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That was a clencher…

lbhsbz

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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..
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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.

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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.

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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.
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stingray11

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Nice work, That's using your head

Sent from my SM-G970U1 using Tapatalk
 

Racey

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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!
 

lbhsbz

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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
 
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lbhsbz

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…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.

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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.
 
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lbhsbz

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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.
 
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