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  1. #376
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Quote Originally Posted by OxxAndBert View Post
    I just use normal turning tools for tapers. Nothing special about the angles.
    Not sure if you’ve seen any of Joe Pieczynski’s videos on YouTube, but he’s got a good one on setting accurate angles on the compound using a DTI.

    Steve
    Hi Steve,

    Is that the one where he uses a dial indicator to follow an existing taper ?
    Best Regards:
    Baron J.

  2. #377
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Quote Originally Posted by shedhappens View Post
    Hi John, the wheel hubs on my Repco T&CG would be much the same as Steves hubs, they are relieved in the centre.
    I believe this is to support the hub at each end to reduce the chance of the hub rocking on a bit of of dust or debris.
    I had to make a longer one today to get a cup wheel over the centre of the table on my radius grinding gadget.
    My hubs have about a 14 deg included taper, i set up one of the existing hubs and used an indicator to dial in the topslde.
    To get accurate angles for your top slide, if your lathe isn't too sloppy, dial in your top slide on an accurate piece of stock held in the chuck, then you should be able to dial in the side of a tool holder parallel to the axis of the lathe. Then you can use a sine calc and indicate on the side of the tool holder the angle of the topslide over a distance of travel of the saddle using a dro or even a 2" travel dial indicator, sine calc https://littlemachineshop.com/mobile/sine_bar.php
    Its a bit of mucking around but it might be an option for you...
    Hi John,

    Thanks for the link.

    Aah that makes sense. Because my taper is very short and steep would there be any advantage in relieving the centre ?

    I've actually made a pair of gauges to aid in setting the compound, I'll post a picture in a few minutes.

    I had the idea of using a form tool with a flat edge to do the male taper. It was the female one that I was having difficulty getting my head around.
    Best Regards:
    Baron J.

  3. #378
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    6,436

    Thumbs up Angle Gauge !

    Hi Guys,

    I've been making an angle gauge for setting the lathe compound to the correct angle for turning the male and female tapers. The gauge is intended to be used in a similar fashion to a fishtail thread gauge. I've made this one from some very hard 2 mm thick aluminium plate. Actually it was the the alloy base of a computer backup data tape.

    I cut a strip 15 mm wide scribed the angle I wanted using a protractor and then sawed it in half down the scribed line.

    17-11-2020-002.jpg 17-11-2020-001.JPG

    I've laid the two pieces on the drawing and the angles match perfectly. The holes were already in the plate, handy for a bit of wire to keep them together.

    Thanks for looking.
    Best Regards:
    Baron J.

  4. #379
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
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    2,651

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    Quote Originally Posted by BaronJ View Post
    Hi Steve,

    Is that the one where he uses a dial indicator to follow an existing taper ?
    No, its this one where he explains in detail what Shed has just written in a single sentence

    https://www.youtube.com/watch?v=YCllVu4K738

    Steve

  5. #380
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,436

    Thumbs up Threading Problem !

    Hi Guys,

    I've hit a problem ! I've got the taper turned on my work piece and have now started to cut a 1 mm thread into the 16 mm diameter part.

    18-11-2020-002.jpg 18-11-2020-001.jpg

    I ground a piece of 1/2" by 3/4" inch tool steel and cut the taper. I got lovely nice curls of swarf of the work. I had to take great care because the chuck jaws were very close to the compound and table. I couldn't have got any closer if I tried.

    18-11-2020-003.jpg 18-11-2020-004.jpg

    Now the threading problem ! I cut the first two or three cuts and then the tip broke off the insert. You can see in the first of these two pictures. Ok ! Just turn the insert round. I had got to 25 thou deep about half way along and the second insert tip broke off.

    I've stopped at this point to try and diagnose why ! Lathe speed about 220 rpm, depth of cut about 3 thou, I took the first cut at 5 thou. A nice clean cut. I checked that the tool was square to the work, it was. I checked centre height, as near as makes no difference. I'm mystified why should the tips just break off ? Am I going too slow. I've cut threads with inserts using the lathe handle on small diameters.

    I'm obviously doing something wrong ! Any ideas, anybody.
    Best Regards:
    Baron J.

  6. #381
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Thumbs up Inserts !

    Hi Guys,

    I got the microscope out and took some pictures of the failed threading inserts. I put another new one in the tool holder and it lost the tip within a couple of threads.

    The more I look at it I'm starting to think that these inserts are junk !

    18-11-2020-05.jpg 18-11-2020-04.jpg 18-11-2020-06.jpg

    These are pictures of the broken faces. Notice how coarse the grain looks, there seems to be odd bits in there.

    18-11-2020-03.jpg 18-11-2020-02.jpg 18-11-2020-01.jpg

    This is looking down on top of the insert.

