Thread: New DC advice sought

Originally Posted by Glenn.Visca

Wow ... you are right - that is very neat. I can see how I might be able to alter it and have the grilled vent lead outside rather than back into the shed.
I would also expect one needs a vent to allow cool air to the motor or it could run the risk of cooking ... would it not ? Or does the general air volume through the whole cabinet allow for cooling of the motor ?

If 6" ducting is used don't forget you will have around 1000 cfm going that enclosure and if you are crafty you can direct the pathway of the air inside the enclosure to go past the motor which will easily carry away the motor heat .

Interestingly I was working out how much heat carrying capacity 1000 cfm of air represents and it turns out to be equivalent to 240 mL/s of water. OK the efficiency of heat transfer between the air and the motor is only likely to be around 1% but that that's still 2.4 mL/s or 144 mL/min which is plenty.

Now lets say you start using power tools with a 50 mm hose attached to ducting - NOW the flow will be down to 50 cfm and you can run into trouble because not enough air will flow through the enclosure and it will over heat the motor - I have done this If you decide to do this is important to open up at least a 100 mm inlet in the line. This also helps to clear fine dust that escapes the power tool dust collection fans.

Originally Posted by safari

Interesting question Glen Visca. I am thinking of completely enclosing my CV1800 so that I can use the outside faces for tool storage. However, I obviously

Originally Posted by safari

need to leave an area for motor cooling but how big? From a sound deadening point of view I guess the smaller the better but I don't want to cook the motor either.
Has anyone got any ideas?

As most of a cyclone is under negative pressure with a cyclone you don't need an enclosure at all, you just vent the outlet outside. The motor does not make a lot of noise and most of the noise comes from the impeller. This can be handled by just wrapping the impeller in something sound absorbent. This arrangement also allows the motor to cool. Have a search for how John Samuel did his.

Thanks once again BobL. I am ducting to the outside via a muffler similar to the Corrimal Mens Shed design and the impeller has also been sound proofed. Because I have a small workshop (1 !/2 car garage), I think from a sound reduction point of view it would be advantageous to also enclose the motor.

Originally Posted by safari

Thanks once again BobL. I am ducting to the outside via a muffler similar to the Corrimal Mens Shed design and the impeller has also been sound proofed. Because I have a small workshop (1 !/2 car garage), I think from a sound reduction point of view it would be advantageous to also enclose the motor.

My understanding is that the motor makes less noise than the air passing through ducting and ports so reducing the motor noise doesn't reduce shed noise significantly.
I suggest taking a look at what John Samuel has done and what actual db's he gets.

Every shop is different, but I can assure you that the bulk of the noise comes from the exhaust ... and by a long way. The next noisiest is the impeller. So, if you do a really good job on the exhaust and the impeller, you are likely in good shape. If I recall correctly Safari did a great job on his cyclone.

I worked on noise suppression until the noise from my cyclone was lower than the noise from my primary machines (table saw, thicknesser, drop saw etc) after which time I stopped. For me, there was no point in continuing.

However, some folk want it quieter than that. Usually, these folk are those that sit at a quiet machine (like a lathe) for long periods. If you want minimum noise my guess is that doing a BobL and parking the machine outside in an enclosure is likely the best option. Add to that a good muffler or similar, and you should be in business. Another option is to enclose the cyclone in a soundproofed enclosure (the exhaust duct should be inside this enclosure).

For those of you considering buying a cyclone, but who want minimum noise, I reckon ronboult's advice would be to buy a CV Max and run it on 50 Hz rather than what I did, buy a CV 1800 and run it at 60 Hz. On my machine the noise doubles from 50 to 60 Hz.

So, you really should start with a stated objective. Mine was to make the cyclone quieter than my primary machines. Done. Your needs might be different, in which case the solution will be different. The other aspect was price. My approach, two lengths of insulated HVAC duct and some insulation around the impeller was dirt cheap. Building an enclosure will make the beast quieter, but you will spend a fair bit more.

