Using large dies

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Using large dies

Home Forums Workshop Techniques Using large dies

  • This topic has 22 replies, 18 voices, and was last updated 3 June 2020 at 20:42 by Nigel McBurney 1.
Viewing 23 posts - 1 through 23 (of 23 total)
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  • #472761
    Ian Parkin
    Participant
      @ianparkin39383

      I cut a lot of large whitworth /unc threads usually on the lathe and then run a hex nut die down them to clean them up.

      Sometimes its hard work just cleaning the thread up removing a small amount of material.

      On a woodworking forum someone has a 1.5inch 6tpi split die and they are wanting to cut threads just with this.

      is it at all possible on steel?

      what would the forum say is the biggest thread that you can cut with a die from scratch on sized steel?

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      #16162
      Ian Parkin
      Participant
        @ianparkin39383
        #472764
        not done it yet
        Participant
          @notdoneityet

          I suppose it depends on how long the die holder handles are.🙂

          When you say a split die, do you mean the usual single piece die or do they have a proper split die (2 pieces), so far more adjustable. Plumbers used to cope with 2” pipe threads and more.

          #472766
          David George 1
          Participant
            @davidgeorge1

            I have a pipe threading set which goes up to about 2 inch but when I did larger sizes I would hire a threading machine. I would also get an apprentice to thread the pipes Usualy used for airlines mainly.

            David

            #472777
            Simon Williams 3
            Participant
              @simonwilliams3

              Cutting a pipe thread – even at quite large sizes – doesn't mean taking all that much metal off because the thread pitch is constant. For 2 inch nominal bore pipe the thread it (from memory) 11tpi so cutting this is a different ball game to cutting 6TPI on a 1-1/2 diameter work piece – that's nearly twice the depth of cut.

              Who needs a gym subscription when you can cut threads for a living and get paid for it.

              I've tapped 2 inch BSPT in 316 stainless with the biggest tap wrench I could hold. You'd need to go and have a lie down afterwards.

              I employed a kiddy once upon a time – we installed air compressor pipe work for a living. He was enormous – 6 foot 4 and built to match, in his early twenties. He told us all sorts of stories about how fit he was and how he went to the gym three times a week.

              He left after the first month, couldn't hack it.

              Happy days.

              Simon

              #472780
              Mick B1
              Participant
                @mickb1

                Of course the depth of the thread is at least as important as the OD.

                It depends on the steel and the state of the die. I've got 8-off 1" 8TPI BSW dome nuts to make for the railway, and because the taps are in decent condition and the steel is quite good BDMS, I can do it if I cheat a few thou on drill size to give meself a bit less metal to shift. And it's lucky there's no particular time pressure.

                But I can remember trying to die-cut some 1" BSW external threads on EN8 using chipped WD dies that might've gone through the desert with Montgomery. I ended up with a ricked neck and horrible galled threads.

                I'd say if you've got good freecutting MS, 10 thou or a bit more undersize, a nice sharp die, a long-handled diestock, some Rocol or suchlike and you've had good coffee and an eggy breakfast, you might have a chance with 1 1/2" BSW.

                But don't be doing it with difficult material, worn dies and wonky diestock at the dog-end of a rough day.

                laugh

                Edited By Mick B1 on 18/05/2020 20:22:48

                #472786
                Ian Parkin
                Participant
                  @ianparkin39383

                  Yes i meant a round split die so it could be opened up a little to start it off

                  the large dies i have are all hex nut type so i generally use a big pair of stiltsons to run them down

                  I just cant imagine trying to do a 6tpi whit over 1” from scratch or even trying to tap with a set of 3 taps

                  #472787
                  JasonB
                  Moderator
                    @jasonb

                    I think trying to cut the thread true would be even more of a challenge than turning the die especially if he wants to use it for chuck mounting.crook

                    #472855
                    Brian Oldford
                    Participant
                      @brianoldford70365
                      Posted by Ian Parkin on 18/05/2020 20:27:03:

                      . . . . .

                      the large dies i have are all hex nut type so i generally use a big pair of stiltsons to run them down

                      . . . . . .

                      So far as I'm concerned die-nuts as you describe are purely for cleaning up slightly damaged or rusty threads, not cutting them from scratch.

                      #472877
                      JohnF
                      Participant
                        @johnf59703
                        Posted by Ian Parkin on 18/05/2020 19:19:40:

                        I cut a lot of large whitworth /unc threads usually on the lathe and then run a hex nut die down them to clean them up.

