How would you repair that broken casting ?
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 21
  1. #1
    Join Date
    Aug 2002
    Location
    FRANCE
    Posts
    1,526
    Post Thanks / Like
    Likes (Given)
    212
    Likes (Received)
    547

    Default How would you repair that broken casting ?

    It's been pretty slow on that forum lately, so I thought I'd throw some food for thoughts.
    Not sure this is the best place for posting. Could have been on the machine reconditionning forum as well, but since it's a deckel casting (from a T&C grinder though), I thought I'd begin here.

    So here we are : I had the opportunity to get a Deckel S11 index head in a trade a few monthes ago.
    Those heads are pretty rare and the reason why I was able to get it is it was broken.

    Below are a few pics of the disaster, the last one beeing a view of the whole deal as it looks like when in good condition and mounted on the machine.

    deckel-s11-poupee-julien761.jpg deckel-s11-poupee-julien763.jpg deckel-s11-poupee-julien765.jpg deckel-s11-poupee-julien768.jpg travail-affutage-fraise-rainure-en-t-affuteuse-deckel-s11-21-.jpg

    As you can see on the pictures the broken part is on the index head itself, the support beeing intact.
    The problem is that the walls on the T-slot are really pretty thin so there's almost no meat.

    I'm pretty set on the general concept of the repair I'll do, but just for the sake of not missing other options, I'd like to know about other's opinion.

    I know the most straightforward repair would be to get rid of the complete T-slot and make another one in a separate part that would bolt on the freshly dressed index head casting,... BUT the external part of the ring with the angles engravings is more or less intact, so that even in its current state, the broken part is invisible when the index head is mated to its support.

    For that reason and in order to preserve the original look of the head as much as possible, I'd like not to be obliged to shave that part.

    Thoughts ?

  2. Likes ballen liked this post
  3. #2
    Join Date
    Oct 2002
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    1,089
    Post Thanks / Like
    Likes (Given)
    100
    Likes (Received)
    216

    Default

    Assuming that the broken away parts are missing, I would mill away the fractured surfaces to establish a flat base plane parallel to the clamping surface. I would then mill and turn replacement parts to fit. I would attach these parts using as many appropriately sized socket head cap screws as I could fit into the replacement parts. A smear of a good adhesive under the parts would not add much strength, but would probably be worthwhile. My first reaction is to use cast iron for the replacement parts, but a mild steel would probably work.

  4. Likes Scottl, TNB liked this post
  5. #3
    Join Date
    Nov 2008
    Location
    Madera county california usa
    Posts
    2,079
    Post Thanks / Like
    Likes (Given)
    18
    Likes (Received)
    480

    Default

    That can be built up via welding.

    Engine re builders have welders for crankshafts that are submerged in granular flux and they weld cast and forged crankshafts every day.

    This could be welded ip then milled back.

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk

  6. Likes TNB liked this post
  7. #4
    Join Date
    Dec 2002
    Location
    Benicia California USA
    Posts
    7,448
    Post Thanks / Like
    Likes (Given)
    1505
    Likes (Received)
    1762

    Default

    Submerged crank welding is almost always done on nodular iron, ductile iron or steel...Grey cast iron...NOT!
    Very different materials.....

    I have a guy that repairs cast iron...He welds it using iron rod and a torch ...repair becomes the same as parent material...No problems with the hard build up that rookies get when arc welding iron...(nickel rod)

    That is one approach...or braze up the area and re machine.....

    Personally i would stay away from any welding /brazing (heat) on this part as it will disturb the other precision bores/surfaces etc....

    I would opt to replace the entire base as you outline above...I realize its more work re-creating the protractor markings...but really not that difficult a task....
    I think i would make the new base from steel...something like mill heat treated 4142 Perhaps "Stress Proof" or even Ductile iron if available.

    Jim's solution above has merit...but still think it almost as easy to make the entire surface when its all done and the finished repair would be better than a patch ..

