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Pipe Diameter vs Performance

31K views 45 replies 15 participants last post by  ORBlackFZ1 
#1 ·
My question is regarding the size of pipe from my Jet DC1100 to my Jet 12" jointer and Grizzly 20" surface planer.

Will I get better dust collection performance by running a 5" or 6" flexible hose from the DC to the tools rather than my 4" flexible hose?

Here are some of my woodshop details:
Dust Collector - Jet DC1100 with a Jet canister. It has a 6" port with a twin 4" adapter. It has been modified to include "Vortex" technology. (To get the Vortex, I used a Wok. The improvement was significant in keeping the filter from clogging.)

Second Stage filter - Shop design with a Thein baffle. See attached Sketchup and photos.

4 port manifold - Shop design and built. See photo. It has a blast gate for each port.

Hose - 4" flexible hose is used for large tools. 2-1/2" hose at each smaller tool.

Current power tools using the DC
:
- Craftsman Hybrid table saw (4" dust port)
- Rikon 18" bandsaw (4" dust port)
- Delta 17" drill press (4" dust port)
- Grizzly 20" surface planer (5" dust port)
- Jet JJ-12 jointer (4" dust port)
- Milwaukie Sliding Compound Miter Saw (2-1/2" dust port
- Shop design router table (4" & 2-1/2" dust port)
- Ryobi Scroll Saw (2-1/2" dust port)
- Grizzly Oscillating Sander (2-1/2" dust port)

Here are some of my thoughts.
1. I am a one person shop. Only one tool is used at a time. My shop is about 525 sqft. (Visualize a three car garage with a full bathroom in it.) I have a 10' ceiling with an 18" high beam running down the center, which reduces the overhead clearance to a little over 8' in the shop center.

2. I am ok with moving my DC and/or Second Stage filter between my two main work areas. I usually use the larger tools together. i.e. jointer and planer, table saw and router, etc. I use the smaller tools on my workbench and just run 2-1/2" flexible piping to them.

3. I feel the shop is too small to run permanent piping. Permanent piping appears to be a low cost/benefit ratio to me. My current thinking is that purchasing a higher performing movable DC would be more cost effective (and flexible) than running permanent piping to get better performance. Another thought is the size of the flexible piping. Is it more cost effective to just change the piping size to 5" or 6" for my jointer and planer?

4. I am just now getting into using rough cut lumber. I have been learning how to get the most out of my jointer and planer over the last few months. I purchased them both used from CL listings. I had my first 600+ bdft of maple delivered in May 2013. The load cost me $700 delivered and stacked below my back deck. The wood's moisture content is down to 20%. I have tuned up the jointer and planer with new blades and a good cleaning. While the maple drys, I have been practicing on other rough cut lumber.

5. I would like to improve the dust collection for both the jointer and the planer. I currently run a 4" flexible hose from my second stage filter to the jointer. The Jointer's dust port is poorly designed. I have already redesigned it, but not made the changes. I am trying to decide if I should change the port to a 5" or 6" opening.

6. The surface planer appears to do ok, but I think it can be improved. The planer has a 5" dust port, so I have 10' of 5" flexible pipe, a 5" to 4" reducer and then 4" flexible to the second stage filter. I believe that I would see an improvement if I could get 5" all the way back to the DC.

Let me know if there is any other information that I have forgotten.

Any suggestions would be appreciated.
 

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#2 ·
First I want you to know I am no expert on DC's and piping. I did do my own and for the most part it works ok. My main runs are 6 inch with 4 inch drops to each tool. I think 5 inch with my system would have been better because there is quite often about an inch of saw dust laying in the bottom or the 6 inch pipe. I will clean out if I let it run. I'm thinking the volume of air that comes through the 4 inch is enough to carry the saw dust, but when it hits the 6 inch pipe the flow volume drops and the heavier particials fall the the bottom of the pipe.

Maybe this is easier to visualize. If you had 4 inch to each tool, and that went to a 18 in main trunk. The volume flow in the 18 in is much less than in the 4 in. The 18 inch would fill up with saw dust until it got to a point where the flow/volume increased to where it carried the particals to the collector.

