raw stock .379 O.D. round. Need to bring to .3753-.3757. Hollow Mill? Burnishing tool
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  1. #1
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    Default raw stock .379 O.D. round. Need to bring to .3753-.3757. Hollow Mill? Burnishing tool

    The part is not big enough to grind to size. Customer supplies material that comes from the overseas parent company (JIS).

    I thought about a roller burnishing tool but they are very expensive. My Dad is thinking hollow mill.

    I have to hold a 32 finish and am afraid of retract tool marks on the part.

    I was thinking the retract marks from my tooling would come from not having a radius on the tool edge. Maybe carbide inserts would prevent this?

    Brown and Sharpe screw machine. Chamfer/Cutoff job. 1.00" long. Need to bring O.D. to .3755 and hold for long runs.

    Any advice or help is greatly appreciated.

    Material is equivalent to 4140 cold drawn annealed.

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    burnishing that would absolutely NOT work. All you are doing is pushing the peaks into the valleys. Much depends on the pre-burnish finish, but we shoot for a size change of maybe .0003 to .0005. I am not grasping why you cant simply turn it.

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    Have you tried turning it with a box tool?

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    I am lost, why can't you turn it off? You can buy inserts with only a .001 nose radius that work on 4140, is stock fairly round?

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    Centerless grind them after you turn everything else and cut them off. .002 stock per side and you're going to turn them??? I think you are being overly hopeful, but you might make it work!

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    Quote Originally Posted by Dualkit View Post
    I am lost, why can't you turn it off? You can buy inserts with only a .001 nose radius that work on 4140, is stock fairly round?
    Or grind it for that matter. Is it an out of round issue?

    It might be helpful if the OP could share what the part looks like

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    Quote Originally Posted by Dan from Oakland View Post
    Centerless grind them after you turn everything else and cut them off. .002 stock per side and you're going to turn them??? I think you are being overly hopeful, but you might make it work!
    With my revolving bushing bearings in good shape and likewise for the guide bushing, running stock that is fairly round without tapers I could hold +/-.0002 on my 16mm CNC Swiss. I haven't used a grinder since I was in Cali 10 years ago, all of them I used wanted .005 per side left, not .002.

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    Quote Originally Posted by Dualkit View Post
    With my revolving bushing bearings in good shape and likewise for the guide bushing, running stock that is fairly round without tapers I could hold +/-.0002 on my 16mm CNC Swiss. I haven't used a grinder since I was in Cali 10 years ago, all of them I used wanted .005 per side left, not .002.
    My grind shops all want at least .005 left over.

    I dont use carbide inserts. I grind my own box tools but never put a radius on it. Usually get retract marks but never an issue for customer.

    If I try to use a carbide insert on a box tool it may work. Just dont have experience with it. I was thinking a radius on the tool would eliminate retract marks but I have never tried.

    I see some hollow mills with carbide inserts that look cool.


    I dont know about the material being round or not. I just measured 1 spot and got .379" print needs it to be .3753-.3757 with a 32 finish.

    They do have a swiss screw machine department but they say some of the jobs are too cheap to put on them. I dont know if this was run on their swiss machines or not. If I had a swiss I would run it on that and just turn it.

    My old man like skive tools. They dont really make them for my machines but we can make one if we have to

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    Quote Originally Posted by DanASM View Post
    My grind shops all want at least .005 left over.

    I dont use carbide inserts. I grind my own box tools but never put a radius on it. Usually get retract marks but never an issue for customer.

    If I try to use a carbide insert on a box tool it may work. Just dont have experience with it. I was thinking a radius on the tool would eliminate retract marks but I have never tried.

    I see some hollow mills with carbide inserts that look cool.

    I dont know about the material being round or not. I just measured 1 spot and got .379" print needs it to be .3753-.3757 with a 32 finish.

    They do have a swiss screw machine department but they say some of the jobs are too cheap to put on them. I dont know if this was run on their swiss machines or not. If I had a swiss I would run it on that and just turn it.
    What do you mean by box tool? I have never run a Brownie, and did work somewhere where they got some in right before I was heading for greener pastures. I thought they were similar to Swiss cam autos with sliding head stocks just they handled larger diameter stock. Do your Brownies have fixed head stocks? It was 30 years ago I saw one in person.

    How many parts do you have to make?

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    no sliding heads here. All fixed.

    Model T Box Tool - Hye Tech Machine - Replacement Parts - Davenport - Brown & Sharpe

    it has rollers to keep the part concentric. Works great with Tantung. I have one with the rollers behind the cutting edge so it can turn down hex. The rollers run on the round part already turned.

