Lathe update/questions

A couple of decades as an engineer gives me some room. And in fact, I do now actually earn a portion of my living doing this stuff. That is part of why I shelled out the bucks for a lathe, to enhance my capabilities.

On a lathe yes, NOT on a mill - sorry to disappoint you.

If I did not respect your opinions, I would not have sought them in this recent screwup with the lathe. However, I am not a complete machine shop green horn, and I am a very experienced engineer. I will from time to time disagree with you, and would hope you would be man enough to debate vs. reduce yourself to name calling.

See above.

Bill

Gunner,

It's not about purism, it's about practice. I look forward to showing you the RT pieces I made in the fall. Had I not worked out dials and backlash and practiced manual methods, I would not have been able to build them.

Bill

Being an engineer is not the same as making the chips.

I'm not disappointed, YOU said that you are a newbie on a lathe...MY comment was to your comments regarding using a lathe

And just where did I reduce myself to name calling? Well, other than refering to myself, that is.

Jim,

Mine appears to be fine in that orientation, but I see where you are going.

One thing that made me cringe was stepped block used in airplane construction. They've apparently worked for decades, but it sure looked like an crack waiting to happen.

Do you undercut the shoulder? Or, do you face the shoulder first and then turn any radius adjacent to it? I understand the related movements, but I do not quite see how to apply it.

Bill

No, but I do both. Granted I am much more of an engineer than a machinist.

That's because I am a newbie on a lathe. But when it comes to other aspects of machining, I cease to be newbie.

What you seem to find annoying is a combination of thinking through a complex decision and a considered disagreements about machining in general that arose along the way.

"keep that in mind, the newbie part that is". "but you barely have the questions". If I look around, I will find a crack about "a week and a half" or something. Sounds like name calling to me.

Bill

It's only a problem for small, short parts running between centers. I use collets if at all possible.

Where are they used? My aircraft construction books are mainly training manuals for WWII production workers. I don't plan to build an airplane but there's a lot of generally useful metalworking info in them.

Depends on the job. The loaded inner side of a needle-bearing axle journal would be undercut axially into the shoulder, then faced smooth. The outer end would be grooved (to end the thread, but same idea) since it isn't loaded as much. I'm not making race cars, just oversized stainless steel wheels for lifting equipment used outdoors. BTW, unhardened journals and welding-rod needles work fine, like they do on floor jacks.

Generally the finish on the diameter is more critical so I rough the length, finish the diameter, then risk a groove from re-establishing the tool position on the shoulder.

It helps enormously that I almost always get to specify and design the part, either for my home projects or for an electrical engineer who lets me do whatever I want after I slip "Young's Modulus is, uh, 29E6 for this steel" into the discussion.

Jim Wilkins

Cause Ive learned a LOT in those 12 yrs?

If I dont know how to cut metal, I cant tell if a machine is working correctly or not, and if the problem is machine related, program or operated related.

IE..I know how its Supposed to work..so when it stops doing it correctly..I have to find out why., and how to correct it.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Bill, Im sure you turn out fine work. I look at things from a production viewpoint. Its my job to make sure machines and operators turn out the maximum amount of work, to specs, in the shortest amount of time. Its one of the things I do for a living in the Meat World.

Ive seen some marvelous work turned out with a hacksaw and a file. Atistry in metal. The idiot savant Abraxis is an example.

One of the old exercises for apprentic machinist was to make a perfect cube, using nothing more than a file, for a grade. Took a considerable amount fo time to do, yet all apprentices had to do it.

Me..Id stick it in a shaper and face the thing properly, then surface grind it to tolerance. Doesnt take anywhere near as much time, time I can spend learning/making/doing other things, or out shooting, nailing the lady friend or playing with the critters (not necessarily in that order of course ) Other people would use a mill of some sort...chuckle..but Im a shaper head at heart.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Jim,

A 5C setup will appear, but not right away.

It was a long time ago. I know who showed it to me, and AFAIK can still contact him, which I should do. For now, my recollection is that they were used to connect pieces of sheet metal onto spars or similar structures. That's pushing quite a few cobwebs out of the way, so take it for what it is worth.

Enjoy the books!

Same here. I design with the strengths and weaknesses of my machines firmly in mind.

