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| cut an internal thread |
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| Rob.Wilson:
Hi Lads Sorry for the crap drawing :lol: :lol: Rob |
| Ned Ludd:
Hi Rob You get the same effect by moving the top slide, for each pass, by half the in-feed on the cross slide. but this way saves you having to upset your carefully set to parallel top slide. For those who like the set over top slide method, if you haven't made yourself a cross slide stop, do so. it makes life soooo much easier. The style of tangential threading tool from Eccentric, or Rick Kruger, also works extremely well with the set over top slide (for external threads) because it has positive rake on the cutting edge. It really is a pleasure to see long curly swarf when thread cutting. Ned |
| Bogstandard:
--- Quote ---I think for a beginner the top slide left as standard is the best place to start. Later once confidence has been gained then is the time to start more arcane procedures, after all how are you to know the set-over-top-slide method is better without trying the standard way first. --- End quote --- The way I see it is that we are here to help, and not to confuse. I find that the above statement is a**e about face. The 'standard' way as mentioned above isn't, in fact it is far from it. The normal method taught on how to cut threads is to use the topslide (compound) offset method. As shown by Rob above. This will produce a well cut thread with good results, with much reduced loading on machine and tooling. Not much to worry about when using large machines, but on some small workshop lathes it can mean the difference between success and failure. Once you have that under your belt, then you can experiment on using plunge cutting, just to find out just what the weaknesses your machine and tooling has. Sometimes you get away with it, sometimes you don't. Bogs |
| j45on:
Thanks for all the advise guys :thumbup: very much appreciated I shall defiantly be trying some external threads at the weekend :hammer: I would not have to cut the internal thread if I had not ruined the end that already had a internal thread :lol: |
| techonehundred:
One other thing to remember when cutting Internal threads is where the threads stop. Are you threading to a bottom? If there is enough room, I bore an area at the end of the threads just deeper than the major dia. of the thread that will give clearance to the threading tool. Without the clearance, It is easy to break a tool if you don't stop in exactly the same place(ignore if this is a throughhole and you can thread all the way through). Here is a quick COC drawing with paint to illustrate. Once you do it mark the tool for start and finish of relief area.(I use a sharpie or felt pen) That way you know where the end of the threads are without trying to contort to see inside. |
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