help the rookie with a lathe fundamental question

[52 Ford]

At one shop we had a tall drill press, we could scribe a center to .oo5 with looking through a loop and with Chicagoing our punch this way or that, and drill press: center drill one end and then the other.

At the grinding shop, we had a center point grinder that we could move a center often back to one-tenth or so.
Grinding a part with zero stock you had to be right on when you first sparked.

Just with bench centers, or a long lathe, one can chuck a Norton 60* center lap and with pushing down on the high side you can move a center by tenths.

And he said he "won't be posting another question here". Sort of disappointing that people get offended so easily...

I'm not saying his question wasn't a good one, but the saying "ask a stupid question, get a stupid answer". He asked for advice aimed at a ROOKIE and got it.

I did think it was odd that a newbie had a fancy lathe like that.

Frankly, if I were him (was him... were him... grammar be hard), I'd just rephrase the question and ask it again.

 

[michiganbuck]

"Chicaging". Me's thinkin' you either made that word up or it's a typo. In either case, it's sort of a fun sounding word. "Chicagery".

Sorry I meant Chicagoing. My bad just spelled wrong. Anything goes in Chicago so jury-rigging a center..or anything jury-rigged is that,

Hey Buck can you Chicago this lose keyway?

Oh, you tilt your punch at an angle and smack it, you get closer...then angle smack it again and be near zero. Then, you touch it with the center drill point only and loop it to be a buy, or smack it again.

Actually, I think chicagoing a center is in How to Run a Lathe, I forgot what page...darn.

 

[52 Ford]

Sorry I meant Chicagoing. My bad just spelled wrong. Anything goes in Chicago so jury-rigging a center..or anything jury-rigged is that,

Hey Buck can you Chicago this lose keyway?

Oh, you tilt your punch at an angle and smack it, you get closer...then angle smack it again and be near zero. Then, you touch it with the center drill point only and loop it to be a buy, or smack it again.

Actually, I think chicagoing a center is in How to Run a Lathe, I forgot what page...darn.

No need to apologize, just giving you a hard time.

Makes sense, though. I guess it's a regional saying - I'd never heard it before, but of course I'm in south-east Virginia, born and raised.

By the way, since you aren't taking claim to the work "Chicaging" or "Chicagery", I should inform you that they're pending an official definition (haven't figure one, yet) BUT the official pronunciation is "She-cage-ery" and "She-cage-in(g)"

 

[eKretz]

Little advice OP: having a college degree, or even two, or how ever many you want to fan out to make yourself feel good, will not make you the smartest guy in the room. Here or anywhere else. There have been many dazzlingly brilliant men (women, cats, etc.) over the course of history that have had none. Bragging about that does not put you in a good light.

We often say this here but it bears (frequent) repeating. GIGO. Garbage In Garbage Out. If you don't give good information from the start when you ask your question and frame it in such a way that helps others to help you, you can't expect to get good help. Don't take offense at others' attempts to help when it's not germane to your wants and needs if you didn't give them the necessary, basic and complete information to give you a good answer at the start of the process.

As far as a taper issue goes, alignment of part centers is not a likely culprit. They would have to be atrociously badly out of line IMO to cause much if any taper. More likely to cause out-of-round or concentricity issues. The center in the part being located anywhere but on true center (and held there somewhat rigidly by the chuck at the other end) will try to push/pull the tailstock constantly away from center but that direction changes constantly as the part rotates... If you are chasing an inconsistent taper problem you should probably check for tool wear issues, tailstock spindle OD fit to bore and possible inconsistent clamping, or a bad live center bearing first. If the taper is consistently the same amount off you likely need a tailstock offset.

 

[swarfless]

Actually my very first post eludes to the fact I am trying to master extreme precision.

Obviously the PhD didn't include English .. 'elude':to avoid or escape by dint of dexterity or skill: 'allude': to refer casually or indirectly.

 

[TedinNorfolk]

If the material is that rough-and occasionally it is-I will roll it about to see where the bend is,and give it a good smack on the anvil.

 

[DDoug]

Little advice OP: having a college degree, or even two, or how ever many you want to fan out to make yourself feel good, will not make you the smartest guy in the room. Here or anywhere else. There have been many dazzlingly brilliant men (women, cats, etc.) over the course of history that have had none. Bragging about that does not put you in a good light.

We often say this here but it bears (frequent) repeating. GIGO. Garbage In Garbage Out. If you don't give good information from the start when you ask your question and frame it in such a way that helps others to help you, you can't expect to get good help. Don't take offense at others' attempts to help when it's not germane to your wants and needs if you didn't give them the necessary, basic and complete information to give you a good answer at the start of the process.

Qty (3) pages into this, I'm thinking the OP is another clandestine visit from our friend "Servicecar rider"....

 

[Tyrone Shoelaces]

At one shop we had a tall drill press, we could scribe a center to .oo5 with looking through a loop and with Chicagoing our punch this way or that, and drill press center drill one end and then the other.

