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  • #16
    Originally posted by CCWKen View Post
    That would be the way to go. A few bricks or a sack of concrete, propane torch and something to melt the aluminum in is all you need for a one-off. No need to get fancy and build a foundry. Pour it into a leveled open oil sand mold.

    Originally posted by Bob Engelhardt View Post
    9.25 diam x 7/8 is quite a bit of aluminum - a 4" crucible almost 5" deep. I'm not saying a few bricks and a propane torch won't work, but it will likely be pretty frustrating. More heat would be better - a weed burner or multiple torches.
    I have built a torch and a foundry and have an a8 size crucible which gives me more than enough room to cast the blank I need.

    I've tried twice to cast the blank now and been unsatisfied with the results, i run into the same problems as when i'm casting ingots.

    Porosity is not too bad, acceptable I would say , somewhere between 3 and 4 on this chart. http://berntsen-foundry.com/wp-conte...0.54.21-AM.png

    My biggest concern is how brittle the cast aluminium is. I thought initially I had overheated it and by not degassing or fluxing that was affecting things but I have made some ingots from known 7075 and another batch from random scrap and both are the same. I am using soda for degassing and lite salt for fluxing.

    I am concerned that the gear teeth will break off in use, from my tests it doesn't take a whole lot of force to break this stuff, especially when its thin like a gear tooth, any tips or are my concerns without validation?

    The grain structure when broken is much more gritty than that of what i'm melting, is this just how it is with cast aluminium?

    I'm glad I built the foundry but I get the feeling that i'm going to end up buying some material anyway!!

    Comment


    • #17
      Hello here too if your the chap asking about milling vices, did you see the post from the chap making resin changewheels on a professional DLP/SLA resin printer to order for harrison's on the mig welding site? Not sure I'd want to do the 127 in that, but the smaller ones seem good candidates. I've 3d printed on a fdm machine in nylon sucessfully too and I'd be quite happy to run a smaller nylon gear.
      For now I run a tufnel gear in my drivetrain full time, it reduces ringing and acts as a sacraficial gear to the drivetrain, protecting my 127T from damage :-)
      Also don't you need a 100 gear to do true pitch translation with the norton box also? I only just fitted my norton gearbox in place of a CBA unit, so I'm still figuring out the different gears needed.

      Comment


      • #18
        Yep, it's me!

        I don't believe I have seen that post else I'd be tempted.

        I am making the 2 smaller gears from POM.

        I have files for a 127t gear and a 100 to 127t adapter than my friend tried to print in PLA for me but unfortunately the sizes were just too big and ran into problems with the print lifting and deforming. His printer is very much a hobby machine.

        The 60t intermediate gear currently on my lathe is tufnol, to my knowledge it came supplied that way.

        Not according to the manual I don't. 50t on the top shaft, 40&60t on the intermediate shaft and 127t on the bottom shaft gives the majority of metric pitches, a couple pitches such as 1.75 need the 60t swapped for a 63t on the intermediate shaft.

        Do you have a manual? I can email you it if you don't

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        • #19
          If you have cad/drawings for the 127, worth mentioning, if not to buy a 127, it might give you some horsetradery collateral to get a smaller gear printed if thats what you want to do instead.

          Thanks for the offer but I have a paper copy of the original l5/l5a operating manual, and note it has some charts for gear ratios but my machine is somewhat of a mongrel and I'm not certain which parts have been changed already when it had a metric conversion done to it by a previous owner. I haven't yet checked the leadscrew to know which it is yet so the only way to be sure is to measure everything.
          What would be really a good find would be the actual gear ratios of the positions for each of the two levers + the ratios from the detent position lever positions in the norton box, then knowing the pitch of my leadscrew I could work back through the geartrain and calculate any gear combo I needed. There is one for the later 3 lever + moveable lever box on the squaretop l5a and later models, but the two levers + detent position lever version is eluding me so far. I suspect after searching that I'm going to spend a evening or two counting teeth on very small gears to find this out & I have to take the norton box off again to machine the leadscrew shorter so it can be done then.

