Shed Power

[dai sensei]

I've got a 20amp line going to the shed, and then 15amp line to all the 10amp sockets, there are no 15 sockets. Most machines are 1hp or less except the bandsaw that is currently 1.5hp. The cyclone currently runs on a 1hp motor that I know is under powered and I want to upgrade with the 3hp motor with 10amp plug that I have.

Question is, with the bandsaw at 1.5hp and a possible upgrade to 2hp, would the 3hp dusty running at the same still be Ok? I don't start the 2 at the same time.

I'm thinking 4.5hp @ 750 watts = 3375 watts divided by 240V = 14.1 amps hence ok.

If I also upgrade bandsaw to 2hp in future, 5hp @ 750 watts = 3750 watts divided by 240V = 15.6amps puts me over the limit in shed line but ok to house line.

Cheers
Neil

[Bohdan]

The cyclone currently runs on a 1hp motor that I know is under powered and I want to upgrade with the 3hp motor with 10amp plug that I have.



Upgrading to a higher power capable motor will make no difference unless you also speed up the fan, because if your DC was overloading the current motor it would be slowing down and overheating.

The only way to find out what the motor is doing is to put an ammeter into the circuit.

[dai sensei]

Upgrading to a higher power capable motor will make no difference unless you also speed up the fan, because if your DC was overloading the current motor it would be slowing down and overheating.

Sorry, underpowered as in not enough suction, not that the motor is under powered for fan. I would be installing effectively new cyclone system


The only way to find out what the motor is doing is to put an ammeter into the circuit.

I'm trying to establish if ok before installing the upgrade. I guess I could plug in the 3hp dusty motor but it wouldn't be under load.

[doug3030]

What size is the circuitbreaker?

Startup current is only momentary and is unlikely to cause anything more serious than tripping the breaker. Giving it a try is a low-risk option. It just might work.

This situation just goes to highlight how inadequate the power availability in most sheds is for home hobbyists. There is usually enough to run a dust making machine or two but not enough to protect your health by being able to run adequate dust collection as well.

Cheers

Doug

[BobL]

Unless you are cutting close to full width timber it's pretty hard to get a BS to even draw half its rated power.

I have a current meter on my BS and 90% of the cuts are made at less than half its rated power.

A DC will draw power dependent on load (i.e. degree on UNrestrictedness). I seem to remember you have 100 mm ducting? in that case you will never get improved performance no matter what size motor or cyclone you use.

Even running 3 x 4" ducts on a BS reduces the DC load. EG on my 3HP/6" system the normal unrestricted flow draws 9.3A but when connected to the BS via 3 x 4" ducts it draws 8.3A

[dai sensei]

What size is the circuitbreaker?

20amp


Unless you are cutting close to full width timber it's pretty hard to get a BS to even draw half its rated power.

I have a current meter on my BS and 90% of the cuts are made at less than half its rated power.

You are probably correct Bob, although mine is a 16" BS and I do push it to its limits. Hence why I thought about upgrading motor to 2hp. Still going strong though so an upgrade would only be if motor burnt out


A DC will draw power dependent on load (i.e. degree on UNrestrictedness). I seem to remember you have 100 mm ducting? in that case you will never get improved performance no matter what size motor or cyclone you use.

Even running 3 x 4" ducts on a BS reduces the DC load. EG on my 3HP/6" system the normal unrestricted flow draws 9.3A but when connected to the BS via 3 x 4" ducts it draws 8.3A

Yes mine is all 4" ducting. My current cyclone is run however on only a 1hp unit, with the intake opened up so it gets more suck, but still more a chip/course sawdust collector rather than a real dust collector. Being a woodturner it goes every where anyway and hence why I use decent masks for the fine stuff.

I would have thought a 3hp with decent fan would get an increased suction, even with the current 4" ducting, I would have thought?

[BobL]

I would have thought a 3hp with decent fan would get an increased suction, even with the current 4" ducting, I would have thought?

Well a 1HP DC normally generates about 325 CFM through a 4" duct.
Increasing the fan size and using a 3HP motor might get you to 425 CFM but you simply cannot get much more than this through a 4" pipe without it starting to sound like a jet engine.
4" duct simply cannot maintain a high enough flow rate to capture fine dust at source from most wood working machines.

You will need at least a 3HP and 6' ducting to pull the 1000 CFM needed for turning. Then you can even do away with masks.

[dai sensei]

... you simply cannot get mush more through a 4" pipe without it starting to sound like a jet engine....

Thant's what I was expecting, increased but noisier


..Increasing the fan size and using a 3HP motor might get you to 425 CFM

But is what you are saying, although a motor/fan can generate 1200cfm, through a 4" duct I can't get more than 425cfm?


