lapping a 50mm (2") ID through hole 160mm (6" long) in steel cylinder - Page 2
Close
Login to Your Account
Page 2 of 4 FirstFirst 1234 LastLast
Results 21 to 40 of 62
  1. #21
    Join Date
    Nov 2009
    Location
    Michigan USA
    Posts
    1,128
    Post Thanks / Like
    Likes (Given)
    84
    Likes (Received)
    236

    Default

    Quote Originally Posted by EmanuelGoldstein View Post
    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.
    EmanuelGoldstein please elaborate on which hone you mean. I thought you where talking about the hone with 3 spring loaded pads.

  2. Likes ballen liked this post
  3. #22
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,820
    Post Thanks / Like
    Likes (Given)
    1779
    Likes (Received)
    1003

    Default

    Getting off track, but the lathe is a 15-year-old Weiler Commodore 230 (unfortunately not mine) which has led a pampered life. 30mm (1 1/4") diameter boring bar choked up to minimum required length and a new sharp insert and slow feed for the final passes. Let off almost all of the chuck pressure to avoid pushing it out of round. I've measured the result carefully with a bore gauge and the diameter range is 50.00-50.01. Slides easily over a ground 50mm steel shaft so the hole is also straight. Surface finish inside is good enough that 10 microns in diameter should be enough to clean it up.

    Just in case, I will leave an extra 20 or 30 microns when I grind the outside. Then I'll lap the inside. That way, if I do need to take more off the inside, I have some wiggle room, because this is going to be a split sleeve and the delta between outside and inside is what matters.

    Edit: I have some "time-saver" green lapping compound available in a variety of grits. Is that suitable? Or do I want something that embeds?
    Last edited by ballen; 12-18-2019 at 09:20 AM.

  4. #23
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,820
    Post Thanks / Like
    Likes (Given)
    1779
    Likes (Received)
    1003

    Default

    Quote Originally Posted by athack View Post
    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.
    Thanks, that looks like a good solution, but I can't find them for that price in Germany, and don't want to spend the money for a one-off. What's the range of these laps? Can you go +-10% on the diameter? In other words will the 2" lap go from 1.8 to 2.2 inches? Or is the range much narrower?

  5. #24
    Join Date
    Nov 2009
    Location
    Michigan USA
    Posts
    1,128
    Post Thanks / Like
    Likes (Given)
    84
    Likes (Received)
    236

    Default

    Quote Originally Posted by ballen View Post
    Thanks, that looks like a good solution, but I can't find them for that price in Germany, and don't want to spend the money for a one-off. What's the range of these laps? Can you go +-10% on the diameter? In other words will the 2" lap go from 1.8 to 2.2 inches? Or is the range much narrower?
    The range is small. Size it is made to plus .015". If you push it up to far they start to become slightly out of round.

  6. #25
    Join Date
    Jun 2008
    Location
    Bellingham, WA
    Posts
    4,056
    Post Thanks / Like
    Likes (Given)
    976
    Likes (Received)
    2201

    Default

    Quote Originally Posted by Limy Sami View Post
    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)
    A variation of a split lap one could easily make in the shop that would expand more or less uniformly along the length of the lap:

    1)Turn a 6061 aluminum cylinder a few thou under the bore size and 4 to 6 inches long.

    2)Bore it 1/2" on center for its length.

    3)Split it lengthwise on the table saw or band saw on just one side

    4)Drill and tap 3 holes that are off center and span the slit ending blindly on the far side of the split.

    5)Use setscrews to drive the cylinder split open until it is just a snug (but not grabby) fit.

    6)Place it on a mandrel made up of all-thread turned down to 3/8" (to get rid of threads) on one end.

    7)Chuck up in a cordless drill, charge it with the grit of your choice, and hone to your hearts content. Be sure to have the lap pass out of the cylinder ends by and inch or so to avoid leaving the openings of the cylinder undersize compared to the more central portion of the bore. Drive the cylinder open as needed to get the cut right.

    Denis

  7. #26
    Join Date
    Apr 2018
    Country
    UNITED KINGDOM
    Posts
    2,824
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1313

    Default

    Quote Originally Posted by athack View Post
    EmanuelGoldstein please elaborate on which hone you mean. I thought you where talking about the hone with 3 spring loaded pads.
    Portable Hones and Accessories - Sunnen

    Not the ones with the spring-loaded pads, you're right, those don't do much. Portable hones work similar to machine hones, they are tightened with a screw thread to put pressure on the stones evenly around the mandrel. You can get very good results with them - I know a couple of race engine guys who prefer them, and they win races on a national level so it's not total bee ess.



    How much he didn't leave in the bore is knda scary tho. I'd be happy to i.d. grind that but would want at least four or five thou to get the taper out. Honing, two or three maybe to get rid of the boring bar feed marks. He didn't leave doodly-squat !

    What's a surprise when you id grind something is how out of round the part starts. You can generally see the pressure from the chuck, the wheel will touch in three or four spots first and not grind all the way around until you've fed in several tenths. You think the bore is round when you start but the reality is different ... that's difficult to see even with a dial bore gage because it's three-sided.

