2016 POTD Thread Archive

[great white]

Laminated and rebound my "new to me" MOLO and added the appropriate pages:





Printed off and laminated myself a lubrication chart for the wall:

 

[chevydyl]

Ground both sides, and found something interesting on side b, a strange pattern that would spark heavy when ground over....

See those light colored streaks in the Y direction? It would spark heavy on those areas, also when I made the first rough pass those areas didn't hit, they were about 5 tenths low.... maybe it's chitty cast iron
I'll also spare you the photo of my spark out pass, done with a slow dress
Side A had a great finish, and did not have those streaks, you can see them on the ends as well

 

[FOMOGO]

Still looks pretty good, maybe something settled to to one side during the pour, or something got embedded in the stone. What is the intended use? Mike

 

[chevydyl]

It will be a lap when finished.
It's definitely not something in the wheel, it's something from when it was made/poured.

 

[autonoz]

Never worked on a bike

 

[wawoodman]

My first "real" job in the middle 60s was in my uncle's bike shop. I would come in after school and assemble the bikes needed for the sales floor.

All Schwinn and Raleigh. I must have done hundreds of them over the years. I could probably do them blindfolded!

 

[Franko]

One of my last bikes as a kid was a Raleigh English Racing Bike. It had thin tires and a 3-speed shifter.
I took it to a service station once to air up a tire. Being a bit ham-fisted with the air hose, I exploded the tire in my face. I was covered with black powdered rubber and bits and was psychologically scarred for life.
I had to carry the bike about 10 blocks to get it back home.

I still can't air up a tire without worrying about it exploding.

 

[Dan_S]

See those light colored streaks in the Y direction? It would spark heavy on those areas, also when I made the first rough pass those areas didn't hit, they were about 5 tenths low....

My guess would be some slag got in during the casting process, or they something crystallized oddly.

Maybe this, but I would need to call my father to be sure (35+ years in the steel making business).
https://en.wikipedia.org/wiki/Austenite

 

[Ripthorn]

More knobs for my guitar, including a pair for a dual concentric potentiometer. I cut the smallest knob a tiny bit short and broke into the hole drilled for the shaft. I may patch it with something, or let it stand out as a "feature". These may not even be the final knobs. Who knows...

 

[chevydyl]

Thanks dan, I'm not sure about the issue but I did contact speedy metals and they may replace the stock. Sucks cause I already got time into this part, odd thing is Side A shows no sign of the streaks, the ground finish is as expected, perfect. When I flipped the part to grind B and touched off, taking the wheel down another half thou it didn't hit the streaks... so after that pass I moved the Z -.0015 for a final roughing pass, and you could hear and see everytime the wheel passed over the streaks. Also now that I think about it, when I side milled the ends I used an 11/16ths hss em, cleaned up nice but you could see the light area in the center, for no reason other than to try I chucked a 5fl half inch carbide finish em and spun it to 4200rpm and fed at 5ipm, .0013 doc, it also required multiple passes as the first pass left the hollows just like when ground. Very strange, like those areas drew back.