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Elninio
08-22-2006, 03:01 PM
...so what happened is I bought the smallest cross sliding vice from busy bee and put it on my 8 inch delta drill press. Just about a week later i arrange a freind that i met at the skatepark to give me a really old and really beefy bmx stem, the redneck by S&M. Here is what it looks like:

http://www.revolutionbike.com/STEM-REDNECK.gif

Dont let the proportions fool you, this stem is HUGE and long. As a comparison I took this photo of the redneck in comparison to another stem that ive been working on

http://i111.photobucket.com/albums/n122/elninio123/Picture011.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture005.jpg

So i managed to machine it down from 18oz to just over 10 oz. Here are some pics:

http://i111.photobucket.com/albums/n122/elninio123/Picture008.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture004.jpg

Elninio
08-22-2006, 03:01 PM
http://i111.photobucket.com/albums/n122/elninio123/Picture010.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture007.jpg

surface finish was poor at first because the drill press spindle has ALOT of play in the spline, but i managed to overcome that with an extremely low feed. EXTREMELY! like 20 minutes per inch!

http://i111.photobucket.com/albums/n122/elninio123/Picture008.jpg

Mission accomplished. Next to hit the mill is:

http://i111.photobucket.com/albums/n122/elninio123/Picture002.jpg

Elninio
08-22-2006, 03:10 PM
here is a list of operations i did to it:

shaved the back, slotted the face block of the stem, slotted the stem, drilled a hole thru the middle of the stem, then made it into an oval shape. milled channels in the sides of the stem where it clamps to the steertube. All this was done with a 9/16'ths mill. I would have milled some material from the top too but its not yet my stem so my freind said to not to do it (what a wuss!).

topct
08-22-2006, 03:36 PM
I have tried that drill press milling machine. Very frustrating.

I see a lathe chuck. Look at this setup,

http://vts.bc.ca/metalshop/SB9mill/sb9mill.htm

Much better. And you have a drill press to help make those pieces.

You did have better luck than I did however.

john hobdeclipe
08-22-2006, 04:22 PM
Be careful about how much weight (strength) you remove from critical components. A broken handlebar stem is usually instant disaster.

The safest place to trim weight is the rider.

bob_s
08-22-2006, 10:58 PM
Be careful about how much weight (strength) you remove from critical components. A broken handlebar stem is usually instant disaster.

The safest place to trim weight is the rider.


And remember that "road rash" trims rider weight really fast!

torker
08-22-2006, 11:53 PM
Chris....glad to hear you're finally getting to do some machining even if it is slow, perhaps a bit crude and goes against the norm.
At least you are learning and I'm bettin you now see what all the ol' guys cautioned you about.
And you are going to learn from your mistakes...I just hope you don't break your melon in the process :D
Russ

abn
08-23-2006, 02:18 AM
Awesome to see your progress...congratulations! Be careful as others have stated...even the pros over do it sometimes with the weight removal thing, proceed with caution but by all means proceed.

Wirecutter
08-23-2006, 11:11 AM
I broke a regular steel handlebar stem once, and can only say that I was surprized I wasn't killed instantly. Or was I?

-Mark

Elninio
08-23-2006, 05:13 PM
yea my dad was saying that i "f****d" it up when i machined the sides of it but you gotta understand that this stem is HUGE and that there are much smaller stems with very similar or even more machining. I'm also very careful where i take my bike - only riding the quarterpipes and spines.

Check this out http://easternbikes.com/a/products/frames/GrimReaper/GrimReaper.html

even I (me being oriented to super light parts) dont approve of this and it is successful model, seems to be pretty solid.

torker
08-23-2006, 08:50 PM
Christian...here's what my nephew Dustin is up to lately...
http://www.fatbmx.com/modules/news/article.php?storyid=1724
Russ

Elninio
08-24-2006, 02:47 PM
holy cow! hes a legend. With your help i bet you guys could start a really serious bmx company :D

pcarpenter
08-24-2006, 04:31 PM
Don't let the size of parts be the only determining factor in deciding whether you can get by with cutting on them or reducing their proportions.

Strenght of material can determine how much of it you need. I don't mean just aluminum vs. steel, but things like which alloy and how it is heat treated.

With most things (think aircraft or automotive parts) we have seen things get lighter and less bulky over the years, but it is due to changes in material and manufacturing processes, not just because someone decided to mill off a chunk and see if they could get by with it....although I am sure there is some of the latter done too;)

Break a yoke like that and you could end up with a stem in the nuts...or the chest... or a broken neck. If you want to see what the failure mode is like, take off the handlbars and try to ride the bike. Now imagine that in the middle of heading down a half-pipe.

Paul

Elninio
09-14-2006, 04:18 PM
heres some progress on that other stem, this one has been done using the milldrill,

http://i111.photobucket.com/albums/n122/elninio123/Picture015.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture014.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture012.jpg

http://i111.photobucket.com/albums/n122/elninio123/Picture013.jpg

havent trammed the mill yet because i cant afford a dial indicator with magnetic base, by the time i do that i will have put a homemade powerfeed on the mill made from the 1/2 hp motor from my 8 inch drill press, so next week maybe. I havent machined everything on the stem so if you see a crappy finish with dents and remainder of black paint its from before the machining, i only faced it where necessary because im gonna buff it to a shine =-)

Your Old Dog
09-15-2006, 12:06 PM
Have to say that I admire you for not just up and quitting because you don't have a shop full of machinery. Someday you'll have the cash to have the same shop many of us do now and you'll be way ahead of the game! Not only that, If I need to find you I'll know where you spend a good deal of your time and not in a bar somewhere.