john11668
Aluminum
- Joined
- Oct 25, 2009
- Location
- Cumbria, UK
Hi Folks
I apologise that it is some time since I have visited .
I have a current problem in that I wish to cut a 26 tpi thread (internal actually but I know that doesnt matter ) on my metric bantam lathe . Leadscrew is 6mm pitch .
I have the 127 change gear and followed the instructions in my manual (I attach the relevant section )
Lever positions B so y=2, and 5 so z =8 and compound is 127/120 so according to my calcs
driver should be 28 and Driven 55,
giving a tpi of 25.984 which as they say is close enough for government work.
But after a test cut my thread gauge tells me I have 30 tpi so clearly i am doing something wrong
The manual to me is not really very clear so can anyone help me find what my mistake is.
I apologise that it is some time since I have visited .
I have a current problem in that I wish to cut a 26 tpi thread (internal actually but I know that doesnt matter ) on my metric bantam lathe . Leadscrew is 6mm pitch .
I have the 127 change gear and followed the instructions in my manual (I attach the relevant section )
Lever positions B so y=2, and 5 so z =8 and compound is 127/120 so according to my calcs
driver should be 28 and Driven 55,
giving a tpi of 25.984 which as they say is close enough for government work.
But after a test cut my thread gauge tells me I have 30 tpi so clearly i am doing something wrong
The manual to me is not really very clear so can anyone help me find what my mistake is.