How do you square the parting tool?

[wsippola]

I just eyeball it to 90 deg. Once in a while, I'll find it's a touch out and have to reposition. Never had a problem breaking one (well not due to misalignment).

[tornitore45]

I just eyeball it to 90 deg.

Digressing a bit... some people are blessed with a keen eye for dimensions, angles, level and squareness, some are abysmally short.
This may account for the wide disparity of methods.
Of course there are situations where micrometer and/or indicator are the only choice.
I relay on eyeball a lot, and am pretty good at, anything not critical particulaly in woodworking. I set stuff level and the wife argues, out come the spirit level and is dead on.
Identifying common screw threads is no problem either.
I am not bragging, is just one of those natural talents; like playng music or carrying a tune, which I could not do to save my life.

[Frank Ford]

I keep one tool holder loaded with a 1/2 x 1/2 piece of steel, just for the purpose of realigning the tool post. Takes only a second or two to pop out the tool I'm using, stick in this one and hold it up against the tailstock ram as I tighten the tool post quite squarely aligned:

[redneckalbertan]

What should a person square off of? I guess a better question would be is there something better than others to square off of? I've always square off of the work piece in the chuck. There has been mention of Chuck face and tail stock ram.

[websterz]

I hold a 1-2-3 block against the chuck between jaws and then bring the QCTP over to it. Once the 1-2-3 has the QCTP square I tighten the locknut. Having your tool square is of major importance in parting.

Exactly the same method I use. Here I thought I was being all clever.

[SteveHGraham]

Webb got off the best shot so far.

Am I the only one who invariably gets a crap finish when parting?

[tornitore45]

Am I the only one who invariably gets a crap finish when parting?

NO

My lathe has no auto cross feed, therefore my experience is limited to manual advancing and manual dripping oil.
Parting is a delicate balance between aggression and moderation. Staying in the sweet zone between rubbing and digging in is a challenge with a small machine and manual feed. Yet it can be learned, has been a while since my last "Pling" of the tool.

That said it goes that I can not expect a good finish and consider parting the same as cutting the blank, it just happens to be done last instead of at the beginning. If a good finish is required I make allowance and face it with a better suited tool.

[Harold_V]

As a matter of pride, I almost never rely on a parting cut for final sizing of a part. There's more than one reason for that, as a parting tool typically yields a less than good finish, but it's also not always flat. For small work, I like to leave ten thou or so for a facing cut. When parts are run in soft jaws (almost always for me), the end result is a much more uniform (and attractive) piece of work.

Many will argue that the second operation adds cost to a part. Sometimes you have to look beyond that---as the work you do bears your name. How you wish to be perceived by others can trump cost. That was my philosophy when I was actively machining (and refining precious metals) and it served me well. Some folks will willingly pay a premium for better quality.

Harold

[JTiers]

I would NOT eyeball it.....

Lay the parting tool along the flat face of the chuck, if you are using one..... that will be a good reference.

Getting it truly square, and keeping it cutting are two of the magic points to successful cutoff

[seal killer]

All--

I do it Harold's way: I never make the parting operation the final cut. BUT, the reason I have been doing it this way is due to INEXPERIENCE. (However, I have had no problems parting.) Since I have absolutely no concern for the time it takes on any job, doing it this way was natural.

--Bill

[Harold_V]

All--

I do it Harold's way: I never make the parting operation the final cut. BUT, the reason I have been doing it this way is due to INEXPERIENCE. (However, I have had no problems parting.) Since I have absolutely no concern for the time it takes on any job, doing it this way was natural.

--Bill

One of the reasons I use that method is that the part in question often requires an operation, anyway (chamfer, for example), so why not face the piece, too? The end result tends to be far more attractive (and almost without fail, of better quality). It's good shop practice, although you're likely to get at odds with the guy who thinks everything revolves around money and will settle for less than perfect in favor of increasing profits, albeit just marginally.

Harold

[tornitore45]

increasing profits, albeit just marginally.

Rant Mode ON
This is the malaise of all industry lately. Ever since I switched from industrial electronic to commercial/consumer electronic I felt at odds with management and their philosophy. Basically design stressed to the limit of making it just through the warranty. Warranty is meant to weed out defect, not planned failures. Customer have a life expectation in mind. A pair of shoes is expected to wear not delaminate, a TV is expected to last at least 10 years if it can not be repaired economically.

Eventually consumer wise up to the corner cutting mentality and switch brand (not always and option), case in point was DELL skimping on support just when their product required the most. Saving were indeed marginal at best.

I am glad retirement took me out of the silly race.
Rant Mode OFF