                        Sometimes its hard work just cleaning the thread up removing a small amount of material.

                        Ian, when you have gone to the trouble of setting up your lathe to screw cut the thread why not just cut it to size and you will have a better more accurate thread than finishing with a die ! Measure it with wires or a thread mic if you have one or use the mating part as a gauge.

                        John

                        #472881
                        Vic
                        Participant
                          @vic

                          I had difficulty cutting a thread with a 3/4” UNC Tap In aluminium alloy recently.

                          #472883
                          Tim Hammond
                          Participant
                            @timhammond72264
                            Posted by Brian Oldford on 19/05/2020 09:04:07:

                            Posted by Ian Parkin on 18/05/2020 20:27:03:

                            . . . . .

                            the large dies i have are all hex nut type so i generally use a big pair of stiltsons to run them down

                            . . . . . .

                            So far as I'm concerned die-nuts as you describe are purely for cleaning up slightly damaged or rusty threads, not cutting them from scratch.

                            I was always taught this, but I've noticed on several videos I've watched on YouTube, the Americans seem to have proper thread-cutting dies in a hexagon shape. Has anyone any further information on this?

                            #472889
                            Alistair Robertson 1
                            Participant
                              @alistairrobertson1

                              My first employer had a big collection of taps and dies in wooden boxes all ex War Department and US Army.

                              Although we used most of them there were a few boxes of large pipe taps and dies i.e up to 6" Whitworth Pipe. We never really looked in to them until the time came to clear them out with the metal going to the scrappy and the boxes were used for home projects. One of the tap boxes was built from 4" thick by about 18" wide by 36" long bits of wood hinged together to make it 8" thick! There were a couple of boxes of tap and die holders about 7 foot long and it wasn't until we were scrapping them that we realised that there were extensions to go on each end of these die-stocks. The total length of the die handle must have been nearly 20 feet! Needless to say they were still in the protective grease and had never been used. There was a ratchet system on the die holder to allow a back and forth action to cut threads in situ.

                              It made you wonder at the sanity of someone who organised to get these made at what must have been enormous expense when the money would have been better spent on armaments or even food imports. They were obviously not engineers. One of my old workmates had a workshop bench for many years made from one of the boxes and another had a very robust kennel that outlived a few of his dogs!

                              #472897
                              Martin Kyte
                              Participant
                                @martinkyte99762

                                The limiting factor practically speaking as far a I am concerned would be the ability to stop the workpiece turning.

                                regards Martin

                                #472899
                                S.D.L.
                                Participant
                                  @s-d-l
                                  Posted by Tim Hammond on 19/05/2020 10:18:45:

                                  Posted by Brian Oldford on 19/05/2020 09:04:07:

                                  Posted by Ian Parkin on 18/05/2020 20:27:03:

                                  . . . . .

                                  the large dies i have are all hex nut type so i generally use a big pair of stiltsons to run them down

                                  . . . . . .

                                  So far as I'm concerned die-nuts as you describe are purely for cleaning up slightly damaged or rusty threads, not cutting them from scratch.

                                  I was always taught this, but I've noticed on several videos I've watched on YouTube, the Americans seem to have proper thread-cutting dies in a hexagon shape. Has anyone any further information on this?

                                  The McMaster website shows Hex Dies as thread repair as per UK practice but they do show the conversion holder in the clip below.

                                  Would be easy to mage similar at home

                                  hex die holder.jpg

                                  Steve

                                  #472901
                                  SillyOldDuffer
                                  Moderator
                                    @sillyoldduffer

                                    Posted by Alistair Robertson 1 on 19/05/2020 10:38:51:

                                    It made you wonder at the sanity of someone who organised to get these made at what must have been enormous expense when the money would have been better spent on armaments or even food imports. They were obviously not engineers. …

                                    Done that way as a result of painful military experience. For want of a nail the shoe was lost etc. The young men who had to repair artillery pieces on Guadalcanal in 1942 did so with minimal training and experience. You'd be amazed what military men break by accident, never mind what the enemy are up to. The last thing soldiers need is to find replacements damaged in transit or rusty in the tropics due to inadequate packaging, or that the only set is 2000 miles away due to shortages. So the military overstock and box to the extreme to guarantee stuff will be available when needed. Not insane, just extremely wasteful.

                                    Dave

                                    #472984
                                    Mick B1
                                    Participant
                                      @mickb1
                                      Posted by SillyOldDuffer on 19/05/2020 11:20:58:

                                      So the military overstock and box to the extreme to guarantee stuff will be available when needed. Not insane, just extremely wasteful.

