Vaughn Kaloust
05-17-2013, 5:57 PM
WARNING! This mod was only done because my shop is above 5,000 feet in altitude. I am trying to get the same type of performance that others get closer to sea level. I would guess that making this modification to the same dust collector operating at sea level might overload the motor.
After starting this thread, http://www.sawmillcreek.org/showthread.php?197861-How-to-measure-dust-collector-performance, trying to get help understanding my dust collection, I finally came to the conclusion that the cause of my disappointment with my system was because of altitude. The members who responded, who have much more experience than I will ever have, led me through a series of test which led to the theory that my HF 2 hp dust collector needed a bigger impeller.
Here were the main points:
1) I didn’t believe that my unit was performing as well as others were reporting their HF units were.
2) My ducting is short, sweet, well designed with 6 x 6” gates connected to one 15’ length of 6” duct, and then directly to my machines which are all in a row along that 15’.
3) Removing all of the above, and also disconnecting the exhaust side of the system so I was only testing the blower and motor, I was only able to achieve a SP of 6” WC connected directly to the inlet (no airflow).
4) With a full load, my motor was only drawing 8.5 amps. This was with a completely open inlet and outlet. When hooked back up to the manometer to the inlet, (no airflow), the motor pulled about 7.2 amps. This indicated that the motor was really barely under any stress and was effectively being under worked.
The decission:
Because of the thinner air at 5,000 foot altitude, the unit needed a bigger impeller to achieve enough air movement to effectively collect dust. I should mention that I am not talking about fine dust collection, but rather getting the big stuff from my table saw, band saw, etc.
The fan housing appeared to be able to accept a larger impeller, and the motor should be able to spin a larger impeller too.
So, taking all this into account, I decided to try a larger impeller. But although others suggested a few different units in the 12” range, such as Rikon, and Grizzly, I used something different.
The Grizzly unit that one person tried failed because it was too big and heavy. The circuit breaker could not bring the unit up to speed before tripping. I tried to get one from Rikon, but they insisted on having the serial number of my unit to sell me one.
I took a chance and ordered a Jet 12” steel impeller, part # AB411059. I didn’t know much about it at all, but I was tired of not finding an answer to my problem.
What I used:
262485
As you can see, the unit is much bigger. It measures exactly 12”, and I am very thankful that that’s all it was because any bigger, and I wouldn't have been able to get it into the housing. It seemed well made, and although heavier that the stock one, it seemed only slightly heavier, and I thought it should work fine.
It also had 6 blades, as opposed to the 7 that was on the original. I had no idea what effect this might have on the performance.
You can also see that the blades are curved in the exact same way as the stock HF blades. I didn't know this in advance, and it just turned out that way. I wasn't sure if this was good or bad, because many have said that the unit would operate better if the blades were curved the opposite direction. It seems that HF is one of the only units that use this configuration. I may test this later by trying to reverse the direction of motor. Well, maybe?
So, when placing the new impeller in the unit, it turns out that the shaft on the motor is 20 mm but the new fan was ¾” or 19mm. I had to remove the hub on the new fan, and turn it on my mini lathe to enlarge it a little to 20 mm. No problem, it went fast, and I think I could have even done the same by using a dowel and some sandpaper.
The key was only slightly too big, so I hit that on my belt sander to get to final fit.
Now, I am not kidding, this new fan was a tight fit and I doubt that any larger impeller, whether blade length or width (a little over 3”), would have worked. I had to really maneuver the fan to get it on the shaft.
These are two pictures of the before and after, and you can see the overall fit is tight, although the picture on the right gives the illusion that there is more room than there actually is.
262486262487
Results:
I can't lie, I was pretty scared to fire this thing up. Thank goodness I have a remote, and could stand around the corner of my shop to protect myself from shrapnel. I had the inlet completely blocked to reduce the load on start-up. I got around the corner, and hit the button on my remote.
The unit started with a very slow, but continuous increase in RPM. It took about twice as long for it to wind up as the stock unit did. It was a little louder, but at a lower pitch than stock. It sounded like comparing a V-8 to a V-6 with a lower, more powerful sound.
