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    Quote Originally Posted by rokbottom View Post
    My guess is the part is only about 8-10mm dia, under 1/2 inch?
    Makes it super hard to get the high surface speeds you guys are talking of doesn't it?
    Maybe that should have been mentioned in the O.P.? If that is the case, yes, it will be difficult to even get the necessary RPM out of most machines. In which case he can either experiment with different parameters of tool grinding and depth of cut, resign himself to leaving a little filing and polishing stock or use a toolpost grinder.

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    I have to state this...…..NONE OF YOU KNOW WHAT YOU ARE TALKING ABOUT.

    I'm a golden oldie from way back, did my apprenticeship in the late 50's, and one thing I learned when working with mild steel and HSS cutting tools to get a good finish is that you want to go dead slow in the revs for the final finish cuts and use coolant all the time.

    OK..…...mild steel, that soft stuff everybody uses for just about anything and using conventional tooling and methods for finishing is a recipe for bad finishes.

    Try this, it is for FINAL finishing only ...…..I use a flat top parting type tool, honed sharp with NO top rake and a 4mm + wide blade to finish mild steel to a chrome plated mirror finish......how?

    Well, the secret is in the tool presentation and the rpm.

    Run your lathe at 50 rpm for a piece of steel say 50mm, 25mm or 12mm diam.....it doesn't matter, the bigger the diam the slower you want to go...... and get the tool flat front face as square to the work as is possible...…..IT MUST BE DEAD FLAT TO THE WORK PIECE AND DEAD ON CENTRE HEIGHT.

    Then you apply a depth of cut about .2mm or say .005" .006"......002" works well too.... and use a coarse feed....this will compensate for the time it takes at slow rpm to feed the tool along the job.

    What is happening is the steel peels off the work like foil, not being torn off if you go too fast.

    YOU MUST HAVE THE TOOL CUTTING ON AS BROAD A FACE AS POSSIBLE.....DEFINATELY NOT A POINTY TOOL WITH A SHARP TOP RAKE.

    A tool with a .500" wide face and maybe a 5 deg top rake works very well for a quick travers.....but it must be kept wet with water/oil bases coolant at all times and dead square to the job or you will get a spiral groove from the end edges.

    I have used this for finishing practically all metals to a high polish like finish....brass works exceptionally well and alumin(i)um too.

    The broad face of the tool allows a fast feed rate......experimentation in this method is an eye opener.

    I'd just like to mention that the old lathes, with back gear like the Old 1930 Colchester Bantam I have and currently use, and the 1940's 9" South Bend models I've use years ago, all with their back gear low speeds are ideal for this method.

    BTW,,,,for final finishing I use this method when I do screwcutting to get threads that are polished......the finish tool is a flat top form tool for the thread form.
    Ian.

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    Exactly what I was experimenting with for myself during apprenticeship until master saw what I was doing to forbid it to me. Slow is always correct. Under time pressure speed up and decrease feed with an angled tool, in the direction of skiving. Two equal finish passes. If first one fails, you have a last chance for correction. In series, you have one final pass and adjust from part to part. If surface demands are higher, grind. Grinding needn’t be slow. YouTube

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    Quote Originally Posted by CarbideBob View Post
    Grind a contrary tool? Please explain.
    Bob
    YouTube

    Also called a vertical shear tool or something along those lines. I rarely use them cause they are slow but they can take super light cuts where a regular tool would rub.

    And to all you guys running in back gear.....how the hell do you make any money? I get it that it works in a pinch but how can you be competitive quoting a job running 100 SFM or less in steel? If I did that I either wouldn't have any work or be running at $10 an hour.

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    Did you hear Matt chuck his Mic at 3:15?

    R

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    Quote Originally Posted by Hardplates View Post
    YouTube

    Also called a vertical shear tool or something along those lines. I rarely use them cause they are slow but they can take super light cuts where a regular tool would rub.

    And to all you guys running in back gear.....how the hell do you make any money? I get it that it works in a pinch but how can you be competitive quoting a job running 100 SFM or less in steel? If I did that I either wouldn't have any work or be running at $10 an hour.
    Hey, that will be perfect for me when I need to make qty (2) shaft-bore adaptors for a rotary oil seal test. Spend an extra 10 minutes on the setup pieces, and then let 'em run on the tester for 1000+ hours. Not everyone is here for race to the bottom commodity parts.

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    Quote Originally Posted by Crabtree View Post
    I have to state this...…..NONE OF YOU KNOW WHAT YOU ARE TALKING ABOUT.

    I'm a golden oldie from way back, did my apprenticeship in the late 50's
    Yeah, ok Boomer.
    To say none of us know what we're talking about is bullshit.
    So you know of some tricks that you HAD to use 65 fuckin years ago, big deal. Those "tricks" are pretty much not needed with today's machines and technology.