  8. Likes Dumpster_diving liked this post
  9. #27
    Join Date
    Nov 2009
    Location
    Michigan USA
    Posts
    1,128
    Post Thanks / Like
    Likes (Given)
    84
    Likes (Received)
    236

    Default

    Thanks for the pics and info.

  10. #28
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,820
    Post Thanks / Like
    Likes (Given)
    1779
    Likes (Received)
    1003

    Default

    I appreciate the advice I got here and thought it would be appropriate to post some pictures of my quick-and-dirty lap. All the images are in this album: https://www.practicalmachinist.com/v...e-lap-lapping/

    I made the lap out of three pieces. Two are aluminium (50 and 35mm round) and the other is steel (13mm hex). At the top left is a sleeve about 250mm (10") long with OD 50mm and ID 35mm. I've slit it 6 times, and made it to be a snug but free fit in the ID I am going to lap (standing on end in the back). Inside the sleeve goes the lower part, which is 35mm aluminium. The left end is tapered with an 8mm tapered reamer (metric, 1:50) and threaded M8 at the bottom. I split it into six segments by hand on a bandsaw. The bandsaw slots go to the start of the M8 thread. The middle part is from 13mm hex steel. I have threaded the end M8, and then machined a taper that is slightly steeper (say 1:45) than standard metric.



    Here it is with the taper-expander in place:



    Assembled (this is held together with a 3mm taper pin through the turned down part of the sleeve at the left end):



    Here's the end view showing the expanding part in the middle. I have oriented it so that each of the expanding segments pushes two of the outer segments.



    Here it is in use (chucked into lathe, with a towel on the ways to catch excess lapping compound):


    This is the inside of the cylinder after lapping with "Time saver medium (green) lapping compound" using WD40 as a lubricant



    This is about 10 microns (0.0004") larger OD than I was aiming for, so EG was right that I should have left a bit more meat. But it doesn't matter since this will be a split sleeve, I will just make the OD oversize by the same amount.

    A few observations:

    - I did not make grooves for the lapping compound, figured that the slits would work OK.

    - Even though the sleeve was a slip fit dry, as soon as I added lapping compound I could only get my part about 1/4 of the way onto the lap before it jammed. This tends to bell-mouth the part. What works better is to put the lapping compound into the sleeve slots with a toothpick, then place part onto the sleeve. Then once the lap is rotating blast a bit of WD40 inside the center portion. Centrifugal force carries the WD40 outwards through the slots, carrying lapping compound with it.

    - Very little lapping compound is needed. If the lapping action has decreased, a shot of WD40 down the center axis will carry lapping compound from the slots back to the work.

    - I am happy with the finish and size. But I can indeed see four regularly spaced marks near one end, which must be where the chuck jaws were pressing the part in and so the surface is now slightly larger ID. For this application those marks don't matter but I would need to remove another 10 microns of ID to get rid of them completely.

    Thanks again for the helpful advice!

    Cheers,
    Bruce
    Last edited by ballen; 12-23-2019 at 02:10 PM.

  11. #29
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    7,831
    Post Thanks / Like
    Likes (Given)
    1826
    Likes (Received)
    5505

    Default

    Good work, and thanks for the update.

    And it's sort of annoying that we can't clamp thin wall tubes in a chuck without getting that distortion, it's one of the reasons I'm a fan of six-jaw units. They have their drawbacks, but when in good nick they're great for tube work.

    That, or soft jaws bored to the OD.

  12. Likes ballen, triumph406 liked this post
  13. #30
    Join Date
    Jun 2008
    Location
    Bellingham, WA
    Posts
    4,056
    Post Thanks / Like
    Likes (Given)
    976
    Likes (Received)
    2201

    Default

    Next time, how would you hold the part when boring it so as to avoid the telegraphing of the four-jaw teeth? I guess I am thinking along the lines of putting a “heavy” piece of aluminum or steel (a block 1” thick and 3” square perhaps) in the 4-jaw and boring it to fit the OD of the part. The part could be secured with loctite or cyano glue. Alternatively the block could first be band sawed on one side and the kerf temporarily shimmed open while the block is put into the chuck bored to size (like boring an emergency collet) and remove the shim and clamp down and dial in the part. The outboard end would need to be supported in any event by a steady rest.

    Nice work on the lap! And thanks a lot for reporting it’s effectiveness and practical tips on its use.

    Denis

  14. Likes ballen, Hopefuldave liked this post
  15. #31
    Join Date
    Jul 2008
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    681
    Post Thanks / Like
    Likes (Given)
    270
    Likes (Received)
    412

    Default

    One thing to keep in mind, when honing an automotive cylinder wall. You do not want the slickest finish. A properly honed cylinder wall should have a desired finish for proper break-in. I.e. some light roughness to carry oil during break-in. Different rings and application can often dictate the desired finish. Disclosure, I'm not an expert by any means, better minds and reading should get you closer on this subject. Just wanted to possibly save you some grief in this area. Good luck and keep us posted.
    Hodge

    Edit: I went back and reread, it just hit me this may not be an automotive application. If so my apologies.

