Homemade Lathe Headstock EXTERNAL Gearbox

[Tuomas]

Awesome work!

[Toolmaker51]

Thanks for the comments. Recirculating oil pump would be very nice addition to this project, but I wanted to make it simple. There are plenty lathes with oil bath system and they are working just fine.

Your gearbox, entire development, and presentation gets my vote for "Tool of the Week". Forever!

Benefits from recirculating oil are probably suited to equipment with long run cycles, where baths aerate lubricants to unhappy plain bearings.

Bath oiling works perfectly satisfactory. Suits many gear forms including hypoid and spherical or roller bearings.
I've noticed some work better, where the engineering provides 'paths' for oil to reach components above the fluid level.
Rotating gears transfer oil upward readily, even at slow speeds. Slingers [oil knives] are common in small engines.
Shafts grooved with a shallow long pitched helix generate lengthwise travel. Most are rounded, not vee'd grooves.
Oil wicks [capillaries] are very effective; cotton cord or pipe cleaners wrapped loosely around light gauge stiff wire. Position these over oil ports of bearing housings. About the first boxed gear train I worked on included small balconies; reservoirs to better feed remote capillaries.

[dkwflight]

Hi guys,

Fabricated external lathe gearbox and finally managed to test it. I run it for very short time in order not to destroy gears. No oil in gearbox.

As there are couple of people who couldn't wait to see it in operation (rossbotics wrote: Looks great, cant' wait to see the finished product)
I posted it now before it is completely finished.

I would assemble it completely in a day or two and fill oil inside (ISO 46 hydraulic oil) and buy 925 mm v-belt (presently 900 mm v-belt is outside pulley groove), but I received an urgent call from crewing manager and had to pack my luggage and join the vessel very urgently. So that has to wait until I am back home again. Then I will post video of assembling gearbox and with fully completed gearbox (painted as well) in use.

Poor design of belt change and bad choice of spindle speeds made me to do something about it. Whoever has this type of lathe knows exactly what I am talking about. I was thinking about this project for a couple of years already and during my last contract I spent more than 3 months calculating speeds and what gears to buy. I made so many calculations and I made more than 500 different drawings always changing something. There was also an idea to have 18 speeds, but that would be overkill. Still there is possibility to install two additional gears (55 and 33 teeth) and get additional 6 spindle speeds: 125, 250, 375, 500, 750 and 1500. It can happen. I am in China again and gears (google translated it from Chinese as precision spur gears #45 steel tooth surface induction hardened) are very cheap here. Chinese gears for Chinese lathe.
Total weight of gearbox is close to 50 kilograms and that's the reason why it sits on very strong support. It is also placed far away from the chuck so it is not in the way of chuck key.

Once I was happy with my calculations and drawings, I bought all that stuff which can be seen in attached pictures.

What can't be seen in video is that I also installed drain plug at the bottom of gearbox (smaller oil eye glass) and glued rare earth magnet inside in order to collect steel particles.

Materials used:
mild steel, SS 316 and SS 304

I estimate that I spent little bit less than 100 dollars for all material, but now I have fully functional and user friendly lathe. Needless to say that I spent plenty hours of my vacation time for fabrication of this gearbox.

Best regards
LMMasterMariner

I would realy like to see the complete gear box and drawings if it fit my mini lathe
Good luck
Dennis

[hobbybob]

Great job!
This is such a project what makes me very enthousiastic to go to my shop and make some nice stuff!

[LMMasterMariner]

Hello Denis,

I am presently preparing drawings for 18 speeds gearbox and will post them once completed.
It will fir mini lathe but you must make some strong support for it.

Best regards
LMMM

[LMMasterMariner]

Update / Upgrade
===========

In order to upgrade this gearbox and make an overkill, I have alredy ordered and received 2 gears; 33 and 55 teeth.
Paid total 3.73 USD for both of them. Picture of speed chart together with new gears attached.

I also decided to install recirculating pump and prevent "churning".
Will buy recirculating pump together with tank, pumping capacity 1.2 liters per minute. Price up to 25 USD max.
Picture attached.
Google translated from Chinese:
Taiwan genuine 1.2L liters / 1.8 liters electric lubricant pump / CNC electromagnetic pump / machine automatic oil pump
It can be found on the following web pages:
https://item.taobao.com/item.htm?spm...cket=12#detail

https://item.taobao.com/item.htm?spm...cket=12#detail

https://item.taobao.com/item.htm?spm...cket=12#detail

https://item.taobao.com/item.htm?spm...cket=12#detail

https://item.taobao.com/item.htm?spm...cket=12#detail

Will also buy 2 distributors for copper pipes; each 8 lines and will have 8 lines for gears and 8 lines for 8 bearings.
Picture attached.
Google translated from Chinese:
B type adjustable resistance proportional distributor / TK oil distributor / oil / oil valve / lubrication branch
Picture attached and it can be found at the following web pages: Check the prices.......
https://item.taobao.com/item.htm?spm...id=44406509307

https://item.taobao.com/item.htm?spm...cket=12#detail

https://item.taobao.com/item.htm?spm...cket=12#detail

Best regards
LMMasterMariner

[redearthbonsai]

very nice work. Do you have any links for buying the gears them self and a parts list? I went to the sight but failed to have it pull up anything but tiny RC car gears.

[LMMasterMariner]

Recently bought 33 and 55 teeth gears from taobao at China.

https://item.taobao.com/item.htm?spm...cket=15#detail

https://item.taobao.com/item.htm?spm...cket=15#detail

Prices are for Chinese market. The same can be found at aliexpress but prices are much higher.

Best regards
LMMasterMariner

[wizard69]

I must say this is one impressive build!!

What is the idea behind the adjustable bearing flanges? Is it to overcome layout precision or to allow slightly different center diameters in the gear sets? Frankly in all my years in industrial maintenance I’ve never seen such flange mounted bearings.

One item worth consideration is the output belt. You will have a lot of torque capability on that belt. As a result you may get slippage or even a broken belt. Something to consider.

[LMMasterMariner]

hello wizard69,
the only reason for these adjustable pillow blocks was that I found them cheap and idea was that I could adjust the gap between gears very easily. (which I actually did, but it wasn't easy). gap can also be properly adjusted using ordinary bearings and will use 6203 bearings for my new gearbox.
cheers
lmmastermariner