Asian 7 x 12 Mini Lathe

D

djb-systems

Registered
Registered
Joined
Feb 20, 2023
Messages
20
Hi All

I am new to all things lathes and I bought the lathe to make small parts for models and robotics.

My lathe is one of the Asian 7 x 12 Mini Lathes which well for me worked great for a few months (Second Hand) turning basic stuff, then the speed detector / tacho I think it is, failed, no big deal as I roughly knew where I needed the speed to be for turning, then a click and a pop later and the speed controller has went up in a puff of smoke, ahhh the joys, but I have heard this is a common problem. The Lead screw also has issues, but I think some of the sacrificial gears? are broken being made of plastic.

So I need to fix the issues.

So my first question is, what is the best way to proceed, I have heard that a lot of people with these lathes get rid of the Control System and the Chinese AC motor and upgrade to a DC motor with a much better speed controller, when I looked this up, the amount of google posts is a little overwhelming, so looking for advice on this.

Second question, since my gears are broken, is there anyway I can get rid of them but still have the ability to cut gears and have a power feed, I know I could use a separate motor on the lead screw but I believe the spindle motor and lead screw are synchronised using the gearing system, so not sure how that would work.

Just as a side note I may further down the line look into a CNC conversion so fixing my current issues that would also benefit if I do decide to do CNC would be great.

So any help is appreciated.

P.s Slightly off topic, I just recently bought one of those Vevor 17.7 x 6.7 milling tables for using with my pillar drill, anyone with experience of these as to be honest it works great as a paperweight, but as a milling table its terrible, terrible castings, lead screw nuts are not even drilled and tapped straight ect. Have I just bought a dud, or is this the quality of these tables.

Cheers

DJ
 
I'm currently looking into a DC motor for a bench mill , and yes lots of info out there . Look at Youtube , also a Co. called Galco has converters (ACto DC) https://www.galco.com/15dve-dart.html?utm_source=adwords&utm_medium=&utm_campaign=PMax: Shopping - InStock - LV - G &utm_term=&utm_content=&utm_id=18138612685&utm_device=c&utm_network=x&utm_mt=&source=AdWords&gclid=EAIaIQobChMImYep46qL_AIVHBitBh0_DgfSEAQYAyABEgLeo_D_BwE
It can add up fast and get expensive .
Another source for stuff is https://littlemachineshop.com/They sell replacement parts .
Mark .
 
Yes, all the “Chinese milling tables” are pretty bad. But, they should really be called drill press positioning tables since the only material you’ll be able to “mill” with a drill press and one of these is tofu.

Btdt. If you need a mill start saving and shopping. As for the lathe there is a guy who repairs the boards.

olduhfguy.com

Olduhfguy.com

Repair Service for Mini Lathes and Mini Mills
olduhfguy.com olduhfguy.com

John
 
You could 3D print the broken gears. They probably break when overloaded but than there is less damage to other components. I have 3 3D printed gears in my big lathe and have made POM gears to replace them. But the 3D printed gears last more than a year now so if they fail, I will replace them by another 3D printed gear.
I have a 600W servo motor (as second motor) for my bigger (CNC) lathe. It is/was a trial to see if I can replace my 1.5 kW motor by a servo motor. That way I can use the servo motor to index the spindle position for cutting gears, radial and axial drilling, knurling, grinding tools, etc. I took me a long time to get things right (servo tuning) but I have got it working. So if you consider CNC your lathe, this is something to consider.
I have a Lichuan 600W A4 servo that comes without tuning software and that made things complicated.
I have documented the CNC conversion of my small lathe that still can be used manual. I did the CNC conversion of my bigger lathe the same way.
 
Hi All

Thanks for the replys, I am in the UK so I only buy from within the UK as our import charges and taxes just dont make buying outside the UK worthwhile, well for me anyway.

I dont really need a mill, on occasion when I do, my pillar drill works fine with the small milling table I have, i wanted a bigger work area hence why I bought the vevor table to my dismay.

Hmmm, 3D printing the gears is an option if I can find the 3D models of them.

I got really sidetracked on youtube due to the videos of people using old washing machine motors for lathes, mills, bench grinders ect and I have a free supply of these. I do like the servo idea, I have seen what can be achieved using indexing and making my own gears would be awesome for robotics.

Cheers

DJ
 
I have uploaded a FreeCad file file for making gears. It has a spreadsheet for the gear parameters. You can use this FreeCad file to make the STL files for 3D printing.
In this video, I explain how I make my gear cutters and gears on the mill and on the lathe.
 
If you're thinking of cnc conversion putting in a low voltage DC motor (from a thread mill for example) makes sense. However if you're just wanted to fix it easier way woukd be to repair the board. BTW I don't think the original motor is AC. I think it is high voltage DC motor. That's why it is so expensive. If you replace it with a more commonly used DC motor you'll also need a powerfull power supply.

Do you know anyone who can do electronic repair (a hobbyist with a good lab etc)? If the motor is fine I wouldn't replace it just because. I had my control board blow up too (I suspect swarf got into the motor and shorted it) and if I remember correctly I had to replace few parts (two transistors, two dual shottky diodes). Then adjusting it requires a bit of fiddling. The first time I thought I was done it woukd work fine during summer, but when temperatures dropped it wouldn't start until I readjusted a potentiometer inside. Also,did you check the fuse?

Regarding gears, I second the 3d printing idea. I heard about people baking them for more strength. I'm not sure this is really necessary.

The connection between the chuck and the lead screw through gears is needed for threading. It is possible to achieve it with a stepper motor on the lead screw in cnc conversion too.
 
You may want to contact https://www.arceurotrade.co.uk/ regarding replacement parts. There is a fellow in the US that repairs motor controllers, his web site is here. There may be someone who does something similar on your side of the pond. Olduhfguy does ship internationally.

Both LMS (Little Machine Shop) and his site have a troubleshooting guide if you have the equipment to do it.
 
Hey All

Sorry I have not posted for a bit regarding my Lathe, work has been hectic, with external audits.

So yes my lathe has a 180 Volt DC, 550 watt Brushed DC Motor @ I think 0.5 or 0.75 HP, the control board is fried, I could replace it for like or use an ac speed controller and bridge rectifier, however I have just been given an 180 Volt DC Motor @2.5 HP with controller with a bonus of a Sick Stegmann Absolute Rotary Encoder, in essence I now have a 2.5 HP Brushed Servo Motor, now this would be a massive upgrade for the lathe as I could get rid of the gears and have the ability to do indexing. However the motor is erm on the large side so it does not sit inside the lathe so I will need to find a way to mount it.

This could be interesting, but I have no idea if it will work, if it does then I will upgrade the lead screw with a ball screw and use a stepper motor for finer control.

Cheers

DJ
 
You must log in or register to reply here.
Back
Top