    Cheers Ross

  8. Likes Sauerkraut, Colt45, ballen, TNB liked this post
  9. #5
    Join Date
    Mar 2017
    Country
    LATVIA
    Posts
    34
    Post Thanks / Like
    Likes (Given)
    6
    Likes (Received)
    14

    Default

    There is little "meat" in the broken off part, so I doubt milling a substitute and screwing it in place would work (I would definitely use metal filled epoxy as well), and if you would mill out larger section, and the repair part would include "base" for those raised walls, then you might as well go ahead and make a new part altogether, as Ross suggested, more work, but a guaranteed result, then experiment with the casting.

    Brazing with bronze - will most likely distort the whole part enough to require machining all over again.

    I've once successfully repaired a broken in half cast iron part by "buttering" the joint with a MIG and regular er70s2 wire before joining both peaces together (no other methods worked for that particular casting), the technique is odd, but worked out, you basically weld it cold, short beads, 10mm max (~1/2"), peen them instantly after you lay the bead down, and then cool down with air, continue the build up as necessary, I kept it no warmer than you could easy rest your hand on it (the place where you just put the bead down), needless to say - takes a long time. Peening takes care of internal stresses after welding, and since you don't let the heat spread to the rest of the part, there should be no distortion. The problem is that you'll need to machine it, and there will be hard spots... also the wall thickness on the inner ring way be an issue for this to work. Just a backup idea.

  10. Likes TNB liked this post
  11. #6
    Join Date
    Dec 2008
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    8,312
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    2208

    Default

    usually use a high nickel rod recommended for machinable weld. if you use wrong stuff it will be too hard to machine.
    .
    others use brazing rod. it will be different color but if done with torch it takes care of preheat and slow cooling just from the torch brazing and will normally be machinable
    .
    small cast parts are often ductile iron this is not recommended for any weld repairs as heat from welding will weaken it.

  12. Likes TNB liked this post
  13. #7
    Join Date
    Nov 2002
    Location
    St.Louis, Missouri, USA
    Posts
    1,883
    Post Thanks / Like
    Likes (Given)
    108
    Likes (Received)
    409

    Default

    I really hate the idea of putting the kind or heat on that part welding would require. I have one of those heads and the spindle seems to run in spindle quality bearings, never had it fully apart so don't know the exact make up but even if the bearings are off the shelf replacement assemblies warp age on the bores would be a concern for me. For that reason only I lean towards your original idea of making a replacement flange and bolting it in place. Just my two cents worth.
    Dan

  14. Likes TNB liked this post
  15. #8
    Join Date
    Aug 2008
    Location
    Sussex, England
    Posts
    3,091
    Post Thanks / Like
    Likes (Given)
    12
    Likes (Received)
    616

    Default

    Like jz79 i've used the "buttering" process on several occasions with perfectly satisfactory results. Modern inverter welder turned down to minimum useable current with a small rod of the most ductile general purpose breed you can lay your hands on has worked best for me. Low end rods sold for amateur use seem to be as good as any. Presumably they are formulated with a heavy "idiot proof" mix so the inexperienced and unschooled have chance of getting a result.

    Last time I used rods from LiDL, a limited stock, German headquarters, supermarket chain that livens up its basic food line with weekly offerings of inexpensive tools, hardware, clothes et al. Tools in particular are always keenly priced and often far better than they ought to be for the money.

    Trouble with "buttering" on grey cast iron is the base material variability. You have to catch on quickly as to how its going to behave during the first two or three passes if you are going to get a proper job. Done right distortion can be down in the undetectable range. Once repaired a lathe apron fractured through three bores when machine was dropped leaving the bores in line and true to size. Bit lucky there I think.

    Clive
    Last edited by Clive603; 05-17-2018 at 02:34 AM.

  16. Likes ballen, TNB liked this post
  17. #9
    Join Date
    Jul 2007
    Country
    UNITED KINGDOM
    Posts
    4,289
    Post Thanks / Like
    Likes (Given)
    2020
    Likes (Received)
    1817

    Default

    My thoughts for what they're worth (not much!):-
    The break is on the faces where the clamping screws pull. You three options.
    1) replace some of the 'T slot' with a machined piece that is bolted or brazed to the original casting after machining off enough material to give a mounting surface. You may be able to make a dovetailed slot in the original sides to help retain the replacement.
    3) Replace all of the 'T slot' with a graduated ring turned and milled from steel or cast iron and bolted/screwed to the original casting after machining all of the origninal "Tslot' ring off".
    2) Build up the broken parts with 98% Ni welding rod and re-machine the T slot afterwards. Use about 450°C preheat to limit the distortion.

