Announcement

Collapse
No announcement yet.

Lathe tailstock casting repair?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    The Metal Butcher Ah, you may kick yourself but unfortunately it's not a fix. Doozer would be right and it would be genius but for the top part of the tailstock. I did think of joining the two pillars together for support but the gap between them exists for the shaft the cam rides on for the lock. That shaft passes through about level with where the screws bear.

    Found some blow torches that don't cost an arm and a leg but also don't have reviews saying how much they suck (excluding the usual "there's always on!"). I'm figuring that I can try brazing it and if it doesn't work I can still mill it out and full it with steel. The only thing that worries me is that as far as i can tell, brazing seems to happen between 800 and 900°C. Am I likely to either crack or warp the casting?

    Assuming that's not a worry, should I be looking at brass rods or silicon bronze....or something else?
    Fluxes seem to be in powder form. Do you have to mix them or do they just melt at temp?

    Comment


    • #17
      Look, not being rude, but if you are asking basic brazing questions like this, cast iron isn't the place to start. Also, yes you will distort the casting.

      The small screws you mention are probably there to lock the setting once you've adjusted it with the other screws. I don't think they are for angular adjustment, I've never come across a tailstock with angular adjustment and I can't think why you'd need it. You should have slackened the small screws slightly, made the adjustment, then tightened them back up again.
      'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

      Comment


      • #18
        I absolutely would not braze that! It is almost guaranteed to change shape and be totally worthless! As suggested above, get the other piece off and make one piece to go across. You indicated that the locking shaft goes there, Just make the piece "U" shaped with a slot in the middle for the shaft. Use Allen socket head screws and drill and tap all the way through the casting to get the most threads possible. Use you choice of JB Weld or Super Glue to help with the bedding, but it will not provide much additional strength.
        Peter
        Grantham, New Hampshire

        Comment


        • #19
          Originally posted by Richard P Wilson View Post
          Look, not being rude, but if you are asking basic brazing questions like this, cast iron isn't the place to start. Also, yes you will distort the casting.
          Had you taken the pieces to a welding or fabrication shop (ironmongery) on Friday, the tailstock would either be repaired or they would have told you they couldn't braze it without distortion of the casting. Then you could proceed at full speed with a different solution.

          Along with the advice from someone in the trade, you may have walked away with the piece of steel needed for an alternative repair.
          Last edited by reggie_obe; 09-05-2020, 11:57 AM.

          Comment


          • #20
            Woah, hang on a tick (and forgive me if I'm reading the tone wrong here). I'll be the first to admit that this was almost certainly my own fault here. I'll further admit that my knowledge of brazing could be written in 20x20 writing in the head of a pin.....and you can choose whatever measurement system you like for those units. My lack of knowledge is precisely WHY I'm asking the questions. I know "a lot" and by that, I mean that I know enough to know that what I know utterly pales in comparison to what I don't know. This is the same reason I scorn those who claim to be "experts" in the field I work (which is IT but I would presume the same applies to most fields).

            I'm not bemoaning the cost of buying the steel to fix my mistake or of the tools to braze it if that should be the preferred method of fixing it. I'm simply asking what the recommended way of fixing it would be. I was leaning towards brazing because I'd end up with a tool (and a new skill) that could be useful in future. If it's inappropriate for this case, that's fine and I'm sure I'll manage with techniques I'm more familiar with (and yet hadn't thought of).

            reggie_obe There's a much more limited availability of people here that I could take this to for either a fix, materials or wisdom. I do know a welder and I'm pretty site he's good enough that he'd have told me it wasn't suitable for him to fix. Even if there were someone that could help, I'm not sure that they'd appreciate me turning up at their door unannounced, currently!

            It's comforting to know that a replacement casting is available should I screw this up that badly - I always prefer a way out/back. That said, I'm quite happy to fix it if it's possible....and that's why I've asked for the accumulated wisdom that's ahead of my experience. If it's possible to st least be trying something that isn't doomed to failure, that's got to be a good thing, no?!

            Comment


            • #21
              Originally posted by Cenedd View Post
              reggie_obe There's a much more limited availability of people here that I could take this to for either a fix, materials or wisdom. I do know a welder and I'm pretty site he's good enough that he'd have told me it wasn't suitable for him to fix. Even if there were someone that could help, I'm not sure that they'd appreciate me turning up at their door unannounced, currently!

              It's comforting to know that a replacement casting is available should I screw this up that badly - I always prefer a way out/back. That said, I'm quite happy to fix it if it's possible....and that's why I've asked for the accumulated wisdom that's ahead of my experience. If it's possible to st least be trying something that isn't doomed to failure, that's got to be a good thing, no?!
              You don't practice welding or brazing on something important and based on your words, time was a critical factor. You don't have to "know" a welder or fabricator, that why they have a business. They want your money, not a friendship.
              Unless you live on a tiny island or some remote village, there is probably one or business that could handle the work, just walking in the door. Maybe you even have a blacksmith in town.