          The 100/127 translation gear was from a old post found on google located on PM for a L5 with 13" centre height? so maybe its wrong and it applies to a 3 lever machine only, Im not sure as my machine arrived with the 127T mounted in the geartrain and I have a 100T in the cabinet amongst others. I had a older l5 before this so some of the changewheels I have were from that also, so not sure where the 100 originated from.
          http://www.practicalmachinist.com/vb...n-help-195421/
          Last edited by MrFluffy; 10-27-2017, 09:55 AM. Reason: fixed the markup on the link

          Comment


          • #20
            Originally posted by MrFluffy View Post
            ... The 100/127 translation gear was from a old post found on google located on PM for a L5 with 13" centre height? so maybe its wrong and it applies to a 3 lever machine only, Im not sure as my machine arrived with the 127T mounted in the geartrain and I have a 100T in the cabinet amongst others. I had a older l5 before this so some of the changewheels I have were from that also, so not sure where the 100 originated from.
            The 127 tooth gear is used because it's the smallest integer multiple of 25.4 you can have (1"=25.4MM). Where the 100 tooth came from I don't
            know, though I'm sure you can find the explanation by asking Google. Whether you use a 100, 50, or 200 tooth gear doesn't really matter. All you
            are doing is changing the ratio by a multiple of 2. If you look at the threading chart on an imperial lathe, the rows are all multiples of 2 of each
            other allowing you to compensate for a 50 or 200 tooth gear.

            Location: Long Island, N.Y.

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            • #21
              I would start with a piece of steel plate and torch or saw out a blank. for the bigger gears I would put 3 holes in it for my chuck jaws to engage. That allows boring the ID, facing one side and turning the OD all in one chucking. I would not waste time making the thin webs you see on cast gears. It adds nothing to the performance.

              What are you going to use to index the 127 tooth gear? The standard index plates on a dividing head won't do it.

              I have the metric conversion gears on my SB 10K. If it would be helpful I could photograph the change gear chart for you.
              Last edited by Illinoyance; 10-27-2017, 09:05 PM.

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              • #22
                Indeed. That seems to be why they sell for big money, they are hard to index.

                Of course, other gear combinations are very close, and in any reasonable length of thread the difference will be undetectable, less than the imprecision of other parts of the system. And those gears may already be available.
                3751 6193 2700 3517

                Keep eye on ball.
                Hashim Khan

                If you look closely at a digital signal, you find out it is really analog......

                Comment


                • #23
                  Got some sheet Tufnol if that's any help, I bought it to convert my Harrison L6 but that's as far as that project is, Sir Jhon gave me some info on what's needed, I'm assuming that the L5 is the same as the L6 so what exactly are you planning, I get that the input shaft of the box is 127t, the rest escapes me at the moment, desensitised from working out change wheels by never having to do it in work, point and click, even on huge lathes.
                  Last time I set up a gear train was on my old ML10 (bought new at the works no less, I hope the barsteward that nicked it rips his ball sack moving it )
                  I do like the old Harrison lathes, lovely machines apart from the palm breaking 4 way toolpost clamp,
                  I need to get a quick change,
                  If you want some Tufnol PM me
                  Mark

                  Comment


                  • #24
                    If you are tempted to try the barbell weights steer clear of the vinyl covered ones as they are often filled with something other than cast iron.

                    With an iron weight I suggest use a grinder or better still a sharp cold chisel and remove all the raised lettering etc before putting it in your machine, that will save a lot of interrupted cutting.

                    I have used these weights for a few projects and really the only down side is the mess when 'getting under the skin'. My source is usually one of the charity shops.

                    The most practical way of indexing to cut one gear may be to beg, borrow or steal a 127 gear from someone and latch index from that.
                    Last edited by The Artful Bodger; 10-27-2017, 04:49 PM.

                    Comment


                    • #25
                      re casting brittleness. You might try heat treating a sample to see if it improves. Also try asking on Madmodder as they have a couple of more regular casters on there.
                      I fit is any reassurance on strength I have some Britannia changewheels that are as cast teeth, ie the teeth were cast not cut and a rather thin root peg profile about 1/10 thick and they have survived.