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    Yes that HSS broad-nosing method does work, I have done that myself also. But it's a pain in the ass to grind and set up the tool, and it isn't feasible for modern production. It absolutely does produce a near mirror finish if you get everything right though. I measured with a profilometer once and that method achieved an 8Ra finish. I still use it now and again for reaming and spotfacing. It's a bit tough on the reamers though, makes the hole run to the small side.

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    Quote Originally Posted by Hardplates View Post
    YouTube

    Also called a vertical shear tool or something along those lines.....
    Okay that makes sense. Plenty of weird things going on here and getting the grind right is not so easy.
    Chip weld occurs in a range of speeds and pressures. Where is dependent on a whole bunch of things happening as that chip forms.
    This is a range so you can be above it or below to cure the problem. Slower does work just as faster does.
    It's a no-mans land you don't want to be in.
    Obviously faster is faster but sometimes your spindle or setup can't go fast enough so you go the other direction.
    Bob

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    Quote Originally Posted by Crabtree View Post
    I have to state this...…..NONE OF YOU KNOW WHAT YOU ARE TALKING ABOUT.

    I'm a golden oldie from way back, did my apprenticeship in the late 50's, and one thing I learned when working with mild steel and HSS cutting tools to get a good finish is that you want to go dead slow in the revs for the final finish cuts and use coolant all the time.

    OK..…...mild steel, that soft stuff everybody uses for just about anything and using conventional tooling and methods for finishing is a recipe for bad finishes.

    Try this, it is for FINAL finishing only ...…..I use a flat top parting type tool, honed sharp with NO top rake and a 4mm + wide blade to finish mild steel to a chrome plated mirror finish......how?
    I occasionally have some "one off" stuff where this could come in real handy.

    Thanks much,

    -Ron

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    True my finish passes have been quite shallow.. Will try deeper cuts next time and crank the speed.

    Interesting comment on Crabtree. Actually when I read that I remembered that once when I used parting tool to wipe surface on soft steel it actually produced mirror like surface. It didn't sound good nor I don't think it produced accurate dimensions but it certainly was mirror like surface.

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    Tool pressure cam be tricky with that method when turning diameters. I used to use it a lot when finishing larger radiuses with HSS form tool on the lathe - beautiful finish.

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    This video may be of interest to some. I like the way the maker really clearly lays out the exact insert used and his actual parameters so that it should be possible to replicate what he is doing vs reporting in relative terms (fast, deep, rapid) his parameters.

    YouTube

    Next time I am in the shop I ma going to also try out the slow shearing method described in a couple posts above. It is good to know more than one approach to a given problem. It will also be interesting to see just how coarse a feed rate can be used and compare the net feed rate in IPM for the shearing method vs the higher RPM feed rate.

    This has been an interesting thread.

    Denis

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    Quote Originally Posted by CarbideBob View Post
    Grind a contrary tool? Please explain.
    Bob
    That’s what the old steamer guy that showed me his lathe tools called it. I’ve heard others call it a “back knife”. Concept similar to a broad nose shaper tool on steroids for low pressure shearing. Depth of cut limited to .003”-.005”. It will cut soft black pipe nicely & you cant find the weld seam on the sewage steel…

    Quote Originally Posted by litlerob1 View Post
    Did you hear Matt chuck his Mic at 3:15?

    R
    C’mon Rob! I’ve never chucked a tool, parts maybe → into the scrap bin. I lay mics down spindle & anvil first then let go of the frame. It’s my habit to carry wood around to set tools & stuff on a bench or cart. With the cart below when the wood is thin just letting a tool end drop an inch or too sounds like a drum. The cart is NOT FOR SALE! EVER!

    Most of the time I ground bearing diameters after rough turning. Time mattered little as the OEM price of very low volume parts to the railroads was crippling expensive.

    Good luck guys,
    Matt
    Attached Thumbnails Attached Thumbnails toolscart_partshouse.jpg   toolscart_partshouse2.jpg  

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    Quote Originally Posted by Hardplates View Post
    YouTube

    Also called a vertical shear tool or something along those lines. I rarely use them cause they are slow but they can take super light cuts where a regular tool would rub.

    And to all you guys running in back gear.....how the hell do you make any money? I get it that it works in a pinch but how can you be competitive quoting a job running 100 SFM or less in steel? If I did that I either wouldn't have any work or be running at $10 an hour.
    Well, the guy did ask how to manage mild steel for a good finish.

    What I recommended doesn't take all day because the feed rate is much faster than a normal turning operation...…..it's mainly when you want to super finish a work piece with a bright shiny appearance.

    Sometimes you want to have a piece of work that is a personal show piece, not something you had to polish up with emery and oil etc.

