Thread: 1000 c f m

Originally Posted by mannum3

I believe 1000 cfm can be achieved with reasonable cost and careful planning, I could be wrong, what do you think?

There's quite a few variables here.

- Source of power.

Who has 3 phase power at home (probably just BobL )

Who has 15 amps in the shed. If so how many circuits? If you have one 15amp circuit it is probably powering the dust maker rather than the dust extractor, so if you want to run 15 amp dust extraction you need two 15 amp circuits. (I am guessing maybe 5% of us have one 15amp circuit less than 1% of us have two or more)

Whose shed has one single 10amp circuit most likely with one or two double GPO's? Often there will also be outlets on he garage circuit inside the house as well, just to make things more difficult. (That will be the vast majority of us)

- practicality

Probably at least 50% of us are renting and not in a position to spend a lot on modifications to power supply or knock holes in walls. We have what we have and we just have to make the best of that.

Originally Posted by BobL

The other thing a lot of DIYers forget is that for a very small (3 x 3 x 2.4) shed a standard large 3HP DC (e.g. a DC7) located outside the shed is effectively right next to most machinery in that shed. More importantly the DC7 will vent the entire volume of that shed in less than 1 minute. This means in about 10 minutes the air in that shed could be as fresh as outside air. It seems like over kill but provided the machinery has been opened up and allowed to breathe that is all that is needed for such a small shed. The last time I looked new DC7s were not that expensive and they come up fairly often in the classifieds.

Yes, BobL is right again. Thats what we need - a 3m x 3m shed with two 15amp circuits! Anyone ever seen one? You would HAVE to put the dusty outside the shed - there would not be room for it inside with the tablesaw, bandsaw, lathe, jointer, ticknesser, timber rack, router table etc etc etc...

So that hopefully puts the problem in perspective. So what can we as a group come up with for a solution?

For the sake of simplicity, lets standardize the problem to something that is probably not too far from what most of us have to work with. Lets say a two-car garage or freestanding shed of about 6m x 6m to 8m x 6m, Lets give it two double GPO's on a single 10 amp circuit (therefore you can plug in four appliances to a total consumption of 10 amps. Lets say we can put the dusty outside the shed Lets also say we can run an extension lead to another 10 amp circuit somewhere in the house,

What can we all make of this?

Cheers

Doug

Edit: Before anyone asks, I have not just described MY shed. I have more room and power than that. I wanted to reduce it to something achievable by anyone anywhere.

Don't split-system aircon units need 3-phase (the big ones that are ducted to the whole house, not just one room) and could you hook in to that circuit for the dust extraction?

[QUOTE=doug3030;1867297 ] Who has 3 phase power at home (probably just BobL )[/QUOITE]
Nope - just 240V. I do have 7 machines running 240V 3 phase motors - all using VFDs. I also have are 4, 415V machines at the tree loppers yard.

Who has 15 amps in the shed. If so how many circuits? If you have one 15amp circuit it is probably powering the dust maker rather than the dust extractor, so if you want to run 15 amp dust extraction you need two 15 amp circuits. (I am guessing maybe 5% of us have one 15amp circuit less than 1% of us have two or more)

I have 4; compressor, TS, one is shared between the plasma cutter/welder/DC and one is for a 3HP Linisher and one at the other end of the shed is for testing motors.

BTW it is possible to run a 3HP 3Phase DC from a 240V - 10A power point via a VFD because a VFD can be programmed to never go above 10A. It ramps the power up slowly so start up currents are not an issue. I wouldn't do this on anything other than a DC because when the air flow stalls the current drawn by the impeller motor drops. The VFD has built in protection anyway. A suitable VFD costs about $150 which may or may not be cheaper than installing a dedicated 15A PP.

Yes, BobL is right again. Tha'ts what we need - a 3m x 3m shed with two 15amp circuits! Anyone ever seen one? You would HAVE to put the dusty outside the shed - there would not be room for it inside with the tablesaw, bandsaw, lathe, jointer, ticknesser, timber rack, router table etc etc etc...

Yep - good point and can appreciate the issue for people that rent

So that hopefully puts the problem in perspective. So what can we as a group come up with for a solution?
For the sake of simplicity, lets standardize the problem to something that is probably not too far from what most of us have to work with. Lets say a two-car garage or freestanding shed of about 6m x 6m to 8m x 6m, Lets give it two double GPO's on a single 10 amp circuit (therefore you can plug in four appliances to a total consumption of 10 amps. Lets say we can put the dusty outside the shed Lets also say we can run an extension lead to another 10 amp circuit somewhere in the house

For sheds attached to the house 15A circuits are not that expensive. If you have 2 x 10A circuits the VFD solution above becomes possible.

If building a shed from scratch it becomes a design/build priority matter - if folks allocated 10-15% of their shed build budget to power it would not be a problem.

If all you have is one 10A circuit I would get a large squirrel cage fan with a 1/3 or 1/2HP motor on it and use it to vent the shed. It will vent the shed of fine dust as quickly as a DC 7 through 150 mm ducting.
Don't connect it to a machine though as it will choke - those fans generate very little pressure.

Originally Posted by elanjacobs

Don't split-system aircon units need 3-phase (the big ones that are ducted to the whole house, not just one room) and could you hook in to that circuit for the dust extraction?

I would say, not without modification by a qualified electrician. I have an air conditioner in my home that is on a separate 15 amp circuit, but the air conditioner is hard-wired in and there is no power point on the circuit. Even if there was apower point as well, you would not be able to run another 15 amp appliance on the same circuit at the same time.

