Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Sanding down a seatpost

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Sanding down a seatpost

Old 03-10-11, 09:33 PM
  #1  
-holiday76
No one cares
Thread Starter
 
-holiday76's Avatar
 
Join Date: Jan 2008
Location: Yardley, Pa
Posts: 6,142
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked 78 Times in 52 Posts
Sanding down a seatpost

Has anyone ever sanded down a seatpost ? I've heard of people doing this with stems so why not a seat post? I have a 3t 27.2mm seat post that I'd love to use on my Gios which seems to take a 27.0 seat post. It's fluted, but I think that the flutes won't be inside the frame so that part shouldnt be an issue.
__________________
I prefer emails to private messages - holiday76@gmail.com
Jack Taylor Super Tourer Tandem (FOR SALE), Jack Taylor Tour of Britain, Px-10, Carlton Flyer, Fuji The Finest, Salsa Fargo, Santa Cruz Tallboy, Carver All-Road .


-holiday76 is offline  
Old 03-10-11, 09:37 PM
  #2  
Grand Bois
Senior Member
 
Grand Bois's Avatar
 
Join Date: Mar 2005
Location: Pinole, CA, USA
Posts: 17,415
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 442 Post(s)
Likes: 0
Liked 16 Times in 16 Posts
I've sanded down and then repolished a couple.
Grand Bois is offline  
Old 03-10-11, 09:44 PM
  #3  
-holiday76
No one cares
Thread Starter
 
-holiday76's Avatar
 
Join Date: Jan 2008
Location: Yardley, Pa
Posts: 6,142
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked 78 Times in 52 Posts
did you use a grinding wheel to do the sanding part? How do you keep it from going out of round? Or does it even matter?
__________________
I prefer emails to private messages - holiday76@gmail.com
Jack Taylor Super Tourer Tandem (FOR SALE), Jack Taylor Tour of Britain, Px-10, Carlton Flyer, Fuji The Finest, Salsa Fargo, Santa Cruz Tallboy, Carver All-Road .


-holiday76 is offline  
Old 03-10-11, 09:55 PM
  #4  
RobE30
Wherever I may roam....
 
Join Date: Oct 2009
Location: Topton Pa
Posts: 1,893

Bikes: A few bikes

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Damn, I was hoping that you had a 27.0 seat post floating around. I need one for the Mondia
RobE30 is offline  
Old 03-10-11, 09:56 PM
  #5  
mazdaspeed
Senior Member
 
mazdaspeed's Avatar
 
Join Date: Jun 2007
Location: WA state
Posts: 4,823
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
I'm also interested in hearing what the best way to do this is.
mazdaspeed is offline  
Old 03-10-11, 09:59 PM
  #6  
rothenfield1
Senior Member
 
rothenfield1's Avatar
 
Join Date: Jun 2009
Location: Montereyish
Posts: 2,329
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
I was wondering about this too. I recently used fine sand paper on the light superficial scratches with so-so results. But the deep gouges would require aggressive sanding or grinding. On the same topic, sort of, some old frames have a massive amount of gunk built-up in the seat tube that causes even a new post to stick, which requires twisting to remove. What method, if any, do you use to clean the seat tube. I hope I'm not distracting your thread holiday76.
rothenfield1 is offline  
Old 03-10-11, 09:59 PM
  #7  
DRietz
Senior Member
 
Join Date: Oct 2009
Posts: 2,708
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I was going to have Khatfull do one for me, but I got busy and never replied to him. Rude, I know. We love you, Keith!

We had decided the best way would be to find something that fit inside the seatpost to mount it on a drill. That way, you could just apply pressure with some emery cloth and get 'er down.

If anybody finds something that fits inside a seatpost relatively well, let me know. Or, if anyone in the Bay Area has a lathe, mounting on one of those would work too.

To Rothenfield1: the best way to clean the seat tube is to ream it.
DRietz is offline  
Old 03-10-11, 10:20 PM
  #8  
Otis
Senior Member
 
Join Date: Mar 2006
Posts: 2,756
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Likes: 0
Liked 9 Times in 9 Posts
The best way to change the size would be to cut it on a lathe. But if sanding is your only option. Make a clamping block by boring a 1" hole in a small chunk of 2" x 4" then split it down the middle. Then you can use both halves to clamp the post in a vise or to a bench top with a c-clamp. Cut strips of wet-dry sandpaper about an 1" wide along the long side of the sheet. Sand using a "shoe-shine" motion using soap and water in a spray bottle as lubricant. Keep turning the post in quarters as you go to keep everything even.

