Dust Collector ??

2bits · Post by **2bits** » Wed Jan 04, 2012 6:19 pm

I found a Shopsmith Dust collector last weekend and my plan was to change out the three 2 1/2 inch ports to a 4". my reasoning was to attach it to one of the trashcan type cyclone lids which has 4" ports. Then, I could reduce down to fit the Shopsmith or "Y" off if I needed a couple of 2 1/2" intakes. I went to the Shopsmith site and they no longer sell the 4" elbow.
My question is, Did they stop offering this for good reason? I looked at the Dust Collector and could not see a place to swith out to a 4" intake.
Any suggestions,comments, and/or advise will be sincerly appreciated.

damagi · Post by **damagi** » Wed Jan 04, 2012 8:25 pm

2bits wrote:I found a Shopsmith Dust collector last weekend and my plan was to change out the three 2 1/2 inch ports to a 4". my reasoning was to attach it to one of the trashcan type cyclone lids which has 4" ports. Then, I could reduce down to fit the Shopsmith or "Y" off if I needed a couple of 2 1/2" intakes. I went to the Shopsmith site and they no longer sell the 4" elbow.
My question is, Did they stop offering this for good reason? I looked at the Dust Collector and could not see a place to swith out to a 4" intake.
Any suggestions,comments, and/or advise will be sincerly appreciated.

Lack of popularity is what I remember reading.

http://www.shopsmithacademy.com/SS_Arch ... ection.htm

That sawdust session has some discussion of dust collection, and a design for a box which combines the intakes. However, you should be able to easily adapt using a 4" port and some plywood.

If you remove the shopsmith nameplate there are 4 phillips head screws which hold the inlet adapter in place. remove those and you are at the main inlet.

FWIW, I recently sold my SS dust collector in favor of one of the famous HF 2HP ones...need to install the thien baffle and get it set up now that i think about it.

8iowa · Post by **8iowa** » Wed Jan 04, 2012 9:33 pm

A 4" connection on the DC3300 is probably not a good idea. This statement contradicts the deeply ingrained assumption that "the bigger the pipe the better the flow".

Consider the fact that testing has shown that the velocity of the airstream has to be at a minimum of 3500 ft/min in order to keep dust and chips suspended in the turbulent airflow. As long as a dust collector meets this velocity requirement, and has enough capacity (cu. ft./min.) to take away the dust & chips as fast as the machine generates them, then the the dust collector will perform adequately.

With 2 1/2" ports and hoses (one 10' and another 16') the DC3300 satisfies that condition. I have two DC3300's, one here in Gainesville and the other in my Upper Peninsula workshop. The DC3300 works fine on all my tools except for a 3 HP 15" planer. Even with this planer, if I keep my cuts to no more than 1/32" the DC3300 has enough capacity.

If one is to change to 4" connections on the DC3300 the velocity will decrease inversly to the ratio of cross sectional area. Thus a velocity of 3500 ft/min would fall to only 1360 ft/min. Dust & chips would then accumulate in the hoses and piping and the system would fail.

Going to a 4" system would then require a larger dust collector with more HP in order to get the velocity back up to 3500 ft/min. Sadly, many home hobbiest woodworkers, who have very limited space to begin with, are oversizing their dust collector systems (not to mention additional electrical expense).

"The bigger the pipe the better the flow" mindset is a tough nut to crack. Frankly, I doubt that my above discussion has even made a "dent".

2bits · Post by **2bits** » Wed Jan 04, 2012 11:53 pm

I guess I'm a little confused here

If the DC has three 2 1/2" ports,then the combined ports would equal 7 1/2 ". 8iowa, I guess I am missing something here. Please forgive my ignorance in calculating airflow.
I am trying to figure the best way to use a cyclone type pre-collection can to keep the "big" stuff from getting sucked into the impellars on the DC. I am hoping to not create some "Frankensucker":eek: looking contraption with a mass of hoses and reducers (unless it works:D ).
The other option I was cosidering was to get a 4" "Y" and reduce it to two 2 1/2"s to connect to the 4" outlet on the cyclone trashcan lid. I don't want to have too many adapters/reducers etc. to reduce airflow to an unusable flow.
I will still have to reduce the 4" intake to connect to the shopsmith or router table ports. Any additional thoughts will be appreciated.

damagi · Post by **damagi** » Wed Jan 04, 2012 11:57 pm

2bits wrote:I guess I'm a little confused here If the DC has three 2 1/2" ports,then the combined ports would equal 7 1/2 ". 8iowa, I guess I am missing something here. Please forgive my ignorance in calculating airflow.
I am trying to figure the best way to use a cyclone type pre-collection can to keep the "big" stuff from getting sucked into the impellars on the DC. I am hoping to not create some "Frankensucker":eek: looking contraption with a mass of hoses and reducers (unless it works:D ).
The other option I was cosidering was to get a 4" "Y" and reduce it to two 2 1/2"s to connect to the 4" outlet on the cyclone trashcan lid. I don't want to have too many adapters/reducers etc. to reduce airflow to an unusable flow.
I will still have to reduce the 4" intake to connect to the shopsmith or router table ports. Any additional thoughts will be appreciated.

~15 sq inches of area is the 3 2.5" ports combined, while one 4" port is 12.56 sqin

8iowa · Post by **8iowa** » Thu Jan 05, 2012 9:45 am

A dust collector needs to do two basic things, keep the velocity at or above 3500 ft/min, and have enough capacity, cu ft/min, to take away the dust & chips as fast as the machine generates them.

Capacity is a function of the size of the fan and the HP driving it. A 2 HP dust collector is going to have more capacity than the DC3300, probably over 1000 cu ft/min as opposed to 380 with the 1/2 HP DC3300. This also enables the 2 HP unit to keep the velocity at 3500 ft/min or higher with a 4" piping system.

Thus, a 2 HP dust collector with it's 4" diameter pipes and hoses will certanly collect the dust and chips from your home workshop. However, if the DC3300, with it's 2 1/2" hoses will also accomplish the same result, why would a small shop hobbiest want to devote more valuable space to the larger unit? Can you imagine stepping over 4" hoses on the floor, or having 4" pipes on the limited space walls and ceiling? A 2 HP motor will also likely require an electrical upgrade.

The DC3300 has three 2 1/2" ports. There is a slight loss of capacity going from one hose connected to two, however the velocity requirement is still met. The nature of an AC induction motor, with it's flat speed torque curve, will enable the motor to increase power as the second port is opened, possibly up to 3/4 HP. (another misunderstood fact is that opening up the intake on a blower will actually increase the the amount of air flow and drive the motor HP higher) I've never tried to operate the DC 3300 with all three ports in use.

With the DC3300, the reason the velocity requirement is still met with two ports open is because the openings are still 2 1/2" diameter (4.9 sq in). It's this diameter that determines the velocity, not the addition of the square inches of both ports.

Just keep in mind the fact that anytime you go from a 2 1/2" hose to a 4" opening, the velocity will decrease by a factor of about 2.5, and dust & chips accumulation might be a problem.

JPG · Post by **JPG** » Thu Jan 05, 2012 3:21 pm

The area of a 2 1/2" hose is 4.9 in².

Most 2 1/2" hoses that I have are effectively 2 1/4" which gives an area of 3.97 in².

The three hose ports on the dc have a total area of slightly less that 12 in².

Although that is only slightly less than a 4" 'hose' as Nick has illustrated in the saw dust session on dc system design, the ss dc cannot provide both sufficient air flow and static pressure to work effectively with 4" ducts.

IMHO the reason the 4" adapter is no longer offered, is it was a bad idea and customer dissatisfaction ensued when offered.

Now as for 4" from dc to separator, then smaller to pickup points, I think that would work, but keep the 4" section short.

P.S. I meant to link to Nick http://www.shopsmithacademy.com/SS_Arch ... ection.htm

robinson46176 · Post by **robinson46176** » Thu Jan 05, 2012 3:40 pm

This is a very appropriate subject for me this month since I am setting up my new shop and dust collection is such a big part of it. I have a lot of thoughts on the subject and a long history of collection in the shoe repair business but mostly only in theory in the woodshop. For years I only had shop vacs in the woodshop and since I now have a 2 HP HF and a 1.5 HP Penn State collector I have just been using them as portable and stepping over the 4" hose when needed. I will start out the same way in the new shop since I don't really know what the layout will settle into in actual use. I have 2 large cyclones and will likely use the slightly smaller one in the woodshop It came out of my uncles shoe shop and was sat up in the basement. It has a small box about 6" tall and maybe 16" square on the bottom of it with a front panel attached with 2 wing-nuts to open it to empty it out daily. It used a big cloth bag up on the top where the air exited. It was at the end of the collection line under pressure. I will use it ahead of the blower much like a huge Dust Deputy. I expect to cut most of the bottom out of that clean-out box and bolt on a short big hose into a drum. In this case the cyclone will be under suction rather than pressure as it was in my uncles shop. Instead of the bag on top the exiting air will be filtered by the bags on the regular dust collector.

Now...
I am giving some thought to setting up both of my collectors in a manner that will allow me to run either one or both of them at the same time... I haven't worked on that one a lot yet but want to consider it. My 5 HP planer moves a "LOT" of chips at full cut on rough lumber. In some really rough stuff I have taken as much as 1/4" off in a pass.
A lot depends on what I find myself doing. If I am going to be running a huge batch of rough stuff and the weather is decent I may just roll the planer to the door or outside and just let it blow the shavings all outside and then clean up with a rake. Another option is to set up a 6" radial vane blower I have and pipe the shavings directly to a farm wagon or my old farm dump truck.
On another note one of my BIL's bought a 1HP collector that seems to do a fine job but only makes about half of the noise. It is still a conventional motor. I do not like the collectors with a universal (brush type) motor. While effective they really seem to scream loudly.
I am also planning a squirrel cage unit for quiet fume venting and maybe for fine (floats in the air) sanding dust.

.

2bits · Post by **2bits** » Thu Jan 05, 2012 6:14 pm

I did watch this Sawdust sessions http://www.shopsmithacademy.com/SS_A...Collection.htm a couple of times and I am not sure how he connects the "octopus" to the DC.
I think I will first try using a couple of elbows from the 2 1/2 ports to a 2 1/2 tee, then use a reversed 4"to 2 1/2" reducer (increaser) and as short of a section of 4" as possible to the cyclone exhaust side. Then run a 4" "Y" off of the cyclone intake and reduce it down to 2 1/2" for most uses and try a short run of 4" for the times I use the planer.
It may not perform to optimal standards, but if it keeps the dust out of the air and in the can I will be happy.
This reminds me of a Fire Hydralics class I took some 20 odd years ago. Using the friction loss formulas it was concluded that the hose lays we used in wildland firefighting would not work. We spent days debating with the city guys that, while it may not provide the reccomended g.p.m. at the nozzle, we did get water up the mountain and the fires were put out.

beeg · Post by **beeg** » Thu Jan 05, 2012 6:27 pm

2bits wrote:I found a Shopsmith Dust collector last weekend and my plan was to change out the three 2 1/2 inch ports to a 4". my reasoning was to attach it to one of the trashcan type cyclone lids which has 4" ports. Then, I could reduce down to fit the Shopsmith or "Y" off if I needed a couple of 2 1/2" intakes. I went to the Shopsmith site and they no longer sell the 4" elbow.
My question is, Did they stop offering this for good reason? I looked at the Dust Collector and could not see a place to swith out to a 4" intake.
Any suggestions,comments, and/or advise will be sincerly appreciated.

That DC was designed for 2.5 hose.