              Comment


              • #22
                Reggie

                Do you live in the UK? If so, its a different UK to the one I live in. 50 years ago, yes my small town had a number of small engineering companies, including one that specialised in welding. A nearby town had a foundry
                Now the foundry has gone, and my small town doesn't have any manufacturing industry left.
                You would anyway need to know that a welder is competent with cast iron, most are not, because cast iron isn't as common as it was. Sujre, they'll 'have a go', but that isn't what you want on an important lathe part is it.
                I do live on a small island, its called the United Kingdom.
                'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

                Comment


                • #23
                  A longer adjusting screw that reached the "back" of the remaining pillar seems easiest
                  and would have the advantage of discouraging the remaining pillar from snapping off
                  as it will be getting squeezed instead of pushed .
                  --
                  Tom C
                  ... nice weather eh?

                  Comment


                  • #24
                    Replace the broken pillar with a 1/2-13 bolt, so the offset screw has something to push on.

                    -D
                    DZER

                    Comment


                    • #25
                      Richard P Wilson reggie_obe I'm really not trying to disrespect the UK here. I'm sure there are skilled people around and because of suggestions previously from members here, I've looked into commercial surface grinders and found one locally that did excellent work on my mill table. Mostly though, I'm not aware of them. You don't get a machining job shop or a welding shop here that people just walk into....at least not as a common thing. And the thing is, they don't want my work or my money. I'm too small-fry. While the surface grinders did great quality work for me, I'm fully aware as a small business owner myself, that at best I made them no profit and they were good enough to humour me with their services. Were I to go hassling them on a regular basis they would be wise to either price me out of the market or tell me where to go. It sounds harsh but I'm just not the kind of customer that's going to put food on the table for their kids and I'll not pretend that I'm ever likely to. This is a hobby for me and I enjoy both fixing things and increasing my knowledge (at a rate that work and life allows) but I'm neither in a position to buy my way out of ignorance nor pretend my 'problems' are important enough to give someone grief about. Time is of the essence only in that I don't want to wait two months and pay for a part of there's an easier way. Nobody's going to die if my lathe up and walked away on me, let alone simply can't do tail support or drilling. It's irritating and I'd prefer to have the options available to me is all. I've got round the time-critical parts by simply ordering some 6mm bar rather than turning it down from a 10mm bar I had. Yes, it's irritating when I should have been able to do it on the spot but fortunately the post wasn't as bad as it can be (and tracking suggested it was going to be) and I "got 'er done". The means of fix is largely educational - I could wait two months for parts...but, well, this forum's full of those that aren't keen to do that if they have an alternative...and that's why I'm here....albeit to learn (and keep doing so).

                      Comment


                      • #26
                        It'll warp, but will it warp enough to matter? I'm saying this somewhat rhetorically as someone who has spent the last 25 years welding for a living. Being that its a tailstock base casting, I presume it'll be clamped down tight to the bed when in actual use, so warpage won't be a factor in the location of the center line. I say that because you are only building up one area, and not heating all the way across the part.

                        If you are *very* concerned about warpage, you can take a heavy piece of plate -- say 1-inch thick -- and clamp the part solid to that while brazing. Then use a very slow post-heat and cool down.

                        Pity I already cut mine up for parts, I had an entire seig lathe that I butchered for other projects. I could have sent you the casting for the cost of postage.

                        Comment


                        • #27
                          Glue it back together, then drill and bolt it from the bottom

                          Comment


                          • #28
                            This is just a lump of metal for adjusting screws to push against. Mill the break flat, mill the other one off while you're at it before it breaks. Drill & tap through something like M12, screw & loctite a couple of round pillars in, maybe 18mm diameter (eyeballing sizes here). Once the loctite is set, mill small flats where the screw contacts.

                            Ian
                            All of the gear, no idea...

                            Comment


                            • #29
                              Have ordered some flat bar to insert and machine. I thought initially that it wouldn't be a problem to bolt all the way through but having put a square against it I think it would disrupt (if not hit) the base where it rides the V way. I think I should be able to get away with it by adding more screws (not too many!) offset towards the middle and one in from each side if I can avoid the set screw hole sufficiently.
                              At absolute worst I can order a replacement casting if I make a horrible mess of it. I strongly suspect that what arrives wouldn't be a drop-in replacement though and would need finishing/fitting to the top casting....so not a shortcut anyway.

                              Comment


                              • #30
                                why not drill and counterbore the broken part for a socket head cap screw and tap the base. the break will hold everything in alignment to do the drilling and tapping.

                                Comment

                                Working...
                                X