small amount in a glass spice jar and just give it a good shake before using it. I've been going that route since coming across this info:

Machinist's Workshop magazine actually tested penetrants for break
out torque on rusted nuts. Significant results! They arranged a subjective
test of all the popular penetrants with the control being the torque
required to remove the nut from a "scientifically rusted" environment.
Penetrating oil .......... Average load
None ..................... 516 pounds
WD-40 .................... 238 pounds
PB Blaster ............... 214 pounds
Liquid Wrench ............ 127 pounds
Kano Kroil ............... 106 pounds
ATF-Acetone mix............ 53 pounds
tiger1964, what's your method for getting leverage on that post? I've had good luck with putting the post in a vise and twisted the frame.
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Old 07-11-18, 03:00 PM
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RJ the bike guy has some good youtube videos on removing stuck seat tubes. I haven't tried his techniquies, but it is worth a look.

The Acetone ATF mix is pure acetone, not nail polish remover. Home Depot, Lowes and your local hardware store sell acetone.
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Old 07-11-18, 03:13 PM
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As previously mentioned, try the thermal cycling method - get the post good and hot (well, not TOO hot, don't melt the post or soften the welds or de-temper the frame) and then dunk it in a large bowl of icewater. Repeat that a few times and then let it sit with the mixture of ATF\acetone for a few days.

If this is an alloy post in a steel frame, lye is an extremely effective way of removing the seatpost by completely destroying it.

I needed to use the lye-fueled 'removal with extreme prejudice' method with the post that was stuck in my 1986 Trek.

Good luck!
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Old 07-11-18, 04:17 PM
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I'd say keep the exposed end of the aluminum seat post submerged in salted ice water. Heat the frame with a propane torch. The steel expands very little. The aluminum shrinks a lot (relative to the steel) if you get it cold. Try to keep the seat post cold as you heat the frame a little.
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Old 07-11-18, 04:31 PM
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Originally Posted by Bad Lag View Post
I'd say keep the exposed end of the aluminum seat post submerged in salted ice water. Heat the frame with a propane torch. The steel expands very little. The aluminum shrinks a lot (relative to the steel) if you get it cold. Try to keep the seat post cold as you heat the frame a little.
Where is that liquid nitrogen container when you need it?
Actually dry-ice in contact with an aluminum seatpost had an effect too.
Trouble with the penetrant tests, is for the most part are concerned with both steel nut and bolt.
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Old 07-11-18, 04:32 PM
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There is no magic bullet. Deal with enough stuck posts or stems, and you will find out every method fails, except cutting it out.

As the chart above shows, ATF/acetone is your best shot for penetrating compounds. So its worth a try.

And realize you can and probably WILL put more pressure on a frame trying to free up stuck parts. I've bent a frame trying to do it.
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Old 07-11-18, 04:32 PM
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Originally Posted by tiger1964 View Post
Hmm, I do have a plumbing torch. Also, a point-n-shoot pistol-grip thermometer, I wonder what's a "safe" temp?
Solder will melt at approx 360degF. Keep it eell under 300 and you should be good. I would not hit the soldering joints directly. Do NOT try to cool the frame down by spraying cold water at it.
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Old 07-11-18, 05:29 PM
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Originally Posted by Bad Lag View Post
I'd say keep the exposed end of the aluminum seat post submerged in salted ice water. Heat the frame with a propane torch. The steel expands very little. The aluminum shrinks a lot (relative to the steel) if you get it cold. Try to keep the seat post cold as you heat the frame a little.
Given aluminum's ability to rapidly change temperature, I would heat the frame (and seat post), and then dunk just the exposed seat post in ice water when your at max temp. The resulting rapid cooling should have more of an effect than trying to simultaneously heat and cool,

If you have the top of the seat post cut off, dumping super chilled liquid through the seat post would be another way of rapidly cooling it from the inside out, creating a peak differential in temp between the steel and aluminum. The goal is to get the corrosion that is bonding them to break. Then immediately smack the post with a hammer or twist it out.
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Old 07-11-18, 05:43 PM
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If you have one of those gel type freezer packs, you could wrap the seat post in that while applying heat to the seat lug. Coefficient of thermal expansion is much greater in aluminum than steel, so you need to keep it colder that the seat lug.

