Boring Head How to Question
Close
Login to Your Account
Results 1 to 17 of 17
  1. #1
    Join Date
    Dec 2005
    Location
    Waukesha, WI
    Posts
    1,792
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    580

    Default Boring Head How to Question

    Criterion boring head in a mill, happens to be a Deckel FP1. Boring 2” diameter through hole 4” long. Complication is that the first half inch is 2”, then the bore expands to 2.030” for 3”, then the last half inch is back at 2”. So how to do this. How do I extend the boring bar while I’m in the bore? I think a boring and facing head might do this, but I don’t have one of those.


    Sent from my iPhone using Tapatalk

  2. #2
    Join Date
    Jan 2014
    Location
    Temecula, Ca
    Posts
    3,276
    Post Thanks / Like
    Likes (Given)
    1396
    Likes (Received)
    4259

    Default

    is the 2.030 dia for clearance? What tolerance, does it need to be bored, or are just the 2.000 dias close tolerance?

    If the 2.030 is clearance, I would do that with a necked em, then bore the 2.000 dias.

    Otherwise, you'll need to do the 2.030 by feeding down off center, then feeding over to cl, then down.

  3. #3
    Join Date
    Sep 2004
    Location
    south SF Bay area, California
    Posts
    2,064
    Post Thanks / Like
    Likes (Given)
    158
    Likes (Received)
    685

    Default

    Do you have a rotary table?

    If so, you could first center the workpiece bore on the table axis, the adjust the RT-and-workpiece-assembly is coaxial with the spindle to bore through to 1.980 inch or so diameter.

    Once that's done, reset the spindle to place the top edge of the boring cutter a half inch into the hole, turn on the spindle, move the machine table 0.015 inch laterally, and feed along the bore slowly while rotating the rotary table.

    Finally, return the rotary table and workpiece to coaxiality with the machine spindle to finish the 2 inch diameters.

    Yes, it's a clumsy way to do the job . . . but it can work.

  4. #4
    Join Date
    Mar 2005
    Location
    Kansas
    Posts
    7,899
    Post Thanks / Like
    Likes (Given)
    486
    Likes (Received)
    3757

    Default

    Bore your 2-inch diameter to finish. Then position the tip of your boring bar in the correct spot to start your 2.03. Put your machine in neutral so you can turn the spindle by hand. Adjust the head out a few thou and turn the spindle until the bar is mostly free. Rinse and repeat until you are at your 2.03 dimension. Then put the spindle in gear and bore to proper depth. You may need to rework the clearance on your cutter so the heel doesn't wipe out the 2.000 bore as you feed the cutter into the bore. If the transition dimenson is critical, start towards the middle and finish the bottom dimension. Then switch to a back bore boring tool and finish the top dimension.

  5. #5
    Join Date
    Jun 2012
    Location
    Chicago, USA
    Posts
    1,566
    Post Thanks / Like
    Likes (Given)
    11
    Likes (Received)
    124

    Default

    Not sure what your part looks like, but if it would fit in a lathe it seems like it'd be more straightforward

    Edit: I'm sure that's obvious to the OP, given his post count. But may not be obvious to all readers

    Sent from my SM-N960U using Tapatalk

  6. Likes partsproduction liked this post
  7. #6
    Join Date
    Dec 2005
    Location
    Waukesha, WI
    Posts
    1,792
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    580

    Default

    Quote Originally Posted by Larry Dickman View Post
    is the 2.030 dia for clearance? What tolerance, does it need to be bored, or are just the 2.000 dias close tolerance?

    If the 2.030 is clearance, I would do that with a necked em, then bore the 2.000 dias.

    Otherwise, you'll need to do the 2.030 by feeding down off center, then feeding over to cl, then down.
    Yes. Don’t see how a necked em would do it unless I was on a rotary table, which I’m not.


    Sent from my iPhone using Tapatalk

  8. #7
    Join Date
    Dec 2005
    Location
    Waukesha, WI
    Posts
    1,792
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    580

    Default

    Quote Originally Posted by leeko View Post
    Not sure what your part looks like, but if it would fit in a lathe it seems like it'd be more straightforward

    Sent from my SM-N960U using Tapatalk
    That’s for sure. It’s a cross bore in a 20” long casting so would take a big lathe and some fixturing headache.


    Sent from my iPhone using Tapatalk

  9. #8
    Join Date
    Dec 2005
    Location
    Waukesha, WI
    Posts
    1,792
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    580

    Default

    Quote Originally Posted by gbent View Post
    Bore your 2-inch diameter to finish. Then position the tip of your boring bar in the correct spot to start your 2.03. Put your machine in neutral so you can turn the spindle by hand. Adjust the head out a few thou and turn the spindle until the bar is mostly free. Rinse and repeat until you are at your 2.03 dimension. Then put the spindle in gear and bore to proper depth. You may need to rework the clearance on your cutter so the heel doesn't wipe out the 2.000 bore as you feed the cutter into the bore. If the transition dimenson is critical, start towards the middle and finish the bottom dimension. Then switch to a back bore boring tool and finish the top dimension.
    I’m kinda liking this idea. Thanks. I think it’s doable.


    Sent from my iPhone using Tapatalk

  10. #9
    Join Date
    Mar 2005
    Location
    Kansas
    Posts
    7,899
    Post Thanks / Like
    Likes (Given)
    486
    Likes (Received)
    3757

    Default

    Quote Originally Posted by adh2000 View Post
    I’m kinda liking this idea. Thanks. I think it’s doable.


