That was a clencher…

[lbhsbz]

Working on a brake caliper for a 1964 Maserati 5000GT…one might say it’s a bit rare. One of the pins was fucked up that held the parking brake arm on the caliper…had to be drilled out. I’m pretty sure it was about 1/2 sheered, but nothing made any sense while I was trying to extract it. Ended up with a fucked up hole in the casting.

Who knows what iron this is…some sort of ductile I imagine.

Fixtured it in the mill vise using the 2 good hole with appropriate sized drills as pins to get it straight, then bored everything out to 1/2”…almost cleaned up the holes…close enough at least..

Turned up a chunk to snug/slip fit….material was getting pretty thin so I didn’t want to risk cracking it with a press fit.

Chopped it off, chamfered the ends, and TIG brazed it in place with SiBr filler…which is my go-to when I have no idea what materials I’m working with. Did a pre-heat and a post heat and held my tongue just right…and it didn’t crack. I got lucky.

SiBr is harder than woodpecker lips…can’t hardly drill though it. Had to use a 1/4” carbide endmill to make my pilot hole, but it all worked out. Just happened to have a screw machine length drill in the right size to finish the hole…then chopped out the middle part and machined the gap to size…works like a champ after a bit of “blending” on the EXL wheel.

 

[stingray11]

Nice work, That's using your head

Sent from my SM-G970U1 using Tapatalk

 

[Racey]

If you are every doing cast or ductile iron repairs in the future preheat and use either ER-Ni55 or ER-Ni99 nickel rod when TIG welding.

The preheat needs to be at least 350 degrees.

It works excellent and is very strong

The wire is expensive but you only need it occasionally.

Nice work with the ER-CuSi though, it definitely should be fine for what you are doin!

 

[rivermobster]

Nice work!

 

[lbhsbz]

If you are every doing cast or ductile iron repairs in the future preheat and use either ER-Ni55 or ER-Ni99 nickel rod when TIG welding.

The preheat needs to be at least 350 degrees.

It works excellent and is very strong

The wire is expensive but you only need it occasionally.

Nice work with the ER-CuSi though, it definitely should be fine for what you are doin!

I've wanted to try Ni99 filler on cast, but this wasn't the job to learn on....and I don't have any. I have some scrap caliper castings from various OEM suppliers from the '60s....it would be really cool to be able to weld up holes and re-thread them and machine a new bleeder or tube seat. I have no idea how tapping a weld repair on cast would work...it'll probably draw all the carbon into the weld and be impossible to cut.

I was getting worried trying to drill through this repair...drills wouldn't even scratch it....the carbide endmill struggled a bit too. Time for more experimenting I guess...and studying processes. I was real careful to control the heat and not bring the CI into solution...but maybe something happened that I couldn't see.

Edit...I guess I could machine up a bleeder seat (sort of like a blind time-sert) and weld or braze the whole damn thing in after I overdrill the hole. Damn...I'm a genius

 

[lbhsbz]

…continuing this repair. From first glance…the caliper body had some damage but the hole looked fairly intact and I figured I could use it…not so. I believe a repair was attempted before, poorly, which explains my confusion while disassembling.

The hole accepts a press fit 0.329” pin.

I turned up a 3/8” pin with one end to .328” and used that in the spindle to align the caliper in the mill. Then decided to take it out to 11/32” (.343”) because it’s close enough and I make a custom pin.

Here’s after boring through the first hole….not sure how the hell this happened.

I bought the longest endmill I could find at McMaster, but i still run outta 11/32” with about 3/8 Depth to go…so as soon as I can make some noise this morning, i’m gonna throw the endmill in the lathe and grind a releif in it for 1/2” or so where the flutes meet the shank…that should give me the depth I need. Then I’ll fill the gash with epoxy and bore it again. I’ll turn up the new pin so the interference occurs in the top section of the hole. McMaster has 3/8" dowel pins with 10-32 extractor threads already machined in them...so I'll start with those, since tapping 10-32 holes in stainless is not on my list of favorite things to do.

Should work.

 

[lbhsbz]

Made all new stainless pins this morning…(re-using a couple of the good old ones)

 

[lbhsbz]

Success! Guessing what size the lower hole ended up was fun…crept the pin down about .002” at a time until a light smack got it halfway in. It works. Finally done.

Well…almost. Gotta make the crossover lines.

 

[traquer]

Nice work!