It also took a full minute for the fan to stop after I shut it down. I didn't time the original one, but I bet this one takes twice, or even three times as long to wind down. Without doing a single test, I suspected that this mod may have worked as I hoped.
I ran it for quite a while, both loaded and un-loaded before doing any test, but I could already tell this thing was moving a lot more air.
Original Impeller:
Static Pressure = 6” WC (no air flow)
Un-loaded Amps = 7.2
Fully Loaded Amps = 8.5
Un-scientific Test = This thing kinda sucks.
New Impeller:
Static Pressure = 9” WC (no airflow)
Un-loaded Amps = 8.5
Fully Loaded Amps = 10.2
Un-scientific Test = This thing REALLY SUCKS!
After the test, I hooked everything back up. All ducting, the Thien separator, and exhaust bag, connected again. My table saw is the furthest tool from the dust collector, and also one of the worst tools to collect from. I opened the TS gate, and turned the collector on. There was quite a bit of noise as the collector seemed to be sucking the dust from the saw, so I shut it down and opened the access door for the saw.
WOW! I had never seen the cabinet so clean, unless I used my shop-vac to clean it.
I turned it back on to watch what was happening under the saw. There was a huge difference in the sound, and in the turbulence in the cabinet, plus almost all of the sawdust was being collected. Now I suspect that many of you have seen this with your dust collection systems, but for me, this was a first.
Now, this is all premature because I just finished the test a few weeks ago, and have not had significant amount of time with this set-up in use, but my initial excitement was so high, that I had to post this.
Your results could vary, and if you have a bad experience, forget I wrote this!
Also, keep in mind that in my opinion, I am just achieving with the Harbor Freight unit what those of you at lower altitude probably already experience. I am not trying to hot rod the unit to perform like a 5 hp cyclone.
Another member, Roger Rayburn who is also located at a similar altitude, has done the same mod based on my results. I can tell you I was a little afraid that this might go south for him, and it would be because he followed my lead. Luckily, he is well aware that I don't know much about any of this stuff. Hopefully he will join in on this post and give his results and impressions.
Anyway, very happy with the initial performance and want to thank all of the members who helped me make these improvements.
After starting this thread, http://www.sawmillcreek.org/showthread.php?197861-How-to-measure-dust-collector-performance, trying to get help understanding my dust collection, I finally came to the conclusion that the cause of my disappointment with my system was because of altitude. The members who responded, who have much more experience than I will ever have, led me through a series of test which led to the theory that my HF 2 hp dust collector needed a bigger impeller.
Here were the main points:
1) I didn’t believe that my unit was performing as well as others were reporting their HF units were.
2) My ducting is short, sweet, well designed with 6 x 6” gates connected to one 15’ length of 6” duct, and then directly to my machines which are all in a row along that 15’.
3) Removing all of the above, and also disconnecting the exhaust side of the system so I was only testing the blower and motor, I was only able to achieve a SP of 6” WC connected directly to the inlet (no airflow).
4) With a full load, my motor was only drawing 8.5 amps. This was with a completely open inlet and outlet. When hooked back up to the manometer to the inlet, (no airflow), the motor pulled about 7.2 amps. This indicated that the motor was really barely under any stress and was effectively being under worked.
The decission:
Because of the thinner air at 5,000 foot altitude, the unit needed a bigger impeller to achieve enough air movement to effectively collect dust. I should mention that I am not talking about fine dust collection, but rather getting the big stuff from my table saw, band saw, etc.
The fan housing appeared to be able to accept a larger impeller, and the motor should be able to spin a larger impeller too.
So, taking all this into account, I decided to try a larger impeller. But although others suggested a few different units in the 12” range, such as Rikon, and Grizzly, I used something different.
The Grizzly unit that one person tried failed because it was too big and heavy. The circuit breaker could not bring the unit up to speed before tripping. I tried to get one from Rikon, but they insisted on having the serial number of my unit to sell me one.
I took a chance and ordered a Jet 12” steel impeller, part # AB411059. I didn’t know much about it at all, but I was tired of not finding an answer to my problem.
