Motor upgrade chinese lathe

R

riversidedan

H-M Supporter - Silver Member
H-M Supporter - Silver Member
Joined
Feb 17, 2021
Messages
468
been using a 7x14 chinese lathe that works fairly well but the motor is garbage!! :guilty: esp when parting chokes and stalls out!

>>>>>>it needs a better motor so am looking for alternatives and ideas and am thinking the motor would have to be screwed down behind the HS with some belt drive device......WILL POST SOME PIX SOON....
 
Last edited:
Pictures always help, and it does not exist without pictures ---
 
Variable speed correct? Are there any adjustments on the board? You might be losing a good deal of torque if it's mis-adjusted
 
I upgraded my Sieg 7x14 to a 800W brushless using a motor+controller 'kit' from AliExpress. It's a big improvement, especially at the low end.
 
riversidedan said:
been using a 7x14 chinese lathe that works fairly well but the motor is garbage!! :guilty: esp when parting chokes and stalls out!

>>>>>>it needs a better motor so am looking for alternatives and ideas and am thinking the motor would have to be screwed down behind the HS with some belt drive device......WILL POST SOME PIX SOON....
Click to expand...
There is a adjustment fof torque in the control box.
As draws more amps it increases the voltage so motor does not stall.

FYI the day my DC dies I planned to switch a brushless motor.

Dave
 
One thing you may already be aware of and may have made modifications to ameliorate, is the lack of built-in rigidity in the Chinese 7x14's and the generally questionable state of fit and finish that it arrives in.

These rigidity limitations can constrain the usefulness of a motor upgrade (not much point putting a 4 litre V12 in a mobility scooter!:grin:)

Here's what I have been doing/planning to my Weiss WBL1835 (Amadeal in the UK's AMA714B model, very similar to many 7x14s out there)

Okay, I did getAmadeal to have a 750W (1HP theoretically) brushless motor installed in mine as part of the deal.

I used a combination of a Grizzly manual (fair play to Grizzly, their mini-lathe manuals are very well written) and ArcEuroTrade's pictorial guides to improving the fit and finish and setup for their Seig C3 and SC3 lathes (my WBL1835 is very similar to these lathes) for my initial setup. Here's the link to those guides if you haven't seen them:

Projects & Articles - Arc Euro Trade

A series of projects showing how to modify your machine using some of the products available from Arc Euro Trade Ltd. We hope you find them useful.
www.arceurotrade.co.uk www.arceurotrade.co.uk

So, I'm in the process of various optimising modifications. I've already swapped out the ball bearings to angular contact bearings and have added a carriage lock.

I also have a cast iron toolpost rest to replace the compound in the pipeline (currently got a few parts in brass I'm turning that are required by my better and wiser half, so they come first!:grin:) and am going to fill as much of the empty space in the bed as I can with epoxy granite.

Before installing the carriage lock I parted off a piece of 1214L at just under 3/4" but it took a long time and initially I was making dust rather than chips (on reflection I think it was I initially left the RPM at my standard mild steel speed, rather than dropping down as I should have, noticably I started to get a nice hiss and decent chips as I got just over halfway, where obviously, the effective RPM was slower) and made a sound like I was torturing a cow.

The volume of the sound may also have been due to the fact that the lathe is bolted directly to a 1/4" mild steel stand top.

I'm waiting on a local kitchen worktop maker to supply me with a piece of granite offcut that they'll drill the necessary holes in (it's entirely possible I'll end up with my lathe bolted to a rather fetching pink granite lathe stand top!:grin:) that will go in between the mild steel plate and the lathe.

That should provide me with some extra vibration damping and prevent me from being visited by any local animal welfare groups! :grin: It's worthwhile considering doing that.

I also got an upside-down parting tool holder from Eccentric Engineering (already had their tangential tool holder, which is a nice bit of kit) to be used with the lathe running in reverse but I haven't tried that out yet.

Hopefully some of this will be useful. ;)
 
Last edited:
Look for an adjustment labeled IR or I/R on the circuit board- that's the torque compensation pot
When it's adjusted correctly the motor should be able to take heavy cuts without slowing down
 
Last edited:
I stuck a treadmill motor on my 9x20, the only down side is low torque at very slow speeds, but thats never been a problem.
Lack of rigidity in the cross slide/top slide setup is the main cause of parting woes. Solve that and parting will never be a problem again.
 
savarin said:
I stuck a treadmill motor on my 9x20, the only down side is low torque at very slow speeds, but thats never been a problem.
Lack of rigidity in the cross slide/top slide setup is the main cause of parting woes. Solve that and parting will never be a problem again.
Click to expand...

Solving the problem of low torque at very low speeds with a brushed d.c.. motor is a matter of using the right controller. I replaced the 1 hp 1725 rpm a.c. induction motor with a 2.5 hp 4090 rpm brushed d.c. motor. The two motors have approximately the same torque at their rated speed. Initially, I tried a simple Variac for speed control with lackluster results at low speed. Next I tried a PWM speed control, again with less than satisfactory low rpm performance.

Then I built a custom controller which uses PWM but also includes speed feedback from an encoder to senses a decrease in speed with additional load and increases the duty cycle of the pulse width accordingly up to as much as 100% if necessary. The result is that I have a 100:1 available range on rpm and have useful torque as low as 5 rpm at the spindle.
 
You must log in or register to reply here.
Back
Top