minilathe speed reduction

Hi Michael,

I havnt followed all of this thread but if your minilathe is a CJ18a from Amadeal then it is a brushed dc motor.

I have a CJ18 and I was just speaking to Amadeal about something else and I asked them about brushless minilathes. They have a brushless version which is about to be announced but they wont have stock for another month. So all their minilathes to date have been brushed motors.

Can I just ask why you feel it necessary to go to the trouble of modifying your lathe, your choice of course but my CJ18 I think is fine speed wise. Low gear: 39 - 1080 High gear: 97 - 2504 and I dont think it is short of torque it seems to have plenty of power.

Ron

Apologies Russell, I should have clarified. Many of our competitors in the mini-lathe product field state 'POWER = xxxW'... for marketing purpose. They fail to state or use the word 'INPUT' in front of the word POWER in their marketing. So, for example, when a new person is making comparisons they read POWER: 600w in the specifications of a competitor, and think that it is better than 500w Output POWER which is stated on SIEG specifications, because their eyes only focus on the word POWER.

There are many such examples, but potential buyers only find out if they ask us, or if and when they need replacement parts.

Ketan at ARC.

Apologies not needed Ketan. Such misleading marketing must be annoying for you. Still, it's not as bad as the quoted power ratings of much audio equipment.

Russell

Excuse me for not quoting the long post, but it might give some the impression that all electronics are unreliable

Experience seems to be showing that 3-phase inverters and brushless DC motor controllers are more reliable than brushed motor controllers. We seem to be getting few if any reports of the latter failing compared to a regular trickle of failed brushed motor controller boards.

I suspect this is due to the lack of potential hazards like arcing and build up of carbon causing shorts (I must strip my mll's motor and clean it out/fit new brushes as a precaution!) which don't affect the other motor types. Also the more sophisticated motors often have SOAR protection (safe operating area) and guess when things may be goiing wrong and decrease output (or just stop!)

Neil

Never heard of SOAR being applied to an electromech device such as a motor that has 'intelligence' to know when things are going wrong....Please elaborate...

I have a brushless SC2 mill and SC3 lathe, if they are overdriven they stop and the fault light comes on.

There is a view that all 'marketing' is intended to be misleading.

Tim

True, and this idea of stopping under overdriven event, initially took a while for SIEG to sort out, when programing the chip on its control board for the brushless motor.

Reading the other thread, where Keith Moat has a brushless motor version, with gears, he seems to be having issues with 'the motor seems to want to take teeth off the drive belt rather than stall as I found out when the tool dug in once'.... so it is difficult to say in his case how and/or at what point is the 'overdriven' issue addressed, in such a combination of brushless motor with metal gears drive.

I would only slightly correct Neil. The control boards for SIEG's brushless motor offering are more reliable, but there are still a few failing due to various reasons - mainly loose wire connection (due to transit) - user related - or dirty power supply related. Very few are direct component related.

Ketan at ARC.

Edited By Ketan Swali on 29/08/2018 17:42:03

For example, my VFD models the temperature profile of a typical motor and calculates its temperature given the use it's given. It derates the motor if it calculates that it is likely to overheat. The modelling can be made more accurate by by adding motor-specific data.

I'm not saying all controllers are this sophisticated (although some are cleverer!) but even the stop if overloaded (in software rather than through a cutout) is something i would count as an example of this.

Neil

"Also the more sophisticated motors often have SOAR protection (safe operating area) and guess when things may be goiing wrong and decrease output (or just stop!)"

Sorry Neil, but your post came across as tho' the 'intelligence' resided with the motor....not the controller you eluded to in your response to my question..

Edited By John Rudd on 29/08/2018 19:38:33

Are electronics reliable? When I were a lad transistors were '3 legged fuses'. Capacitors went bang, resistors open circuit, joints dried, selenium stank, and colour TVs caught fire. As the whole world has gone to hell since a 12 year old girl from Human Resources made me retire, the same must be true of electronics. In my opinion mini-lathes are worse than mobile phones - I never use one without wearing an aluminium foil hat and a lead apron.

Meanwhile, back in the real world, Nurse tells me electronics are less likely to fail than the mechanicals. Certainly true of all the cars I've scrapped!

Dave

PS very happy with all the electronic controllers in my workshop.

Edited By SillyOldDuffer on 29/08/2018 20:01:33

Ah we've crossed wires - a hazardous situation for any motor!

Neil

I wouldn't trust it meself - but what do I know.

What the regular postings on motor drive board issues confirm is that any idiot can design a circuit that will drive a motor. But skill and experience is needed to select components, and add components if required, to allow the drive to ride through motor faults and external problems such as under and over-voltage and transients without failing.

It's one reason why industrial electronics is more expensive than that found on hobby grade machines.

Andrew

Don’t worry about it Michael J. This is a hobby, relax, use your lathe and make some swarf.

Ketan at ARC

As mentioned Michael, my minilathe is also a CJ18a and as I pointed out it is powered by a brushed motor not a brushless, but it is non the worse for that.

I would not worry about the torque and the top speed, with the high and low gear settings the lathe has a good range of speed and it is not short of power.

I agree with Ketan, use the lathe and have some fun, I,m sure you wont find the lathe a problem.

Ron

Edited By Ron Laden on 31/08/2018 22:32:47

Edited By Ron Laden on 31/08/2018 22:33:26