At the grinding shop, we had an ExCellO center point grinder that we could move a center often back to one-tenth or so.
Grinding a part with zero stock you had to be right on when you first sparked.

Just with bench centers, or a long lathe, one can chuck a Norton 60* center lap and with pushing down on the high side you can move a center by tenths.

Practices like that are referred to as “ Manchestering “ over here. As I’ve worked in the Manchester area all my life I sort of resent that.

Regards Tyrone.

 

[Tyrone Shoelaces]

Jones & Shipman and Cen-T-Lap made center grinders but they didn't do it from raw, they were intended to grind accurate centers after heat treat, before finish grind. A couple of places made facing and centering machines for use on soft bars, both single end and double end - G&L, Seneca Falls, Hey, maybe another one or two - but not really suitable for a small or home shop.

Over here “ Giddings, Lewis and Fraser “ made ending and centring machines. I believe “ Fraser “ made them before they were taken over by “ Giddings & Lewis “. The ones I saw had two milling heads and two centring heads, one each on either side of a long vice. The bars were fastened in the vice, then milled to length before both ends being centred simultaneously.

They seemed to work really well.

Regards Tyrone.

 

[eKretz]

Over here “ Giddings, Lewis and Fraser “ made ending and centring machines. I believe “ Fraser “ made them before they were taken over by “ Giddings & Lewis “. The ones I saw had two milling heads and two centring heads, one each on either side of a long vice. The bars were fastened in the vice, then milled to length before both ends being centred simultaneously.

They seemed to work really well.

Regards Tyrone.

We had similar machines, don't remember who made them. They were a good serviceable way to quickly get a piece of stock up in the lathe and get started. If more precision was needed, we'd retool the centers further into the process.

 

[michiganbuck]

QT: Eric: [As far as a taper issue goes, the alignment of part centers is not a likely culprit.]

Good point there...and one might even add bed bend and twist in the machine level and set.
Some really good videos on that.

and even something a minor as the quality of the centers in the part.

Here is an old PM thread on lathe taper. There are a number of threads on this subject..That is why a good thread title is important, so one can search a subject.

https://www.practicalmachinist.com/...e-your-lathe-96812/?highlight=lathe+bed+twist

*Another rant about reading a book: With reading a book on a subject you learn more than just one thing.
So some questions/answers may be solved before you have every new problem.

Interesting the title of this thread made by the Op is. Thread: help the rookie with a lathe fundamental question.

 

[Nmbmxer]

I normally pad the jaws with some aluminum or copper and grab the least amount of stock I can and have it not flop about. Use an indicator and a "precision adjusting tool" and knock the end around to minimize runout. Then center drill it at 100rpm or so. Put a center in the TS and turn a band then flip it in the chuck and do it again.

I reworked a pivot pin the other day that was 36" long and 3.5" OD and needed to clean up the end where it was mushroomed so much caught in the bore and the snap ring groove was mashed in. I probably had an inch of it in the 12" chuck while putting in the center hole. Faster to indicate it in that fool with setting up the steady rest. The shop lathe has .020" of runout at the chuck so you have to find ways to work around it, for example you can't set the steady in front of the chuck and slide it back to quickly set it up. And the steady likes to ruin the plating on the pins, though the nylatron gsm pads I normally use help with that.

 

[eKretz]

QT: Eric: [As far as a taper issue goes, the alignment of part centers is not a likely culprit.]

Good point there...and one might even add bed bend and twist in the machine level and set. There are a number of threads on this subject..That is why a good thread title is important, so one can search a subject.

Yeah bed wear can cause all sorts of problems too. I've run lathes that were so bad that they cut tapers in different directions all the way down the shaft on different diameters. For some of those I would offset the tailstock for each diameter! Granted those were really big workpieces where filing and polishing in would take forever, and on fussy bearing fits. Otherwise I'd have just bumped the tool with an indicator. (No readouts on those machines). Ahh, good times.

And I absolutely agree, Buck. Good thread titles are very important. As is good thread subject introductory information in the OP.

 

[eKretz]

I normally pad the jaws with some aluminum or copper and grab the least amount of stock I can and have it not flop about. Use an indicator and a "precision adjusting tool" and knock the end around to minimize runout. Then center drill it at 100rpm or so. Put a center in the TS and turn a band then flip it in the chuck and do it again.

I reworked a pivot pin the other day that was 36" long and 3.5" OD and needed to clean up the end where it was mushroomed so much caught in the bore and the snap ring groove was mashed in. I probably had an inch of it in the 12" chuck while putting in the center hole. Faster to indicate it in that fool with setting up the steady rest. The shop lathe has .020" of runout at the chuck so you have to find ways to work around it, for example you can't set the steady in front of the chuck and slide it back to quickly set it up. And the steady likes to ruin the plating on the pins, though the nylatron gsm pads I normally use help with that.

