When I started working, there was a lathe TOS MN80 in my work place, which, outside of working time I could use without any restrictions. Gradually, in my mind an idea arose - why not make a little and simple lathe using this TOS MN80. I quickly realized that this was unreasonable and, if I wanted a cheap machine, the proper way was to buy a Chinese lathe. Therefore, I was not very keen - and so spread the work over 13 years. Months would pass without any work, and then, in moments of inspiration, I would make some parts. I did not strive to make all the parts myself and if I found some suitable, I used them, for example, the leadscrew (without micrometer dials) and cross slide (also without some parts). The bed and basic plate (bottom plate, over which the bed is mounted) were made on a milling machine. All other parts were made on a TOS MN80 lathe, which, of course, restricted the sizes I could go up to. Up to the condition shown in the pictures (without tailstock), the machine was completed in 2010, after which I adjusted it a bit and made some testing details - the results were eminently satisfactory. In 2012, I packed the lathe up because I had to change my flat. Until now (June, 2021) I have never unpacked it.
My intention was to build a lathe for making parts with a length up to 250 mm and diameter up to 100 mm over the cross slide and 160 mm over the bed. The machine was supposed to allow the production of a part without rotation symmetry, therefore, it should be strong and of a vibration-proof design. For this reason, a strong base plate (the bottom plate over which the bed is mounted) was included in the construction. I had thought about mounting the lathe on the cast-iron base from a sewing machine that I have in my attic, but it took up so much space that I changed my mind and mounted the motor as shown in the pictures.
The lathe has a centre height of 96 mm above the bed and 52 mm above cross slide and admits 250 mm between centers; the weight (with motor) is 45 kg; the dimensions of the bed are 415 mm, 70 mm and 25 mm; the slide travel is 250 mm with resolution 0.05 mm and the cross slide 120 mm, with resolution 0.05 mm. On the bottom of the slide frame, there are two bronze clamp bars for vertical backlash adjustment and holding the slide - these are controlled by two hexagon head bolts that are only partly seen in the pictures. The cross backlash of the slide is adjusted by two brass slotted bolts while the bronze bar (inside the frame) is fixed to frame with four M8 bolts (they are not shown in the pictures). In cases of turning a part with diameter of 100 to 190 mm (above the bed), the tool post can be shifted to the left. In other cases, for the purpose of more a more favourable distribution of effort, it is mounted as shown in the pictures (to the right). The headstock spindle is bored o take a 17 mm diameter bar and the 3-jaw chuck an 80 mm Czech TOS.
The 180 Watt motor turns at 1470 rpm with the belt pulleys providing a 735 rpm spindle speed. The motor is started using the left toggle switch and short push of the central button - the right-hand toggle switch reverses the motor.
The spindle bearing is a single bronze piece with diameter at the front of 37 mm and 36 at the rear, the axial backlash of spindle being regulated by cylindrical head screw on the washer set against the belt pulley.
My plans are to add an adapter for a quick replacement of the cartridge on а chuck plate, finish the tailstock, mount a more powerful motor with frequency inverter drive for speed regulating and mount a compound rest for turning tapers. I have the most of these parts started, but not yet finished. I do not intend to make a gear for screw cutting because meanwhile I have bought a used but fully equipped TOS MN80 lathe.
In conclusion, I express my sincere admiration for your site. Now, I cannot strictly remember when was the first time I got on your site. I reckon it was back in 2005. Since then, usually every week, I visit your site and, with anticipation, wait for new monthly additions.
My best wishes, Dimitar Vesselinov Karaivanov in Bulgaria (Sofia).