Have fun!

John

Hi John,

The reason I am thinking of enclosing the motor is because I am going to sheet the outside of the cyclone and muffler to gain as much tool storage as possible on the outside face in my small workshop. As you can see from the photo the muffler and the impeller surround has taken care of most of the noise generated from these areas.

https://www.woodworkforums.com/attach...2&d=1370586358

I thought that at the same time I would continue the sheeting to the roof hence my query as to what size of air entry is required to avoid cooking the motor. I don’t usually shut down the cyclone while I am working out how to proceed with the next operation and the sound of the motor is just an added distraction that would be good if I could make it as quite as possible.

I don't think you would learn anything from the work that I have done because most of the ideas have come from you and BobL.
The first two photos show the saw and jointer from a previous post
Table saw.jpgJointer.jpg

The next two photos show new work on the lathe and drill press. I still have to turn a bell cone on the lathe for the intake.

Drill Press.jpgLathe.jpg

Although it has been a long road and there is still some work to be done such as an overhead dust extraction guard for the table saw, I am more than happy with the results I am achieving with the ClearView.

Originally Posted by safari

. . . .
The next two photos show new work on the lathe and drill press. I still have to turn a bell cone on the lathe for the intake. . . . . .

Although nowhere near as critical the Bell Mouth Hood should work equally well on the DP as well.

Originally Posted by safari

Hi John,

The reason I am thinking of enclosing the motor is because I am going to sheet the outside of the cyclone and muffler to gain as much tool storage as possible on the outside face in my small workshop. As you can see from the photo the muffler and the impeller surround has taken care of most of the noise generated from these areas.

Safari,

I am sorry I cannot help you with ensuring the motor stays cool ... never done it before.

I too am happy with my cyclone. The difference in my shop is quite remarkable.

Cheerio!

John

Just to add my experience, my DC is outside, the top half of the unit (the motor, fan housing and cyclone) is enclosed in a cabinet made from freezer panel, no airflow to the motor other than that provided by the motor fan, the blue smoke is still contained in the motor at most it might run for 2 to 3 hrs at a time, I probably should get up there and check how hot it does get a quick rough test is the palm of the hand on the motor, can I leave it there or is it too hot, about 60°C is the limit for most of us, if I can't hold a hand on it then I need to be thinking about some additional cooling to the fan motor.

If it ran 8hrs a day I'd be keeping an eye on temp rise in the motor, when I put a VFD on the DC there is a function that monitors a psuedo temp via current draw so all things being equal it should stop or alert me to a potential problem.

A pipe (say 6" or so) coming from outside an enclosure to meet up with the fan end of the motor should provide cooling and then the hot air has to be allowed to escape from the enclosure, a fan might still be needed to overcome any pressure within the enclosure, it could be switched on via thermost or just come on when the DC is turned on.



Pete

Originally Posted by pjt

Just to add my experience, my DC is outside, the top half of the unit (the motor, fan housing and cyclone) is enclosed in a cabinet made from freezer panel, no airflow to the motor other than that provided by the motor fan, the blue smoke is still contained in the motor at most it might run for 2 to 3 hrs at a time, . . . .

The top half of a cyclone represents a fair size volume and more importantly, your cyclone and impeller made of metal and will act as a sort of heat exchanger transferring heat from the motor to the air inside the enclosure through the metal walls of the cyclone and be carried away with the exhausted air. I'd say this is a significantly different setup from enclosing just the motor.

Thanks for the replies. The enclosure will be 860mm square and around 300mm high. I will cut two holes on opposite sides for air entry and exit big enough to put a hand through to feel the temp of the motor as per Pete's suggestion and modify things as necessary.

Originally Posted by safari

Thanks for the replies. The enclosure will be 860mm square and around 300mm high. I will cut two holes on opposite sides for air entry and exit big enough to put a hand through to feel the temp of the motor as per Pete's suggestion and modify things as necessary.

I can see two problems with this.