  16. #32
    Join Date
    Aug 2005
    Location
    Toronto
    Posts
    4,850
    Post Thanks / Like
    Likes (Given)
    3286
    Likes (Received)
    3720

    Default

    Here are several adjustable internal laps I've made. They are roof flashing soft solder to steel, went that way to keep the cost down and they are also easily replaceable. They just work, simple to make and you get a great finish with straight, round, consistent diameter bores. Adjust the length to suit the length the bore, lap should be less than 1/2...1/3 usually seems about right




  17. Likes ballen, Hopefuldave liked this post
  18. #33
    Join Date
    Jun 2008
    Location
    Bellingham, WA
    Posts
    4,056
    Post Thanks / Like
    Likes (Given)
    976
    Likes (Received)
    2201

    Default

    Quote Originally Posted by Mcgyver View Post
    Here are several adjustable internal laps I've made. They are roof flashing soft solder to steel, went that way to keep the cost down and they are also easily replaceable. They just work, simple to make and you get a great finish with straight, round, consistent diameter bores. Adjust the length to suit the length the bore, lap should be less than 1/2...1/3 usually seems about right
    Mcgyver,

    How do you get a the good smooth fit of the flashing to the steel? Do you slip roll the flashing first and then solder?

    How do you attach the larger steel lap end to the smaller shaft?

    Those look like a nice solution.

    Denis

  19. #34
    Join Date
    Aug 2005
    Location
    Toronto
    Posts
    4,850
    Post Thanks / Like
    Likes (Given)
    3286
    Likes (Received)
    3720

    Default

    thanks Denis, a few more photos. I tin the copper and steel before soldering so its mostly just sweating them together, all with solf solder. The copper is thin enough that annealed its an easy hand bend. Handle is brazed to the head, trying to keep the braze to one side so its expandable. Its used with the work turning and tool floating (hand held)




  20. Likes ballen, Hopefuldave liked this post
  21. #35
    Join Date
    Jun 2008
    Location
    Bellingham, WA
    Posts
    4,056
    Post Thanks / Like
    Likes (Given)
    976
    Likes (Received)
    2201

    Default

    Thanks again. Well done!

    Denis

  22. #36
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,820
    Post Thanks / Like
    Likes (Given)
    1779
    Likes (Received)
    1003

    Default

    Quote Originally Posted by Hodge View Post
    Edit: I went back and reread, it just hit me this may not be an automotive application. If so my apologies.
    This will become a split bushing for holding a 50mm grinding spindle in a 60mm clamp. I'll post some photos as I finish it in the next days.

  23. #37
    Join Date
    Sep 2011
    Country
    GERMANY
    Posts
    2,820
    Post Thanks / Like
    Likes (Given)
    1779
    Likes (Received)
    1003

    Default

    Quote Originally Posted by Mcgyver View Post
    Adjust the length to suit the length the bore, lap should be less than 1/2...1/3 usually seems about right.
    I'm confused about that. I understand how a lap which is short lets you tune the diameter along the bore. But I had thought that the lap needed to be longer than the bore if you want to ensure that the bore is straight. This is the reason why my lap is 250mm long even though the cylinder I am honing is only 160mm.

  24. #38
    Join Date
    May 2003
    Location
    Walla Walla Wine and Wild Turkey
    Posts
    4,664
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    354

    Default

    Some, may enjoy the construction of this Kent Moore, Harley Davidson connecting rod lapping tool. The connecting rods used roller bearings available in .0002" in steps of oversize. this tool would resize the rod races.

  25. Likes ballen, Hopefuldave liked this post
  26. #39
    Join Date
    Aug 2005
    Location
    Toronto
    Posts
    4,850
    Post Thanks / Like
    Likes (Given)
    3286
    Likes (Received)
    3720

    Default

    Quote Originally Posted by ballen View Post
    I'm confused about that. I understand how a lap which is short lets you tune the diameter along the bore. But I had thought that the lap needed to be longer than the bore if you want to ensure that the bore is straight. This is the reason why my lap is 250mm long even though the cylinder I am honing is only 160mm.

    I don't want to come across as gods gift to lapping, perhaps a longer lap is better. I only know limited amount from making and using the above The shorter worked well and let you hold the work without having to provide the lap going through very far the other side which could be a problem with the larger sizes. I do want all parts of the lap be exposed to all parts of the bore so I can feel any diameter differences, which I guess you could get with either short or longer. If there is slight banana curve I haven't been able to detect it. I can't provide a quantitative argument, but with fine abrasive the sensitive to tight spots is so high I think it would tend work it self straight, i.e. straight is the path of lease resistance....but that's semi informed opinion not the definitive word .....however it is support by some of the results, i.e. very fine long fits that don't bind.

  27. Likes ballen liked this post
  28. #40
    Join Date
    Sep 2006
    Location
    Stillwater, Oklahoma
    Posts
    1,343
    Post Thanks / Like
    Likes (Given)
    96
    Likes (Received)
    720

    Default

    IIRC Forrest has written elsewhere on honing. I notice that he's back engaged in another thread so I would hope to have a contribution from his experience.

  29. Likes ballen liked this post

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
  •