This may very well be the dumbest question ever posted on The Creek, but if a guy over builds his shop with a 5 horse Clearview, has anyone considered a variable rpm such as on my G0766 for lathe work that kicks up little dust such as green wood to keep noise down?
Contributor
I don't think it's so dumb. I bought a CV-Max with the 3 phase motor and the same kind of VDF the Aussies use to get 60 cycle from their 50 cycle service. The reason is to be able to run it full bore for wood turning or using a couple machines at the same time and turn it down for lighter needs like when power carving with a miniature high speed grinder (350,000 to 500,000 rpm types). Now all I need to do is put it all together and make the ducting.To keep the noise down on any DC you need to enclose it or put it in another room. It will make less noise running at lower speeds. The 3 phase adds about $25 over the single phase and the VDF which was about $250US with delivery from China.
Is it simply a matter of replacing the plugin on the cord like when my sil wired my garage for the Grizzly G0766?
Was that $250.00 U.S.
He did not have to add anything else for the lathe.
Contributor
Bill I took his opening post as wanting a variable speed cyclone like you would get if you bought a lathe. He wants to turn down the speed to reduce noise if he isn't producing much dust, as when turning green.
The VDF is wired in place of a motor switch as it serves that function too. The Max doesn't come prewired with cords or plug. You supply to suit your installation unless you get their switch package.
To so me $250US is the same as $250.00 U.S. so I take the easy way out as I type one fingered.
I still hunt and peck with one finger, too.
Moderator
One SMC member uses a VFD to adjust the frequency of his cyclone from his country's native 50 hz to 60hz for better performance from the motor. I see no issue with that concept as long as it's done correctly. That said...it may be simpler to merely build a closet for the cyclone (and compressor) and let it work at peak efficiency all the time.
--
The most expensive tool is the one you buy "cheaply" and often...
Member
I run a Clearvue on a VFD in Australia to get it up to 60 or even 63Hz and down to 50Hz when using hand tools etc. The other benefit over noise is a much lower power consumption - in the order of 50% less.
Cheers, Dom
Contributor
Hi Bill, obviously you'll need a 3 phase motor for use with a VFD.
The other issue may be duct velocity and keeping enough airflow for the cyclone to separate the material...Regards, Rod.
Member
A 2 pole motor at 50hz is 3000rpm and 3600rpm at 60hz which is a ~16.7% reduction in speed. Not a 50% reduction in amp usage. Maybe you closed a bunch more gates too?
Interesting read
https://sawmillcreek.org/showthread....amp-draw/page3
Member
Originally Posted by Mike Heidrick
Hi Mike,
Look up "Fan Laws" to learn more about the relationships between fan speed and flow, pressure and power developed. The laws hold up reasonably well in real-life application but they do seem to vary depending on the particular fan curve and system that it is connected to. The 50% was a rough approximation, and I realize that I should have said running at 60Hz requires approximately 50% more power than at 50, not that running at 50Hz uses 50% of the power at 60Hz - syntax error on my part.
In effect, increasing rpm by 20% should theoretically provide 20% more airflow, 44% more pressure and require 72.8% more power. In reality the numbers vary a bit from this depending on the particular setup.
I just went out and ran my Clearvue. With gates wide open, at 50Hz, it is drawing 13.2 amps and at 60Hz it is drawing 18.7 amps - nearly 50% more power.
I have measured the maximum static pressure on a couple of occasions and this seems to follow the fan law fairly closely.
Cheers,
Dom
Contributor
I run a 7.5 hp motor with a vfd ( Cincinnati Fan RBE 9 ) and vary the speed and run it at 55-65 hz. It is basically similar to the Oneida Smart with a manual speed adjustment. The ability to run above 60 hz is limited, both by the rpm limit of the impeller, and the design of the blades. Curved blade impellers are designed to top out cfm at a certain rpm so a hobby guy can't overamp the motor if run wide open under a number of conditions. That means you don't get much bang for the buck if trying to speed up the motor over 60 hz. Curved blade impellers are also low pressure so reducing the speed works fine when you just want an air cleaner for the shop, but not when running a machine. To get a benefit from speed changes, you need to oversize the blower and generally run a straight blade radial fan. That will run at higher pressure although the noise will be higher as well.
If i were to run a CV with a vfd, it would be the 16" max impeller but, again, the only real benefit to running slower would be as a whole shop air cleaner. Dave
No reduction in noise, Dave?
Member
As the bloke who developed using the VFD with the CV for Oz use let me make a few observations and suggestions. Using the VFD has quite a few advantages.....
No hard start hence no limitations on how many times it can start, apparently there is some sort of limitation per hour or so some here have said.
No huge current draw on start, at the most we see 18 amps momentarily on a 240V supply
Variable speed as needed
I run mine day to day at 65 hz and all the bits are still attached to the impeller, I have been advised not to run it at over 70hz and I still don't know where the fan curve starts to fall over.
Using three phase supply as compared to single phase supply is the ultimate as a VFD can be used not to create three phase but to control the speed, mine runs this way because we have three phase connected to the house and workshop.
The Powtran VFD CV Oz and most others I suspect can have a cheap remote control plugged into it, mine is a $10 garage opener and I wear it on a lanyard around my neck.
I am no longer the Oz distributor for Clearvue but I will answer any questions on the technical side if I can. Dominik is very well versed on this as well especially the fan performance and technical side and I defer to him in this aspect of it.
Chris
Everything I like is either illegal, immoral or fattening
How does my G0766 lathe differ from using a VFD on a Clearvue? My sil wired my lathe to run without 3 phase power and I can control the speed. Are you saying I will not have that option if he installs a VFD on a Clearvue?
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