Well done - just don't mention permitivity or you'll get an earful ;)

Bill

Gunner,

I have no argument with that. However, building custom weirdness as I do, it has been invaluable to me to be able to function absent encoders for every axis a new machine or fixture brings into play.

May your spindles run true.

Bill

An operational difference between mill and other tools (RT, lathe, etc) is that direction is often reversed on a mill, less so on lathe compound or RT.

I view the DRO on a mill like an autodark welding helmet. I'd gotten along fine without either for quite a while, but after trying them I decided if either quit working it'd be replaced before sundown. That eventualy happened with the (ancient) DRO on my mill, and it was indeed replaced before sundown.

I don't have a DRO on the lathe and don't feel any need for one.

I'm pretty good with electrical engineering too. One of my tasks as a lab and CAD room manager at MITRE was showing young EE co-op students how to use the schematic capture and simulation tools. That quickly turned into how to make simple, practical, efficient designs instead of the cookbook stuff they knew from textbooks. One guy used a relay coil to sense low battery voltage in a portable device. In addition to opening when the batteries discharged, it significantly hastened it. Another ordered a case of Polaroid film for the scope camera to figure out exactly how fuses blow. He was really downcast when I showed him the I-squared-T curves in the back of the Littelfuse catalog. They knew the theory reasonably well but none of the practical details.

When I received my chemistry degree the profs told us 'Congratulations, but you aren't yet a chemist. What we've taught you qualifies you to listen and understand when you get a job and they explain how everything really works.'

The earfulls at MITRE were about digital radio communication theory, which makes thermodynamics look easy.

Jim Wilkins

Interesting. I've seen machinists' faces go from smug to panic when the part I wanted them to make required some careful hand work, like filing to a curved line. It didn't help that I had made a sample.

Jim Wilkins

After using a file for many years I was shown by one of my engineering workshop instructors, when he saw me filing a radius, how to file a radius correctly and it made the world of difference to the outcome. I thanked him but have often wondered why such basic information was not taught as standard, maybe it was thought we didn't need to know that sort of thing because of the courses we were on and it way too basic. It's not something I have ever run across in a book either but have not looked specifically for it.

Magnet hint: this is not a good place for supermagnets. Ordinary ceramic magnets are better. Supermagnets hold well -- but they also hold ferrous swarf with such tenacity they're about impossible to clean. Ceramic magnets can be cleaned in a jiffy with a blast of compressed air.

I was taught to scribe the curve, file a 45 bevel, then cut down the points to an octagon, then cut those, etc, keeping the flat widths equal, just like planing a wooden ship spar round. The first cuts were with a rasp, the last with a single-cut "hand" or "pillar" file.

What is your method?

Jim Wilkins

I've done the same but I was thinking of filing the final smooth curve. On say a 90 degree corner and holding the piece with each face at about

45 to horizontal what I did originally, as I had never been shown, I just moved the file forward and rocked it from the near face to the far face so the contact point travels away form you to create the curve. The instructor showed my to start with the file parallel with the far face and moving the file forward, rock it back, to end the stroke with the file parallel to the near face, in this way the contact point travels back towards you during the operation. This instantly gave me a much better finish and radius and it's the way I've done it ever since..

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I certainly would not want to try to read 0.000-0.500" on a dial the diameter of mine, while 0.000-0.100" works out fine. How big a Monarch is yours -- the 10EE or one of the larger ones? That 4 TPI leadscrew suggests a larger machine to me.

Note that I have a spare compound from an earlier Clausing picked up from eBay, and the dial diameter is about half the one which I have. If I ever have to put that one into service, I will transplant the dials from the newer one onto it -- or make a new set of dials. (Actually, since the dial is a collar around the actual mounting of the crank to the leadscrew, all I need to do is to turn and graduate a larger collar -- and make something to hold the index line to match it.

Enjoy, DoN.

The cube test is a fairly common one but back in the "Old Days", according to my Apprentice Master, you made a surface plate. You took three raw castings and using a planer machined them as flat and smooth as you could get them. Then, using a hand scrapper, you made them really flat. To check you tried the three pieces against each other, back and forth, scrape a bit here and scrape a bit there. Of course you also made your own scrapers and ground your own tool bits.

When you got a surfacer plate to where the boss said it was "good" you could call yourself a machinist.

Bruce-in-Bangkok (correct email address for reply)