    If it's production you're into then leaded steel is the way to go...….S12L14 (OZ supplier code) is the stuff I used to buy when I ran my 1-1/4" Taylor capstan lathe back in the late 90's.

    I ran HSS form tools 25mm wide, no top rake, into 32mm diam stock and plunged straight in to get a good finish at 400 to 500 rpm.
    Ian.

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    Other than the guy above, does anyone practically use HSS for Turning anymore???

    He's bragging about 165 SFM in mild steel.

    R

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    Quote Originally Posted by Crabtree View Post
    I have to state this...…..NONE OF YOU KNOW WHAT YOU ARE TALKING ABOUT.

    I'm a golden oldie from way back, did my apprenticeship in the late 50's, and one thing I learned when working with mild steel and HSS cutting tools to get a good finish is that you want to go dead slow in the revs for the final finish cuts and use coolant all the time.

    OK..…...mild steel, that soft stuff everybody uses for just about anything and using conventional tooling and methods for finishing is a recipe for bad finishes.

    Try this, it is for FINAL finishing only ...…..I use a flat top parting type tool, honed sharp with NO top rake and a 4mm + wide blade to finish mild steel to a chrome plated mirror finish......how?

    Well, the secret is in the tool presentation and the rpm.

    Run your lathe at 50 rpm for a piece of steel say 50mm, 25mm or 12mm diam.....it doesn't matter, the bigger the diam the slower you want to go...... and get the tool flat front face as square to the work as is possible...…..IT MUST BE DEAD FLAT TO THE WORK PIECE AND DEAD ON CENTRE HEIGHT.

    Then you apply a depth of cut about .2mm or say .005" .006"......002" works well too.... and use a coarse feed....this will compensate for the time it takes at slow rpm to feed the tool along the job.

    What is happening is the steel peels off the work like foil, not being torn off if you go too fast.

    YOU MUST HAVE THE TOOL CUTTING ON AS BROAD A FACE AS POSSIBLE.....DEFINATELY NOT A POINTY TOOL WITH A SHARP TOP RAKE.

    A tool with a .500" wide face and maybe a 5 deg top rake works very well for a quick travers.....but it must be kept wet with water/oil bases coolant at all times and dead square to the job or you will get a spiral groove from the end edges.

    I have used this for finishing practically all metals to a high polish like finish....brass works exceptionally well and alumin(i)um too.

    The broad face of the tool allows a fast feed rate......experimentation in this method is an eye opener.

    I'd just like to mention that the old lathes, with back gear like the Old 1930 Colchester Bantam I have and currently use, and the 1940's 9" South Bend models I've use years ago, all with their back gear low speeds are ideal for this method.

    BTW,,,,for final finishing I use this method when I do screwcutting to get threads that are polished......the finish tool is a flat top form tool for the thread form.
    Ian.
    I decided to try this method to see how it worked in my hands. I used my surface grinder to grind a zero rake straight-faced 3/8” HSS tool with 4 degrees of relief. I set the tool right on center and set it up a couple ways to see which worked better. I wanted to see if angling the face of the tool so that it was not perfectly parallel might give a wider cutting action and better surface than dead parallel. It looks like parallel was better.

    I tried it without a nose just dead sharp at the left end. Predictably, it scored the work in a spiral pattern matching the .0075 IPT feed as I ran it at 50 RPM on 1” 1018. So I honed a small nose—about .010 radius (though Crabtree did not mention this) on the headstock side. That pretty much eliminated the scoring.

    I used a light source under the bit to see when it was lined up dead flat against the work.

    I used some brushed on cutting oil.

    The results of this cutting method were quite good—-chrome plated good? No. Might be possible if I were more familiar with the technique. But still, much better than the furry surface we have all seen (like the first post here) when using less than optimal carbide cutter or HSS technique. And about as good as I can get running a good carbide cutter at fairly high speed and with decent DOC. It was slow. I could cut about .35 inches per minute using the coarsest feed setting on my EE.

    img_6125.jpg


    So there you have it. It is a technique that works well and might have a role to play in some circumnstances. Maybe Crabtree can show how to get that chrome finish.

    Denis

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    That broad nose deal has also been mentioned by Forrest Addy on the forum as a way to get a nearly ground finish on ways such as lathe beds using a planer.

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    Quote Originally Posted by eKretz View Post
    I used to use it a lot when finishing larger radiuses with HSS form tool on the lathe - beautiful finish.
    Ah, the old "put it in neutral then spin the chuck by hand" trick

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    Wow 2 whole pages on how to get a finish in an old clapped out lathe...

    1) - emery paper / cloth
    2) - emery paper / cloth > then finer emery paper / cloth / lapping compound

    (and yes I've run manual machines before, just haven't done it to make money in quite a while...)


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