Hi
I found this topic In MEW Forum. If you Google "bv25b-l lathe" it brings up lots of dealers selling this lathe.
This was the lathe I bought for my home workshop and did some modifications-improvements to get a better performance.
The Topslide angle that several mention is totaly down to personal preference myown being as follows.
The angled topslide set at 29.5 degrees is what is used for thread cutting 60 degree threads
1) Set the tool to touch the workpiece and set Crossslide Dial to zero.
2) Move apron to allow the tool to advance on the Crossslide and advance the tool to the depth of thread required.
3) Zero the Crosslide Dial again.
4) Zero the Topslide Dial then retract the tool with the TopslideHandle until it will clear the Workpiece by moving the Apron.
5) Advance the tool with the Topslide and take the first cut
6) STOP The Chuck and retract the tool with the Crosslide and REVERSE the Apron with the Leadscrew Engaged.
7) Stop and Advance the Crosslide back to Zero.
8) Advance the tool on the Topslide.
9) Keep repeating 6) 7) & 8) until the Topslide dial reads Zero
If you got it right the Thread just needs tidying up.
Not being nimble enough with my advancing years I have fitted a 180 volt DC motor that extends the Variable Speed range from 40 to 2500 RPM
The original was 115 to 1620 in six steps
Eric