This may not have nothing to do with saw dust, but if you have 1/2 inch water hose, you will get a certain amount of water through it a specified psi over a specified time. If you switch to a 3/4 inch hose, at the same psi you will get 7 times more water out of it over the same length of time.

This goes to show, just a little diameter change can make a big difference in output. I assume this is true with vacuum dust collectors also.

The only one that plugs occasionally is the 4 inch from my planer which is a 13 inch delta. It only plugs if I really take a big cut. It also depends on the shape and size of chips also. But plugs at the planner output hole.

This info may or not be of any help. Just my 2 cents.
 
#11 ·
First I want you to know I am no expert on DC's and piping.

This may not have nothing to do with saw dust, but if you have 1/2 inch water hose, you will get a certain amount of water through it a specified psi over a specified time. If you switch to a 3/4 inch hose, at the same psi you will get 7 times more water out of it over the same length of time.

This info may or not be of any help. Just my 2 cents.
Not sure where you got that info from, but it's a little bit off. Switching from 1/2" to 3/4" might get double the flow or so, certainly not 7 times. Pipe capacity as a rule of thumb is 4X increase in capacity when doubling the diameter.
 
#4 ·
You may find just replacing some of the long flex runs with straight 4in pipe will have a big improvement.

A Wood magazine article on common dust collector flaws.

Flex is perhaps 3x the pressure drop of straight pipe.

http://www.woodmagazine.com/woodwor...st-collection/avoid-common-duct-design-flaws/

Another Wood magazine article on how to calculate the pressure drop of a system.

http://www.woodmagazine.com/woodwor...llection/figure-dust-collection-needs/?page=3

Everything we add in a system, pipe, fittings, blast gates, adds pressure drop. More pressure drop, lower air flow. As some point the air flow may be too low to keep the debris in the air stream, and then clogging can happen.

Each manufacturer will recommend a maximum duct size for a given machine. If you go too large a diameter, the air flow is again too low and the system will not carry the debris.

I think you should be looking at minimizing the amount of hose and fittings, they may be killing your performance.

Last year I removed a couple of "Y" fittings, replaced short radius 90's with long radius 90's, removed a 90, etc. This had a big improvement on suction and airflow at the machines.
 
#6 ·
I agree with Dave's comments. In addition, going from a larger hose at the tool down to a smaller hose at the DC is not generally the best approach. You may get better results with a 4" hose all the way to the tool. But, I'm not sure about that. If your DC has the airflow capacity for 5" (which it should since it has a 6" port), taking it all the way back to the DC at 5" should help. 5" all the way should be better than 4" all the way.
 
#7 ·
Thanks. That was my thinking also.

What do you think about going to 6" all the way? I was thinking about trying an experiment with purchasing a 5" to 6" convertor and trying out the 5" hose from the planer to the DC. It would be a minimal investment and give me some good direction. If the 5" worked, then I could just purchase 10' of 6" and try it.

The more I think about it, the more reasonable it sounds.
 
#9 ·
ORBlackFZ1 said:
Thanks. That was my thinking also.

What do you think about going to 6" all the way? I was thinking about trying an experiment with purchasing a 5" to 6" convertor and trying out the 5" hose from the planer to the DC. It would be a minimal investment and give me some good direction. If the 5" worked, then I could just purchase 10' of 6" and try it.

The more I think about it, the more reasonable it sounds.
6" could be better. At some point you will no longer get a benefit from increasing the hose size. And, as has already been stated, if you go with a hose that is too large for the DC, then you won't have sufficient velocity.
 
#14 ·
I have been reading Sandor Nagyszalanczy's book titled "Woodshop Dust Control". He had some of the same suggestions that have been posted on this thread. So, I decided to try a few of them.