  18. Likes TNB liked this post
  19. #10
    Join Date
    May 2011
    Location
    Texas
    Posts
    87
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    11

    Default

    Call it the "modified Jim Williams": mill the fractured parts and create plugs for that area, but instead of cap screws use dovetail "teeth" below the (corrected) fracture line, plus the adhesive of your choice. I say this because I don't see enough room there for threaded holes large enough for reliable screw attachment. If the inserts are anchored in the metal through fit instead, and kept from shifting by Loctite-- and if you don't crank on it like the gorilla who broke it-- you preserve the maximum original German metal while putting it back to useful work.

  20. Likes TNB liked this post
  21. #11
    Join Date
    Jan 2016
    Country
    AUSTRALIA
    Posts
    11
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    7

    Default

    Slightly left of field idea.
    The indexing he’d is for a grinder and dare I say not a huge amount of load.
    Why not make some extended curved t nuts that have a much wider contact area and are the size of the broken away section. There should be 2 clamping bolts and the nuts used are generally much smaller than you could make fit that.
    Not ideal I know but if it a low likely hood of clamping directly in this section then it might just be practical.

  22. Likes wheels17, ballen, neilho, TNB liked this post
  23. #12
    Join Date
    Mar 2006
    Location
    Vershire, Vermont
    Posts
    1,719
    Post Thanks / Like
    Likes (Given)
    979
    Likes (Received)
    451

    Default

    Quote Originally Posted by Porsche Nut View Post
    Slightly left of field idea.
    The indexing he’d is for a grinder and dare I say not a huge amount of load.
    Why not make some extended curved t nuts that have a much wider contact area and are the size of the broken away section. There should be 2 clamping bolts and the nuts used are generally much smaller than you could make fit that.
    Not ideal I know but if it a low likely hood of clamping directly in this section then it might just be practical.
    There's no such thing as a left of field idea. It's all good.

    The ideal iteration would be a curved T-nut that is much longer than the break so as to always span the break. Full circle would be even better, just so the two mating parts could rotate smoothly without the ends of the T-nut catching on the edge of the break. Obviously, the difficulty is getting the wide part of the nut into the circular T-slot.

    Conceptually, the complete circular T-nut could be made up of two rings, one of which corresponds to the narrow part of the original T-nut when viewed in cross section, and one the wide part. The wide ring could be cut into sections just short enough to drop into the break, and the narrow ring dropped in on top of the many segments of the wide ring and held to the wide segments with screws.

    My first trade was weldor, cast iron being some of it, so I'm comfortable welding the stuff, but given the paint repair and (often) remachining to fix distortion, I avoid welding on precision tools unless there's absolutely no other way.

  24. Likes TNB liked this post
  25. #13
    Join Date
    Aug 2002
    Location
    FRANCE
    Posts
    1,526
    Post Thanks / Like
    Likes (Given)
    212
    Likes (Received)
    547

    Default

    Thanks for your valuable advices and opinions.

    A few more pictures and thoughts :

    img_1756.jpg img_1765.jpg img_1762.jpg

    img_1767.jpg img_1764.jpg


    Making a part that would replace the entire T-slot and bolt on the index head is (to me) the last recourse idea.
    Beside the problem of the angles engravings that I have no mean to redo, this repair would necessarily add some overall thickness to the head and therefore, move the centerline in the horizontal plane.
    No big deal for the standard tailstock since it is bolted on the head itself, but the S11 also has other types of tailstocks that are bolted and centered on the table T-slot (with some provision for lateral adjustments though).
    Anyway, the idea is to avoid to change anything to the original design as much as possible (with the additionnal benefit of leaving all options opened).

    As you can see on the pics, the graduated part of the collar is absolutely intact so in my opinion, it's worth making every possible efforts to preserve it.