                                      Dave

                                      Nevertheless I can remember one factory I worked in getting such a large order for 'Wands, Marshalling' that we were convinced there was someone on an aircraft carrier somewhere shovelling 'em over the side…

                                      laugh

                                      #472992
                                      Ian Parkin
                                      Participant
                                        @ianparkin39383

                                        John f

                                        I do screwcut on the lathe to size but i run the hex nut dies down after just to make sure they are the right fit

                                        i make chuck adapters for woodworking lathes and its surprising how many dont fit even though I’ve used my spindle or sample threads or nuts so I’ve found that running the tap/die down my cut thread makes them work.

                                        the other day i had a chap send me a commercial 1 3/8 6tpi whit adapter that would not go on his lathe he sent it to me it wouldn’t go on my dummy spindle but running a tap down it cleaned it up..didn’t seem to remove any metal..but afterwards it went on my spindle and the customer was happy.

                                        My original post was about someone agin on a woodwork forum who wanted a die holder 3 1/8” dia to use his round split die to cut a male 1.5 “ 6tpi on a steel bar… I dont think that would be possible at all…but ill stand corrected if someone says they can do it…

                                        #473071
                                        Nicholas Farr
                                        Participant
                                          @nicholasfarr14254
                                          Posted by S.D.L. on 19/05/2020 11:10:35:

                                          Posted by Tim Hammond on 19/05/2020 10:18:45:

                                          Posted by Brian Oldford on 19/05/2020 09:04:07:

                                          Posted by Ian Parkin on 18/05/2020 20:27:03:

                                          . . . . .

                                          the large dies i have are all hex nut type so i generally use a big pair of stiltsons to run them down

                                          . . . . . .

                                          So far as I'm concerned die-nuts as you describe are purely for cleaning up slightly damaged or rusty threads, not cutting them from scratch.

                                          I was always taught this, but I've noticed on several videos I've watched on YouTube, the Americans seem to have proper thread-cutting dies in a hexagon shape. Has anyone any further information on this?

                                           

                                          The McMaster website shows Hex Dies as thread repair as per UK practice but they do show the conversion holder in the clip below.

                                          Would be easy to mage similar at home

                                          hex die holder.jpg

                                          Steve

                                           

                                          Hi, I made a couple of round to hex adapters out of a couple of 30mm nuts, 15 years or so ago when we had a breakdown at work and the only way to clean up a couple of threads was a couple of hex dies which we didn't have in those sizes at the time. Never had seen any adapters before.

                                          cimg2816.jpg

                                          Regards Nick.

                                          Edited By Nicholas Farr on 19/05/2020 19:05:07

                                          #473112
                                          old mart
                                          Participant
                                            @oldmart

                                            A professional pipe threading machine has sets of adjustable dies in a die box, they never use split dies. Back in the 70's I used Rigid and Facom machines. Production threading on lathes before cnc's came out was mostly carried out using die boxes rather than single pointing, as it was much quicker.

                                            #473162
                                            David George 1
                                            Participant
                                              @davidgeorge1

                                              The pipe thread set I have has separate blades which are adjustable and when I worked on a lathe this style of threading head was used for larger threads over 1 inch and were fitted to tailstock MT 4 which released when the tailstock was stoped by saddle which was hit by sliding tailstock.

                                              20200520_072420.jpg

                                              David

                                              #477290
                                              vic francis
                                              Participant
                                                @vicfrancis

                                                Hi interesting answers. a couple of weeks ago I had to make a 6tpi 60 degree worm for a model traction engine which had unfortunately dropped off in transit… after a few trials to determine the size ect changewheel setting I cut it:however I out of all if the machine die chasers I did not have a 6tpi so ordered a unc set of four off off ebay for 10 quid ex coventry type most likely for pipe… if you use one of these in a spring tool holder that will give you the correct form after sc roughing out…( grind some of the teeth off) no need for die nuts and 3 shredded wheats… however screwcutting is hard on motors and switch gear… err anyone got a spare brooks motor!? Good luck!

                                                #477301
                                                Nigel McBurney 1
                                                Participant
                                                  @nigelmcburney1

                                                  Why not go back to the earliest lathe practice,screwcut the thread to just a little oversize and finish the thread with a high speed steel machine chaser ,do not use the very early type hand chasers ,their use was mainly on brass. When using a chaser under power the chaser has to be withdrawn very quickly at the same time as the half nuts otherwise your thread will turn into a number of parallel rings .

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