welding a tiny part

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hi all-I have a couple of broken Shimano bicycle shifters that might be repairable by welding.  The problem is that the pawl on a tiny steel part has been damaged and no longer engages the teeth inside the assemble, preventing the shifter from shifting to smaller rear cogs.  Shimano does not sell replacement parts for this, they only sell the entire shifter lever, which is very expensive.  The part is about the size of a dime (small!); here's a picture showing the damage (at 5 o'clock, or lower right side):http://www.norvil.net/pedal/service/...chtpawlc01.jpgFor those interested, here's a link to the excellent web site that describes the overall problem:http://www.norvil.net/pedal/service/shimanosti/My question is this:  Is it possible to weld the tip of the broken part so that a new pawl could be fashioned afterward?  Machining the deposited weld material is easy for me, but the welding part itself has me scared.  I have both a MIG welder and acetylene, but I'm a near novice with both, and something this small looks like it requires a specialized piece of equipment.  I am pretty sure that even on the lowest MIG setting with the smallest diameter wire, I would blow the part into next week before I successfully welded onto just its tip.Jim
Reply:How hard is that part ? Will a file scratch it ? If it needs to be hard, whack the tip off flat and silver solder a piece of HSS drill bit on it and shape with a 1/8 burr and stones. A jeweler-clock man is your friend for that kind of stuff.Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:Is it just steel?  I'd think there are plenty of people here with the skills needed to build up that corner with TIG.  Then you can file it down to the correct profile.
Reply:The proper way to alleviate the problem would be to learn enough Japanese so that you could converse with them.  Convince them that their engineering or production on that part was defective.  They send you a bunch of spares and commit Seppuku."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:LOL on the SEPPUKU Oldendum!  That was great.  Kinda like the Japanese bank president who did himself in after one bad quarter results.MagicHat
Reply:I had a look at the kit. Get a piece of D2 from a machine shop and low temp silver solder it on. A jeweler can do it in 3 minutes.Unhardened D2 will still be perfect for that. The idiots should have made it out of D2 CRA to begin with.I would have expected more out of them. They were the best......in the day.More modern day junk Are you old enough to know what a Zebrakenko is ? errrr/was ?Last edited by Burpee; 03-13-2014 at 06:45 PM.Reason: ERRRRRR/WASBubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:The damned part is either sintered or a MIM (metal injection molded) part if it's steel.  Whatever.  If it ain't pot metal, you could just braze something on the tip.  It's done all the time with old cast Iron gears."USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:I was (until a couple years ago when I closed shop) a Shimano Warranty repair center for fishing reels.  (Same function for all major reel brands.)  Talk about small parts!  Long story short, about 12 or 15 years ago Shimano sent me a few bicycle shifters in a shipment error which they would never acknowledge.  Had to reorder the parts I originally needed and pay double shipping.  Maybe I can help you.  It's a blind shot.  E-mail me if you want to pursue.  I think I still have them somewhere.  Shifter may work for you or internal part may be interchangeable."[email protected]"Jerry30+ yrs Army Infantry & Field Artillery, 25 yrs agoMiller 350LX Tig Runner TA 210, spool gunLincoln 250/250 IdealArcESAB PCM 500i PlasmaKazoo 30"  vert BSKazoo 9x16 horiz BSClausing 12x24 lathe20T Air Press
Reply:Originally Posted by OldendumThe damned part is either sintered or a MIM (metal injection molded) part if it's steel.  Whatever.  If it ain't pot metal, you could just braze something on the tip.  It's done all the time with old cast Iron gears.
Reply:Im sure I could fix it
Reply:Easy. Just lay some stainless fill on it and bloop it with one hi current pulse. Then file it to shape.Welding/Fab Pics: www.UtahWeld.com
Reply:If its that rare and I could not tig weld the edge, I would draw up a cad file and water jet it to shape out of say 416 stainless and finish the back side on the lathe and then run it threw the heat treating oven. I can not see the back side to see any other detail.
Reply:thanks for all the advice, I will try the silver solder approach...
Reply:this looks like a good match for my needs:i wish i had a laser like that...
Reply:It does, but you probably don't want to know what it costs.  Pretty cool process though.  Wish I had a laser that could do that. . .