    As for me, any form of welding is definitely out of question.
    I don't master the techniques involved so even if some of you had good experiences with the buttering process, this is not something I would try. Let alone for a repair for an accessory rare as hens teeth...

    Making a part that would replicate the T-slot only in the broken area seems extremely difficult due to the lack of meat.
    The wall thickness of the T-slot is in the order of 6/7mm (1/4) and we're talking about cast iron...
    There's not much more stock at the bottom, due to the general shape of the casting.
    So I have hard time imagining a repair part held in place with screws or anything comparable.

    An aggravating factor is that the broken area is precisely located where the T-bolt rests (there are two of them, located at 04:00 and 10:00.

    The simplest repair, and one of the first ideas I came up with was to simply relocate the T-bolts to move them outside the broken zone. It would be as simple as drilling two holes in the support at say 02:00 and 09:00... but it's not enough since there are operations requiring the tilting of the head that would still put the T-nut in the broken zone.

    I like the idea of making extended T-nuts. The ideal would be an integral T-nut that would, indeed, cover the full circle... but how to get it in ?
    That's what I've been thinking about and I already have a few ideas...
    The concept is the same as Neilho's idea, but I'd like -if possible- to avoid screws to assemble the ring and segments.
    Screws require holes that would weaken the (necessarily) very narrow ring.

    One should also probably re-think the junction between the ring and the two bolts that tightened the T-nuts in the original design.
    I have other ideas to reinforce the joint between the head and its support, but please keep your suggestions coming.
    Last edited by TNB; 05-17-2018 at 05:43 AM.

  26. Likes AlfaGTA liked this post
  27. #14
    Join Date
    Nov 2008
    Location
    Madera county california usa
    Posts
    2,079
    Post Thanks / Like
    Likes (Given)
    18
    Likes (Received)
    480

    Default

    Since it has a huge gaping hole...

    Could one make a ring of correct size that would fit then cut and bend it a bit like a split washer then thread it into the space?

    Given it is now ugly one could mill it out just a bit to fit or allow ir to fit then make a cover plug that can be epoxied in place just to cover the hole.

    Sent from my SAMSUNG-SGH-I337Z using Tapatalk

  28. Likes kwijibo99 liked this post
  29. #15
    Join Date
    Aug 2002
    Location
    FRANCE
    Posts
    1,526
    Post Thanks / Like
    Likes (Given)
    212
    Likes (Received)
    547

    Default

    Quote Originally Posted by Tony Quiring View Post
    and bend it *a bit*
    I fear that "bit" would exceed the elastic limit of any of the usual materials know to man for that kind of application !
    By far.

  30. #16
    Join Date
    Jan 2003
    Location
    Imlay City, Michigan
    Posts
    1,656
    Post Thanks / Like
    Likes (Given)
    61
    Likes (Received)
    129

    Default

    I have made lager t-nuts for a Kurt swivel vise base to increase the clamping capacity......was used for mounting an angle plate to the base for quick angle changes.

    T, you could make the circular t-nut in sections and then assemble in the t-slot......you could make it simple or complicated? I’m envisioning a t-nut with overlapping sections to maximize strength?

    Good luck with your project, I’m sure it will turn out great!

    Kevin

  31. #17
    Join Date
    Dec 2002
    Location
    Benicia California USA
    Posts
    7,448
    Post Thanks / Like
    Likes (Given)
    1505
    Likes (Received)
    1762

    Default

    T:
    Can't tell from the photos, if there is thickness in the bottom of the damaged area....would it be possible to machine out the inner ring that forms the inside of the "T"

    Think with the inner ring removed you could easily make a full curcle "T" nut and cut it in half and feed the half's into the outer side of the "T"....
    To get the inner ring back...perhaps a "hat" shaped part that could be threaded ,like a large screw into the center position....Made from good steel it could easily have thinner sections to allow for the threading.
    Installed using 272 Loctite...repair locks the half "T" nuts in place.
    Inner ring fabricated and threaded into position semi finished...then milled to true up the "T" faces and heights...t
    The ring is then removed and the half "T" nuts fitted....then the ring is reinstalled ....

