JasonB | 25/11/2021 07:17:23 |
![]() 25215 forum posts 3105 photos 1 articles | Though good old belts and pullies do still come into it. Ketan mentions the KX3 having a lower torque at low speed than the SC4, One reason for this is that the pullies are about the same size on spindle and motor for the KX3. But on the SC4 and SX2.7 they are more like 3:1 giving the motor a much better mechanical advantage. I suspect both motors run at the same sort of MOTOR speeds and it is just the pully ratio that determines min & max SPINDLE speed for the two. SX2.7 is only a single belt speed, it's the SX3.5 with high and low |
Ketan Swali | 25/11/2021 07:33:13 |
1481 forum posts 149 photos | Posted by JasonB on 25/11/2021 07:17:23:
SX2.7 is only a single belt speed, it's the SX3.5 with high and low Oops yes, Jason is correct. My mistake. I had confused the SX2.7 with another machine. Apologies. Ketan@ARC
|
Michael Gilligan | 25/11/2021 10:13:29 |
![]() 23121 forum posts 1360 photos | Posted by Michael Gilligan on 24/11/2021 20:25:21:
Posted by Neil Wyatt on 24/11/2021 18:53:10:
[…] Torque increases as speed decreases for a brushless motor […] . I am genuinely surprised, Neil … Could you please explain ? Thanks MichaelG. . Having noted Ketan’s very helpful response yesterday … I have just downloaded this paper which should make interesting reading : https://iopscience.iop.org/article/10.1088/1757-899X/100/1/012004/meta MichaelG. |
Howard Lewis | 26/11/2021 12:51:51 |
7227 forum posts 21 photos | Yes, My lathe is old fashioned (being nearly 20 years old, and is large by Model Engineering standards and having a 6" swing over the bed. The standard single phase motor is 2 hp, but having chosen VFD thought that 1.5 hp three phase would suffice. The motor drives a belt to a countershaft with a three sheave pulley, and has a back gear to increase the torque available at the spindle, if required. Aided by three driver / driven changewheels and a Norton box, a wide range of feeds and thread pitches can be obtained. (Not all of them standard! ) The SC3 has the standard brushed motor, so is treated with more respect. Howard |
Ketan Swali | 26/11/2021 12:58:27 |
1481 forum posts 149 photos | Hi Howard, small correction: SIEG C3 is brushed motor with hi/lo gear drive. SIEG SC3 is brushless motor with belt drive. Ketan at ARC |
Howard Lewis | 26/11/2021 13:06:46 |
7227 forum posts 21 photos | Hi Ketan! Quite right! It IS a C3 Slip of the mind. tongue, or finger!, Probably all! Creeping senility Howard Edited By Howard Lewis on 26/11/2021 13:07:20 |
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