The Shop > Tools

Boley 5LZ lathe

(1/2) > >>

For several years i have owned a Boley 5LZ lathe . This is a very high class lathe and is a pleasure to use . The headstock is belt driven as it was thought better than a gear drive for high quality surface finish .
The drive to the side shaft  is also belt drive to make the sliding and surfacing feeds as smooth as possible
The main drive belt needed changing and this is quite an involved job .
The headstock pulley is supported on a separate set of bearings to the headstock main shaft to eliminate any side loading from the tension of the drive belt distorting the headstock shaft
The headstock pulley is on roller bearings and the headstock is on tapered  hardened bronze bearings
To change the drive belt the headstock shaft is removed then the drive pulleys ,the lead screw is centrally mounted so as not to give any side loading to the carriage  it is also totally enclosed and this has to be removed as well
This takes about 4 hours to do and about the same to rebuild 
It is now all back up and running ,There is a write up on this lathe

 I do a lot of screw cutting on my Boley and I have been  lucky enough to acquire a d32 threading attachment  ,this is the holy grail of attachments and rarer than rocking horse manure , It works by auto advancing the tool at each pass . Once the tool is set it is possible to make multiple threads with out altering any settings.

When screw cutting the tool is set to the  minor diameter the tool is then retracted by moving   the rear  lever to the left . At the start of each cut the lever with the black ball handle is moved to the right and then to the left at the end of each cut .This auto advances the tool by a amount set by a graduated dial on the the top of the engagement lever.
The number of cuts before it reaches full depth can be set between 6 and 21 .
At the end of each cut the headstock is electrically braked and auto reversed at 4 times the cutting speed so the lead screw is never disengaged while screw cutting   
The auto reverse is carried out by 2 micro switches on the rear of the saddle
For internal threading  a extended tool holder is used with the cutter upside down and cutting on the opposite side .
I dont have the internal tool holder so will need to make one 
There is a small graduated knob at the rear for final micro adjustment of thread depth
First job is to make 2 adjusting nuts for the diff in a 1911 Crossley car these are 2.375 inch by 16 tpi


A very nice lathe and an amazing attachment.

I invariably leave the leadscrew engaged and reverse the lathe - no chance of making a mistake. Having to stop, wind out, reverse, wind in plus a bit, forward etc etc can be a bit of a bind. Not so with your attachment.



--- Quote from: smiffy on December 27, 2023, 05:14:04 AM ---...This auto advances the tool by a amount set by a graduated dial on the the top of the engagement lever.

--- End quote ---

Could you say whether each increment of advance is the same or does it vary? For instance if your total infeed was 0.100" and you want to cut in four passes, will it advance 0.025" each time?

I ask because all the modern insert threading catalogues (Sandvik, Seco, Iscar, etc.) divide the total infeed up into non-equal increments so that the volume of metal removed each time is the same.

A manual version of that, if it existed, would be very clever.

Once you get to final depth, does the auto-reverse work indefinitely should you wish to make one or more spring cuts?

I have only just received the tool and am still investigating it . I will take it apart at some stage to investigate its inner workings  but too busy at present . According to the instruction in the manual the infeed decrees as the tool advances  .
Regardless of the number of passes the infeed distance remains the same .

Once the final depth is reached as many spring passes as required can be made .

The final sizing can be adjusted by the small thimble at the rear of the tool this which is  is graduated in + or - 0.01mm per division
When I get the tool set up and working I will report on how it performs.

At present I am using a retractable tool holder as designed by G H Thomas which works well but this should take screw cutting to a new level ,particularly for repetition work.


[0] Message Index

[#] Next page

Go to full version