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  1. #61
    BobL is offline Member: Blue and white apron brigade
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    In most cases I reckon sanding above about 400 is a waste of money.
    If you want a shiny surface it's probably better to jump from 400 to a buffing wheel.

    But just like fine abrasive paper a buff won't remove scratches.

  2. #62
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    Quote Originally Posted by BobL View Post
    In most cases I reckon sanding above about 400 is a waste of money.
    If you want a shiny surface it's probably better to jump from 400 to a buffing wheel.
    But what if you don't want a shiny surface? What if you want a satin sheen? 800 grit will give you that. There's a LOT of grits between 400 grit and the finish from a buffing wheel. Many times I've sanded through 400, 600, 800, 1000 and 1500. Metal pens being one example.
    Chris

  3. #63
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    Default Finish

    Hi

    I think you would achieve a better finish if you use a tool with a small radius on the point , your tool appears to have a sharp point on it which isn't the recommended shape for a decent surface finish.
    Attached Images Attached Images

  4. #64
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    Quote Originally Posted by mathuisella View Post

    As you can see in this picture i'm using a brazed carbide tool and it works very well at removing material and leaving a pretty nice finish.

    Attachment 392585

    After it's all said and done, i sand it all and it finished up looking like this compared to the old one. I believe it's a bit better Note: sanded down from 180 to 2000 grit sand paper.

    Attachment 392583
    Hi Mathu,

    Those two pictures don't even look as though they have been turned on the same machine !

    I don't think even sanding or filing would produce such a rough finish. Something else is going on here !

    That finish looks like the lathe tool has been run back and forth on the work, and the lathe saddle is not set up properly so its able to rock as its moved. Check the saddle gibs for play. You will find that the saddle will get tighter as you get closer to the tailstock. The difference will be due to the wear in the shears near the chuck end.
    Best Regards:
    Baron J.

  5. #65
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    Quote Originally Posted by BaronJ View Post
    Hi Mathu,

    Those two pictures don't even look as though they have been turned on the same machine !

    I don't think even sanding or filing would produce such a rough finish. Something else is going on here !

    That finish looks like the lathe tool has been run back and forth on the work, and the lathe saddle is not set up properly so its able to rock as its moved. Check the saddle gibs for play. You will find that the saddle will get tighter as you get closer to the tailstock. The difference will be due to the wear in the shears near the chuck end.

    thank you

    may i ask where the saddle gibs are ? ( feel like an idiot haha )

  6. #66
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    Quote Originally Posted by morrisman View Post
    Hi

    I think you would achieve a better finish if you use a tool with a small radius on the point , your tool appears to have a sharp point on it which isn't the recommended shape for a decent surface finish.


    Thank you

    the cutting side is the whole left face of the tool, it's a carbide bit and used it to remove material, about .5mm at a time. going from right to left, any more and the machine doesn't like it.

  7. #67
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    It is just a plate mounted at the rear of the saddle, there will be 2 set screws , screwed up from underneath to secure it .
    If you grab the back/rear of the saddle you should be able to lift it until the (gib) keeper plate hits the underside of the bed.

  8. #68
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    Quote Originally Posted by pipeclay View Post
    It is just a plate mounted at the rear of the saddle, there will be 2 set screws , screwed up from underneath to secure it .
    If you grab the back/rear of the saddle you should be able to lift it until the (gib) keeper plate hits the underside of the bed.

    Ah, thank you

    i'll tighten it up tomorrow and make another part

  9. #69
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    Don't know about tightening it up to much, normally there could be upwards of .060" or more clearance.
    If you feel it needs to be closer you will need to shim it, you will also need to check the the carriage does not bind along it's travel.
    Are you power feeding or still feeding manually?

  10. #70
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    Quote Originally Posted by mathuisella View Post
    Thank you

    the cutting side is the whole left face of the tool, it's a carbide bit and used it to remove material, about .5mm at a time. going from right to left, any more and the machine doesn't like it.
    It cuts at the tip, not on the left side.
    If you look at your picture you can see the marks from the chatter on the left side shoulder where you have engaged the tool full depth on the left face.

  11. #71
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    Default

    Hi Mathu,

    I've not been able to find any drawings of your lathe parts to be able to identify the gibs or the adjustment screws for it.

    On my lathe the gib and the adjusting screws are on the front of the saddle just below the crosslide feed handle. And are adjusted to prevent the saddle twisting as it is traversed along the bed. There are anti lift plates at the back where on the Myford the saddle lock is fitted.

    It might be a good Idea to get a copy of the Southbend book "How to run a lathe" its well worth having !

    Edited to add this picture from the South Bend lathe manual !

    Saddle Gib Screws.png
    Best Regards:
    Baron J.

