Thread: Clearvue CV1800 / Max Impeller Install - Home Garage Workshop

Originally Posted by BobL

I don't understand why people use those splitters, The most flow you can get is 800 cfm (2 x 400 cfm for each 100 mm duct) although they should be call turbulence boxes and so probably don't even generate this much flow. You are better off using 2 x 150-100 mm Y's and 3 x 100 mm take offs. It's a lotcheaper and generates a total of 1200 cfm around the BS - even if you leave the 3rd one open above the saw to catch residual escaping dust.

This prompted a question I have been meaning to ask. There has been a lot of emphasis on 6" all the way to the machine. On a bandsaw as an example, I will be looking at 3 pick ups. Because I will be connecting all three to the same 6" suction line, would I get benefit from keeping all three at 6" or, as I was planning, keep the main line to the cabinet at 6" and use 4" under table and another 4" overhead.
I am not worried about cost, but it would be less bulky and untidy to use 4" if there is no real benefit to keeping all three at 6"

Bauldy

Bauldy
As I understand it 3 x 4" have the same air flow as one 6" so you should be good to go with 3 x 4". I have used a 4" and 5" on my bandsaw and plan to use the same on my Tablesaw. May expand to 4" and 6" on tablesaw if BobL thinks it is better
Ron

Thanks Ron,

Yes I understand they are equivalent area, but just wondered if I could get any "more" from 3 by 6"

Perhaps I am just trying to get greedy!

With the Table Saw, I was thinking of a 6" main and 4" to the guard, but that was due to the practicality of getting a 6" to the Guard.

John Samuel will jump in to remind me of his excellent solution to that, but that may be a bit much in this round of modifications for me.

The other factor is that I will only be using a modified 2Hp unit, which may not get the benefit from all of this 6" ducting, but I am trying to set it up ready for the day I may take the Clearvue leap!

Bauldy

Originally Posted by Bauldy

This prompted a question I have been meaning to ask. There has been a lot of emphasis on 6" all the way to the machine.

The real emphasis should not be on ducting size but on maintaining the 1000-1200 cfm all the way to the machine.
This can be done with 3 x 100 mm ducts or two by 125 mm ducts or even a 225 mm duct.
Multiple small ducts in parallel are just a PITA
AND
Using larger than 150 mm for most DIY setups runs the risk of losing so much air speed so that sawdust will drop out of suspension.

On a bandsaw as an example, I will be looking at 3 pick ups. Because I will be connecting all three to the same 6" suction line, would I get benefit from keeping all three at 6" or, as I was planning, keep the main line to the cabinet at 6" and use 4" under table and another 4" overhead.
I am not worried about cost, but it would be less bulky and untidy to use 4" if there is no real benefit to keeping all three at 6"

Using 3 x 150 mm will result in the air speed dropping too low and sawdust may drop out of suspension.
If 3 x 150 mm ducts are used and they each have about 350 cfm the nominal air speed will be 1782 fpm which is a long way short of the target of 4000 fpm.

Even a table saw with a 100 mm on the guard and 150 mm on the cabinet will have an air speed on the low side for the 150 mm duct (3600 cfm) although mine never seems to clog up and I have about 7 m of horizontal duct run in that line. It helps to every now and then close the 100 mm blast gate and that seems to pick up any residual sawdust.

3 x 150 mm might make sense on a big sanding machine but what sort of trunk line are you going to feed them into - if its another 150 mm duct then there is no benefit, if it is into a 200 or 225 mm duct then 2 x 150 mm (2000 cfm) would be definitely worth doing, 3 x 150 mm assumes you have a impeller than cam pull >3000 CFM.

Originally Posted by BobL

It should be much more efficient than that. If that was VFD efficiency the difference (~750W) has to be dissipated as heat by the VFD. 750W would generate the same heat output as 7.5 x 100W light globes - the back of the VFD would be glowing red hot. The difference is probably due to the operational inductive phase factor of the motor.

I spoke with an electrician and knowledgable technician at work about the 18 amps at 234.5v input vs 8.6amps per phase at 229.5v output (I measured the voltages under load this morning). He believes that the discrepancy between the input and output current is most likely due to the VFD not producing a clean sine wave current / voltage but more likely a stepped or squared off wave. This makes using the 1.732 or RMS conversion to equate the three phase current to single phase invalid and is why the numbers don't add up. He believes that there should be 5-10% loss through the VFD. Seems logical.

Originally Posted by DomAU

I spoke with an electrician and knowledgable technician at work about the 18 amps at 234.5v input vs 8.6amps per phase at 229.5v output (I measured the voltages under load this morning). He believes that the discrepancy between the input and output current is most likely due to the VFD not producing a clean sine wave current / voltage but more likely a stepped or squared off wave.