You will need at least a 3HP and 6' ducting to pull the 1000 CFM needed for turning. Then you can even do away with masks.

Whilst sanding yes, but not turning, turning produces shavings (and dust) to be directed away from the piece and any ducting. Especially whilst turning stuff that is >300mm dia so the blank is between the chisel and the duct/scoop. I was turning tables over 700mm dia just the other day, that's when out bring out the big fans to push/pull the fine dust away from you, but I still wear the masks too.

[BobL]

Thant's what I was expecting, increased but noisier
The noise is generated at the machine port and the last thing we all need is more noise as this also negates the the whole wide of putting a DC and its noise outside.
I'd hate to have to wear ear muffs every time I used my DC.


But is what you are saying, although a motor/fan can generate 1200cfm, through a 4" duct I can't get more than 425cfm?

Correct.

It sounds like you haven't been following the discussions in the dust forum where I have been rabbeting on about this for the last decade.

The bigger fans and motors produce more POTENTIAL flow, but only provided bigger ducts are used. To get more air through small ducts requires much more pressure than standard DCs are capable of generating. You need the pressures of a vacuum cleaner to get significantly more flow through a small pipe but unfortunately VCs use small very high speed impellers with low flow rates. At work we had high speed turbo fan (basically a large vacuum cleaner impeller) and you had to wear ear muffs around that. Why resort to that when it's unnecessary. You will have to resign yourself to replacing your 4" system with a 6" if you really want to control dust in your shed.

2" ducting is limited to about 125 CFM, 4" to about 425 CFM and 6" to around 1250 cfm.
Note how even though the area of the duct doubles the max flow increases by a factor of about 3 at each step. This is the wall resistance effect coming into play. Engineers should know about this.


Whilst sanding yes, but not turning, turning produces shavings (and dust) to be directed away from the piece and any ducting. Especially whilst turning stuff that is >300mm dia so the blank is between the chisel and the duct/scoop. I was turning tables over 700mm dia just the other day, that's when out bring out the big fans to push/pull the fine dust away from you, but I still wear the masks too.

Fans are useless at blowing away the visible dust. Fine dust stays suspended in air for many minutes. By then the air (and fine dust) that the fan has blown away has recirculated back around the back of the fan onto the operator. 1000 CFM will clear all the fine dust away from even a 700 mm table being turned on a lathe. 1000 CFM is the equivalent of the removal of a sphere of air of diameter of about 1m every second ! It won't catch all the chips or the visible bust but they won't hurt you like the fine dust will .

BTW You will need a Bell Mouth hood to get 1000 CFM through a naked duct opening.

Turning 700 mm tables should be done using a Clearvue Max (2000 CFM) so that 2 x 6" hoods could be used that feed into an 8" trunk line.

[dai sensei]

Correct.

It sounds like you haven't been following the discussions in the dust forum where I have been rabbeting on about this for the last decade....

Bugger. Yes I was following, but have forgotten :- :rolleyes:


Fans are useless at blowing away the visible dust...

Unless they are mounted in the window sucking it outside :U


You will need a Bell Mouth hood to get 1000 CFM through a naked duct opening..

My lathe does have a ~500mm x 500mm gulp connected to the ducting


Turning 700 mm tables should be done using a Clearvue Max (2000 CFM) so that 2 x 6" hoods could be used that feed into an 8" trunk line.

The point I was making is that some blanks/lathes are just to big, combined with the fact that shavings can be flying from side to side/forwards and backwards, depending on the cut positioning so you just have to accept you can't catch everything. Whilst working at Robbos I have been working on blanks up to 10m long. He has a dirty big fan at one end of the workshop mounted on the external wall sucking the fine dust outside. Works surprisingly well for the fine dust, you can see the visible dust (and assuming the invisible too) being removed, but of course useless for the shavings.

Mind you my big lathe that turns the tables/monster bowls is in the top carport that has no DC at all. You'd cry at how much shavings and dust is in my workshop at the moment :rolleyes:


Thanks for the input though Bob.

I will consider going to 6" ducting around the main workshop, just at the moment I have the 3HP motor and fan, but not the 6" ducting nor spare $s

[BobL]

Unless they are mounted in the window sucking it outside :U
Sure, but sucking is different to blowing, especially if it removes air completely from the workspace.