Sometimes just cycling heat on the post and lug may be enough to break the joint loose.

are you trying to save the seat post?
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Old 07-11-18, 06:21 PM
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Shoot - actual acetone. I have cans of about everything else in the workshop: boiled linseed oil, naphtha, denatured alcohol and mineral spirits and after 35 years owning an old house I don't remember why I bought most of them. But no acetone.

Originally Posted by nlerner View Post
tiger1964, what's your method for getting leverage on that post? I've had good luck with putting the post in a vise and twisted the frame.
Good idea, I started with an 18" set of water pump pliers ("Channel-Locks"), was going to graduate to "Vise-Grips", but I do own a vise.

Originally Posted by Bad Lag View Post
I'd say keep the exposed end of the aluminum seat post submerged in salted ice water.
Interesting, I guess I then try to quickly move the bike to the vise.

Originally Posted by wrk101 View Post
There is no magic bullet. Deal with enough stuck posts or stems, and you will find out every method fails, except cutting it out. [SNIP] And realize you can and probably WILL put more pressure on a frame trying to free up stuck parts. I've bent a frame trying to do it.
Ouch... and OUCH.

Originally Posted by zze86 View Post
Solder will melt at approx 360degF. Keep it eell under 300 and you should be good. I would not hit the soldering joints directly. Do NOT try to cool the frame down by spraying cold water at it.
Thanks for that number. I'm used to "sweating pipes" with solder, I had always presumed brazed frames used a product with a higher melting temp.

Originally Posted by satbuilder View Post
If you have one of those gel type freezer packs, you could wrap the seat post in that while applying heat to the seat lug. Coefficient of thermal expansion is much greater in aluminum than steel, so you need to keep it colder that the seat lug. [SNIP] are you trying to save the seat post?


I have various freezer products to try. No, the old post is toast. There's a nice looking one on the For Sale forum but want to get the old one out first to check the seat tube inner diameter before buying anything as a replacement.
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Old 07-11-18, 06:33 PM
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Originally Posted by tiger1964 View Post
the old post is toast.
assuming this is a steel frame and an aluminum post, take a look at the lye method I posted a link to earlier. You've already stripped the paint off the frame and you aren't trying to save the post, so the only thing you need to worry about preserving is yourself.
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Old 07-11-18, 08:00 PM
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I know this is common, but no-one has mentioned:

Seat post in vise. Bike inverted. Lots of penetrant (I like kroil, but acetone/atf fine) from inside BB down into seat tube.


Let sit..

Use leverage of frame to just break loose seatpost.
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Old 07-11-18, 09:59 PM
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Originally Posted by zze86 View Post
Solder will melt at approx 360degF. Keep it eell under 300 and you should be good. I would not hit the soldering joints directly. Do NOT try to cool the frame down by spraying cold water at it.
Frames are not built with tin-lead or any other type of solder. They use brazing alloys. By definition, brazing alloys melt at much higher temperatures than solders.

Brazing alloys melt at 450 C or higher, depending upon the alloy. Brass melts at around 900 C. "Silver solder", not a solder at all, pure silver melts at 960 C. You can use materials like those because steel melts at around 1400 C, a full 400 C higher. For comparison, your 360 F for solder is 180 C.

Aluminum melts at 650 C.

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Old 07-11-18, 10:05 PM
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Originally Posted by repechage View Post
Where is that liquid nitrogen container when you need it?
I thought suggesting that was too off-the-wall until I saw the lye video. LN2 is MUCH safer than that lye technique.

One could always drill/mill out the post. Save just the last bit of wall thickness and ream out the final bits. How about a lathe and a boring bar?
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Old 07-11-18, 10:46 PM
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Originally Posted by Bad Lag View Post
Frames are not built with tin-lead or any other type of solder. They use brazing alloys. By definition, brazing alloys melt at much higher temperatures than solders.

Brazing alloys melt at 450 C or higher, depending upon the alloy. Brass melts at around 900 C. "Silver solder", not a solder at all, pure silver melts at 960 C. You can use materials like those because steel melts at around 1400 C, a full 400 C higher. For comparison, your 360 F for solder is 180 C.

Aluminum melts at 650 C.
Thanks for the data. I know solder for frames is at a higher temp but I specifically went with the lower number of tin lead solder. There is no reason to get the frame hotter than this. You're just trying to expand the metal a bit is all. You could get it red hot if you wanted to but seems kind of overkill.

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Old 07-11-18, 11:10 PM
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Originally Posted by Bad Lag View Post
Frames are not built with tin-lead or any other type of solder. They use brazing alloys. By definition, brazing alloys melt at much higher temperatures than solders.

Brazing alloys melt at 450 C or higher, depending upon the alloy. Brass melts at around 900 C. "Silver solder", not a solder at all, pure silver melts at 960 C. You can use materials like those because steel melts at around 1400 C, a full 400 C higher. For comparison, your 360 F for solder is 180 C.

Aluminum melts at 650 C.
Low temp solder is occasionally used for small stuff, so it is reasonable to use that as a limit. Along the same lines, 350F is the start temp for tempering steel.

I usually stick with the boiling point as a safe a temp for everything.
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Old 07-12-18, 06:52 AM
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Originally Posted by Reynolds 531 View Post
I know this is common, but no-one has mentioned:

Seat post in vise. Bike inverted. Lots of penetrant (I like kroil, but acetone/atf fine) from inside BB down into seat tube.


Let sit..

Use leverage of frame to just break loose seatpost.
Just don't break frame. I've done it. Frames are not designed for the side to side forces the average person can put on it doing this operation. And be sure to NOT touch the stays! Use the seat tube and head tube as your two grip points.

As far as the lye method, potentially very dangerous. Think twice before trying that option. IMHO, the average homeowner does not have adequate equipment to handle lye properly.

I've seen both pure acetone and acetone with additives at Walmart in the nail polish area. Just check the labels.


bill
licensed professional chemical engineer with 35 years in the chemical manufacturing business; worst accident in my career involved lye solution

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Old 07-12-18, 08:46 AM
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Originally Posted by repechage View Post
Where is that liquid nitrogen container when you need it?
You know, my wife works at NASA and I've seen dewars of that stuff sitting around -- not sure how she'd get it home, however; Tupperware would be inadequate, I figure.

Originally Posted by Reynolds 531 View Post
I know this is common, but no-one has mentioned: Seat post in vise. Bike inverted. Lots of penetrant (I like kroil, but acetone/atf fine) from inside BB down into seat tube. Let sit.. Use leverage of frame to just break loose seatpost.
That, with our without heat, is the next attempt.

Originally Posted by Bad Lag View Post
Frames are not built with tin-lead or any other type of solder. They use brazing alloys. By definition, brazing alloys melt at much higher temperatures than solders.
Figured as much.

Originally Posted by Bad Lag View Post
How about a lathe and a boring bar?
I so badly want some machine tools but not even my wife is that forgiving on bike-related purchases.

Originally Posted by wrk101 View Post
Use the seat tube and head tube as your two grip points.
Something tels me to keep my "heat-proof" grilling gloves handy...
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Old 07-12-18, 10:50 AM
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Chemical solutions to the problem (intentional pun there). Dissolve the corrosion products wedging the two together rather than the massive seat post, itself.

Use oxalic acid to dissolve corroded steel.
What dissolves aluminum oxide but won't hurt steel?
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Old 07-12-18, 12:07 PM
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Physics is your friend. You can exploit the differences in thermal expansion between steel and aluminum alloys to free your seatpost. Aluminum expands / contracts with heat almost exactly twice as much as steel. (13x10^-6 vs 6.8x10^-6 in Fahrenheit) Heating can help, in that it expands the aluminum more than the steel, crushing the oxidation products, and potentially opening up a tiny bit of room when things cool back down for penetrating oil. Multiple cycles may do the trick. Even better, get the seatpost cold. Dropping the seatpost / seat tube from 75F to -13F (boiling point of Difluroethane -- compressed air in a can) will create a .0006" gap between the seatpost and seat tube. It doesn't sound like much, but I've had very good luck with clamping the seatpost inverted in a vise, filling the seatpost / tube with a healthy dose of inverted "air-in-a-can", and giving it a go. Once it breaks free, you can tug and rotate to further grind up the oxides and free the seatpost. Dry Ice or liquid nitrogen would be even better, but are progressively harder to acquire / work with.
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