For polishing I would start with 220 or finer depending on the amount of scratches, then work up to 1000 before buffing. To knock .2 mm off you might want to start with 80. Just make sure you are diligent about removing the scratches between each grit as 80 will leave some nasty marks. It helps to wash the post in water between each grit so you can see that the scratches are being erased and you do not co-mingle the grits.
Otis is offline  
Old 03-10-11, 10:30 PM
  #9  
DRietz
Senior Member
 
Join Date: Oct 2009
Posts: 2,708
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Otis - do you know of anything that would fit or expand into a seatpost's inner diameter?
DRietz is offline  
Old 03-10-11, 10:58 PM
  #10  
Otis
Senior Member
 
Join Date: Mar 2006
Posts: 2,756
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 81 Post(s)
Likes: 0
Liked 9 Times in 9 Posts
Originally Posted by DRietz View Post
Otis - do you know of anything that would fit or expand into a seatpost's inner diameter?
Hard not to give a smart-ass response to that...........But:

I do not know of anything offhand but if you looked through enough wood and metal working catalogs I'm sure there's something that would work. An adjustable reamer could probably be used, if you had a drill press with a large enough chuck to hold it. There's adjustable rubber arbors that hold sandpaper rolls that may come in a size that would work? You could probably just use a wood dowel with a slight taper and a wood/metal thread stud centered in one end to use to chuck it.

It might be hard to get something to keep the post turning true as you apply pressure. once it's turning off-center your going to be screwed. A drill press is not a lathe.
Otis is offline  
Old 03-10-11, 10:58 PM
  #11  
buldogge
Senior Member
 
Join Date: Dec 2009
Location: St. Louis, MO
Posts: 1,684
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I either turn the post down on a lathe, or I just take a ball hone to the seat tube. We're talking .004" here!
buldogge is offline  
Old 03-10-11, 11:01 PM
  #12  
AngelGendy
Nipples of Steel!
 
AngelGendy's Avatar
 
Join Date: Feb 2011
Location: ABQ
Posts: 413

Bikes: Borthwick, Specialized, Ross

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
I recently took a 27.2 down to 27.0 with a belt sander just turned it slowly and checked it often it worked well.
AngelGendy is offline  
Old 03-11-11, 07:47 AM
  #13  
Glennfordx4 
Holy Spokes it's Batsman!
 
Glennfordx4's Avatar
 
Join Date: Nov 2008
Location: South Jersey
Posts: 1,961

Bikes: Too many Bicycles to list

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 89 Post(s)
Liked 63 Times in 44 Posts
Originally Posted by DRietz View Post
I was going to have Khatfull do one for me, but I got busy and never replied to him. Rude, I know. We love you, Keith!

We had decided the best way would be to find something that fit inside the seatpost to mount it on a drill. That way, you could just apply pressure with some emery cloth and get 'er down.

If anybody finds something that fits inside a seatpost relatively well, let me know. Or, if anyone in the Bay Area has a lathe, mounting on one of those would work too.

To Rothenfield1: the best way to clean the seat tube is to ream it.
I use a small dia drum sander with a drill bit extender to clean inside of seat post ( note if you have a braze on's for a water bottle remove them 1st) tubes. I just used it to clean up the seat tube on my Schwinn Crosscut which had destroyed a SR TCO post when I removed it from so much crud & corrosion that built up on the inside.

Glenn
Glennfordx4 is offline  
Old 03-11-11, 07:56 AM
  #14  
rootboy 
Senior Member
 
rootboy's Avatar
 
Join Date: Apr 2005
Location: Wherever
Posts: 16,755
Mentioned: 90 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Likes: 0
Liked 124 Times in 73 Posts
A tough nut to crack in a precision way. There is a tool designed to hold the inside diameter of a tube on a lathe or, drill press. It's called an expanding chuck. I have a couple but both larger than the ID of a seat post, and, they're designed to hold one end of the tube while the other end is supported on a tailstock center. Not an option on a seat post. An expanding, rubber sanding drum probably won't work as most of them are designed to be tightened with a nut on the outboard side of the drum, the part that would be buried inside the seat post. You might be able to make something but the trouble might be more than it's worth. Held in a metal lathe, the portion held in the chuck is the same portion you need to turn down, making that method difficult. Even with all the tools and machines I have available, I believe I'd revert to the hand-held sandpaper method if I were attempting this. A seat post is not as critical to keep perfectly cylindrical as a stem would be, of course.