Holes the sides of a box will not clear hot air from the top of the box which is where the motor is located - the holes will need to be at the top and bottom of the box to generate a thermal driven air flow.

Next, don't be surprised is a lot of noise escapes from the holes. To reduce the noise coming out of the holes, baffles will be needed but this will prevent you from putting your hand inside and will slow any air movement down

On my externally located compressor enclosure I installed a cheap digital thermometer that measures the air temperature inside the enclosure and a 120 mm x 240 V fan that vents the chamber through a semi baffle arrangement. The fan is wired so that it comes on when the compressor fires up.

I just remembered that Chris Parks (I think) posted an idea of cutting into the main duct and taking off a small pipe that sucks a crossflow of air from the motor enclosure end thus creating a cooling stream over the motor. Can't find it now of course but could be an idea worth developing.

Originally Posted by safari

I just remembered that Chris Parks (I think) posted an idea of cutting into the main duct and taking off a small pipe that sucks a crossflow of air from the motor enclosure end thus creating a cooling stream over the motor. Can't find it now of course but could be an idea worth developing.

Safari,

You are right. It was Chris parks who suggested that. He suggested it when I was considering enclosing the entire cyclone. For those who wanted to enclose the motor it sounded like it was worth investigation. A smallish pipe connected to the inlet duct that led back to the motor enclosure and which drew air through the motor enclosure should keep the motor cool. It would use minimal air, would always be working when the cyclone was on and would not require a fan to keep air moving over the motor. It would require some experimentation to get the size of the tube right, as well as the inlet size and position/direction of air flow over the motor, but I'll bet BobL could give a reasonable starting point for those experiments.

Cheerio!

John

Originally Posted by John Samuel

Safari,

You are right. It was Chris parks who suggested that. He suggested it when I was considering enclosing the entire cyclone. For those who wanted to enclose the motor it sounded like it was worth investigation. A smallish pipe connected to the inlet duct that led back to the motor enclosure and which drew air through the motor enclosure should keep the motor cool. It would use minimal air, would always be working when the cyclone was on and would not require a fan to keep air moving over the motor. It would require some experimentation to get the size of the tube right, as well as the inlet size and position/direction of air flow over the motor, but I'll bet BobL could give a reasonable starting point for those experiments.

Well it just so happens that I have done some air flow measurements on fans on 2.2-3 kW electric motors. Because of the way they are mounted on motors it is quite difficult to do the measurement but anyway I measured ~100 cfm at 50Hz but it is not all that well directed so you could probably get away with less depending on the size of the motor. !00 CFM at 50 Hz means much less at 25Hz so fellas running these with VFDs have already been testing the fan situation out on motors whether they knew it or not.

DC pressures requires a 2.5" duct to pull 100 cfm but because of the above I reckon you might get away with 2" but no less than this. If you decide to run at 60Hz you might need more flow so you might need 3"ducting.

I have been messing about a fair bit with 3 phase electric motors lately. and I found a 3-4kW motor on a pile of scrap which was jammed tight from rust but I pulled it apart and got it going.
It had no fan inside it and I was going to make a fan but one of the metal work boys suggested that if I was planning to use this on a VFD at low speed an externally powered fan might be a better option. As it so happened I already had a 240V x 120 mm diameter fan from an old mainframe computer so I tried that out and it seems to work OK although I have not run the motor itself under load.
I measured this fans volume output and it's around 55 CFM .

It turns out to be very similar to this one which is the same one I have on my compressor enclosure
http://www.altronics.com.au/index.as...=item&id=F1030
This one says it pulls 105 CFM and guess what - that's about double what I get although it is not exactly the same fan.

So rather than cutting your way into the ducting, adding one or two of these or something bigger to the box is probably all you need to do.
Maybe you could set two up and that would guarantee the 100 CFM.

Whatever you do don't restrict those fans in any way as they generate stuff all pressure and they will just whimp out. You will have to use baffles to prevent noise escaping from their openings.