I finished putting a new 6" port on my Jet JJ-12 jointer today. I had a couple of 6" to 5" reducers that I picked up at the local box store that I used with the 10 feet of 5" flexible hose that I ran between my Jet DC1100 and my Jet JJ-12. What a huge difference! The 20 foot of 4" flexible pipe was definitely a huge Static Pressure Loss!

I went ahead and ordered some 6" flexible hose from Woodworkers Supply to try next. It will be interesting to see how much difference the 6" makes over the 5".

Now, I have to make a new cover for my pre-seperater filter so it can handle 6" flexible hose. Anyone have suggestions for some inexpensive 6" ports?
 
#15 ·
Jet 2 hp 1200 with 5 in duct data

I changed all my hoods to 6 in then bought a Super Dust Deputy (SSD) after seeing the action of a small Dust Deputy. I failed to read the clearly marked box on the SSD that states a 5 in intake. Oops.

I bought long 6in to 5in tapered reducers from Home Depot (HD) adding this to the 6in hoods. I borrowed a Alnor Anemometer model RVA+ and measured the intake numbers at several spots with the results as follows;

1) 6 in impeller opening with a 90 degree joint measured 5676 fpm/1114 cfm

2) 6 in impeller opening with above plus 2 each 90 degree joints and 4 ft 6 in metal snap together duct 26 gauge from HD and it measured 5004 fpm/1001 cfm.

3) above data hooked to the SSD sitting on a 55 gal drum and 5 feet of 5 in metal duct from the intake of the SSD measured 5852 fpm/1170 cfm,

4) using 8 foot of 6in flex instead of 4 foot of 6in metal duct from the impeller to the SSD did not make much of a change when compared to #3 (5447 fpm/1089 cfm).

I did not hook up a 4 in duct but I believe using Bill Pentz data shows that just increasing to 5 in will give you better numbers. Therefore, I would have used all 6in duct, but due to my inability to read clearly marked info I used 5in with a lot more air/dust captured vs using 4in duct. I called Oneida and there will not be a 6 in intake and they do not recommend changing the intake size. Oh well I'll start taking reading lessons with the grandkids.
 
#16 ·
fredtina:

Thanks for posting the data, you have inspired me to continue upgrading my port sizes and pipe diameters. I have almost convinced myself that it is time to give up the portability of my setup and put in fixed piping.

Eric
 
#17 ·
Finished the Thein Top Hat

I finished the Thein Top Hat separator. It works very well. I also switched from 4" hose to 6" hose between the DC and separator. It makes a big difference! Next I will be integrating the separator in with my DC to shorten the 6" hose from 10' to 6".

I also changed the 4" hose between the separator and the Jet JJ-12 jointer to a 5" hose. I will upgrade it to a 6" as soon as I get another one. After a week of using the jointer with the new setup, I had no chip clogs in the jointer!!!

Here are some photos so far.

Photo #1 shows the Thein Top Hat separator on my barrel with 6" diameter hose.

Photo #2 shows a clamp that I made for the Jet DC-1100 to replace the standard two (2) 4" ports with one (1) 6" port. The DC-1100 port actually will accept the 6" flexible hose with a clamp, but I wanted to be able to quickly unhook the hose when I need to clean the workshop. The clamp allows me to twist the T knob and pull the hose connector out quickly.

Photo #3 shows the Thein Top Hat separator from the front. It is 8" tall and 20" in diameter. It has 6" port for both inflow and outflow.

Photo #4 shows the Thein Top Hat separator from the back.

This Top Hat designed separator replaces an in-barrel design that I have been using for a couple of years. The top hat has so far worked far better than the in-barrel design. I get very few "fines" in my filter or in my fines bag.

The only change that I would make is to widen the drop slot from the 1-1/4" dimension to 1-3/4 or even 2". The 12" wide jointer produces some chips that are large enough to get stuck in the 1-1/4" wide slot.

This project is worth the time, money and effort to build. If you would like more information, visit

http://www.jpthien.com/smf/index.php?board=1.0
 

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#18 · (Edited)
Sorry for tailgating this thread but my questions are exactly in line with the discussion.