My lathe does have a ~500mm x 500mm gulp connected to the ducting
A gulp is better than a naked hood but it's not as efficient as a BMH mainly because if the Gulp has any sort of depth it needs to be well back from the work. A BMH is flatter than most hoods so it can be placed closer to the work as well as generating an increased incoming air speed well out in front of its opening



The point I was making is that some blanks/lathes are just to big, combined with the fact that shavings can be flying from side to side/forwards and backwards, depending on the cut positioning so you just have to accept you can't catch everything. Whilst working at Robbos I have been working on blanks up to 10m long. He has a dirty big fan at one end of the workshop mounted on the external wall sucking the fine dust outside. Works surprisingly well for the fine dust, you can see the visible dust (and assuming the invisible too) being removed, but of course useless for the shavings.
I agree that catching all the chips, especially from very large work, is a near impossible task and a mega ventilation setup is needed. Top down ventilation is better than sideways ventilation and if I was doing that sort of work I would go for something like an Evap AC fan in the roof so that it blows clean air down over the operator. One of the local members has this setup and I did some dust measurements on it and it works brilliantly especially as he has a relatively small shed.

One thing I notice when using the BMH on spindle work is that chip scatter is much reduced. Instead of it spraying all around the shed most of the chips fall withing a 1m radius around the front of the lathe.


Mind you my big lathe that turns the tables/monster bowls is in the top carport that has no DC at all. You'd cry at how much shavings and dust is in my workshop at the moment :rolleyes: Nothing surprises me these days. I was in a team of blokes that picked up machines from a deceased estate where the sawdust was ankle deep in the walk ways and knee deep elsewhere in the shed. We had to spend a couple of hours cleaning up before we could get any of the gear out.

In order of priority the following is what I recommend
1) Vent or put the DC outside
2) use 6" ducting and a DC that can make full use of the 6" ducting
3) Open up dust ports and air pathways on machinery to suit the 6" ducting

[Ausworkshop]

Nothing surprises me these days. I was in a team of blokes that picked up machines from a deceased estate where the sawdust was ankle deep in the walk ways and knee deep elsewhere in the shed. We had to spend a couple of hours cleaning up before we could get any of the gear out.

Interesting read. Makes me wonder what he died of, was it a dust related illness?

I only use 65mm pvc pipe as that was the diameter of my ring blower that I got for free so I just went with the same diameter through the whole lot. I do all my sanding next to a fan that is facing out of the shed but obviously I am not using powerful enough blower or diameter pipe for fine dust at the machines.

I set mine up years ago before so much research results were available online and not many hobby woodworkers even knew what DC stood for.
Instead of trying to achieve this holy grain of dust extraction I like the idea of a fan pushing clean air down, I'd been thinking about adding one to the roof to remove all the hot air in summer when I'm using the computer in the shed and not making dust.

Maybe I should try and get one that I can run in reverse as well? Remove all the heat build up in summer or flip the switch and use it for fresh air down while I'm making dust. I'm guessing most fan blades are designed to operate better in one direction though and reversing it using electronics could be a problem if it's AC. I could get up on a ladder and flip it physically or rig up some contraption, perhaps I'm over thinking all this and really should just focus on a complete upgrade for my DC.

Or just cut more holes in my roof, have some facing down and some facing up??

[BobL]

Interesting read. Makes me wonder what he died of, was it a dust related illness?
He died from pneumonia, but 10 years before he died he developed some sort of wood dust related allergy but kept working for a few years ankle deep in sawdust. Eventually he became so breathless he had to stop using machinery and for the last few years could not even go into his workshop. This is by no means the only case I have seen in a similar situation.


I only use 65mm pvc pipe as that was the diameter of my ring blower that I got for free so I just went with the same diameter through the whole lot. I do all my sanding next to a fan that is facing out of the shed but obviously I am not using powerful enough blower or diameter pipe for fine dust at the machines.
65 mm ducting attached to a standard DC draws around 150 cfm which is not much more than a good vacuum cleaner.
Do you at least vent that out of the shed?



Maybe I should try and get one that I can run in reverse as well? Remove all the heat build up in summer or flip the switch and use it for fresh air down while I'm making dust. I'm guessing most fan blades are designed to operate better in one direction though and reversing it using electronics could be a problem if it's AC. I could get up on a ladder and flip it physically or rig up some contraption, perhaps I'm over thinking all this and really should just focus on a complete upgrade for my DC.

If I was doing this I would use one with a motor that is capable of running at 3 phase, 240V, and then use a VFD to run it. Look up VFD in the Electronics section.
a) you could then vary the speed as requried, including at greater than 60Hz to really pump some air around
b) it could be reversed at the flick of a switch on the VFD.

One of my two blowers that I use in my shed has a VFD on it and its great to be able to run it flat out or slow enough that it cannot be heard. I never run it backwards because the fan has stuff all efficiency running backwards and for summer I have AC.