What I used:
262485
As you can see, the unit is much bigger. It measures exactly 12”, and I am very thankful that that’s all it was because any bigger, and I wouldn't have been able to get it into the housing. It seemed well made, and although heavier that the stock one, it seemed only slightly heavier, and I thought it should work fine.
It also had 6 blades, as opposed to the 7 that was on the original. I had no idea what effect this might have on the performance.
You can also see that the blades are curved in the exact same way as the stock HF blades. I didn't know this in advance, and it just turned out that way. I wasn't sure if this was good or bad, because many have said that the unit would operate better if the blades were curved the opposite direction. It seems that HF is one of the only units that use this configuration. I may test this later by trying to reverse the direction of motor. Well, maybe?
So, when placing the new impeller in the unit, it turns out that the shaft on the motor is 20 mm but the new fan was ¾” or 19mm. I had to remove the hub on the new fan, and turn it on my mini lathe to enlarge it a little to 20 mm. No problem, it went fast, and I think I could have even done the same by using a dowel and some sandpaper.
The key was only slightly too big, so I hit that on my belt sander to get to final fit.
Now, I am not kidding, this new fan was a tight fit and I doubt that any larger impeller, whether blade length or width (a little over 3”), would have worked. I had to really maneuver the fan to get it on the shaft.
These are two pictures of the before and after, and you can see the overall fit is tight, although the picture on the right gives the illusion that there is more room than there actually is.
262486262487
Results:
I can't lie, I was pretty scared to fire this thing up. Thank goodness I have a remote, and could stand around the corner of my shop to protect myself from shrapnel. I had the inlet completely blocked to reduce the load on start-up. I got around the corner, and hit the button on my remote.
The unit started with a very slow, but continuous increase in RPM. It took about twice as long for it to wind up as the stock unit did. It was a little louder, but at a lower pitch than stock. It sounded like comparing a V-8 to a V-6 with a lower, more powerful sound.
It also took a full minute for the fan to stop after I shut it down. I didn't time the original one, but I bet this one takes twice, or even three times as long to wind down. Without doing a single test, I suspected that this mod may have worked as I hoped.
I ran it for quite a while, both loaded and un-loaded before doing any test, but I could already tell this thing was moving a lot more air.
Original Impeller:
Static Pressure = 6” WC (no air flow)
Un-loaded Amps = 7.2
Fully Loaded Amps = 8.5
Un-scientific Test = This thing kinda sucks.
New Impeller:
Static Pressure = 9” WC (no airflow)
Un-loaded Amps = 8.5
Fully Loaded Amps = 10.2
Un-scientific Test = This thing REALLY SUCKS!
After the test, I hooked everything back up. All ducting, the Thien separator, and exhaust bag, connected again. My table saw is the furthest tool from the dust collector, and also one of the worst tools to collect from. I opened the TS gate, and turned the collector on. There was quite a bit of noise as the collector seemed to be sucking the dust from the saw, so I shut it down and opened the access door for the saw.
WOW! I had never seen the cabinet so clean, unless I used my shop-vac to clean it.
I turned it back on to watch what was happening under the saw. There was a huge difference in the sound, and in the turbulence in the cabinet, plus almost all of the sawdust was being collected. Now I suspect that many of you have seen this with your dust collection systems, but for me, this was a first.
Now, this is all premature because I just finished the test a few weeks ago, and have not had significant amount of time with this set-up in use, but my initial excitement was so high, that I had to post this.
Your results could vary, and if you have a bad experience, forget I wrote this!
Also, keep in mind that in my opinion, I am just achieving with the Harbor Freight unit what those of you at lower altitude probably already experience. I am not trying to hot rod the unit to perform like a 5 hp cyclone.
Another member, Roger Rayburn who is also located at a similar altitude, has done the same mod based on my results. I can tell you I was a little afraid that this might go south for him, and it would be because he followed my lead. Luckily, he is well aware that I don't know much about any of this stuff. Hopefully he will join in on this post and give his results and impressions.
Anyway, very happy with the initial performance and want to thank all of the members who helped me make these improvements.