Edit: I spoke too soon. just went down and looked at my expanding sanding drums and two of them indeed tighten with a nut on the inboard, or shank side of the drum, making this a viable option if you can find one of the right diameter. Held in a drill press, the other end of the post, the clamp casting area, would still need to be supported and I think I would use Otis' split block method, clamped to the drill press table and perhaps lined with some felt to avoid scratching the post up near its top. This might work and would give you a level of precision greater than hand-held sandpaper.

Last edited by rootboy; 03-11-11 at 08:31 AM.
rootboy is offline  
Old 03-11-11, 08:38 AM
  #15  
rhm
multimodal commuter
 
rhm's Avatar
 
Join Date: Nov 2006
Location: NJ, NYC, LI
Posts: 19,807

Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...

Mentioned: 565 Post(s)
Tagged: 0 Thread(s)
Quoted: 1886 Post(s)
Liked 472 Times in 294 Posts
Someone whose math skills are more advanced than mine (this would include just about everyone) might want to check me on this, but:

I would take a flat file and cut a series facets 3 mm wide onto the surface of the seat post; there would be room for around 30 facets. Each facet should meet the neighboring ones at the surface of the 27.2 post, forming a series of 30 ridges. Then I'd file each ridge down, resulting in around 60 facets, each around 1.5 mm wide. Then I'd file all those ridges away, aiming for a round shape. Then I'd put the file down and do the shoeshine thing with wet 320 grit sandpaper, followed by 600 grit, 1000 grit, and finally polish. I think that would result in a 27.0 post....
rhm is offline  
Old 03-11-11, 09:23 AM
  #16  
bennie222 
Senior Member
 
bennie222's Avatar
 
Join Date: Apr 2010
Location: Austin TX
Posts: 302

Bikes: '16 Cannondale Slate, '12 Fisher Cronus, '85 Pinarello Triatlon, '98 Sampson Z7 Pro Road Ti , '96 Merlin Titanium, '95 Cannondale V500, '72 Gitane TdF, ' 89 Merckx Corsa Extra, '85 Centurion Ironman pink/yellow, ' 85 1st gen Fuso.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I have a 27.0 post I could be talked out of for you guys in search of one... It came off of this bike, its an SR Laparade style with black accents. It's not terribly long though, you're probably looking at the max height in the pic. I had a 27.0 Thomson post I've been carrying around for 10 years that I put on it so I can convince myself that it was useful to hold onto the thing for that long. PM me with an offer. Cheers.
bennie222 is offline  
Old 03-11-11, 09:36 AM
  #17  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 14,086
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 403 Post(s)
Likes: 0
Liked 86 Times in 66 Posts
I use a piece of 80 grit sand paper and rotate the post and paper combo. When it gets close I switch over to 220 to reduce grit lines and then 600.

Adjustable reamers can purchased at Harbor Freight if one is so inclined to open up a seat tube.

Last edited by miamijim; 03-11-11 at 09:50 AM.
miamijim is offline  
Old 03-11-11, 09:43 AM
  #18  
-holiday76
No one cares
Thread Starter
 
-holiday76's Avatar
 
Join Date: Jan 2008
Location: Yardley, Pa
Posts: 6,142
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked 78 Times in 52 Posts
Originally Posted by bennie222 View Post
I have a 27.0 post I could be talked out of for you guys in search of one... It came off of this bike, its an SR Laparade style with black accents.
i may take you up on that if my sanding fails.
__________________
I prefer emails to private messages - holiday76@gmail.com
Jack Taylor Super Tourer Tandem (FOR SALE), Jack Taylor Tour of Britain, Px-10, Carlton Flyer, Fuji The Finest, Salsa Fargo, Santa Cruz Tallboy, Carver All-Road .


-holiday76 is offline  
Old 03-11-11, 09:58 AM
  #19  
canopus 
Senior Member
 
canopus's Avatar
 
Join Date: Mar 2009
Location: Kingwood, TX
Posts: 1,591

Bikes: Road, Touring, BMX, Cruisers...

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 135 Post(s)
Liked 172 Times in 110 Posts
Originally Posted by rothenfield1 View Post
On the same topic, sort of, some old frames have a massive amount of gunk built-up in the seat tube that causes even a new post to stick, which requires twisting to remove. What method, if any, do you use to clean the seat tube. I hope I'm not distracting your thread holiday76.
Probably the best way is is go to Advance Auto Parts or Sears and get a flexible Wheel cylinder hone, use that with some oil and a drill, quickly and gently. It doesn't take a lot to clean up a seat post tube. They make hones with three adjustable stones but I think whose will tend to remove to much material and will probably get chipped/stuck in the seat post slot cutting.

