I would like to present my screwcutting apparatus for Schaublin 70.
For the watchmaker, in my opinion, Schaublin 70 is the best precision lathe. I would like to have a multi-functional screw-cutting apparatus for the lathe. This attachment to the machine I decided to make myself.
Taking as a basis the threading attachment of the sample of the 50s, I developed my own design that would be suitable for a new spindle with a radial-thrust ball bearing 7206.
If possible, I wanted to make the tool more versatile and mobile. Schaublin 70 is now mainly used for prototyping. It is very important that you can quickly and conveniently rebuild the device for a new operation, or even disengage and perform other work on the lathe without removing the threading attachment. It is clear that the fewer links in the chain between the spindle and the lead screw of the longitudinal carriage, the less error there will be. Need a compromise.
It took me about two months to develop the whole construction.
The base is made of cast iron. I did not find a foundry.
The wreath of the drive gear is wider than the gears. Two intermediate gearwheels and the driven wheel on the axis of the rotary heart, are also wider and rotate more stable.
In total, the apparatus has about 150 parts. Almost 50, like bearings or bolts, I bought. The produced parts are mostly made of steel C45, then I tempered them and let go, then polished, and sandblasted. Also I made chamfers, sometimes manually, and some details were corrected again on the machine. I manufected all by yourself.
The handle of the rotary heart is corrugated, hardened, tempered and blackened
The device has built-in 7 bearings, at this the design is unpretentious in operation.
The screw cutting machine is essentially a gearbox that allows the longitudinal carriage of the cross slide to move for a certain length during the rotation of the spindle. The set has 17 interchangeable gears, with which you can perform the most common thread, both metric and inch. Planting them into triple lira extends the range of possibilities. With these combinations in mind, I calculated the set of the interchangeable gears.
Through the built-in rotary heart, both right and left threads can be cut. The disconnect device with adjustable stop allows you to switch the machine on or off automatically or manually.
Attachment for screwcutting can also be used as an automatic drive to the cross slide.
- screwcutting perform milling cutter and vertical joints;
- after a hardening a thread to polish;
- depending need any standard or special curly thread to select a suitable cutting tool;
- perfect thread windings to get;
- to control the size of the internal and external threads and, if necessary, to reach the missing size or, on the contrary, to get rid of excess, which is practically impossible to make with a threading tool.
Technical data of Threading attachment for Schaublin 70
- Attachment for screwcutting by carriage and universal joints by cardan shaft for the inner and outer thread.
- Used with open and closed headstocks type W12.
- Leitspindelsteigung 1 mm
- Maximum lenght of screwcutting = 52 mm
Set of change gears:
- 30-33-35-38-39-40-45-46-50-60-70-75-80-85-100-120-127 (17 gears)
- metric thread to perform with a pitch: 0,075-0,08-0,10-0,125-0,15-0,175-0,20-0,225-0,25-0,30-0,35-0,40-0,45-0,50-0,55-0,60-0,70-0,75-0,80-0,90-1,0-1,25-1,50-1,75-2,0-2,25-2,50-3,0-3,50-4,0 мм
- Whitworth threads to perform with 90-80-72-68-64-60-56-52-50-48-46-44-42-40,64-40-38-36-34-32-30-28-26-24-22-20-18-16-14-12 pitch.
Стандартное оснащение и аксессуары:
- the drive wheel with 40 teeth for mounting on the spindle;
- retractable propeller shaft with replaceable extension(120 mm);
- >means for fixing on the compound slide with a release mechanism;
- pawl for link and unlink of the device;
- replaceable extension, length 190 mm;
- replaceable extension, length 250 mm;