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| spuddevans:
--- Quote from: bogstandard on July 31, 2009, 07:39:30 PM ---Tim, The steam gland screws shouldn't go all the way into the gland nut, as they are used to compress material in there. So after your first cut with your die, turn the die around and use the unmarked side. It should then cut the thread almost to the shoulder, as the die shouldn't have a lead in taper on the 'bad' side. If the die has a lead in on both ends, I usually grind down the die on the 'bad' side to get rid of the lead in, purely to allow me to cut a full depth thread right up to a shoulder. I would suggest you grind up a specific undercut tool, about 0.02" (0.5mm) wide, as you will need it for all sorts of threading to a shoulder. Maybe not on this project, but for others in the future. If you are single point cutting, you really need a small undercut to drop into anyway. Bogs --- End quote --- Do you think I need to remake the gland nuts or is there enough thread on them? I can remake them as I havent yet drilled and tapped the packing gland (And it should remain concentric as it's mounted in an ER32 collet chuck that I can remove it in the ER32 chuck to turn up some new gland nuts using the 3jaw. (I'll make 4-5 nuts as Kvom mentioned that the valve packing glands are the same)) I'll grind up a specific undercutting tool too. I will be single point cutting on pretty much all the threads on this build as I have yet to make a tailstock die holder. I generally single point until near depth-of-thread and then clean up with a die. Tim |
| bogstandard:
Tim, The ideal method is to assemble the nut and gland together and tighten them up. Then drill the pair together to make a matched set. You might have to superglue the screw in, to stop it being unscrewed out when drilled from the other side, as really, you should turn the bore spigot and drill the central hole at the same time, to ensure that things are concentric to the bore. As shown on this bit of an article. http://madmodder.net/index.php?topic=1370.msg12873#msg12873 A little bit of heat afterwards will break the superglue lock. I personally would remake the screws, as you don't really have enough thread on there to hold the packing in position without the screw 'cocking over'. After you have drilled the thru hole, you can go back and countersink the top of the screw, and inside the gland itself, so that it forms the packing into a nice compact ball. I am very impressed by the way you single point cut all your threads. I only do it when absolutely necessary. If only everyone could pick up the technique, as you have, they would soon realise for those special one off's, there is no need to go chasing around the country for taps and dies. Keep up the good work Bogs |
| rleete:
I generally single point most of my threads. I find it one of the most satisfying jobs to do on the lathe. Makes you feel really good when two parts spin together just right. |
| spuddevans:
--- Quote from: bogstandard on August 01, 2009, 05:04:10 AM ---I personally would remake the screws, as you don't really have enough thread on there to hold the packing in position without the screw 'cocking over'. After you have drilled the thru hole, you can go back and countersink the top of the screw, and inside the gland itself, so that it forms the packing into a nice compact ball. --- End quote --- I think that it'll be better to do like you say and remake the screws, I would have to make 2 more for the valve seals so I may as well churn out 4 ( or maybe one or 2 extra just in case the unthinkable happens and I make a tiny catastrophic mistake :lol: ) And as I'm at a point that I can interupt in the making of the packing glands, I may as well do the remake. That'll be the 2nd item to do tomorrow afternoon, 1st will be to grind up a thin grooving tool to make a more reasonably sized undercut for the threads. --- Quote ---I am very impressed by the way you single point cut all your threads. --- End quote --- Dont be that impressed, while I do find it enjoyable, I do it out of need as I dont have a way of holding a die on the lathe ( unless I handhold it gripped in a pair of vicegrips, but I somehow doubt whether I could create a square and parallel thread form that way :lol: ) I guess when I get around to making a tailstock die holder I will fall into the easier way of just using that, but until that time I have to do things the slightly harder way. --- Quote from: rleete on August 01, 2009, 12:53:25 PM ---I generally single point most of my threads. I find it one of the most satisfying jobs to do on the lathe. Makes you feel really good when two parts spin together just right. --- End quote --- There is a great satisfaction to be found in single pointing a thread and then screwing on a commercially made nut or fitting, and seeing the 2 parts match up. :beer: But then again, there is great frustration in single pointing what you think is a M6 thread and then wondering why the M6 nut will only screw on about 1 turn, and the M6 die wont even attempt to go on square, and then realising that some idiot ( me ) has left the leadscrew gears set up for M5 thread :doh: :doh: :doh:, Or even more frustrating is finding out that the freshly cut thread has the proper depth of thread but that the overall diameter is just a fraction too big to screw in easily, and by some idiot's ( me again ) effort to screw said oversized thread in, the thread shears off in the tapped hole and then you have 2 parts to make again :doh: Tim |
| Darren:
Tim, I don't know how others get on, but I find single pointing produces far better and squarer threads than dies. Don't be in too much of a hurry to get those dies in......not for precision work at least.... :thumbup: You're doing a grand job as always...thanks for the write-ups.... :thumbup: |
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