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| AcieraF3:
Hi all, Been busy moving back from the UK to the Netherlands, back to my machines! On my Boley 5LZ lathe (metric) there is no screw cutting dial and I think that there is no possibility to mount one since the lead screw is placed in the centre of the lathe ways and completely covered. This lathe have a separate lead screw (for screw cutting) and "feed" screw (for automatic feeds during turning) is you now what I mean. My question is: is it possible to cut threads without a screw cutting dial and is there an other way than just not disengaging the half-nut. Thanks in advance Teun |
| DaveH:
Teun, --- Quote from: AcieraF3 on August 25, 2011, 09:37:05 AM ---My question is: is it possible to cut threads without a screw cutting dial and is there an other way than just not disengaging the half-nut. Thanks in advance Teun --- End quote --- The first part of your question is Yes you can cut threads without the dial (I very rarely use mine), but you have to leave the half nuts engaged all the time, until the thread is finished. Your second part -sorry I'm not too sure what you are asking there - my brain cell can only handle one bit at a time :lol: :beer: DaveH |
| Lew_Merrick_PE:
--- Quote from: AcieraF3 on August 25, 2011, 09:37:05 AM ---Been busy moving back from the UK to the Netherlands, back to my machines! On my Boley 5LZ lathe (metric) there is no screw cutting dial and I think that there is no possibility to mount one since the lead screw is placed in the centre of the lathe ways and completely covered. This lathe have a separate lead screw (for screw cutting) and "feed" screw (for automatic feeds during turning) is you now what I mean. --- End quote --- Teun, The point of a threading dial is to coordinate the position of your saddle (cutter) to a specific angular orientation of your leadscrew. The mechanism to do this is a worm gear that is driven by your leadscrew, right? It does not matter where the connection between the leadscrew and the worm gear is made so long as you can see the threading dial as you are working. At the very simplest, a single index position will work for every pitch of screw-cutting you wish to do so long as you can close the half-nut when that marker lines up at your dial, right? One thing to think about is a flex-shaft drive. Once you have the worm gear mounted to your leadscrew, a flex-shaft can bring the rotation out to (just about) wherever you wish. It only needs to be rigid enough to rotate the threading dial properly. |
| Arnak:
Hi, Have a look at this thread http://madmodder.net/index.php?topic=5439.0 It is a very simple to make thread cutting tool, with that you can leave the half nuts engaged all the time you are cutting the thread. I have made one and can report that it works very well. :D You do not need to make the dovetail part as a rectangular piece of steel can be used instead to fit straight into an existing tool holder. There is a good diagram in the latest issue of MEW. Martin |
| andyf:
--- Quote from: Lew_Merrick_PE on August 25, 2011, 10:46:27 AM --- The point of a threading dial is to coordinate the position of your saddle (cutter) to a specific angular orientation of your leadscrew. The mechanism to do this is a worm gear that is driven by your leadscrew, right? It does not matter where the connection between the leadscrew and the worm gear is made so long as you can see the threading dial as you are working. At the very simplest, a single index position will work for every pitch of screw-cutting you wish to do so long as you can close the half-nut when that marker lines up at your dial, right? --- End quote --- Lew, what you say is true, and when cutting inch threads with an inch leadscrew it helps non-engineers like me who aren't in a hurry to use only one mark on the dial. But cutting metric threads on a metric lathe requires the worm wheel to be changed to suit the pitch being cut. 14, 15 and 16 teeth cover the common small metric threads up to M10 or so, and are often stacked on the same shaft, which can be moved axially to bring the right one into play. Teun's problem is that, with his concealed leadscrew, he can't easily change his worm wheel. One solution, if the construction of his lathe permits, would be to add an extension to his leadscrew at the tailstock end, threaded at the same pitch (though it needn't be the same diameter). Then, a threading dial could be mounted on the end of the bed, where he can get at it to change the worm wheel. Andy |
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