I've forgotten I have done some CRO measurements on the signal shape and it's actually the reverse - what comes out of the VFD is generally pretty sinusoidal but what is seen in the input side (mainly reflected by the VFD back down the mains) is pretty awful, see VFD current waveforms and values

A good quality current clamp meter can cope with fairly crappy waveforms but many cannot cope and also cannot handle frequencies away from 50Hz.
You can sort of test this by checking your VFD output at 50Hz using the clamp meter.

There's also in the above post some info on current comparisons before and after the VFD but unfortunately none with the VFD display current itself. I must do that again some time especially now that I have true RMS clamp meter

This makes using the 1.732 or RMS conversion to equate the three phase current to single phase invalid and is why the numbers don't add up. He believes that there should be 5-10% loss through the VFD. Seems logical.

Even 5 - 10% is still as much as 400W - thats 4 x 100 W light bulbs - still a lot of energy.

Originally Posted by BobL

I've forgotten I have done some CRO measurements on the signal shape and it's actually the reverse - what comes out of the VFD is generally pretty sinusoidal but what is seen in the input side (mainly reflected by the VFD back down the mains) is pretty awful, see VFD current waveforms and values

A good quality current clamp meter can cope with fairly crappy waveforms but many cannot cope and also cannot handle frequencies away from 50Hz.
You can sort of test this by checking your VFD output at 50Hz using the clamp meter.

There's also in the above post some info on current comparisons before and after the VFD but unfortunately none with the VFD display current itself. I must do that again some time especially now that I have true RMS clamp meter



Even 5 - 10% is still as much as 400W - thats 4 x 100 W light bulbs - still a lot of energy.

Thanks Bob. I think I'll put this in the too-hard for no real gain basket. I returned the current clamp already, but its a decent true RMS current clamp operating in it's optimum range and has a NIST traceable calibration certificate. It can operate at various frequencies but is optimized for 50 and 60 Hz. I don't doubt the readings from the clamp so it must be something to do with waveforms etc. The VFD has a HUGE aluminium heatsink (maybe 12 cm deep and the full size of the box) and fan that turns on instantly and stays on at full power even when the VFD is not sending power to the motor so I don't doubt that the VFD generates a significant amount of waste heat to necessitate this (400 watts seems quite reasonable to me).

Bob L, you are clearly expert in this area.

I attend the Phillip Island and Wagga Turnarounds where there is no dust extraction of any kind happening. Power sanding at every other lathe. My only real solution was a 3M mask - at a cost of well over $1K. No mask = lots of tissues and bad sinuses.

At home, I am doing my best ($ a constraint at the moment) to capture the fine dust from my Woodwizz and several router tables. Plus the lathes....

I don't have any measuring gear, but a 200mm main line choked down to 125mm means I don't get an immediate physical reaction. And yes, I am very reluctant to modify my machines, though I do have access to a good metal fabricator. Changing the hood on my Carbatec twin drum sander is much easier to correct than say my Sawstop table saw.

I would like to see more pics on modifications to various machines/tools.

I did split a 100mm wye for my twin drum sander but it didn't work. I am already into $8K on metal ducting and want to get this right.

Originally Posted by Jeff Leslie

Bob L, you are clearly expert in this area.

I attend the Phillip Island and Wagga Turnarounds where there is no dust extraction of any kind happening. Power sanding at every other lathe. My only real solution was a 3M mask - at a cost of well over $1K. No mask = lots of tissues and bad sinuses.

At home, I am doing my best ($ a constraint at the moment) to capture the fine dust from my Woodwizz and several router tables. Plus the lathes....

I don't have any measuring gear, but a 200mm main line choked down to 125mm means I don't get an immediate physical reaction.

What sort of DC do you have?

a 125 mm duct carries about 700 - 800 CFM @ 5870 FPM which will be nowhere near enough for lathe work.

Also when that air flow reaches the 200 mm duct it will be travelling at 2150 CFPM
A target air speed of 4000 FPM is required to guarantee sawdust will stay suspended in the air flow.
The 125 mm ducting is OK but the 200 mm ducting air speed is not.

8K on ducting seems like a lot. I guess 200mm galv ducting does cost a lot but why did you do that given you have $ constraints?
It's also a lot of money siting there doing nothing if you are only feeding it with 125mm ducting and not prepared to open up your machines.

You may well not be feeling anything in terms of dust allergies but harm can still be occurring.