Doug

Originally Posted by doug3030

I would say, not without modification by a qualified electrician. I have an air conditioner in my home that is on a separate 15 amp circuit, but the air conditioner is hard-wired in and there is no power point on the circuit. Even if there was apower point as well, you would not be able to run another 15 amp appliance on the same circuit at the same time.

Doug

We have 4 split systems in our house - 3 of them use 240V 3phase motors with VFDs (not installed by me). They are all hardwired (have their own circuit)

Originally Posted by BobL

For sheds attached to the house 15A circuits are not that expensive. If you have 2 x 10A circuits the VFD solution above becomes possible.

If building a shed from scratch it becomes a design/build priority matter - if folks allocated 10-15% of their shed build budget to power it would not be a problem.

Smilies are great when words fail me.

Originally Posted by BobL

If all you have is one 10A circuit I would get a large squirrel cage fan with a 1/3 or 1/2HP motor on it and use it to vent the shed. It will vent the shed of fine dust as quickly as a DC 7 through 150 mm ducting.
Don't connect it to a machine though as it will choke - those fans generate very little pressure.

Now that is helpful advice and probably achievable by a lot of forum members. In a similar way, I have two bathroom type exhaust fans mounted on a plywood board in the window of my shed that vent lot of air (and therefore dust) to the outside. I also have my machines on mobile bases and move them outside for a lot of work and let the breeze deal with the dust and hook up a 1hp "chip collector" (part of my own dust colection progression as referred to earlier in the thread by Evanism, in his excellent post) to deal with the mess.

Lets keep the good ideas flowing. But remember its about the average amateur shed with limited resources.

Cheers

Doug

It's great to see some consensus.

Question for BobL who mentioned DC7's The spec sheet sayys over 2000 cfm, What is a realistic figure?

That is with large piping, mimimal restrictions, bell mouth opening to a lathe? or 2, or 3 (Mens shed)

I do not need precise figures to 2 decimal places, an estimate to within 100/200 cfm

Cheers Barry

I have a DC7 with 6" PVC ducting.

Can't remember how many inches of WC I needed to move 1000cfm ... But I wasn't there.

The DC7 appears restricted in the path between the blower and the bags. The entry is also restricted.

Originally Posted by doug3030

Smilies are great when words fail me.

Ok, now I have the "words" at last, after careful consideration -

"If someone asks you the time, they do not want you to tell them how to build a grandfather clock"

Cheers

Doug

Originally Posted by Glenn.Visca

I have a DC7 with 6" PVC ducting.

Can't remember how many inches of WC I needed to move 1000cfm ... But I wasn't there.

The DC7 appears restricted in the path between the blower and the bags. The entry is also restricted.

Sorry ... I lied. With an SP test of around 7", I was a tad over 1000cfm.

A DC7 should have a static pressure (SP) of over 8" WC - if it is not generating this there are leaks or the impeller is not well mated to its housing.

Originally Posted by mannum3

It's great to see some consensus.

I'm not sure about this. All I see is old stuff being regurgitated.

Question for BobL who mentioned DC7's The spec sheet sayys over 2000 cfm, What is a realistic figure?

Like most DCs these flow figures are for the impeller, no ducting and no filters performed to a standard which over estimates the real flow by at least 20%.

Like most DCs as soon as 6" ducting is attached it cannot be any more than ~1250 CFM - that is a fundamental limit for 6" ducting.
Bigger impellers doing more revs can generate a greater SP and move maybe 1450 CFM.

A twin bag filter setup will knock a bit off - dirty filters will drop it well down even as low as 800 CFM

Like most DCs connection to a 4" dust port on any machine means it will be down to 400 cfm.

Every time I write these figures I say to myself - this is they last time I'm going to do this - there, I have now put it in writing.

Originally Posted by BobL

A DC7 should have a static pressure (SP) of over 8" WC - if it is not generating this there are leaks or the impeller is not well mated to its housing.

All right, all right [emoji32] ... In my original max sp test, I got a reading of 7 7/8" w.c. .... in my prior post I was going from memory. My bad.[emoji50]

12 months on, I have noticed a few little holes in the housings (courtesy of the little dust trails that make them evident). One of these days I will plug them with sikaflex or bog or something.

With the inlet choked to 140mm, plus the reduction caused by the bullseye, I would still suggest we hover around the 1000 range for an out of the box unit.

My readings were taken on well "conditioned" filter bags. [emoji6]

https://www.woodworkforums.com/f200/scms-dust-extraction-187025-post1810764

Originally Posted by BobL

Every time I write these figures I say to myself - this is they last time I'm going to do this - there, I have now put it in writing.

Is it worth having a sticky thread with figures for the different generic dust extractors? Then you could program a hot key to paste the link every time someone asked

I have the 3hp dc7. Connected to a 10amp circuit. the circuit runs the front half of the house incl. Kitchen. it has 16amp breakers. When I run the dusty, the only other power draws r standby stuff like tv, dvd, clocks, microwave etc. Hasnt given any issues, the wire doesnt get hot. My machinery is all run via a single 15amp circuit. Drill press an orbital sander run without the dusty so I use the 10amp circuit for that. To my knowledge, 3hp is about 9.8 amps. Iirc the houses 10amp circuits were 1.5mm cable, the 15amp is 2.5mm.