lapping a 50mm (2") ID through hole 160mm (6" long) in steel cylinder
Close
Login to Your Account
Page 1 of 4 123 ... LastLast
Results 1 to 20 of 62
  1. #1
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default lapping a 50mm (2") ID through hole 160mm (6" long) in steel cylinder

    Could someone who is experienced please tell me how to make a simple one-off ID lap? This is a through-hole 50mm (2") diameter 160mm (6") long. The part is a small soft steel (O2/1.2842/90MnCrV8) cylinder.

    Details:

    I'm making a cylindrical split bushing to hold a grinding spindle. I've turned the ID on a lathe to 50.00-50.01mm and roughed the OD. Next step is to finish grind the OD to 60mm (2.5"). Before I slot the cylinder, I want to make the ID more uniform and improve the finish. The ID should be 50mm-0+0.02mm (1.9685"-0+0.0008") so I should not lap away more than 10 microns (0.0004") from the ID.

    Thanks,
    Bruce

  2. #2
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,288
    Post Thanks / Like
    Likes (Given)
    14752
    Likes (Received)
    14900

    Default

    Here ya go (fig 12) Laps and Lapping by "Duplex"

    FWIW, IMR ''Duplex'' articles were always good, and I have used the fig 12 method many times - bit of 6000 series Alu works a treat and the lap needs to be at least 1.5 x D long

  3. Likes BugRobotics, Demon73, scojen, Hopefuldave liked this post
  4. #3
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Quote Originally Posted by Limy Sami View Post
    Here ya go (fig 12) Laps and Lapping by "Duplex"
    Fig 12 shows a tapered mandrel carrying a split cast iron sleeve. That would take me longer to make than this part, which is a one-off. Is there anything simpler, which I can make in an hour or two?

  5. #4
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,288
    Post Thanks / Like
    Likes (Given)
    14752
    Likes (Received)
    14900

    Default

    Okay turn a piece of Alu so it just fits your present bore, plus a spiral groove to carry the paste (freehand is fine) drill & tap 1 end (say) 1/2'' UNF x <> 1 1/4 deep but ONLY use the taper tap, split in half down the axis for say 3'' - the longer the slot the easier it expands (hacksaw / band saw / table saw - doesn't matter) and use a bolt to expand the lap (use grease on the thread otherwise they gall)

  6. #5
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Quote Originally Posted by Limy Sami View Post
    Okay turn a piece of Alu so it just fits your present bore...
    Thanks, this sounds quick and easy. What's a good length to make the lap (my part is 160mm/6")? Will expanding the lap at one end tend to taper the bore?

  7. #6
    Join Date
    Oct 2014
    Country
    UNITED STATES
    State/Province
    Maine
    Posts
    939
    Post Thanks / Like
    Likes (Given)
    114
    Likes (Received)
    436

    Default

    If you just need to clean up the bore, how about a ball hone?

    Flex-Hone(R), Cross Hole Deburring, Ball Hones makes nice ones. In the US they are available on McMaster, but I'm sure there is a german source for them or another brand.

    They're not meant for removing much material or correcting geometry, but they will clean up a bore in no time. I usually use LPS-1 as lube and drive it with a cordless drill.

  8. #7
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,288
    Post Thanks / Like
    Likes (Given)
    14752
    Likes (Received)
    14900

    Default

    Quote Originally Posted by ballen View Post
    Thanks, this sounds quick and easy. What's a good length to make the lap (my part is 160mm/6")? Will expanding the lap at one end tend to taper the bore?
    I'd go at least 2 x D - more is better, as for taper - it shouldn't be you SHOULD keep the lap constantly on the move along the bore axis.

  9. #8
    Join Date
    Mar 2013
    Country
    FALKLAND ISLANDS (MALVINAS)
    Posts
    1,782
    Post Thanks / Like
    Likes (Given)
    2190
    Likes (Received)
    1142

    Default

    Reading what Sami said jogged my memory of Edge Precision video on a simple lap, the one he makes is small but should size up ok. Instead of a screw he uses rubber thingamajigs to 'tension' the lap.