    I do see these box tools with carbide inserts. I may have to buy a new/used one.

    Parts could be from 2000-10000. 2,3,4,5 10 times a year.

    They need overflow capacity. I guess they have been turning too much work down cause they are at capacity.

    They have a bunch of parts for me. Rings and pins. 4140 and 400 series SS.

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    We used to be a Brown & Sharpe shop. We don't have any left, but we have kept some of the tooling. I use a Boyar-Schultz box tool with a TPG221 insert in a CNC lathe all the time. You're right that sometimes there is a retract mark, but I'm usually able to adjust the tool to get rid of it. There sure is a bit of magic to setting those box tools. I'd be concerned about the insert cutting that little of material and leaving a nice finish. Though, I guess the rollers would burnish any roughness out... I would have to try it to know if it could work.

    That being said, I would absolutely just cut them off and centerless grind them. We do our own centerless grinding, and I don't know why your grinder needs more material. We can grind just .0001" off a part if we want to.

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    Quote Originally Posted by DanASM View Post
    no sliding heads here. All fixed.

    Model T Box Tool - Hye Tech Machine - Replacement Parts - Davenport - Brown & Sharpe

    it has rollers to keep the part concentric. Works great with Tantung. I have one with the rollers behind the cutting edge so it can turn down hex. The rollers run on the round part already turned.

    I do see these box tools with carbide inserts. I may have to buy a new/used one.

    Parts could be from 2000-10000. 2,3,4,5 10 times a year.

    They need overflow capacity. I guess they have been turning too much work down cause they are at capacity.

    They have a bunch of parts for me. Rings and pins. 4140 and 400 series SS.
    Strike everything I thought about Brownies from the record, I always assumed they had sliding headstocks. Unfortunately with data capped internet I can't go watch videos to learn about them. Hardwired broadband is not available here. I did think you were contemplating buying a CNC Lathe, was that the fixed headstock type or sliding headstock?

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    Quote Originally Posted by Dualkit View Post
    Strike everything I thought about Brownies from the record, I always assumed they had sliding headstocks. Unfortunately with data capped internet I can't go watch videos to learn about them. Hardwired broadband is not available here. I did think you were contemplating buying a CNC Lathe, was that the fixed headstock type or sliding headstock?
    I was looking at bigger 2 axis lathes to cover 1.00"-2.00" to go over the sizes my swiss shops cover.

    I since feel like a 4th axis mill would get me more work.

    Lately a few jobs came through and I saw a 12mm swiss looking nice for it.

    I want to get something that I can run more unattended. A hardinge gt 27 looks great for 2nd op chucker work and under an inch bar fed work.

    I know too many swiss shops. I feel like I would be going after their work if I went that route. Unless I found a dumbed down machine that can run some of my longer running jobs unattended/lights out I dont really feel like going the swiss route.

    They do take up little space and run very little electricity. That in itself is keeping me somewhat interested.

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    I think this may be my solution. I can run my Tantung rectangle turning tools in it.

    Box Tools with Carbide V Rests - Brown-Sharpe SMT

    I have many of these but have never used them. My old man says he never liked them. I guess we just havent seen the right part for it until now.

    The open part of the toolholder will be facing up. When the tool gets to full depth I can index it and it will "fall" away from the part. Leaving no retract mark on the od except for maybe a little mark where the part will be cutoff anyway.

    I have many of these tools and look forward to trying them out.

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    Dan you should seriously look at and older citizen heck even and f12(12mm) or f16(16mm) from the sound of your work that your having difficulties on in the last year these would run them perfectly and you can get them pretty cheap 1k-5k. Of course a new model would be better but its also more money.
    I wouldnt buy one sight unseen though.

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    For starters, a "modern" box toy has a spring loaded insert cartridge that will pop up above C/L with no turning torque on it. (retract)
    Boyer Schultz 2RT is an example, and may or may not get down to your size.
    Actually - I think that I normally turn to 1/4" with that one.
    ???
    (down from 5/8" 1200 LCS)
    I wouldn't touch any of the others that you linked to.


    But it will be much more better to just take it to the grinder.
    .005 is just an arbitrary safety clean-up spec.
    I send stuff to the grinders all the time with .002.
    Worst case scenario is that you have a blem spot that didn't clean up - but will likely measure good anyhow.

    The tol you want.
    The finish that you want.
    The material to doo it in....
    Take it to the bloody grinder!