    Thing here is that the ring does not need to be very structural....the forces of clamping apply force to the ledge of the "T" slot and force the face of the ting to contact with the mating part.....as long as the
    contact surfaces both inner and outer are flat there is little force on the ring where it attaches to the casting....
    Further bu making a full circle inner ..you help the large "T" nut bridge the remaining broken out section.....

    Cheers Ross

  32. Likes TNB, neilho liked this post
  33. #18
    Join Date
    Aug 2002
    Location
    FRANCE
    Posts
    1,526
    Post Thanks / Like
    Likes (Given)
    212
    Likes (Received)
    547

    Default

    Ross

    As you can see on the other pics, the depth of the slot is more or less equal to the width of the graduaetud collar.
    The pics below will give you an idea of the meat at the bottom and back of the T-slot part.

    img_1766.jpg img_1763.jpg

    There's not much to play with, due to the conical shape of the T-slot part of the head... And even less as you get toward the outer side.

    Your idea of a two parts T-nut is interesting, but I think the distribution of the load all around the circle would be less efficient with this option, than with a single part.
    Plus I can't really see how / where you'd put the threading in the head casting, for the inner ring you're talking about.
    Last edited by TNB; 05-17-2018 at 12:55 PM.

  34. #19
    Join Date
    Mar 2006
    Location
    Vershire, Vermont
    Posts
    1,719
    Post Thanks / Like
    Likes (Given)
    979
    Likes (Received)
    451

    Default

    Quote Originally Posted by AlfaGTA View Post
    ....Think with the inner ring removed you could easily make a full curcle "T" nut and cut it in half and feed the half's into the outer side of the "T"....
    Excellent idea. One couldn't get quite a complete circle from the two halves since the second half has to slide past the first already installed half, but close. Trimming the first half's inner edges to accommodate the second half sliding in would get to an almost complete circle, which is probably all that's needed if the threads for clamping are centered between the ends of each ring.

    .....To get the inner ring back...
    Thing here is that the ring does not need to be very structural....the forces of clamping apply force to the ledge of the "T" slot and force the face of the ting to contact with the mating part.....as long as the
    contact surfaces both inner and outer are flat there is little force on the ring where it attaches to the casting....
    Further bu making a full circle inner ..you help the large "T" nut bridge the remaining broken out section.....

    Cheers Ross
    I'd seriously consider not bothering replacing the inner ring. Without it, there'd be some minor "torquing" of the T-nut half when clamping force is applied. And with no inner ring, the T-nut could be full height on the inner section, making it even stiffer.

    On closer look at the pix, it appears that the inner ring doesn't just provide a clamping surface, but also locates a boss for rotation and proper engagement of a gear. Can't tell from the pix whether the depth of the T-slot equals the depth of the inner cavity.

  35. #20
    Join Date
    Mar 2006
    Location
    Vershire, Vermont
    Posts
    1,719
    Post Thanks / Like
    Likes (Given)
    979
    Likes (Received)
    451

    Default

    Quote Originally Posted by TNB View Post
    Ross....
    Your idea of a two parts T-nut is interesting, but I think the distribution of the load all around the circle would be less efficient with this option, than with a single part.
    Horning in here ...

    You're right, but there'd be very little clamping force applied at the ends of the halves, even if it were a single part. There's prob about a thousandth difference between clamping and not, and the T-nut ring will easily deflect by that much an inch away from the clamping bolt.

    Quote Originally Posted by TNB View Post
    I like the idea of making extended T-nuts. The ideal would be an integral T-nut that would, indeed, cover the full circle... but how to get it in ?
    That's what I've been thinking about and I already have a few ideas...
    The concept is the same as Neilho's idea, but I'd like -if possible- to avoid screws to assemble the ring and segments.
    Screws require holes that would weaken the (necessarily) very narrow ring.
    It would, indeed. But.... (you knew that was coming, right ? ) a lot of small screws wouldn't weaken it much. The most important part of the T-nut, where it clamps, is weakened much more by the hole for the internal threads that engage the clamping bolt.

    Intriguing problem.

    Your ideas?


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
  •