[Ausworkshop]

65 mm ducting attached to a standard DC draws around 150 cfm which is not much more than a good vacuum cleaner.
Do you at least vent that out of the shed?

Yes I've always vented it outside the shed through a hole down the back corner of my workshop right next to the blower so that I keep the pipe as short as possible, then I thought maybe it would be better to have a longer pipe, would that help create a bit more suction or the longer run slow it down further? Thought maybe it would work like a turbo or exhaust system and the air blowing out would create more going in like a siphon action.

Anyway after hearing these stories and also been too a few deceased estates from old time woodworkers myself I think I really need to invest in some better equipment. I'm just using a cyclone I cobbled together myself with a large collection bin beneath a modified Triton dust collector top and a bucket and funnel from super cheap auto, works ok, at least it's vented straight out of the shed but there is still a build up of fine dust in my shed over time, I don't always have the mask on when I'm in there, I sit here for hours a day on the computer doing emails so I'd imagine even that is not good for my health because the fine dust is probably always hanging around.

It's probably too late for me now anyway,:weeping: I've come to accept I will probably die from my job no matter what I do. I'm surprised people like Sam Maloof lived so long and worked right up till the end!:o

I can't afford to redo it all, change everything over to bigger duct and spend hours of time doing research (so I don't purchase something that I'm going to grow out of) so for now I'll just keep doing with what I have. I doubt I could get 3 phase in my little shed anyway, -- I had three or four electricians out when I first moved in, asking them for quotes on wiring it up, they never got back to me so I ended up doing it myself with a heavy duty extension lead out the laundry window through some poly pipe and attached to a clothesline cable stretched tight between house and shed.

I always have trouble getting tradesmen to show up out in Gippsland, I'm renting in Officer right now but moving back to my old workshop in Gippsland because it's too expensive and crowded around here now. So now could be my chance to redo it all, I'm actually thinking about putting the duct work around the outside of the shed (my tank water pipes are already there), save space along walls in the workshop and makes it easy to upgrade to larger diameter later.

At the moment I'm putting up pine lining and insulation from Discounted Premium Shed Insulation Australia - Home (http://shedinsulationdiy.com) they are a great family owned business in QLD if anyone is interested in insulating their sheds. You might be surprised how good their foil is with sheds and how much they know about the science behind it all and the insulation industry in general. Read their website if you're interested.

I'll probably be reading back through all your old posts when I have time Bob, I do remember reading some in the past when looking up dust extractor questions. Thanks for contributing so much over the years.

[BobL]

Yes I've always vented it outside the shed through a hole down the back corner of my workshop right next to the blower so that I keep the pipe as short as possible, then I thought maybe it would be better to have a longer pipe, would that help create a bit more suction or the longer run slow it down further? Thought maybe it would work like a turbo or exhaust system and the air blowing out would create more going in like a siphon action.

Longer pipe has more wall friction so it will slow flow down.

[dai sensei]

Sure, but sucking is different to blowing, especially if it removes air completely from the workspace...

Best system I have ever seen was a guy with a huge window 3' behind his lathe with an old 6' aeroplane prop on a big motor of some sort. It sucked the dust and shavings out the window, even the large spirals got sucked straight out. He had to be careful it didn't suck him out LOL

[doug3030]

Best system I have ever seen was a guy with a huge window 3' behind his lathe with an old 6' aeroplane prop on a big motor of some sort. It sucked the dust and shavings out the window, even the large spirals got sucked straight out. He had to be careful it didn't suck him out LOL

I am pleased that I am not his neighbour. :oo:

[Lappa]

I've got a 20amp line going to the shed, and then 15amp line to all the 10amp sockets, there are no 15 sockets. Most machines are 1hp or less except the bandsaw that is currently 1.5hp. The cyclone currently runs on a 1hp motor that I know is under powered and I want to upgrade with the 3hp motor with 10amp plug that I have.

Question is, with the bandsaw at 1.5hp and a possible upgrade to 2hp, would the 3hp dusty running at the same still be Ok? I don't start the 2 at the same time.

I'm thinking 4.5hp @ 750 watts = 3375 watts divided by 240V = 14.1 amps hence ok.

If I also upgrade bandsaw to 2hp in future, 5hp @ 750 watts = 3750 watts divided by 240V = 15.6amps puts me over the limit in shed line but ok to house line.

Cheers
Neil

I had my shed rewired some months ago with a 40A line and sub board. I thought I required 60A looking at my current equipment and future purchases, but I ended up with 40A as all the quotes I got worked out required requirement the same way.
100% for first machine
3/4 for next
1/2 for next
Etc.