RE: Opening up ports
Some good ideas in this thread.
Making 150mm DC ports for workshop machines

Originally Posted by DomAU

Thanks Bob. I think I'll put this in the too-hard for no real gain basket. I returned the current clamp already, but its a decent true RMS current clamp operating in it's optimum range and has a NIST traceable calibration certificate. It can operate at various frequencies but is optimized for 50 and 60 Hz. I don't doubt the readings from the clamp so it must be something to do with waveforms etc. The VFD has a HUGE aluminium heatsink (maybe 12 cm deep and the full size of the box) and fan that turns on instantly and stays on at full power even when the VFD is not sending power to the motor so I don't doubt that the VFD generates a significant amount of waste heat to necessitate this (400 watts seems quite reasonable to me).

The thing is the difference is not 400W, its 750W which is 17.4% i.e. a lot more than 5-10%
According to a couple of websites I looked at a good quality 4kW VFD should lose no more than 5% at full load.
But I don't think this is the problem.

The more I think about it the more I think the distorted waveform going into or reflected from the VFD is not being read correctly by the clamp meter.
I also remember several cases where a Clamp meter on the input has read a lower current than the VFD output - i.e. negative efficiency!
This suggests that using a Current panel or clamp meter on the input side of a VFD can be misleading.

Originally Posted by BobL

What sort of DC do you have?

a 125 mm duct carries about 700 - 800 CFM @ 5870 FPM which will be nowhere near enough for lathe work.

Also when that air flow reaches the 200 mm duct it will be travelling at 2150 CFPM
A target air speed of 4000 FPM is required to guarantee sawdust will stay suspended in the air flow.
The 125 mm ducting is OK but the 200 mm ducting air speed is not.

8K on ducting seems like a lot. I guess 200mm galv ducting does cost a lot but why did you do that given you have $ constraints?
It's also a lot of money siting there doing nothing if you are only feeding it with 125mm ducting and not prepared to open up your machines.

You may well not be feeling anything in terms of dust allergies but harm can still be occurring.

RE: Opening up ports
Some good ideas in this thread.
Making 150mm DC ports for workshop machines

Bob, I am mindful of hijacking the thread.

I bought a 3hp Carbatec cyclone maybe 5 years ago. I just got it hooked up to 3 of my machines. The Woodwizz originally came with 3 inch flex but I changed that to 4 inch. Still far from ideal. The Minimax combo machine has 5 inch plastic ports that will be hard to widen.

I also bought a Clearvue max maybe 3 years ago but it's still not connected. I have at least got both cyclones plumbed to vent outside. When my head is right, I will try to complete the job. The boss is limiting my spending at the moment! Ideally I would like a Micronair 150mm fume arm over my lathes. More $!!!

Originally Posted by BobL

The thing is the difference is not 400W, its 750W which is 17.4% i.e. a lot more than 5-10%
According to a couple of websites I looked at a good quality 4kW VFD should lose no more than 5% at full load.
But I don't think this is the problem.

The more I think about it the more I think the distorted waveform going into or reflected from the VFD is not being read correctly by the clamp meter.
I also remember several cases where a Clamp meter on the input has read a lower current than the VFD output - i.e. negative efficiency!
This suggests that using a Current panel or clamp meter on the input side of a VFD can be misleading.

Yeah, you are probably right. As long as I'm not melting anything I guess it's academic.

Also, looking at the Powtran PI9000 operating manual. The 4 kW single-phase unit (the one supplied with the clearvue) is rated to 35 amps input (at 220V +-10% ) and 16 amps output (at 220V +-10%) - so 27.7 amps single phase equivalent?, whilst the 3 phase unit is rated for 18.1 amps input, 16 amps output (220v +-10%). I wonder if this is an indication of the efficiency of this unit?

It also confirms my assumption that the 4 kW is an output rating, not input, so the VFD is not the limiting factor in the setup - the GPO would be.

Ok. Not enough pictures lately.

Today I purchased some 160 mm ID flex hose from Advanced Duct Systems in Campbellfield (this place seems really good if you want galvanised duct, stainless duct, flex hose of various types etc). I bought some polyurethane medium flex hose. It's not as smooth bore as my other stuff, but it is far more flexible. It's still a lot smoother inside than the typical flex hose I've purchased from Carbatec / Hare and Forbes in the past. Anti-static and anti-fungal as well.

I decided to try my PVC molding trick on the thicknesser to change the port from 4" to 6". It's a bit rough but should work well. I molded the PVC over the existing metal port, then marked a line and cut it down with an angle grinder and thin cut-off disk. I have about 1-1.5cm of overlap. I then drilled and pop-riveted the pvc onto the metal port. I will now silicone the small gaps to fully seal it. Not perfect, but much better than a 4" port.
20160331_191017.jpg20160331_191032.jpg20160331_191042.jpg20160331_191850.jpg

The 2m length of flex, although no doubt a little bit more restrictive than PVC allows me to flip the port from planing to thicknessing without disconnecting etc.

Looks good and is on my todo list as well.
Did you do anything to aid flow into the front of the scoop?