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    I am Ox and I approve this h'yah post!

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    Quote Originally Posted by Ox View Post
    For starters, a "modern" box toy has a spring loaded insert cartridge that will pop up above C/L with no turning torque on it. (retract)
    Boyer Schultz 2RT is an example, and may or may not get down to your size.
    Actually - I think that I normally turn to 1/4" with that one.
    ???
    (down from 5/8" 1200 LCS)
    I wouldn't touch any of the others that you linked to.


    But it will be much more better to just take it to the grinder.
    .005 is just an arbitrary safety clean-up spec.
    I send stuff to the grinders all the time with .002.
    Worst case scenario is that you have a blem spot that didn't clean up - but will likely measure good anyhow.

    The tol you want.
    The finish that you want.
    The material to doo it in....
    Take it to the bloody grinder!


    -------------------

    I am Ox and I approve this h'yah post!
    This is what I have been wanting to do since the beginning. It would make it so much easier. Its just a Chamfer/Cutoff job.

    The guy buys 2 million lbs of steel yearly. He gets better pricing so he can pay me more to machine it and it comes out cheaper in the long run.

    My problem now is the material is supplied by the customer, 1 hour south of me. One of my grinders is 2.5 hours south of me and he is the one I trust and like his pricing.

    I would have to go get the material and continue down to the grinder. If its not same day then I have to come back down and this means 2 days off of work and wear and tear on vehicles, etc.

    So easy yet so difficult. I just have to get samples sent in to get "approved vendor" status. I can ask for more help afterwards. Hell they have a grind shop in house. I could have them do it but they dont want me to keep asking questions right now.

    Just concentrate on the sample parts they say. I can do them by hand and make them pretty. But for production... No way.

    Ox My dad talks a lot about Skive tools on the Multi spindles he used to run. He said he could hold tol. on 100k's of parts. I have never run one but understand the concept.

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    OK, so I Googled and e-bay's 2RT and I didn't find ANY that had the retractable (not a Ford) insert in them.

    Here is what you are lookin' fer.
    Notice the pivot point behind the insert.
    This must have been an optional head?


    I didn't use flash, and the longer shutter time apparently got the best of me, but I think that it is clear enough for understanding?



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    Attached Thumbnails Attached Thumbnails dscn2513.jpg  

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    Quote Originally Posted by Ox View Post
    OK, so I Googled and e-bay's 2RT and I didn't find ANY that had the retractable (not a Ford) insert in them.

    Here is what you are lookin' fer.
    Notice the pivot point behind the insert.
    This must have been an optional head?


    I didn't use flash, and the longer shutter time apparently got the best of me, but I think that it is clear enough for understanding?



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    I am Ox and I approve this h'yah post!
    I get it. I was also thinking of a swing groove/recess tool used as a turning tool. No rollers on that though.

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    Quote Originally Posted by DanASM View Post
    This is what I have been wanting to do since the beginning. It would make it so much easier. Its just a Chamfer/Cutoff job.

    The guy buys 2 million lbs of steel yearly. He gets better pricing so he can pay me more to machine it and it comes out cheaper in the long run.

    My problem now is the material is supplied by the customer, 1 hour south of me. One of my grinders is 2.5 hours south of me and he is the one I trust and like his pricing.

    I would have to go get the material and continue down to the grinder. If its not same day then I have to come back down and this means 2 days off of work and wear and tear on vehicles, etc.

    So easy yet so difficult. I just have to get samples sent in to get "approved vendor" status. I can ask for more help afterwards. Hell they have a grind shop in house. I could have them do it but they dont want me to keep asking questions right now.

    Just concentrate on the sample parts they say. I can do them by hand and make them pretty. But for production... No way.

    Ox My dad talks a lot about Skive tools on the Multi spindles he used to run. He said he could hold tol. on 100k's of parts. I have never run one but understand the concept.

    I've never used one on a multi, but I did make a tool for may old W&S that I was using and a chum came over and seen what I was dooing, and he said that what I had built was a skive tool.
    The one that I built had quite a bit of angle on it so that it started cutting to C/L at the front of the part first and finished at the cut-off - so that it gave some shear as well as kept the part/bar as solid as possible while finishing further away. IDK if they are all built this way or not?
    I think that is gone now.

    But this aint 12L !



    Shirley you can find a grinder a LOT closer than that in your area.

    I would grind after you make the parts, not the bar.
    Too many chances to scratch the bar before processing.


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