    There are no markings or other identification on these inserts other than a label on the box. At £3 each I would have expected better. The original insert that came with the toolbar has done more than a dozen threads before I forgot myself and turned the lathe backwards without backing the insert out.
    Best Regards:
    Baron J.

  7. #382
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

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    John i dont think the rpm would cause any of that, yesterday i cut a 5/16 unc left hand thread on a metric lathe using the vfd to to relocate the tool at the start point. I was peeling off metal at only 5 - 10 rpm at times.
    My first thoughts with something like this are always to check to make sure the tool is rock solid.
    Recheck your gears and make sure they are correct.
    I would say make sure the lathe is running the right way but i know that you know better than that
    Your top slide might be jiggling around so check that also..

  8. #383
    Join Date
    Nov 2017
    Location
    Geelong, Australia
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    57
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    I can't see the toolpost in those photos, which means for such a light toolholder you've got more unsupported length that I'd like.
    That material looks really tough to me too.
    Are you using any cutting oil?
    Are you cutting both sides of the vee, or is your compound offset to ~30 degrees so when you set the cut depth its only cutting on one face?

    My gut feel is the material is tough, and its flexing and grabbing.
    Probably not being helped by the piece of Ssangyong rear bumper I noticed mixed in with the carbide grains though

    Steve

  9. #384
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    Sep 2012
    Location
    York, North Yorkshire UK
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    Hi Steve, Guys,

    Thanks for your help chaps, I thought I was doing well...

    I plunge straight in and yes I do use Temaxol as a cutting oil. Because I was supporting the workpiece with the tailstock I couldn't get any closer without fouling it. I suppose I could have rotated the compound to 90', that would have given me full clearance.

    John, yes I've done that trick a couple of times, put the lathe in reverse and forgot that it was running the wrong way. Fortunately no damage done to anything, the clutch disconnects everything instantly.

    The compound has never been adjusted, but it wouldn't hurt to strip and clean it. Come to think about it its never been oiled either ! I'll consider my wrist slapped for that.

    Yes I thought that the surface of the breaks looked iffy ! I put a new insert in and the tip snapped off about two turns in. I agree that the material is tough, but once I got under the case hardening it seemed to machine quite nicely. I had no trouble getting down to 16 mm diameter with a HSS tool and 25 thou cuts, but I really did need the carbide one to get rid of the outer surface.

    The guy that gave me the material never warned me that it was hardened, all he told me was that it was a scrap length of hydraulic piston rod. In fact I watched the length of it that he gave me being cut off on his bandsaw.

    Anyway that piece has gone in the scrap bin now. I'll go buy a length of 32 mm diameter EN1 and some different threading inserts ! I'm really not chuffed with the ones I've been using.

    Thanks both:
    Best Regards:
    Baron J.

  10. #385
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    Apr 2012
    Location
    Healesville
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    John the reason that i sugested to check your gearing is because i had what looked like exactly the same problem as yours a few years ago.
    I found that i had not set my thread cutting gears correctly and as a result each time i engaged the half nut the tool would start in a diferant position, the cut looked the same as yours.

    What i had done was i had the round dial a couple of numbers off to where it should have been so the thread chasing dial was not timed with the lead screw and the thead started in a diferant spot each time the halfnut was engaged.
    You could try to cut a thread without disengauging the halfnut and see if cutting improves and inserts stop breaking, then check the tpi of the thread
    Attached Images Attached Images

  11. #386
    Join Date
    Dec 2007
    Location
    Adelaide
    Posts
    574

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    Depending on the type of material I'm threading I sometimes take 2 or 3 passes at the same depth of cut or until I see that very little material is being removed, I find it helps with tough material.

  12. #387
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    Nov 2017
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    Hi John,
    I'd grab that piece back out from the scrap, and when you get your new inserts give it another try just to compare.
    Possibly use a shorter test piece that you can hold in the chuck without support and get the toolholder back into the post further. If it works nicely like that with the new inserts, then try the same setup with ones you're having issues with.
    My logic is that decent steel is expensive, hydraulic rod AFAIK is quite consistent, so would be a shame to rule it out as a material source if its a case of tooling or setup being the issue.

    I got onto a source of old hydraulic rod recently so have used a bit of it lately and find it to be as I think you expected.
    Outside is chromed but rips off easily - I use a WNMG insert as they are cheap and robust. The worst bit is the crap that comes off is almost like cast iron powder and a mixture of the hard steel and the chrome flakes. I try to cover the lathe bed a bit and use the shop vac where possible to capture it at the source.
    Once that's done it machines nicely though. I recently cut the ~50mm diam thread for the piston on my press with no issues. My lathe is bigger than yours so will have a bit more rigidity, but its hardly in the peak of condition

    Steve

  13. #388
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    Sep 2012
    Location
    York, North Yorkshire UK
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    Quote Originally Posted by shedhappens View Post
    John the reason that i suggested to check your gearing is because i had what looked like exactly the same problem as yours a few years ago.
    I found that i had not set my thread cutting gears correctly and as a result each time i engaged the half nut the tool would start in a diferant position, the cut looked the same as yours.