    Im guessing aluminium for the lap and charge with diamond, lube with wd40 or similar.

    Cheers
    D

  10. Likes dgfoster, Hopefuldave liked this post
  11. #9
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Quote Originally Posted by Limy Sami View Post
    I'd go at least 2 x D - more is better, as for taper - it shouldn't be you SHOULD keep the lap constantly on the move along the bore axis.
    In my case 2xD=100mm/4" and my part is 160mm/6" long. I could easily make a hone that is longer, say 250mm/10" long. Would that be best? I can run the hone between centers on the lathe, hold the part in my hand and just move it up and down the hone as it runs.

  12. #10
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Quote Originally Posted by DanielG View Post
    If you just need to clean up the bore, how about a ball hone?
    I want to make the geometry better (straight, round, uniform diameter) as well as shiny.

  13. #11
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    19,288
    Post Thanks / Like
    Likes (Given)
    14752
    Likes (Received)
    14900

    Default

    Quote Originally Posted by ballen View Post
    In my case 2xD=100mm/4" and my part is 160mm/6" long. I could easily make a hone that is longer, say 250mm/10" long. Would that be best? I can run the hone between centers on the lathe, hold the part in my hand and just move it up and down the hone as it runs.
    Yep - that'll do nicely, just remember only one end of the lap will expand and IME the easiest way round that is to end for end what you are honing.

  14. #12
    Join Date
    Sep 2006
    Location
    Stillwater, Oklahoma
    Posts
    1,392
    Post Thanks / Like
    Likes (Given)
    103
    Likes (Received)
    751

    Default

    And if you're hand holding the part as you lap you'll get a feel for where the tight spots are and you can work back and forth for an even "feel".

  15. Likes Limy Sami, ballen, Hopefuldave liked this post
  16. #13
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Another question for the experts.

    Suppose I ground a 250mm long steel shaft to 50.000mm and cut some slots in it to hold lapping paste. Could I use that to lap my part? Right now the part is between 50.005mm and 50.015mm. Could I get my part to finished size of 50.020mm with a fixed size lap of 50.000mm?

    This question is really about how the lapping process works. Is lapping done via a thin layer of paste (a few microns thick) between the lap and the work? Or does the lap actually need to make contact with the work?

  17. #14
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    8,424
    Post Thanks / Like
    Likes (Given)
    2015
    Likes (Received)
    5866

    Default

    Quote Originally Posted by ballen View Post

    This question is really about how the lapping process works. Is lapping done via a thin layer of paste (a few microns thick) between the lap and the work? Or does the lap actually need to make contact with the work?
    Two methods of lapping - embedded abrasive and tumbling abrasive. So to answer the above: Yes.

    To your actual question on the steel mandrel - it should work with the right abrasive in a tumbling manner, but some guessing or testing may be needed to find the right grain size and lube.

    One other thing that may help is to frequently let the part (the sleeve) spin in your hands for a second or two, and move your grip to various points so you don't induce a thermal or contact excess cut.

  18. #15
    Join Date
    Apr 2018
    Country
    UNITED STATES MINOR OUTLYING ISLANDS
    Posts
    3,795
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1712

    Default

    You know you can buy a hand-held hone driven by a 1/2" drill for not much money and it will do a much better job. Very controllable and the stones come in different grits. Or an automotive shop that does small engines will have either a horizontal or vertical Sunnen that will do a great job, probably cost less too.

    This is kind of reinventing the wheel .... if you'e doing it for fun that's one thing but if you just want a round straight hole at lowest cost and effort, this method ain't what I'd do.

  19. Likes tim9lives liked this post
  20. #16
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,884
    Post Thanks / Like
    Likes (Given)
    1834
    Likes (Received)
    1038

    Default

    Quote Originally Posted by EmanuelGoldstein View Post
    You know you can buy a hand-held hone driven by a 1/2" drill for not much money and it will do a much better job. Very controllable and the stones come in different grits.
    I thought that these would not improve the geometry (straightness / roundness) but just give a uniform scratch pattern to the surface. Is that wrong?