  12. #72
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    Quote Originally Posted by BaronJ View Post
    Hi Mathu,

    I've not been able to find any drawings of your lathe parts to be able to identify the gibs or the adjustment screws for it.

    On my lathe the gib and the adjusting screws are on the front of the saddle just below the crosslide feed handle. And are adjusted to prevent the saddle twisting as it is traversed along the bed. There are anti lift plates at the back where on the Myford the saddle lock is fitted.

    It might be a good Idea to get a copy of the Southbend book "How to run a lathe" its well worth having !

    Edited to add this picture from the South Bend lathe manual !

    Saddle Gib Screws.png

    this is the underside of the carriage rear ( towards the wall ) I tightened this us and yeah, the carriage is a lot more firmly pressed against the bed/ways and take a fair amount more 'oompf' to move from side to side, and yes it's a bit more easier to move the closer you move towards the chuck.

    195881738_415522666138137_6428517296112283035_n.jpg


    This is a fresh piece i am working on.

    just turned it down to the diameter/thickness i needed and this is the outcome.

    199709787_783970738918964_3821105638462825376_n.jpg202238660_316644016801502_8799718782319088832_n.jpg

    same tool as before

    198646887_267051945217739_8039311089065180746_n.jpg
    Quote Originally Posted by racingtadpole View Post
    It cuts at the tip, not on the left side.
    If you look at your picture you can see the marks from the chatter on the left side shoulder where you have engaged the tool full depth on the left face.

    hmm, that seems odd to me, but yet also makes sense at the same time. i do see the chatter on the left side shoulder that the left face of the tool comes up to. i only cut about 0.5mm at any pass and the chatter i expected when i got to the face as its about 10mm contact area instead of 0.5mm and is too much for the machine, but i wanted to get it cut all the way to the corner so i turned the machine off and reset my tool the moment the chatter began at the end of each pass ( i hope that makes sense )

    maybe i just need to go and get a carbide bit holder and inserts.

  13. #73
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    Hi Mathu,

    If you haven't got a copy of the book I mentioned, drop me a PM with your Email and I'll send you a copy !
    Best Regards:
    Baron J.

  14. #74
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    If that’s a piece of hot rolled, that finish is about as good as it gets.
    You may get a little better using a tool with a radius at the nose, but hot rolled is hot rolled, you will never get an Instagram machinist picture from it.
    Picture attached is hot rolled mild steel cut with a DCMT carbide tool on my 9”. The insert has a .4mm radius on it, the finish is only marginally more consistent than what you achieving, that will be largely due to the power feed on both axis.

    To cut shoulders like that, work along to the left, withdraw the tool along the shoulder in a facing type cut, return to the start, touch off (dials should match where they were last cut) and go again (if you can keep track of the dials in your head then you can skip the touching off and advance the tool). If it’s a precision part either set a stop or an indicator to establish the shoulder in the same place each cut.
    Attached Images Attached Images

  15. #75
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    Quote Originally Posted by racingtadpole View Post
    If that’s a piece of hot rolled, that finish is about as good as it gets.
    You may get a little better using a tool with a radius at the nose, but hot rolled is hot rolled, you will never get an Instagram machinist picture from it.
    Picture attached is hot rolled mild steel cut with a DCMT carbide tool on my 9”. The insert has a .4mm radius on it, the finish is only marginally more consistent than what you achieving, that will be largely due to the power feed on both axis.

    To cut shoulders like that, work along to the left, withdraw the tool along the shoulder in a facing type cut, return to the start, touch off (dials should match where they were last cut) and go again (if you can keep track of the dials in your head then you can skip the touching off and advance the tool). If it’s a precision part either set a stop or an indicator to establish the shoulder in the same place each cut.
    Thank you

    left one is hot rolled which i got before i knew what to get, right one is machining steel i got from a local machine shop ( i asked for 12L14 )

    194238914_549239736458989_2857886596862305643_n(1).jpg

    i've been just measuring with tape on the piece itself as what i've been making aren't needing precision and also i can't really do the whole imperial system and the dials on the lathe are imperial.





    oh and the latest piece i've been working with is hot rolled, the thicker section is as it's finished by the initial tool(right side ) , the thinner section has been polished up to 2000 grit sand paper. ( left side ) Sadly i got a bit of chatter on a spot half way down the thinner section which you can feel :'( but alas, it's just a home made piece.

    196315197_314527870144647_5313800958601720643_n.jpg



    I watched this video ( and more of the series she has and found it helpful )

    https://www.youtube.com/watch?v=yBVo8wufsCE





    I'll post back when i get a pice of 12L14 done and see what it looks like but for now, i'm still getting those weird semi random scratches in all parts.

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