WM210V how to cut perfect threads

benmychree said:
Mr Whoopee said it all, a stop is completely un necessary for threading with an inch lead screw, only the thread dial is needed. For metric threading on an lathe with an inch lead screw, the half nuts cannot be disengaged, the lathe must be reversed and the tool backed up to the starting point.
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Show me where I am wrong. If the dial has the same number of clicks as the gear has teeth, the leadscrew will always be at the identical place when any click on the dial is at the top. Now if you are using and end stop to the right of the carriage the thread will always be in the same place when you engage the feed screw. The key to this is the gear and the dial have to have the identical number of teeth and clicks. This allows you to cut any thread that the change gears will allow always starting at the same position without having to reverse the feed screw.

It will be awhile until my gears and threading dial come in, but when in I will show a video of how this works. It is so simple I do not know why it has not been done before.
 
You did not say whether or not the spindle is rotating or stopped while you are doing that routine. A normal thread dial measures inch intervals on the numbered lines, and the worm gear is sized with a number of teeth to reflect that interval. Threads may be cut without reversing the spindle and backing up to the starting point by stopping the spindle, disengaging the half nuts and backing up to the starting point an even number of inches and reengaging the half nuts, this without a thread dial. This does not work with metric threads with an imperial lead screw.
 
You state that it does not work, show me where I am wrong. On this lathe the lead screw is 2mm, but it does not matter. If I have 8 clicks on the dial and 8 teeth on the lead screw the lead screw will be in the identical position when each dial click reaches the top since one full turn of the lead screw moves the dial exactly one click. I guess the first step for you to agree/disagree with this statement
 
I believe the OP has a lathe with a metric lead screw, so "normal imperial thread dial" instructions are not applicable. There are metric threading dials, but they are not as flexible as thread dials on an imperial screw. I believe the OP is working on a solution for threading on a metric lead screw.
 
He states that his method will work with any number of threads he is capable cutting with his change gears, why then are several gears with varying numbers of teeth to suit different ranges of screw pitches necessary on lathes with metric screws?
I am now 78 years old and have been a machinist (apprenticed) since I was 19, and a shop owner for most of that time, I think that I know what I'm talking about, at least for the most part, maybe I'm missing something?
 
WobblyHand said:
I believe the OP has a lathe with a metric lead screw, so "normal imperial thread dial" instructions are not applicable. There are metric threading dials, but they are not as flexible as thread dials on an imperial screw. I believe the OP is working on a solution for threading on a metric lead screw.
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That is interesting, but how does it apply? Do you disagree with the statement that the lead screw will be in the identical position with any click on the dial at the top when the number of clicks on the dial equal the number of teeth on the gear?
 
benmychree said:
He states that his method will work with any number of threads he is capable cutting with his change gears, why then are several gears with varying numbers of teeth to suit different ranges of screw pitches necessary on lathes with metric screws?
I am now 78 years old and have been a machinist (apprenticed) since I was 19, and a shop owner for most of that time, I think that I know what I'm talking about, at least for the most part, maybe I'm missing something?
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So in your history you have never encountered this simple design. I am 75 and also never encountered this design, so what. Repeating over and over that it will not work without spending the time to understand the design deprives you of the ability to learn.
 
weston1968 said:
That is interesting, but how does it apply? Do you disagree with the statement that the lead screw will be in the identical position with any click on the dial at the top when the number of clicks on the dial equal the number of teeth on the gear?
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I have no experience cutting metric threads using a full metric lathe with a metric lead screw. I have only just googled a few recent things that I was able to find. Not interested in arguing about various merits, was only stating that apparently there are metric dials, but they are not universal with pitch settings. I also found that some metric dials have gear sets that can be used on the dial to do certain pitches. This is all I know about it. Trying to be supportive of what you are doing, but it feels as if you are being a little combative.

I don't think you can willy-nilly change pitches and have things work. Take a 1.5mm pitch and 1.25mm pitch. If you moved your stop perhaps it could work. However, neither pitch lines up satisfactorily on a 2mm thread. You can move your initial position, however, so it will line up for that single pitch. There may be other work arounds. I applaud you for trying to make this work, and hope you continue this in this thread, despite any nay saying. Keep on plugging at it!
 
You do not say if the spindle is rotating or not rotating, you say you do the maneuver and wait for the zero position to come around and re engage, which suggests that it is rotating, this is my problem with the maneuver.
 
benmychree said:
You do not say if the spindle is rotating or not rotating, you say you do the maneuver and wait for the zero position to come around and re engage, which suggests that it is rotating, this is my problem with the maneuver.
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benmychree said:
You do not say if the spindle is rotating or not rotating, you say you do the maneuver and wait for the zero position to come around and re engage, which suggests that it is rotating, this is my problem with the maneuver.
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Yes, you wait for the dial click to reach the top and then engage the lead screw while it is turning. Since one full turn of the lead screw is exactly one click on the dial the lead screw is in the identical position when any click on the dial reaches the top. The carriage which is up against the end stop is in the identical position as the last time it was up against the end stop. With both carriage and lead screw in identical repeatable positions the threading tool always starts at the identical point on the work. Thread simply does not matter.
 
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