    Or an automotive shop that does small engines will have either a horizontal or vertical Sunnen that will do a great job, probably cost less too.
    Good point, I'll ask around. But truth is that I would kind of like to do it myself, just to see how it goes. If it takes me an hour to make the tool and hone the hole, that's less time than finding a shop to do it, and interacting with them.

  21. Likes Hopefuldave liked this post
  22. #17
    Join Date
    Nov 2009
    Location
    Michigan USA
    Posts
    1,133
    Post Thanks / Like
    Likes (Given)
    84
    Likes (Received)
    236

    Default

    You can buy a 2" Internal Lap and Arbor to drive it for about $250.00. Will do an excellent job and no fussing around. Try Helical Lap co. or American Lap Co.

  23. Likes ballen liked this post
  24. #18
    Join Date
    May 2017
    Country
    UNITED STATES
    State/Province
    Massachusetts
    Posts
    376
    Post Thanks / Like
    Likes (Given)
    403
    Likes (Received)
    189

    Default

    You were asking about grinding a steel shaft to use as a lap (for a soft steel ID). If you're embedded abrasive lapping I think you're going to want the lap to be a softer material than the material you're lapping. My understanding is that allows the abrasive 'charge' to embed in the lap and not vis versa.

    So if your part is soft steel as you say, I think you want a lap made out of a softer material (like aluminum).

    This is from having watched it done, not done it myself...so YMMV

  25. Likes ballen, tim9lives, Hopefuldave liked this post
  26. #19
    Join Date
    Oct 2013
    Location
    st,louis mo
    Posts
    680
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    354

    Default

    Quote Originally Posted by ballen View Post
    Could someone who is experienced please tell me how to make a simple one-off ID lap? This is a through-hole 50mm (2") diameter 160mm (6") long. The part is a small soft steel (O2/1.2842/90MnCrV8) cylinder.

    Details:

    I'm making a cylindrical split bushing to hold a grinding spindle. I've turned the ID on a lathe to 50.00-50.01mm and roughed the OD. Next step is to finish grind the OD to 60mm (2.5"). Before I slot the cylinder, I want to make the ID more uniform and improve the finish. The ID should be 50mm-0+0.02mm (1.9685"-0+0.0008") so I should not lap away more than 10 microns (0.0004") from the ID.

    Thanks,
    Bruce
    DID YOU SAY YOU BORED THIS 6 INCH LONG HOLE ON A LATHE ? You only left .0002 per side material in this bore? You must have a brand new lathe. The way that I have done this many times is,bore ID .002 small.Use a Sunnen hone to rouNd up and straighten the bore. This will LEAVE ABOUT .0004 PER SIDE TO GET YOUR FINAL SIZE AND FINISH.Use a finer sunnen stone to finish the bore.I do realize that you are going to use a lap.These cut slower than a hone,so therefore you didn't want to leave to much material.If your part is as accurate as you say ,congratulations. I would have used a cylindrical grinder to get it as close as you now have it.Good luck ,Edwin Dirnbeck

  27. #20
    Join Date
    Apr 2018
    Country
    UNITED STATES MINOR OUTLYING ISLANDS
    Posts
    3,795
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1712

    Default

    Quote Originally Posted by ballen View Post
    I thought that these would not improve the geometry (straightness / roundness) but just give a uniform scratch pattern to the surface. Is that wrong?
    Yes, that's wrong I'm not talking about the type with the little balls on whiskers, I mean a real hone. They are just driven by hand rather than being in a honing machine. They can be very accurate.

    But if you only left four tenths to take out - two tenths on a side ? - I'm not sure you're even going to get rid of the feed marks from the boring bar. That's not very much. As Edwin notes, you better hope the boring job was pretty darn good.


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
  •