                      Comment


                      • #26
                        Originally posted by Illinoyance View Post
                        What are you going to use to index the 127 tooth gear? The standard index plates on a dividing head won't do it.
                        I have a universal dividing head with a full set of gears. It wasn't cheap but everything is there.

                        Originally posted by boslab View Post
                        Got some sheet Tufnol if that's any help, I bought it to convert my Harrison L6 but that's as far as that project is, Sir Jhon gave me some info on what's needed, I'm assuming that the L5 is the same as the L6 so what exactly are you planning, I get that the input shaft of the box is 127t, the rest escapes me at the moment, desensitised from working out change wheels by never having to do it in work, point and click, even on huge lathes.
                        Last time I set up a gear train was on my old ML10 (bought new at the works no less, I hope the barsteward that nicked it rips his ball sack moving it )
                        I do like the old Harrison lathes, lovely machines apart from the palm breaking 4 way toolpost clamp,
                        I need to get a quick change,
                        If you want some Tufnol PM me
                        Mark
                        I have a manual with the gear setup in it, there's also online calculators for that. I think I posted the setup a few post ago?

                        I'll shoot you a pm!

                        Originally posted by J Tiers View Post
                        Indeed. That seems to be why they sell for big money, they are hard to index.

                        Of course, other gear combinations are very close, and in any reasonable length of thread the difference will be undetectable, less than the imprecision of other parts of the system. And those gears may already be available.
                        You are right. But I figure if I'm doing it I might as well do it right!

                        [QUOTE=The Artful Bodger;1141371]If you are tempted to try the barbell weights steer clear of the vinyl covered ones as they are often filled with something other than cast iron.

                        With an iron weight I suggest use a grinder or better still a sharp cold chisel and remove all the raised lettering etc before putting it in your machine, that will save a lot of interrupted cutting.


                        Originally posted by Baz View Post
                        re casting brittleness. You might try heat treating a sample to see if it improves. Also try asking on Madmodder as they have a couple of more regular casters on there.
                        I fit is any reassurance on strength I have some Britannia changewheels that are as cast teeth, ie the teeth were cast not cut and a rather thin root peg profile about 1/10 thick and they have survived.
                        I can look into it, it's probably something I'm doing wrong though!

                        Probably worrying over nothing!

                        Comment


                        • #27
                          Originally posted by Baz View Post
                          re casting brittleness. You might try heat treating a sample to see if it improves. Also try asking on Madmodder as they have a couple of more regular casters on there.
                          I fit is any reassurance on strength I have some Britannia changewheels that are as cast teeth, ie the teeth were cast not cut and a rather thin root peg profile about 1/10 thick and they have survived.
                          Many people who observe hardness and brittleness in "found" sources of CI such as barbells and sash weights, etc, say that they get good results from putting the material in the woodstove for a day or so, and letting it cool overnight in the ashes. While not a controlled heat treat process, it seems to improve machinability of the CI, which is often a combination melt of all the scraps that are laying around when those non critical items are to be cast.
                          3751 6193 2700 3517

                          Keep eye on ball.
                          Hashim Khan

                          If you look closely at a digital signal, you find out it is really analog......

                          Comment


                          • #28
                            Buy some round bar 40 or 80ksi Durabar and cut it into disks. Machines like butter with no black dust - just nice little curls.

                            Comment


                            • #29
                              Originally posted by RichR View Post
                              The 127 tooth gear is used because it's the smallest integer multiple of 25.4 you can have (1"=25.4MM). Where the 100 tooth came from I don't
                              know, though I'm sure you can find the explanation by asking Google. Whether you use a 100, 50, or 200 tooth gear doesn't really matter. All you
                              are doing is changing the ratio by a multiple of 2. If you look at the threading chart on an imperial lathe, the rows are all multiples of 2 of each
                              other allowing you to compensate for a 50 or 200 tooth gear.



                              I recognize that chart! What happened to the number 3 slot (.0063)?

                              Andy

                              Comment


                              • #30
                                Originally posted by lakeside53 View Post
                                Buy some round bar 40 or 80ksi Durabar and cut it into disks. Machines like butter with no black dust - just nice little curls.
                                10 inch diameter pieces of any material aren't exactly thick on the ground around here. Thus my problem!

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