Questions tagged [machining]

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16 votes
2 answers
34k views

What is crankshaft grinding and why is it done?

I saw a lot of YouTube videos referring to crankshaft grinding, while watching videos about working on crankshafts. I don't understand what crankshaft grinding does. If we grind a crankshaft, then ...
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12 votes
3 answers
27k views

What size hole should be drilled for an individual tap?

The other day while doing further work on my son's Subaru, I drilled a hole in a piece of angle iron then started using my 1/4-20 tap to cut some threads in the hole. The idea was to have a threaded ...
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9 votes
1 answer
381 views

Machinist Straight Edge Tolerance

I want to purchase a straight edge which I can use to measure the flatness of heads & blocks and other such nifty things. My question is, what is considered a good tolerance for a straight edge? ...
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7 votes
2 answers
6k views

How are crankshaft crankpin journals ground?

In looking at this question: What is crankshaft grinding and why is it done? @Pᴀᴜʟsᴛᴇʀ2 gave an excellent answer that got me thinking. First, lets include the same picture from that answer so we're ...
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  • 9,286
5 votes
3 answers
52k views

Rotor replacement, one or both?

I work at an independent auto repair shop and we seem to have 2 schools of thought, first thought, Mechanic A, one rotor under spec's, the other rotor on the same axle is machinable, replace only the ...
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  • 51
5 votes
1 answer
71 views

Which is longer lasting HSS-E or HSS coated wth TiN?

I'm just gonna purchase taps and dies for my most commonly used metric screws. I want them to last for as long as they can (not that they will be used so often, I just want them like that). I also ...
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  • 173
5 votes
1 answer
73 views

Just the straight facts; nothing edgy

In this question I asked about tolerances for straight edges. For this I have a followup question about length. If I want to purchase a straight edge, I only want to purchase one straight edge which ...
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3 votes
2 answers
1k views

Removing a welded nut

There's a nut welded on my countershaft and I don't like that. How do I remove it while minimizing the chance of damage to the countershaft's threads, as damage would necessitate: a. welding a nut ...
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  • 185
2 votes
4 answers
7k views

Is there a hack to repairing a seized engine?

Last week I drove on the interstate for about 1 mile when my engine died. the oil light never came on but it was low on oil and a couple thousand miles overdue for an oil change. I had it towed to a ...
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  • 277
2 votes
1 answer
30 views

Improperly installed valve guides

I am new at doing cylinder head work and accidentally installed 4 pre spiraled valve guides upside down, can I hammer them back out and reinstall them correctly or do I need to use new ones?
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  • 21
2 votes
1 answer
44 views

Prepping freshly machined block for building

I'm building an engine from the ground up to swap into my project car. The aluminium block has been re-lined with ductile iron sleeves so the machinist sprayed them with white grease to prevent ...
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  • 223
1 vote
3 answers
259 views

Best way to fix (or hack) a warped exhaust manifold?

The front exhaust manifold on my 2002 Ford Escape is warped. The problem is the catalytic converter is integrated into the exhaust manifold so a new one is like $800 and you can't get them at either ...
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0 votes
2 answers
830 views

Why facing the head block?

I have recently came across a problem. One of the rocker fingers (the one that touches the valve stems, and have cam rollers) on my diesel engine head has broken. This resulted in the pistons hitting ...
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  • 45