[lambiam]

I have access to a lathe for metal and am wondering how hard it would be to make my own 24.3mm straight seatpost?

I figure that if I got some 1" round stock material I could just turn it down from there?

It is going to be straight and use the old school seat rail clamp.

What would be the best material? I'm not worried too much about weight...its just for a my casual around the town single speed.

And if there is any other tidbits anyone cares to share please let me know

 

[daleksic]

You'd be better of just picking one up for $10 bucks on eBay.

But if I had to make one i'd go with Aluminium. Turn it down to the correct size and then drill a hole through the middle. Make sure there is enough meat there where you clamp down on it.

If you can get hold of Titanium or a Titanium alloy go with that. If you go with Steel make sure it has a high content of chrom to reduce/eliminate rust.

 

[JustFuzzIt]

I wouldnt recommend it. You risk snappage. You would have to make sure you were using the right material, not just any alluminum. I am no engineer, but I can see bad things coming from this if its not correctly done.

 

[lambiam]

right..thats what i'm afraid of...

but since noone makes 24.3mm...... I might just sandblast what i have and powdercoat it black or something....probably easier that way...

 

[ettore]

Buy a DH post that is too large, then machine it down to the odd size you need. You'll have the quality materials required to make a DH post work, but you will be machining off the outside to make the wall thickness thinner. I am not very well versed with the standard seatpost sizes, but if you can get one pretty close .... why not?

My Thomson Masterpiece (30.9 I think) wall thickness is like 1mm (I could measure if you'd like) and it's trong enough for what I do to it. Now, the one on my Kona (27.2) is probably triple that in thickness ... I could probably machine the outside down quite a bit.

 

[JustFuzzIt]

I would try buying a smaller seatpost and using a shim.

http://www.unicycle.com/shopping/shopexd.asp?id=244

Something like that. You should also be able to jsut make your own with shim material. An LBS should have some with different widths.

 

[daleksic]

I'll vote for the smaller post with shim...

 

[kramnnim]

If weight isn't an issue...I don't see how nearly an inch of solid aluminum could break.

 

[lambiam]

Kramnnim...

thats what i was thinking...just machine the tip to fit the seat rail clamp and be done with it hah...

 

[Danketch71]

You are keeping a lot of weight leaving the inside unbored out. I think most seatposts are hollow on the inside, and maybe you might feel a stiffer ride because of this. Also, seatposts in general are kind of long (1-2.5 ft I think), do you have a really long jobber drill 6" to 15" to drill it out?

Just some thoughts from a machinist/noob MTBer.

 

[Danketch71]

Oops, just saw you don't care about weight. A solid piece of 6061 should be fine.

 

[itgogitrev]

Using solid 6061-T6 is WAY overkill. I'd stay away from steel unless you planned on painting it. Your best bet it to find some scrap stainless piping, 304 is the most common and usually the easiest and cheapest route.

Do not use titanium unless it's fairly thick walled. Unlike steel, stainless, or aluminum, titanium will simply break; it won't bend.