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Thread: The Generic 2HP DC
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3rd February 2017, 12:38 PM #151GOLD MEMBER
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Looks like it should be called a 1HP dusty but the manufacturer has fitted a 2HP motor for marketing purposes.
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3rd February 2017 12:38 PM # ADSGoogle Adsense Advertisement
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3rd February 2017, 12:43 PM #152GOLD MEMBER
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BobL you stated "Blast gates should be attached to the Y junction into the trunk line NOT down near machine."
I am curious as to the reason for this so I was wondering if you could elaborate please.
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3rd February 2017, 01:20 PM #153
Wherever you have a junction in the main trunk you create turbulence, even with correct trunk flow rates some material running through the main trunk could drop out of suspension and down the vertical riser, obviously reduced flow rate in the main trunk make it worse. Placing blast gates at the bottom of the risers or near the machine can cause this material to accumulate behind the closed gate to quite some depth. In a big system like a Men's shed where some blast gates may be closed for long periods of time and a lot of timber is also processed, then this can be a real problem. In a small home workshop maybe not so much of a problem, at lease in my case as I have not had any build up behind my low mounted blast gates (yet). But placing gates as close to the feed trunk as possible is the preferred location.
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3rd February 2017, 02:48 PM #154
Cyclone inside is fine and typical of most home installs, here are a few links with lots of pictures - so jealous
Clear Vue installation
CV1800 Install (Brisbane)
Clearvue CV1800 installation WIP
Clearvue CV1800 / Max Impeller Install - Home Garage Workshop
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3rd February 2017, 02:49 PM #155GOLD MEMBER
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In my experience the cv1800 does not leak and there is no need for any enclosure within the garage/shed.
Just ensure you apply sealer to all joints as directed in the instructions and that your dust bin is airtight etc. More importantly, ensure that any connections on the exhaust side are leak free. I used hvac insulated duct and needed to wrap this in several layers as it did initially leak a lot.
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3rd February 2017, 03:57 PM #156Woodworking mechanic
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Back to my dusty and some new figures.
I decided to carry out the "Generic 2HP dusty Modifications" even though there is no real value in trying to resurrect this unit from the dead but I thought it may help others. I decided to do in two stages. This way I could see what modification did what.
With the figures I posted earlier, i forgot to include the SP at the impellor inlet. This was done with the filter diconnected as its the only way I can get to the pump min the small shed.
It was 175mm WC or 6.89"WC. At the table saw it was 165mm WC or 6.49" WC
Stage 1: I replaced the impellor 5" front with a 6" front. Every thing else remained the same as in my first series of tests.
Before figures are in black, figures after mod are in italic bold
- inches WC at impellor - 6.89 Now 7.28
- Average CFM in the long PCV run in the ceiling is approx 440-460CFM. -- now 420 to 430CFM
a) all connected to table saw - 2.76A now 2.63A
b) table saw disconnected. - 2.78A now 2.67A
c) same but with pipe to filter disconnected - 3.30A Now 3.34A
d) same but with ducting removed from inlet of impellor - 3.36A now 3.98
e) Another test was with the down pipe to the saw disconnected and the filter outlet off 3.59A
f) front off ie. naked impellor - 4.05 A
g) plastic outlet off housing so large rectangular outlet is exposed - 4.55A
So the results seem to show slight improvement with all load off (ie, 3.98A up from 3.36A and SP up from 6.89 to 7.28) but a drop in performance with all load on ie. filter and ducting - Amps drop. Maybe due to outlet still small or maybe because the bigger inlet pipe does not suit the fan as the centre fan section is 5" - as shown at the beginning of this thread or a combination of both.??
I haven't been able to obtain a filter separator to modify and I don't intend to modify mine at this point in time so I will do some readings with the pipe to the filter disconnected but now with 6" outlet and hose and compare it to the above results in c) and CFM. If there is an improvement, I will modify the dust separator.
NB. the now CFM reading was taken with the drop down still connected and should read 456 CFM - see later post.Last edited by Lappa; 3rd February 2017 at 05:15 PM. Reason: Now CFM reading taken with drop down connected
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3rd February 2017, 04:39 PM #157
5" outlet is definitely holding it back now, however it's looking more and more (at least to me) like that impeller is the problem, and I'll bet the flowrate gains you get from the mod will go south as soon as it's under any kind of flow restriction.
Again, thanks for going to all this trouble to get these readings - I'm sure you would rather be doing almost anything else that stuffing around with that stupid DC.
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3rd February 2017, 05:07 PM #158.
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The same effect will happen even if the flow is non-turbulent
The flow in one arm of a junction creates a low pressure zone in the other arm due to a Bernoulli effect, . The resulting vacuum pulls so much dust into the other arm.
I have seen it so badly choked that I have had to poke it vigorously with a stick to dislodge the dust.
The example below will illustrate what I mean
If the machine at B1 generates a lot of dust the dust ladened air flowing past the arms leading to B2 and B3 will generate low pressures in these arms and sawdust will be dragged into these arms choking the blast gate at B2. Then when you go to use the machine at B2 the DC may not have enough power to clear the desposited sawdust.
If you decide you want to put a gate down at machine level then one possibility is to use the setup shown for B3.
