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uses for mill and lathe I'd not thought of before

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Category: The Garage
Forum Name: Tool Tips and fabrication
Forum Description: For tips, hints or "how-to" related to fabricating your own tools. Perhaps a neat home-made or special purpose tool you have come up with (safety first, of course!).
Printed Date: Jul/29/2021 at 11:43pm
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Topic: uses for mill and lathe I'd not thought of before
Posted By: billd
Subject: uses for mill and lathe I'd not thought of before
Date Posted: Jun/13/2016 at 4:16pm
I knew I'd use them - but the ideas I had were not as practical as these uses.
The problem - a starter that looked sort of ok on the outside, but inside was a total disaster. It had sat around with water or wet whatever inside for who knows how long - it was full of sand-like substances and green crud, and the usual flaky rust. It was so much rust I had trouble getting it apart. Pieces that generally fall out when fasteners are removed had to be "persuaded", including the field coil pole shoes, the armature (which itself was rusty, the movable pole shoe, which normally slides freely in an aluminum sleeve and other parts.
I thought what a shame as it was a nice early part numbered starter with the shorter date code normally found 69 and prior, but was coded for 1970.
I had decided all that could be saved was the starter frame - the steel shell, the armature (after removing the rust and rust flakes and cutting the commutator down quite a bit to take the mountains range off of it), and 1 of the through-bolts as the other was so rusty it was thin, and totally corroded into the drive end housing. Even the drive end was nasty where that one bolt went into it.
The green crud was copper oxide which stained many internal parts, the sand was who-knows-what, likely aluminum oxide as that movable pole shoe sleeve was half gone, literally, and of course RUST RUST AND MORE RUST.
Great, I can scrape, file, sand, whatever, to get the outside of the frame cleaned up (it was so bad my blasters had trouble with it), but what about the INSIDE - so rough and with parts of the pole shoes still STUCK FAST inside the frame, unable to blast the thing clean inside, what now?
Hmmmm, I have a boring tool that goes into the tail stock...... ya suppose I can chuck that starter frame up and get it true and cut that crud out of it?
Yeah, let's see -

It took quite a bit of time - learning how to use that boring tool with the lathe, and getting the thing to turn so true that I could turn only the rust and crud out but not remove good steel, but it worked as shown above.

What about the drive end - that threaded hole is down in the housing a ways, and it has to be straight since the bolt is only 1/4" - 20, LONG, and holds some torque while cranking! Can't have that bolt stressed by threading into a crooked hole.
The mill - I can mount that to the mill table and come at it perfectly square, and dead-center with the fine adjustments.
So I used the mill to take out the broken bolt - but when I got the bolt piece drilled and got down to the aluminum I realized the housing was eaten and corroded where the threads were and I didn't really fully trust what remained of the oxidized and eaten threads - so it got milled/drilled for an insert and is now as good as new (unless you look at the pitting, which will be totally internal when all is said and done)

You can see where I drilled the bolt center, and as I got close realized just how bad that thread area was - so I took it farther and used inserts - didn't get photos of that, however. But in the end it's going to be even stronger.
I was able to get the hole perfectly dead-center, and perfectly perpendicular to the mating surface. Due to the sort of cone-shape of course I had to use blocks to mount it square, flat and solid but it worked well.

This is probably old-hat to many of you - I bet some are saying "oh, yeah, I've done that sort of thing a few times." and have used your own lathe or mill for similar repairs but previously, I might have trashed parts like this.

So far I have roughly, close to, 2 days on this one, if you take the weekend hours and the evenings where I went out late and spent some time blasting, cleaning, finding parts and add the time all together.
(There have been times where I've had to pull part 3 or 4 cores to find a certain specific part that was decent enough. I still need to find a decent brush cover band and pole shoe cover, and field coils as these were TOAST. It can take a half hour or more to remove a set of field coils as it takes special tools to remove and then reinstall them properly and they are TIGHT TIGHT!)
This was among the worst I've ever done, but the part number and date code make it one you won't find a ton of. Otherwise, honestly, there's no way anyone could afford 2 days of time SO FAR and there's no way in the world I could ever come out spending that sort of time on a starter.
I estimate in the end it will be roughly 20 hours of time, plus stamped steel parts (brush cover band, pole shoe metal cover among other parts like another bolt, etc. PLATING and so on. )

Be really careful chucking up a heavy piece like the starter frame - I didn't spin it up too fast for this operation and just as well as it's not balanced with the cutouts in it.
For the drive end repairs, the worst that could have happened with have been broken bits or taps.

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Posted By: Green AMX
Date Posted: Jun/13/2016 at 8:06pm
Nice work 
Thumbs Up

69 AMX 390 4speed go pack
72 Javelin 360 auto(sons)
82 Spirit (wife's 1st car)still not done

Posted By: White70JavelinSST
Date Posted: Jan/30/2017 at 8:27am
And that's why owning the tools pays off every time.
Great work Bill

70 Javelin SST, second owner, purchased 1972

Posted By: amcglass
Date Posted: Jan/30/2017 at 9:29am
nice job


BBG Mark Donohue 401

74 Jav/AMX
71 Matador 2dr sedan delivery wagon
1902 Rambler Runabout     

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