Broken piece on lathe
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  1. #1
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    Hi everyone

    I managed to break a piece on my lathe (Not sure what the english word for that piece is).

    I wonder if you guys think I should repair it (welding, soldering etc) or make a new one from steel?

    The piece is made from castiron today.

    See enclosed pictures.




    High reolution pics here

  2. #2
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    I have welded them back together with cast rod but it will never be the same. Thats an unfortunate loss. That one is broke in a very bad place where welding will be a headache.

    You can weld it and it will get you by till you can find a unbroken compound topslide. My buddie broke the topslide on his mazak and the part cost $1,100. [img]redface.gif[/img]

    yep, start the hunt for another topslide or whole new compound.

    sorry.

  3. #3
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    The English word is: Busted

    If you can make one from steel you may be able to add a detail to improve your lathe.
    Since the part is cast iron I would think you would have to silver braze or weld with an appropriate rod. Either process will cause some distortion and require machining to fix.

  4. #4
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    If I make one in steel, is it a problem that it is a bit "softer" than castiron? Do I need a harder variant?

    I have a mill a welding equipment so I should be able to make one in steel.

  5. #5
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    Its toast! Might be best to replace the compound if you can find one. Or you might be able to adapt something from a southbend depending on how it is mounted to the carriage. Have any pics of that?

  6. #6
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    Make a new part from steel. The chance of a satisfactory repair is small and finding a replacement for a Rexvalter is slim.

  7. #7
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    Buy a chunk of Cast Iron Bar Stock,
    3 Reasons...
    ...That part SHOULD be Cast Iron NOT steel
    ...It will take you 1/2 the time to make it
    ...The lathe will cut better when made from CI

    Do not waste 1 min of time trying to weld, silver brase, glue, epoxy, pin, or anything else...
    Make a NEW ONE.

  8. #8
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    Although a differance in hardness,the part can be made a little larger in areas of high stress.
    Considering the size of the lathe I don't see a problem in using steel.

  9. #9
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    As you are in Sweeden, you might have trouble with getting a casting made, I would make it from continuouisly cast iron section. This is available in the UK (at a price), if you want any help, mail me.

  10. #10
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    Repair is not much of an option. I would do as Gary suggests. Get a bar of iron (Durabar 60 or 80?) and start from scratch and make a new one. It is a small enough project.

  11. #11
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    The part would be call the top slide of the compound.

    I agree with others that welding is probably not a good choice. Brazing would get you by for a while.

    I would check with the maker of your lathe and find out how exspensive a new part is. Most of the time, it's going to be high.

    As for the material to make a new part. Cast iron would be the best choice. The can be purchased in bar form here, but I don't know about in Sweden. I would look for a ductile (nodular) cast iron such as 60-40-18.
    JR

  12. #12
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    How did that happen? Let us know how we can avoid doing that.

    As a temporary fix, you could bolt a bar to both sides below the T-slot. Looks like there's plenty of material there for a few tapped holes and some alignment pins. Put the hardened alignment pins close to the break, and the bolts further away.

    Roger

  13. #13
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    New is the best way to go. My expeirence with welding or brazing parts like this is not good. There are no doubt guys that can do it sucessfully but Ive never met them. If it was mine I would look at milling the 2 sides off till they clean up. Then mill a keyway or a slot down each side say 1/2 wide x 3/16 deep. Make 2 plates with this key integral (like a "T" shape) and screw them to the sides. You should do this with the compound fully assembled,gib in and tight etc. Wouldnt be pretty but it will get you running again. Keep the compound cranked back when using it. Not a good way to get some more reach. Had an identcal thing happen at work with a year old 24" engine lathe. They had tapped a hole out at the end of the compound for an Aloris tool post stud. About a week later it busted off like yours. This compound was at least 8" wide. I did something similair to what I described to you above but also filled in the t-slot space with steel .001 loose all over. The Aloris had a 3/4 riser plate under it so a peice of 3/4 was also put on top. Still running great.

  14. #14
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    The lathe is a Model VF-118 Rexvalter AB of Storebro in Sweden. It hasn't been made since the 60s. No chance of finding a new part and little chance of finding a used one. Making one is the only option.

  15. #15
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    I have repaired a compound broke like yours many years ago. Clamp down to a flat bar and mill a keyway in the side of the compound with it clamped down together and to the bar, Do this on both sides. Then mill a key on the side of keyway stock as long as the compound Two pieces needed one for each side.
    Fit the key snug.
    Tap the key in place and drill and tap holes for socket head capscrews on either side of the key and staggered top to bottom.
    Counterbore for the heads and bolt together.
    alabamaed36046
    This compound was about 2.5 inches thick and I used 1.oo keystock with a 3/16 high by 3/8 wide key centered on the side. Ed

  16. #16
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    Ouch. Tough luck on that one.

    I agree with those who say to mill slots on both sides and tap in some support pins/rods/bars on each side. Then I would groove the break and braze it together, including brazing the new steel on each side.

    I might go one step further and braze in the T-nut so it bridges the area between pieces. I know this will limit you a bit if you use any accessories there.

    I would then use the repaired top-slide to machine a new one. Cast iron would be best because of its self lube properties in a slider. Enough oil will overcome that if you make it out of steel though, and if you do some hand scraping on the dovetail parts to help hold the oil in place; incorporate a nipple and oil channel and you can force feed oil to the critical areas.

    Check around for some used/surplus machinery venders in your area. There might be a basket case you can scrounge from.

  17. #17
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    Please tell us how this happened.

  18. #18
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    The more I think on it the more I would be inclined to try a repair anyway. There is nothing to lose and it will only cost some time. Grind off the edges of the break all the way around where possible. Drill and tap a pair of holes on the bottom side of each piece in the flat slide portion.

    Align the parts and bolt a thick flat steel plate to the bottom to hold the parts. Preheat the entire thing to about 350C (660F)and then weld the top and sides with high nickel rod. Let it cool slowly. Then use the tee nut and a thick clamping plate and bolt the top together and preheat again. Weld the bottom. Cool slowly and machine and scrape as needed. Might work.

    [edit]

    Thinking some more instead of drilling and tapping in the flat slide portion just drill two through holes in the middle of each piece and clamp with through bolts.

    The same plate can be used to clamp on both sides. Make the hole in the bigger piece so it comes through the upper machined surface near the tool holder slot.

  19. #19
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    If you would please remove the lower part of the compound we could suggest replacements from common lathes. It looks alot like soutnbend or even an atlas might be easily adaptable.
    Toad

  20. #20
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    This happend when I by misstake had the topslide a long way to the left when doing a cut-off.

    When it's that way, very little supports it under the toolholder.


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