Re: Small Part Machining

john

June 30, 2011 at 11:05 AM

A great place for fasteners in portland area, is Parkrose Hardware. They
have a lot of metric fasteners and everything else..

"The piece is ~20mm L x ~3-4mm D. Drilled and threaded at the center,
perpendicular to the length."

I assume 20 mm L is 20 mm long and the D is depth ? it couldn't be 3-4 mm
diamete..?! How wide ?

I would get a rectagular plate, cut with hacksaw, shape with file, (way
faster then setting it up in a mill) and find a the correct nut. I would
braze, tack tig, etc the nut to the plate. Real proper, would lathe turn
the nut 3-4mm, leave a shoulder and set into hole in plate.

I assume the plate/ nut assembly will fit. If not you could thin the nut
until it does. I would then make sure you get the high strength nut.

3-4 mm of thread is probably not a proper design.

On Thu, Jun 30, 2011 at 10:46 AM, D D PALMER wrote:

> Ouch!
>
> Score another one to the advatages of "numb junk" argument.
>
>
> ------------------------------
> From: sygibson@gmail.com
> Date: Thu, 30 Jun 2011 10:08:20 -0700
>
> To: obra@list.obra.org
> Subject: Re: [OBRA Chat] Small Part Machining
>
>
> I agree with what Jon says. I've broken a seat bolt in the past (during
> rather rigorous mountain biking ... and the results ... were very, very
> painful). I searched high and low for a replacement bolt - and found that
> Chown Hardware in Portland, on SE Stark carries a very very wide selection
> of high quality bolts. I rode using that replacement bolt from Chown for 5
> more years of hard use before retiring that bike.
>
> You do NOT want your seat bolt to break at the wrong time. Trust me.
>
> ~~shane
>
> --
> "Opportunities multiply as they are seized." - Sun Tzu
>
>
> On Thu, Jun 30, 2011 at 9:26 AM, Jon Myers wrote:
>
> I would be very careful picking the material for this part. The parts
> around the seat post tend to be very highly stressed. Often these parts are
> a high strength alloy steel. These parts are typically machined in an
> annealed condition when it is softer and easier to machine. Then the part
> is then heat treated to give it a good mix of hardness, strength and
> ductility. A steel part that is heat treated to full hard can be up to 4
> times as strong as the same part in an annealed (soft) condition.
> -Jon
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>
>
>
> _______________________________________________ OBRA mailing list
> obra@list.obra.org http://list.obra.org/mailman/listinfo/obra Unsubscribe:
> obra-unsubscribe@list.obra.org
>
> _______________________________________________
> OBRA mailing list
> obra@list.obra.org
> http://list.obra.org/mailman/listinfo/obra
> Unsubscribe: obra-unsubscribe@list.obra.org
>
>