    What i had done was i had the round dial a couple of numbers off to where it should have been so the thread chasing dial was not timed with the lead screw and the thread started in a different spot each time the halfnut was engaged.
    You could try to cut a thread without disengaging the halfnut and see if cutting improves and inserts stop breaking, then check the tpi of the thread
    Hi John, Guys,
    Thanks for your comments and help.

    I don't have a thread indicator, so I leave the halfnuts closed, back off and wind back the saddle, usually under power.

    The appearance of what look like split threads is because I didn't realise that the tip had broken off and proceeded to do another cut. I have broken tips off by forgetting to back off and winding back. That piece of material is now history, its gone in the scrap bin.

    I've got a Sandvik threading insert on its way £12 each, bloody expensive ! I'll be really hacked off if I manage to break that one. I've also ordered a foot of 32 mm EN1A-RB3 What ever the (RB3) means. £15 + Carriage.
    Best Regards:
    Baron J.

  14. #389
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    Sep 2012
    Location
    York, North Yorkshire UK
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    Quote Originally Posted by OxxAndBert View Post
    Hi John,
    I'd grab that piece back out from the scrap, and when you get your new inserts give it another try just to compare.
    Possibly use a shorter test piece that you can hold in the chuck without support and get the tool holder back into the post further. If it works nicely like that with the new inserts, then try the same setup with ones you're having issues with.
    My logic is that decent steel is expensive, hydraulic rod AFAIK is quite consistent, so would be a shame to rule it out as a material source if its a case of tooling or setup being the issue.

    I got onto a source of old hydraulic rod recently so have used a bit of it lately and find it to be as I think you expected.
    Outside is chromed but rips off easily - I use a WNMG insert as they are cheap and robust. The worst bit is the crap that comes off is almost like cast iron powder and a mixture of the hard steel and the chrome flakes. I try to cover the lathe bed a bit and use the shop vac where possible to capture it at the source.
    Once that's done it machines nicely though. I recently cut the ~50mm diam thread for the piston on my press with no issues. My lathe is bigger than yours so will have a bit more rigidity, but its hardly in the peak of condition

    Steve
    Hi Steve
    Thank you for your notes.

    With all due respect that piece of material is in its final resting place, the bin !

    I do understand where you are coming from, but for my own peace of mind I'm going to start again with a new piece of material. I've still got the other nine inches of it sat on the floor for future use, but not for this project.
    Anyway after paying £12 for a quality insert I wouldn't be happy risking it on the old work piece.

    I ought to take some micrographs of the threads, I'm sure that there are bits of the carbide embedded in it. You can feel the roughness in a couple of places.

    I must admit I was quite confident when I machined the taper it cut very nicely with long smooth curls of swarf.

    Now to go back to clearing out 40 odd years of junk.
    Best Regards:
    Baron J.

  15. #390
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    Sep 2012
    Location
    York, North Yorkshire UK
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    Hi John, Steve, Guys,

    The compound has never been adjusted, but it wouldn't hurt to strip and clean it. Come to think about it its never been oiled either ! I'll consider my wrist slapped for that.
    I said this earlier. Well I've stripped the slide off and found that it was full of oil, in fact very well lubricated surprisingly. I've never applied any lubrication the whole time that I've had the lathe, so I can only assume that it was oiled when it was built.

    Of course the gib strip fell out when I took the slide off and it was impossible to get it back into place without slackening off the adjusting screws. Once I had got it back in place I had great difficulty adjusting the screws and tightening the lock nuts. Every time I tried tightening the lock nut it caused the slide to bind. Its always been firm but it didn't take much to lock it up.

    So I set to and made a tool for adjusting the screw and tightening the lock nut. This is what I came up with !

    21-11-2020-001.jpg

    I found an 8 mm 1/4" drive socket which was a good fit on the 2BA lock nuts. I also had a short length of 4 mm steel rod and a scrap piece of steel out of a pair of door handles.

    21-11-2020-004.JPG 21-11-2020-002.jpg 21-11-2020-003.jpg

    A few minutes with a file and it was reduced to fit the 1/4" of the socket. Popped it into the lathe chuck and drilled a 4 mm diameter hole through the middle. After filing a screwdriver flat on one end of the rod I bent it through 90 degrees to form a handle. A 2" adjustable wrench on the flats and hey presto, I've now got an adjuster.

    And yes I do have a set of BA spanners where ever the gremlins have hidden them, of course now I don't need them they will, like magic, turn up !

    The compound is all lubed up and adjusted to my liking. That is one job less to worry about.
    Best Regards:
    Baron J.

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