I am putting together a new shop. It's about 600 sq ft in size (20x30ish) with 12 foot ceilings. I have a modest set of power tools but will be getting a new table saw - probably a Griz G1023 3HP or very similar. Only one machine active at a time.

I'm pretty serious about dust collection but there are just too many moving parts in the design process. A while ago I picked up a grizzly G1028Z DC for a song (<$100). Specs: 1.5 HP, 5 micron bag filter, 1300 CFM, 9" static pressure. It's probably a bit under powered for the size of shop and the filter is a dog compared to the current level of technology. So, I may eventually replace it but I would like to use it for a while to get a deeper understanding of DC techniques. Fortunately, my shop has 3 garage doors I can open so fresh air is readily available and my area has a pretty good year round climate.

I am thinking of getting some sort of cyclone separator - Super Dust Deputy seems like a decent choice - to keep the big stuff out of the DC.

So, ducting - I'm thinking a main run using 5" or 6" PVC across the ceiling with 4" flex drops to the tools. Probably 3 drops. The main run will probably be around 20' with a Super Dust Deputy right before the DC input. 5" PVC seems to be pretty rare so maybe I'm stuck with 6".

Questions:
  • Is the Dust Deputy going to choke my DC?
  • Is 1300 cfm too little for a 6" rigid pipe?
  • The Super Dust Deputy has a 5" input port - Would putting a 6 to 5 reducer at the cyclone negate the benefit of a 6" run?
  • I've read that rigid pipe is much more efficient than flex pipe. Would 4" rigid be as good as 5" or 6" flex? There doesn't seem to be a lot hard of data on this topic.

Anyway, thanks for reading this far!
 
#19 · (Edited)
Questions:
  • Is the Dust Deputy going to choke my DC?
  • Is 1300 cfm too little for a 6" rigid pipe?
  • The Dust Deputy has a 5" input port - Would putting a 6 to 5 reducer at the cyclone negate the benefit of a 6" run?
  • I've read that rigid pipe is much more efficient than flex pipe. Would 4" rigid be as good as 5" or 6" flex? There doesn't seem to be a lot hard of data on this topic.

Anyway, thanks for reading this far!
DD; I have no idea, but any separator is going to reduce airflow. Before you spend that much money, take just a fraction of the amount and a little time and build the Thein.


1300CFM: your collector isn't even close to that amount of airflow. You might be getting 1/2 that, probably less....nature of the marketing geniuses that worry more about sales than truthfulness. But if you did move 1300 CFM, that would be probably be about right to put on 6" pipe, even those of use with much larger collectors seldom use 6". The 6" easily allow 1000 CFM (with a 15" woth a 1`5" impeller), and Bill Pentz suggests that's the amount needed at the tool to collect the finest dust. 4" maxes out at somewhere in the 450 (+/-) CFM range.

Reducing at the separator: (my opinion) doing that would make the 6" duct a waste of time/money.

Flex versus solid: I haven't seen anything to support or refute what you ask...but flex is generally considered to have 3X+ the resistance to air flow that smooth pipe has.

Side comment: back in the text of your post you mentioned that "5" PVC seems to be pretty rare"). To my knowledge it's not available at all, At least in the thinwall stuff you want for DC. If you stay with PVC it's 4" or 6"...at even at that the 6" can be hard to find.

All this, of course, is just my opinion and you about those. Suggest you do a little reading here in the areas you are most curious about.
 
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#22 ·
Updated Dust Collection

Thanks to everyone for helping out this newbie. Here are some final photos of my updated dust collection.

I created a new cart for my Jet DC-1100. The update includes:

1. A new platform with a solid framework.
2. 4" diameter - smoother rolling casters.
3. mounting the blower vertically above my Thien Top Hat Separator.
4. A saw dust barrel below the Top Hat.
5. A nice handle for moving the cart around the shop.

The new cart allows me to move the dust collector closer to the equipment and use shorter flexible hoses. This has allowed my CFM at the equipment to be increased as well as the static pressure. I now have noticeable improved dust collection.