    Sent from my iPhone using Tapatalk
    It's also how you cut snap ring or lock ring grooves without a boring and facing head.

  11. #10
    Join Date
    Apr 2004
    Location
    Modesto, CA USA
    Posts
    7,463
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1309

    Default

    I like the bore to 2" all the way then switch. Could you do something with an internal grinder to open up the bore enough to swing the boring head. Maybe mount the grinder to the boring head for ajustability. I have seen photos of home shop types mounting a Dremel to the lathe toolpost for internal and external grinding.
    Bil lD

  12. #11
    Join Date
    Jan 2014
    Location
    Temecula, Ca
    Posts
    3,276
    Post Thanks / Like
    Likes (Given)
    1396
    Likes (Received)
    4259

    Default

    Quote Originally Posted by adh2000 View Post
    Yes. Don’t see how a necked em would do it unless I was on a rotary table, which I’m not.


    Sent from my iPhone using Tapatalk
    I didn't notice it's a manual machine at first. How good are you at drawing circles on an etch-a-sketch? I think Gbent's idea is the only one that's going to work for you.

  13. #12
    Join Date
    Sep 2011
    Location
    Southern Indiana USA
    Posts
    168
    Post Thanks / Like
    Likes (Given)
    18
    Likes (Received)
    79

    Default

    I mighgt be tempted to try and borrow a boring/facing head long enough to do this job. That would make life a lot simpler amd maybe even safer.

  14. #13
    Join Date
    Dec 2005
    Location
    Waukesha, WI
    Posts
    1,792
    Post Thanks / Like
    Likes (Given)
    435
    Likes (Received)
    580

    Default

    Quote Originally Posted by gbent View Post
    Bore your 2-inch diameter to finish. Then position the tip of your boring bar in the correct spot to start your 2.03. Put your machine in neutral so you can turn the spindle by hand. Adjust the head out a few thou and turn the spindle until the bar is mostly free. Rinse and repeat until you are at your 2.03 dimension. Then put the spindle in gear and bore to proper depth. You may need to rework the clearance on your cutter so the heel doesn't wipe out the 2.000 bore as you feed the cutter into the bore. If the transition dimenson is critical, start towards the middle and finish the bottom dimension. Then switch to a back bore boring tool and finish the top dimension.
    Tried this out. Tedious and time consuming but result is fantastic. Did I mention it was time consuming? Also it took a long time. Thanks for the suggestion.

  15. #14
    Join Date
    Jul 2006
    Location
    Cumberland, Maine
    Posts
    469
    Post Thanks / Like
    Likes (Given)
    62
    Likes (Received)
    102

    Default

    I might try a variation on gbent’s method.

    After boring through at 2.000”, position the spindle so the cutter is in the section you wish larger, start the mill, crank the table .015” to the right, and bore a short distance. Back the quill up to your starting point, then repeat but first crank the table back to center, then continue .015” to the left.

    Do it twice more, but this time cranking the saddle in and out.

    You”ll end up with a cloverleaf rather than a round bore in the central part. Within that cloverleaf, you can easily adjust your boring head to cut larger, and feed the full length of the center section.

  16. Likes eKretz liked this post
  17. #15
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    31,260
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    9811

    Default

    Quote Originally Posted by Larry Dickman View Post
    I think Gbent's idea is the only one that's going to work for you.
    That... or he begs, buys, borrows or rents a boring and surfacing head of the Chandler-Duplex and competitors tribes.

    Non-trivial investment if yah near-as-dammit never NEED such, but some might argue that with infrequent use, it is all the more the only kind worth having at all.

  18. Likes partsproduction liked this post
  19. #16
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,858
    Post Thanks / Like
    Likes (Given)
    15294
    Likes (Received)
    15573

    Default

    Quote Originally Posted by gbent View Post
    Bore your 2-inch diameter to finish. Then position the tip of your boring bar in the correct spot to start your 2.03. Put your machine in neutral so you can turn the spindle by hand. Adjust the head out a few thou and turn the spindle until the bar is mostly free. Rinse and repeat until you are at your 2.03 dimension. Then put the spindle in gear and bore to proper depth. You may need to rework the clearance on your cutter so the heel doesn't wipe out the 2.000 bore as you feed the cutter into the bore. If the transition dimenson is critical, start towards the middle and finish the bottom dimension. Then switch to a back bore boring tool and finish the top dimension.
    BTDT many times back in the day, .and it's not that time consuming because you can put 0.005'' DOC on at a time and rotate under power - because the boring bar flexes enough to allow you, …..& 3 X 0.005 = 0.015 on rad, which = 0.030 on dia = job done

  20. Likes gbent liked this post
  21. #17
    Join Date
    Mar 2005
    Country
    UNITED STATES
    State/Province
    Indiana
    Posts
    4,759
    Post Thanks / Like
    Likes (Given)
    1256
    Likes (Received)
    1191

    Default

    Quote Originally Posted by JohnMartin View Post
    I might try a variation on gbent’s method.

    After boring through at 2.000”, position the spindle so the cutter is in the section you wish larger, start the mill, crank the table .015” to the right, and bore a short distance. Back the quill up to your starting point, then repeat but first crank the table back to center, then continue .015” to the left.

    Do it twice more, but this time cranking the saddle in and out.

    You”ll end up with a cloverleaf rather than a round bore in the central part. Within that cloverleaf, you can easily adjust your boring head to cut larger, and feed the full length of the center section.
    This is exactly how I've always done it on manual machines without a facing type attachment or rotary table. Works a treat.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •