I just use a pipe cutter, stick it in without using a file, and go on without any problems.
i think the problem is ppl getting overly tight with the pipecutter, just don’t crank the cutter so much.
That is what my Dad told me (after I got a seat post stuck in a frame). He said if you cut too fast it’ll flare the end a lot more, but even if you do crank it really slowly, filing the outside edge is not usually a bad idea.
It took us an afternoon to get the seat post out of my KH 36 frame after I got it lodged in there. In the process of trying to separate the two pieces, I scratched up the inside of the frame so much that I couldn’t get the post back in even when it was filed. We had to use a round file and a few invented power drill attachments to smooth the inside of the frame again.
Lesson learned: don’t be so impatient with the pipe cutter, and file the edge of the seat post.
This has been what’s worked for me. I haven’t cut too many posts with the pipe cutter, but so far no problems noticed. You have to file if you use a hacksaw anyway, but I don’t think you need to file as much if you make a gentle cut with the pipe cutter. All pipe cutters may not be created equal however, so some may be more flare-prone than others…
I’ve always used a hack saw and file, its quick, easy and clean. The angle grinder looks fun though, I’ve only ever used one for cleaning my uni frame off with a wire brush disk 
Well this thread calls for a note to self! Don’t use a pipe cutter to cut down posts.
You’re doing it wrong!
Soap and water are for washing your hands, not for working with metal.
Unless it’s oil or grease, you shouldn’t be putting it on a seatpost… you’re only going to make things worse.
Really, you can use any oil on your seatpost in a pinch… even motor oil or vegetable oil… just remember to wipe off any excess to keep things clean.
Reciprocating saw FTW!
I love mine (I mean my dads…) cuts through anything in seconds, never had a problem with it, cuts through aluminum, steel, anything! And its huge!!!
For the record, I did file the post after using the pipe cutter. Quite a lot of filing in fact, but obviously not enough.
The pipe cutter causes the bottom to flare outwards due to the pressure from the pipe cutter roller. So it means you can get it into the frame easily enough, but when you try to pull it out, it’s like a rachet- it cuts into the seatube and stops you from pulling up.
It’s almost welded itself into the frame now. I’m going to take it to the bike shop to use a vice and a blowtorch.
maybe you can cut the top off and put a smaller seatpost inside with shims…
I use a small plumbing pipe cutter (made for cutting copper pipe) and take it easy, low pressure, no rush. Then give the cut a quick sandpaper just to take the sharp edge off, bit of grease, job done.
Damn I had the same thing happen to me, I thought the kh tolerances were a bit goofy since I had an 07 post in the new long neck. The seat post now has rings all around it, bare alu from scratching or something. I’ll be using a hacksaw from now on.
Ouch! I never thought about the possibility of the seatpost getting stuck because of using a pipe cutter to cut it.
I have always used a pipe cutter. Gives an even cut. The one thing I do when using a pipe cutter is to make sure that the roller is on the side that I want to keep. That way most of the mushrooming happens on the side of the pipe that I’m going to throw away. I still need to file some, just not as much.
Good warning though. I’ll have to rethink my preference for using a pipe cutter rather than a hack saw.
I’m not sure what you mean. The pipe cutter was an industrial one with rollers on both sides.
We spent an hour wrestling with the frame, and heating it up with a paint stripper. We moved it about 2cm, and then gave up.
I’m getting another KH frame. The alternative was to take it to an engineering workshop to see if they can drill out the seatpost, but the problem is that I don’t have the time to faff around with that, and also, by the time they charge for labour etc, it probably would just be easier to buy a new one.
I’ve had a bad day 
Ken
p/s if anyone doubts the strength of the KH frame, I can vouch for the welds. We gripped the top of the seatpost in a vice, and basically bashed the $@#! out of the frame for over an hour. We also torqued the fork arms with a very large piece of wood, and wrestled with them until my knuckles turned white.
No sign of any cracks in the welds, or bent fork arms as far as I can tell.
maybe i could muscle it out at my house…
or give it a good home…
That would be a bad day. 
The pipe cutter I have has rollers on both sides, but there is a trough on one side that allows the metal to mushroom more on one side of the cut than the other.
I’m going to get myself a good saw guide and then hide my pipe cutter.
I think if you filed it down enough, it might be ok.
But please note that I actually did a lot of filing before sticking it in. And it still managed to weld itself in there.
How to extract that seatpost
I wouldn’t give up on that frame just yet. Is this one of the frames that allows you access to the seatpost through the bottom of the fork crown? If not, cut the seatpost off the frame, leaving approximately 1" sticking out (for purchase to pull on, later). Then take a raw hacksaw blade and go at the seat post from the interior, cutting a slot in it from the inside outward. If you’re patient, you can do this with very minimal damage to the frame. Once the slot is through the seatpost, when you tug on it the circumference will collapse into the blade slot you made and it should come out. If you can access the post through the fork crown, I would concentrate only on the bottom inch or so, since we presume that is where the binding is.
If you do get it out, I’d carefully inspect the frame for any burrs or similar damage that might stick the next seatpost. They can easily be cleaned up with a ream, or even a rat-tail file.
No, it’s a frame that is sealed at the bottom.
I don’t normally give up easily, but I’m also not silly. Spending several hours on something to just save a few dollars is not worth it. I have no attachment to the frame…because it’s new. If it was my Coker frame then that’s a different matter altogether. That has sentimental value, and I’d happily file it down with sandpaper before I gave up on it.
It really is depends on whether there are any KH frames in stock.
Ken how large was the pipe cutter you were using? From what you say re filing, it sounds like it was too big for the job causing excessive flaring of the metal. The pipe cutter I use can only handle up to 30mm dia, with a narrow cutting wheel - see pic. Haven’t had any problems, no need for filing, just a light sand.
Not that it helps much now, but didn’t it feel unusually tight when you started to put the seat post in?
It was about 3 1/2 times bigger than that.