I had fun with creating the joinery. The bridle joints and the mortise/tenon joints are getting easier to create. I am hoping that I will be able to use my joinery skills on something more "showey" than "shop furniture" soon....
 

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#23 ·
Update: continued

I needed a way to be able to empty the saw dust barrel quickly and easily. I designed a couple of "hooks" to hold the Top Hat Separator off of the barrel one (1) inch. The barrel can be slid out onto a small wheeled cart for emptying outside my shop.
 

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#26 ·
Thank you for the compliment.

The joints turned out to be quite fun. The bridle joints on the short pieces, I did with a tenoning jig on the table saw. The bridle joints on the long pieces, I used the band saw.

The "half lap" joints I did on the table saw and used a wood chisel to clean them out. I was going to use the dado blade, but my test cut had too much tear out. I then tried a wood chisel and I got a cleaner cut.
 
#27 ·
Your cart is exactly the project I started yesterday, but I am still in the design phase. I have the same DC with an add on Walmart wok ($5.00) to keep the dust inside the collection bag (works great). The major difference will be that my impeller intake port will be turned 90 degrees from yours to face the output port of the SDD sitting on top on a 55 gal metal drum ($27.00 from Dan the Barrel Man, San Antonio) eliminating one 90 degree turn and some flex tubing.

I was concerned about changing the impeller position to the upside down position and potentially causing undue stress to any bushing/bearings/motor. I had called Jet but they were non-committal about any stress that might occur to making impeller upside down.

You saved me a great deal of design time. Thanks loads, Fred Thompson San Antonio

PS. Home Depot (HD) has 6 inch thin walled, black interior HDPE/SDR 43 pipe for $14.03 shipping free to my local store with delivery time <1 week. Lowe's Online has 666 wye/664 wye/22.5/45/90 fittings that perfectly mate to this pipe. It is available cheap with same free delivery as HD. I assume these are available across the US, but for sure here in San Antonio, TX. I drew blank looks previously asking for the ASTM 2729 pipe/fittings. Apparently they stock it as irrigation pipe.

Order on line with delivery to store because the negative feedback from both stores website mostly complain about damage in shipping. My stores allow to refuse the material if damaged thereby any aggravation with their return policies. I just do not have to accept damage goods at their store. No cost, no problem.
 
#28 ·
Fredtina:

Your cart is exactly the project I started yesterday, but I am still in the design phase. I have the same DC with an add on Walmart wok ($5.00) to keep the dust inside the collection bag (works great).
Yes, the wok does work. I installed a wok in my DC-1100 a couple of years ago. (I paid more than $5 for the wok. I guess I should shop at Walmart more.) The Thien Top Hat Pre-separator works even better than the Wok and I believe makes the Wok modification unnecessary. I may remove it and sell it.

The major difference will be that my impeller intake port will be turned 90 degrees from yours to face the output port of the SDD sitting on top on a 55 gal metal drum ($27.00 from Dan the Barrel Man, San Antonio) eliminating one 90 degree turn and some flex tubing.
Sorry, but I am not familiar with "SDD". Are you referring to a pre-separator? Eliminating bends is always good for improving your CFM (Cubic Feet per Minute) and SP (static pressure).

I was concerned about changing the impeller position to the upside down position and potentially causing undue stress to any bushing/bearings/motor. I had called Jet but they were non-committal about any stress that might occur to making impeller upside down.
I have a background in electrical motors. Unless, the manufacturer used poor quality parts, there will be no additional wear on the sealed bearings. Jet usually has pretty good quality motors.

You saved me a great deal of design time. Thanks loads, Fred Thompson San Antonio
You are welcome. I believe the phrase is "pay it forward".

PS. Home Depot (HD) has 6 inch thin walled, black interior HDPE/SDR 43 pipe for $14.03 shipping free to my local store with delivery time <1 week. Lowe's Online has 666 wye/664 wye/22.5/45/90 fittings that perfectly mate to this pipe. It is available cheap with same free delivery as HD. I assume these are available across the US, but for sure here in San Antonio, TX. I drew blank looks previously asking for the ASTM 2729 pipe/fittings. Apparently they stock it as irrigation pipe.
Corrugated pipe is not usually used for dust collection because it reduces your effective CFM and SP at the machine. It is also a huge electrostatic generator, which makes it much harder to move sawdust particles through the pipe. Corrugated pipe is good for slowing down flows especially water based mixtures.