__________________
1984 Cannondale ST
1985 Cannondale SR300
1980 Gary Littlejohn Cruiser
1984 Trek 760
1981 Trek 710
Pics
canopus is offline  
Old 03-11-11, 10:19 AM
  #20  
mudboy
Senior Member
 
mudboy's Avatar
 
Join Date: Sep 2008
Location: Collegeville, PA
Posts: 1,352

Bikes: Ruckelshaus Randonneur, Specialized Allez (early 90's, steel), Ruckelshaus Path Bomber currently being built

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Tomorrow, either come over and I'll give you the Dura Ace 27.0 I have, or PM me with your address and a time and I'll bring it over.

pruckelshaus AT yahoo dot com
mudboy is offline  
Old 03-11-11, 10:26 AM
  #21  
-holiday76
No one cares
Thread Starter
 
-holiday76's Avatar
 
Join Date: Jan 2008
Location: Yardley, Pa
Posts: 6,142
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked 78 Times in 52 Posts
Originally Posted by mudboy View Post
Tomorrow, either come over and I'll give you the Dura Ace 27.0 I have, or PM me with your address and a time and I'll bring it over.

pruckelshaus AT yahoo dot com
I'll be in touch, but just in case you wondered, I actually need two, which is why I'm still screwing with this other one too
__________________
I prefer emails to private messages - holiday76@gmail.com
Jack Taylor Super Tourer Tandem (FOR SALE), Jack Taylor Tour of Britain, Px-10, Carlton Flyer, Fuji The Finest, Salsa Fargo, Santa Cruz Tallboy, Carver All-Road .


-holiday76 is offline  
Old 03-11-11, 12:04 PM
  #22  
-holiday76
No one cares
Thread Starter
 
-holiday76's Avatar
 
Join Date: Jan 2008
Location: Yardley, Pa
Posts: 6,142
Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 223 Post(s)
Liked 78 Times in 52 Posts
did some minor sanding with 80 and then 150 grit because that's what I had. The post goes in a little better, but I was afraid to push it any further than this.





pay no attention to the bike part explosion.

So I guess a bit more sanding and we'll be good here.
__________________
I prefer emails to private messages - holiday76@gmail.com
Jack Taylor Super Tourer Tandem (FOR SALE), Jack Taylor Tour of Britain, Px-10, Carlton Flyer, Fuji The Finest, Salsa Fargo, Santa Cruz Tallboy, Carver All-Road .


-holiday76 is offline  
Old 03-11-11, 01:37 PM
  #23  
Grand Bois
Senior Member
 
Grand Bois's Avatar
 
Join Date: Mar 2005
Location: Pinole, CA, USA
Posts: 17,415
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 442 Post(s)
Likes: 0
Liked 16 Times in 16 Posts
Originally Posted by -holiday76 View Post
did you use a grinding wheel to do the sanding part? How do you keep it from going out of round? Or does it even matter?
A grinding wheel to remove .1 mm of aluminum? I hope you're kidding!

Some emery paper is all that is needed. I don't use anything too coarse because I sand the full length of the post and have to polish out any scratches that I create with finer paper. You can keep it as round as it needs to be by turning it in your hand. It's not a precision fit.
Grand Bois is offline  
Old 03-11-11, 03:30 PM
  #24  
mudboy
Senior Member
 
mudboy's Avatar
 
Join Date: Sep 2008
Location: Collegeville, PA
Posts: 1,352

Bikes: Ruckelshaus Randonneur, Specialized Allez (early 90's, steel), Ruckelshaus Path Bomber currently being built

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by -holiday76 View Post
I'll be in touch, but just in case you wondered, I actually need two, which is why I'm still screwing with this other one too
Gotcha. I also have a benchmount belt/disc sander that I use for framebuilding. You're welcome to use that if you'd like.

Pete
mudboy is offline  
Old 03-11-11, 05:50 PM
  #25  
RobbieTunes 
Banned.
 
Join Date: Dec 2007
Posts: 27,297
Mentioned: 34 Post(s)
Tagged: 1 Thread(s)
Quoted: 378 Post(s)
Liked 1,395 Times in 902 Posts
I used a B&D workmate and an orbital sander. I slowly rotated it. I used a piece of masking tape to mark the insertion, so I wouldn't have to clean up a lot of sanded post. Started with 80, then some finer stuff, ended with 0000. Then I steel-wooled it with chrome polish and the post looks fine.

Of course, I can't hear a thing now.
__________________

BLDMAMTAOLD


RobbieTunes is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.