The vertical part of the Y has an end cap screwed onto is that can be unscrewed to clear the sawdust.
Screen Shot 2017-02-03 at 1.59.22 PM.png
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3rd February 2017, 05:12 PM #159Woodworking mechanic
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Ran some new tests with the drop down to the saw disconnected so I could compare to my previous CFM readings
a) with the pipe disconnected from the filter
b) the whole outlet removed leaving the large rectangular opening
c) all reconnected so I could properly compare to original CFM
a) Amps 3.5A; average CFM after 3 full matrix tests and fed through a STD Dev spread sheet - 750.66 CFM
b) Amps 3.71A; average CFM after 4 full matrix tests and fed through a STD Dev spread sheet - 901.625 CFM
c) Amps 2.79A; average CFM after 3 full matrix tests and fed through a STD Dev spread sheet - 456.5 CFM
Looking back at my previous post, I took the "now CFM" readings with the drop down still connected - sorry about that - see NB. in that post
I'm going to do a set of readings with the pleated filter removed and a new needle felt filter fitted because I have one.
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3rd February 2017, 05:29 PM #160.
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Lappa all your currents seem a bit low.
I wish you were closer so I could put your motor on my HP rig.
What is the 456 CFM reading for - before or after DC inlet conversion?
For comparative purposes for your
Test a), I got 4.7A and 669 CFM and no difference whether the filters were connected or not
For b) I got ~1000 CFM
My air speed profiles across the 9" test duct are here.
The Generic 2HP DC
How long is the ducting to the saw and what junctions are involved and what sort of connection are you talking about at the TS?
As I think you are seeing this makes a big difference.
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3rd February 2017, 06:45 PM #161Woodworking mechanic
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3rd February 2017, 07:24 PM #162Woodworking mechanic
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Just fitted a seasoned needle felt filter and ran the tests again with the table saw drop disconnected.
3.5A. 665.4 CFM (average of three sets of matrix readings fed thru std Dev spreadsheet)
44% improvement in flow. Better, but still not up to spec.
Think I might leave the needle felt on and store the pleated
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3rd February 2017, 09:10 PM #163.
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Thanks for the info.
The fact that the current never reaches 4A is disconcerting. What does it say on the motor name plate.
That there was no discernible difference with filters doesn't mean there was no difference - I just couldn't detect a difference.
I was using well cleaned needle felt filters.
Is that with the 5" connect between the Impeller and filter housing?
44% improvement in flow. Better, but still not up to spec.
the PVC pipe is approx 7m (just measured - 6.4m) in total including vertical rise. It has 1 x 45 degree, 2 x 90 degrees at each end of the vertical and 1 x Y connector 700mm along from the vertical. At the end of the ceiling run, there is a 90 elbow with blast gate then 2.8m of flexy to the saw.
I have pretty well consistently said, no more than 3m of ducting, minimal junctions and flex.
Although I do something similar in my shed, I wouldn't normally recommend doing that ducting run with a 3HP DC,
This is a graph from BP site
It looks like your DC is somewhere in between the 1.5 and 2HP DCs.
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3rd February 2017, 10:02 PM #164Woodworking mechanic
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Yes. The 3.5A and 665.4 is still with the 5" outlet connected to the filter. As I stated earlier, I'm not about to modify the dust separator inlet to 6" until I can prove to myself it is going to make a difference. Still mulling over the figures.
As stated in a previous post the motor plate states 240V, 7.7A, 2 HP. The only additional info is RPM 2950.
The motor did reach 4.05A with the impellor naked and 4.55A with impellor naked and the plastic 5" outlet removed so the large rectangular outlet was exposed.
Can't help re the length or shape of the ducting - what is, what is. It's either that or no extraction. Can't see myself having a router table, saw table, etc all within 3m of the dust inlet with a short length of flexy and still use them. Looking at the overhead pipe, I could maybe reduce it down to 5m but I couldn't shorten the flexy.
All the flow measurements are approx. 5 m from the dusty.
When I said " spec" it was just a generic term meaning it's not up to what I would have expected a genuine 2HP unit to deliver.
Anyway, now with 600 plus CFM below the saw table and a 50mm Vac to the saw table blade cover, I think it will do the job. Same as the router table.
Saving my monies to put a sub board in the shed so I won't even bother replacing the pleated filter.
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3rd February 2017, 10:22 PM #165.
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Thanks.
Your 665 CFM is almost identical to what I get (669 CFM) under the same conditions - the theoretical limit of a 5" duct at ~8" WC is 680 CFM, so it is all very consistent
I got 825 CFM only once the impeller was mated direct to the filter housing.
Can't help re the length or shape of the ducting - what is, what is. It's either that or no extraction. Can't see myself having a router table, saw table, etc all within 3m of the dust inlet with a short length of flexy and still use them. Looking at the overhead pipe, I could maybe reduce it down to 5m but I couldn't shorten the flexy.
When I said " spec" it was just a generic term meaning it's not up to what I would have expected a genuine 2HP unit to deliver.
The Australian standards method used to measure flow is wrong, and it's for the impeller only (i.e. no ducting no filters and no adapters in front of the impeller.
Saving my monies to put a sub board in the shed so I won't even bother replacing the pleated filter.
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