Metal-cutting chop saw - question

[tarbellb]

Good score!

A excellent, capable saw, one of the most versatile saw out there.

Ive been converted from dry cut to bandsaw over the years here on GJ, guys like Drclyde have made a good case for the pros and cons.

 

[lis2323]

SCORE! I just got the WEN that I mentioned in post #29, above. $150, great shape, extra blades....very happy!

I've only done a handful of test cuts, but I'm already wondering if I'll ever use the abrasive chop saw ever again!

Wow $150!! Congrats [emoji481]


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[PugetDude]

$150.00- Well done, Mark. Keep us posted on how you like it.

 

[seagull369]

This will not work. These saws use universal motors. VFDs will only work with Induction motors.

I think you have that backwards. Those "chopper"/TRIAC devices work plenty fine with universal brushed motors, as long as the wattage of the tool doesn't exceed the amount the speed control is rated for. Choppers do not work well with the induction-type and will overheat them.

Brushed motors also operate just fine on modified sine or even square wave power provided by any given cheap inverter, though you wouldn't want to use that speed pictured control on those kinds of wave forms.

 

[larry4406]

$150.00- Well done, Mark. Keep us posted on how you like it.

Agreed.

Let us know how you like the Wen.

 

[vanapplebomb]

I think you have that backwards. Those "chopper"/TRIAC devices work plenty fine with universal brushed motors, as long as the wattage of the tool doesn't exceed the amount the speed control is rated for. Choppers do not work well with the induction-type and will overheat them.

Brushed motors also operate just fine on modified sine or even square wave power provided by any given cheap inverter, though you wouldn't want to use that speed pictured control on those kinds of wave forms.

No, you misread what I wrote.

I said a VFD will not work properly with a universal motor.

I know it was a longer post, but if you go back and continue reading to the bottom, I explain why this is true.

As for the universal motor speed regulator the original poster had in question, again, as I explained in my post, yes, it will control the speed of a universal motor, but at the expense of torque.

This is a double hit because the gear ratio of the abrasive saw gearbox is approximately twice the ratio of the dry cut saw, and the motor is powered down. The feed rate is going to be much slower as a result. There just won’t be enough grunt behind the blade for the carbide tips to really chew away at the material. It also will dull the blade faster and heat the part more because it is doing more rubbing and less shearing of the material.

 

[seagull369]

I took VFD's for meaning something else, sorry. One of the hazards of writing at 2 am.

The speed control mark-NJ posted in the original message is just a TRIAC, though, not a VFD, as I think you alluded to. To expound on your earlier statement, I don't think VFD's typically work well with single phase induction motors, as are found in most consumer equipment. They're more used on 3-phase.

 

[tarmy]

This is why you get a good metal cutting band saw...

I was fooling around making a project and was needing to scrimp on material...these were the waste cuts. Year and a half old blade that was not a fine tooth blade either.

 

[vanapplebomb]

I took VFD's for meaning something else, sorry. One of the hazards of writing at 2 am.

The speed control mark-NJ posted in the original message is just a TRIAC, though, not a VFD, as I think you alluded to. To expound on your earlier statement, I don't think VFD's typically work well with single phase induction motors, as are found in most consumer equipment. They're more used on 3-phase.

Yup, the VFD, or Variable Frequency Drive comment was in relation to another post suggesting a VFD might work for the chops saw. I just didn’t want misinformation spreading and someone dropping money on a VFD only to find out it doesn’t work with universal motors.

You are also correct, you do loose efficiency with single phase induction motors pretty quick if you stray too far above the 50-60HZ range. They don’t like being sped up because of the impedance sharp impedance rise above 60 HZ. Although all induction motors experience a rise in impedance with increasing frequency, single phase induction motors are particularly vulnerable to lower frequency losses of induction efficiency. The offset winding in single phase motors relies on having a different inductance than the main stator to produce a phase shift and generate a rotating magnetic field. This small winding isn’t enough to maintain a solid rotating magnetic field as frequency drops significantly below rated frequency because there is less and less of a phase change between the two windings. When you go low enough, you essentially end up with them more or less in phase, and the motor fails to work. There phase motors don’t have this issue, and so it is much easier to produce torque at low RPMs with a three phase than single phase.

 

[Deadsquiggles]

I figured I’d ask here instead of starting a new thread. What’s everyone’s opinion on the Evolution R355CPS? It’s a “multi-material” chop saw instead of a true metal cutting saw but it claims with the standard blade that it’ll cut 1/4” steel with no issues. Anybody ever used one or should I bite the bullet and just up to one of the true metal cutting saws like the S355CPSL for $150 more?