Ok folks I have the above lathe. I would like to cut some metric threads.....never done metric before. So i get all set up on my lathe and I'm thinking about the half nut engagement and I realize There is not a chart on my lathe for what number to engage on for a specific thread pitch. I have one for regular inch threads but not one for metric. Where can I get a number chart for metric threads 1-4?
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Question Grizzly G0709
- Thread starter Mike8623
- Start date
Ok if I've got this
I get my gears dialed in for instance for a M4.5x.75 screw I dial my gears in to setting FBSW6
I then engage the lead screw dial (1-4) and apply the halfnut. I then disengage the lead screw dial and leave the half nut engaged.
I then run my v thread tool into the work and make contact at which time I turn on the lathe and make a pass using the lathe red knob lever in the down position (toward the 3 jaw chuck) then after done I push that red knob lever up to reverse the carriage and just go a little deeper at each cut.
I get my gears dialed in for instance for a M4.5x.75 screw I dial my gears in to setting FBSW6
I then engage the lead screw dial (1-4) and apply the halfnut. I then disengage the lead screw dial and leave the half nut engaged.
I then run my v thread tool into the work and make contact at which time I turn on the lathe and make a pass using the lathe red knob lever in the down position (toward the 3 jaw chuck) then after done I push that red knob lever up to reverse the carriage and just go a little deeper at each cut.
- Joined
- Jan 6, 2017
- Messages
- 1,214
From what I'm hearing in your post, there is a good probability that you are about to do some damage to your lathe.
The part you missed in your description above is, Make sure you withdraw the tool from the work before reversing direction. Backlash will break parts if you reverse with the cutter still engaged.
You can leave the half nuts engaged, if you have room. But, If your threading to a shoulder, or working near the chuck, here is a method that can prevent crashing your lathe.
Watch a few videos, such as this one from OxTool. An easier, safer method. Especially if your threading to a shoulder.
There are other ways to do it, and other helpful videos. Just search around.
Another, from Abom.
The part you missed in your description above is, Make sure you withdraw the tool from the work before reversing direction. Backlash will break parts if you reverse with the cutter still engaged.
You can leave the half nuts engaged, if you have room. But, If your threading to a shoulder, or working near the chuck, here is a method that can prevent crashing your lathe.
Watch a few videos, such as this one from OxTool. An easier, safer method. Especially if your threading to a shoulder.
There are other ways to do it, and other helpful videos. Just search around.
Another, from Abom.
Last edited:
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- Nov 17, 2017
- Messages
- 1,525
I use the Abomb method--re-engage the ½nut on the way back out.
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- Dec 18, 2019
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If you observe carefully, his thread dial doesn't move quickly. He catches the mark on the way back to 1, the first instance of it occuring. I'm not sure that this works in general, but the exact way Abom is doing it works on his lathe. If the spindle rotates multiple revolutions, coming to a stop, it will take that many reverse revolutions to sync again, worst case. For some pitches, the sync period is long.
It would be wise to do a few dry runs before actual cutting to confirm this works on your lathe. Use a marker in place of a cutter, it can show timing/threading errors without cutting.
It would be wise to do a few dry runs before actual cutting to confirm this works on your lathe. Use a marker in place of a cutter, it can show timing/threading errors without cutting.