If you are going to use corrugated pipe, spend as little money as you can get away with, because you will want the money later to purchase flexible hose that is designed for moving sawdust.

If you are concerned about flexible hose cost:

1. Shop around for good prices. Rockler has a 15% off sale going on for preferred customers. Grizzly has good prices on their flexible hose. I am very pleased with the 5" and 6" diameter hoses that I received from Grizzly. They are very good quality. I would not order 5" and 6" diameter hose from Woodworker's Supply again. They are ok, but they are definitely less flexible than Grizzly's.

2. Reduce the flexible hose length as much as possible. One of the reasons that I built this dust collector cart was to be able to include the collection barrel and Thien Top Hat Pre-separator all together. This allows me to reduce the amount of flexible hose I need to reach my equipment, which increased my CFM and SP at the equipment. Now I can just move the cart to the equipment I am using. I can use a 4' flexible hose instead of a 28' one.

I have quite a bit of extra 4" flexible hose, now that I have finished my cart. I will store it for a while and if I don't use it in a year, I will post it on Craigslist.

Order on line with delivery to store because the negative feedback from both stores website mostly complain about damage in shipping. My stores allow to refuse the material if damaged thereby any aggravation with their return policies. I just do not have to accept damage goods at their store. No cost, no problem.
Funny...that sounds like something I would post....

Let me know if you have any questions that I can answer.
Eric
 
#29 ·
Awww man!

ORBLACK FZ1 -

I started this topic (http://www.woodworkingtalk.com/f32/craftsman-hybrid-ts-65428/) without seeing your post. Search feature turned up nothing. Glad I ran across it though.

I see you have the craftsman hybrid ts as well and noticed that you mentioned in a previous post that you sealed it up. Would you mind sharing how/what you did to do so? I am working with a harbor freight DC without the thein seperator (will build shortly) but I was looking for improvement in clearing out the cabinet without having to manually move the dust from inside.

Any help would be great. You can post it in my thread to keep yours more on the overall topic you started as I don't wan't to impede on your original subject matter.

Thanks -

Johnny
 
#30 ·
ORBLACK FZ1 -

I started this topic (http://www.woodworkingtalk.com/f32/craftsman-hybrid-ts-65428/) without seeing your post. Search feature turned up nothing. Glad I ran across it though.

I see you have the craftsman hybrid ts as well and noticed that you mentioned in a previous post that you sealed it up. Would you mind sharing how/what you did to do so? I am working with a harbor freight DC without the thein seperator (will build shortly) but I was looking for improvement in clearing out the cabinet without having to manually move the dust from inside.

Any help would be great. You can post it in my thread to keep yours more on the overall topic you started as I don't wan't to impede on your original subject matter.

Thanks -

Johnny
Johnny:

Happy to help. Check out your post for a list of the modifications that I completed on my Craftsman 152.221140 Table saw to improve the dust collection.

Please remember, that I also improved my dust collection system. It may have influenced the improvements that I saw in the table saw.

Eric
 
#32 ·
Follow Up

Hi everyone:

It has been quite a few months and a couple of hundred gallons of saw dust later and my improved dust collection is working great! It was worth all the effort and work to get it improved.

I would like to thank everyone on this forum that contributed their ideas. It was a big help getting suggestions from people.

I have sold my Grizzly G5850z 20" surface planer with a four (4) knife cutterhead. I replaced it with a used 20" Grizzly G0454z (with a spiral cutterhead). I have also upgraded my Jet JJ-12 jointer from a knife cutterhead to a Byrd Shelix cutterhead. It was well worth the $600+. I should have done that a long time ago.