That can work on a long part, sometimes. I've also done it in a pinch. The problem with that method is that often you'll get chatter while putting in the center hole, and when that happens you will more often than not get an out-of-round center. Which means you're probably going to get an out-of-round O.D. as a result. You can get away with it a little more often if at the very end you slow the RPM down to a crawl and just jog or spin the chuck around by hand while keeping a steady pressure on the center drill so it keeps a steady cut going, then let it taper off so it almost stops cutting and then quickly withdraw it. Still not a guaranteed win though. Depends how tight your roundness needs to be. Using the steady is far better.

And, um, sounds like you are using a 3-jaw? And that your chuck is some time past due for a jaw regrind. If I were you I'd have a little chat with your boss exploring how little time that would take and how much prevented lost time it would save during future setups. Also, why don't you use a 4-jaw? Zero runout.

One more for the road: to help keep the surface of your part being rolled on pristine when using rollers on a steady rest, add a little way oil to the surface of your part, and be sure to use a chip shield. Running them dry marks the part up way more.

 

[Mechanola]

I am right now seeing test bars offered on ebay, one 15 inches long, for $81, net, from India. These are ground mandrels with a center bore in either end that allow you judge your lathe.

In this country something similar costs CHF 470, with a SK 40 at one end. Whatever you want to pull into your environment, such a precision mandrel can be straight and round to within 80 millionths of an inch, do yourself the favour. Make sure the tips of your centers are correct, then clamp and start to investigate with an indicator. Most likely only the tailstock is in need of adjustment. It won’t hurt to take it to the bench and dismantle it. Clean everything, lubricate, set to the middle marks, if there are any.

I don’t think it’s bad to turn something from rusty scrap. At least you’ll learn to clean your lathe with it. The tip that was given to dress a piece I find very good. Also, as said by others but not to full clarity, it is possible to give a piece center bores off the lathe. That would be correctly clamped on a drill press or a milling machine (why not).

Everything traditional on CNC equipment is not ridiculous. Do you know what is ridiculous? That CNC lathes only very rarely have a Morse taper in their spindles or at least a cylindrical length ground to a plausible fit. My opinion

So just do your carving there. Contrary to what’s been said you may want to use an HSS tool for the first cut through the scale. The first cut is the deepest comes right from this.

For the pleasure of it:
Heavy Machining - YouTube

 

[guythatbrews]

I normally pad the jaws with some aluminum or copper and grab the least amount of stock I can and have it not flop about. Use an indicator and a "precision adjusting tool" and knock the end around to minimize runout. Then center drill it at 100rpm or so. Put a center in the TS and turn a band then flip it in the chuck and do it again.

This is the way to aproach this job if you do not have a 4 jaw independent chuck and/or the free end is true enough. Sounds like you have some pretty rough stuff.

If you do have a 4 chuck as deep as you can, indicate the free end best as you can, and center drill. As noted before you may get some chatter. Ignore that for now, we'll fix it later. Make the smallest center you can consistent with the needs of the part. That is, you can't make a tiny center on a huge part. Next, pull the part almost all the way out of the chuck so you can bang the tailstock end around just like above. Indicate stock at the chuck, then bang the free end in, go back and forth until both ends suit you. If the shaft is heavy make a pad flat on one end center hole on the other and jam it against the part with the tailstock. It will support the weight and make it easier to indicate the free end in while barely chucked.

Now turn the tailsock end on a center, can be live or dead. I prefer live. In general not as accurate but it is more practical. If you use a live center indicate the actual center as close to the work as you can get. If it wobbles a bit tap the work around until the center doesn't, else the center will not be on center. Now you can make your cut. If you want indicate the live center again before finish cut. The stock may have moved or stressed may have been relieved.

If the stock is small enough for the lathe bore you can finish the other end easily, if not do it in a simalar fashion to the first end.

If the center chatters AND the stock will pass through the spindle after first op just rebore the center. Small centers work better than big centers, I guess becuase there is less center there to be ugly.

Some of the posts mentioned steady rests which you said you didn't have. Get one if you can they are very handy. No use on rough stock but as one of the other posters said stick a collar over the shaft with 4 setcrews in it and, bobs your uncle, you have a steady rest journal.

Often and often will turn a dead center in the headstock chuck. Easy and quick and runs as true as your skill allows. Preference is to chuck and center. Just be sure the tailstock center end is running true as above. Chuck on a "hinge", a strip of shimstock or even a wire ring so the chuck is not emposing any incorrect angular alignment on the workpiece.

And nothing wrong with playing with rough stock. Forces you to learn some technique. We used to make hi pressure steam valve parts and some of the stuff was super special certified carbon steel rough forgings, supllied to us by customer and NOT rough turned. How rough was it? We called the forgings dog turds if that gives you an idea.

Enjoy your hobby. It is a great one. It's how I got started at 9 years old. I would never mention that around here, tho.