The dust clogs are now gone in my Thein Top Hat pre-seperator. The spiral cutterheads produce small square chips instead of "saw dust curls".

Thanks again,
Eric
 
#33 ·
Update: February 2015

Hi everyone:

I thought I would add an update to this thread for anyone that is interested in improving their dust collection.

I emptied my 45 gallon barrel for the 40th time (I think it was 40 times, I might have missed one or two times), since I added the Thein Top Hat pre-separator in Spring 2014. This was the second time I emptied my filter canister, since adding the Top Hat. The first time I had a little less than a gallon of fines in of my canister and the filter bag. All of the rest of the dust fines had been separated by the Top Hat.

Anyway, I decided to see how much of the dust fines were in my canister again. There was a little less than a gallon, just like the first time. If my calculations are correct, then after creating about 1800 gallons of saw dust (45 gallons per barrel X 40 barrel empties). The saw dust bag plus the amount of saw dust in the canister amounted to less than 2 gallons of saw dust that got past the Top Hat (roughly 0.1 percent of the total saw dust. (Your "gallon-age" may vary depending on the dimensions of your Top Hat and the unique specifications of your dust collection hoses, pipes, impeller, motor, etc.)

I believe that is the best I can do without switching to a cyclone dust collection system. I guess that I will have to budget for a cyclone next. Does anyone have a winning lottery ticket that I can have?

Anyways, in the mean time, some member wrote on a thread that I can't find, the best dust collection starts at the point of dust creation. So, time to tackle that aspect of dust collection in between projects! I will have to start a new thread for that topic.
 
#34 ·
Update: April 2015

I finally got the chance to take some CFM measurements with a CFM meter. Just a reminder, I am using a Jet DC-1100, which is advertised as 1100 CFM.

I did not clean the filter or any part of the DC before taking the measurements. The saw dust barrel was about 1/3 full (about 15 gallons). The fines bag had about a cup of fines.

Measurement at the 6" diameter opening for the blower measured on average 680 CFM. No hoses were connected to the opening.

Measurement at the 6" diameter input port for the Thein Top Hat Pre-Separator measured on average 360 CFM. No hoses were connected to the opening.

Measurement at the input of a 10' length, 6" diameter flexible hose measured on average 480 CFM. The hose was connected directly to the Top Hat input.

Measurement at the input of a 10' length, 5" diameter flexible hose measured on average 300 CFM. The hose was connected directly to the Top Hat input with a 6" to 5" reducer.

Measurement at the input of a 10' length, 4" diameter hose measured on average 300 CFM. The hose was connected directly to the Top Hat input with a 6" to 4" reducer.

Some of the results were as I expected.

1. The Thein Top Hat Pre-Separator reduces the CFM from 680 CFM to 360 CFM or about 47% with no hose attached.

2. The difference between using 6" diameter and 5" diameter over a 10' length is 480 - 300 CFM or about 37%.

Some of the results were not as I expected.

1. The Thein Top Hat Pre-Separator reduces the CFM from 680 CFM to only 480 CFM with a 10' length of 6" diameter flexible hose attached or about 29%.

Why is the input of the Top Hat only measuring 360 CFM, yet when I put 10' of 6" diameter flex hose on it, the end measurement is 480 CFM?

I concluded that there must be some turbulence at the input of the Top Hat when there is no hose connected. Adding the hose must make the turbulence disappear.

2. The CFM at the end of the 5" diameter and 4" diameter flexible hose both measure the same, 300 CFM.

I don't have a clue on this one. The only explanation that I can think of is that the 4" flexible hose I used for testing is more efficient material than the 5" flexible hose that I used.

Sorry, but no testing results for the static pressure, yet.

I hope this starts some discussion....
 
#35 ·
I came to your same conclusions as I read through your post. Makes no sense that the top hat reduces it to 380 but adding a hose causes it to increase. Every time you add something it should subtract?

Also, 5" vs 4" should not have the same CFM. Like you said, maybe it's a really good quality, somewhat smooth walled 4" and the 5" hose was ribbed beyond belief?
 
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