shark guard port size

[Steven Triggs]

I'm getting ready to order a shark guard, but am looking for input regarding what port size to order.

Delta Unisaw
Delta 50-760 Dust Collector

I don't have a duct system, and just hook my dust collector up to the tool I'm using with a 4" flexible hose using Rockler's quick connect fittings. My plan is to run a 4" hose from the saw cabinet and a ?" hose from the shark guard to a tee or wye with a quick connect fitting on its single side, and then hook the dust collector's 4" flexible hose to the tee or wye.

Anyway, I have no idea what the pros or cons of using a 2.5" vs 4" port for the guard would be.

Thanks.

[Paul Wunder]

Steven,

Hopefully, the airflow experts will chime in, but here's my take:

If you use the single 5" port off of the Delta 50-760 and run 5" flex to the saw, use a 5/4/4 wye (no T's) you may get enough airflow to use two 4" ports. Using the standard 4" fitting from the DC and 4" flex to a 4' Wye will not give you enough flow. I run my SG with 4" above and below but I am using a 5HP cyclone. I owned a Delta 50-760 and it was strong but I would not expect it to support 2 4" open ports at the same time

[Ryan Wood]

I dont have a shark gaurd but I have been thinking about getting one and what i would do is hook up my dust collector to the dust port in the saw and get a shark guard with a 2.5 dust port and hook my shop vac up to that. By doing it this way you would lose all that suction that you would by having 2 dust ports open at once. The othere reasond I would do this is because a shop vac has more more suction but less voluem than a dust collector.

[Prashun Patel]

I used to have a shark guard with a 4" port wyed from the rear port of the cabinet. Much better than my current saw stop with a 2" port off the guard going to a shopvac.

I vote 4 inch all the way.

[ian maybury]

As the guys say it basically comes down to how much airflow you have - which in turn depends on the capability of your fan, and what you are pulling through.

I don't know the unit Steven, but if it's a genuine 1.5HP running a typical say 12x3in impeller at 3,450rpm it should be capable of 7 - 800cfm if the fan is ported big enough to properly run a short (less than 10ft - the shorter the better) 6in dia flex hose. At that it should in theory be capable of running 2 x4in dia branches at the 350/400 cfm plus needed to give the 4,000ft/min minimum recommended for reliable chip collection and transportation.

To get this airflow (which is around or slightly below the OSHA recommendation - about half of the Bill Pentz/ASHRAE recommendation for effective fine dust entrapment) you would need to check that the fan is as described, or very close to it, and as well as keeping the hose short make sure the branch is a 45 deg Y.

It's hard to finger the effect of filter blinding, but my own experience was that the filters on small bag units blind quickly, and that the airflow (even without a big bore top guard) falls away quickly to become marginal/incapable of decent collection in this situation.

It should be possible to mock it up on your saw for little time and cost before committing to the guard.

Flow balancing could be an issue - if the airflow through the cabinet/lower connection on your saw is very restrictive you could end up finding that the relatively open branch to the Shark Guard would hog most of the flow, and leave the lower connection rather short of 'suck'.

Restricting the duct to the top guard would divert more flow to the cabinet, but could then leave the top guard short. This because fan HP is consumed in overcoming the pressure drop as well as in generating airflow - meaning that the cabinet would consume more than its fair share of the available fan output.

What this really means is that there should be a free flowing 6in dia line all the way from the branch to the filter, and a free flowing 4in dia in both branches to that from both inlets. If either is at any point more restrictive than that then the result will be reduced airflow/CFM at one or both connections.

The other variable is the Shark guard itself. It'd be worth checking with the maker as to how they feel about the set up you plan on running. The reason I mention this is because the guard has large inlet area, and probably needs decent airflow to pull stuff into it. Plus they will probably have a fair idea as to how it will run on you saw and dust collector combo.

I don't know how people get on with these large guards - they could get in the way of some operations.

Bottom line is that if it's as above it can probably be done, but it's sailing fairly close to the wind on fan output..

ian

[Bruce Darrow]

I vote for the 2.5 port.

It's what I got, and it works just fine. I have a 6" port I cut into the side of my PM 66, and the 2.5 overhead, sharing duty with my router table fence, which is on the end of my saw table. The 2.5 is reduced from a 6x6x4 wye on the same trunk feeding the cabinet. I just switch it back and forth as needed. Both lines are gated so I can play with respective volumes. I run a 3HP cyclone.

It is my (non-scientific) take that the dust coming off the top of the saw blade is A) quite fine (although not as fine as sanding dust) and therefore fairly easily captured from the small Shark Guard enclosure, and B) considerably less than that thrown down into the cabinet, so less air volume is needed.

Additionally, I have experienced small chunks of cedar or pine knots being sucked off the table and into the system and thin ripping strips cleaving onto the intake of the guard and flopping around above the spinning blade! This with only a 2.5 port. Very unnerving. But if it will do that, there is plenty enough suction for dust.

[Matt Meiser]

I have the 4 and love it. You can always close a blast gate partly to regulate flow. The only drawback to too much flow is the tendency to pick up small pieces.

[ed vitanovec]

My 4" hose to the Table saw has a wye and it branches off into a 2.5" hose to my Shark Guard, the dust collection works fine and it gets most of the dust.

[Jim Andrew]

I have the 4", and also 4" to my unisaw cabinet, think I would rather have a 5" to the cabinet and the 2 1/2 to the shark guard. The 4" in the cabinet is really not enough, as dust tends to build up down there, and I have to use a stick to push it into the opening to get rid of it. Sometimes a stick will get sucked up into the hose above the shark guard, and it goes right on up into the system, so don't think it is my dust system.

[ian maybury]

A 4in branch to the top guard from a 4in hose seems likely to struggle on a typical small bag filter collector...

ian

[mreza Salav]

Technically, if you have a 5" connected to your DC you'd have to have 4"+3" to get the closest surface area of ducts in ideal situation
(5" gives you 2.5*2.5*pi=6.25*pi and 4"+3" gives you 2*2*pi+1.5*1.5*pi=6.25*pi).
That's what I have on my tablesaw and it works fine.

[David Kumm]

I'd get the three inch port. The unisaw has pretty mediocre internal channeling so you want as much cfm in the bottom of the saw as you can get. The 3" port is small enough to use with a shop vac and big enough to hook into your dust collector when you get a bigger collector. Dave

[Chris Parks]

I'd get the three inch port. The unisaw has pretty mediocre internal channeling so you want as much cfm in the bottom of the saw as you can get. The 3" port is small enough to use with a shop vac and big enough to hook into your dust collector when you get a bigger collector. Dave

Any cabinet TS must have an inlet port equivalent to the exhaust or it will fill with saw dust. Air in equals air out.

[Rod Sheridan]

Hi Steven, 4" is too small to handle a cabinet port and an overhead guard port.

My saw has a 5" cabinet port with an internal hose and blade shroud, and a 2" port on the blade guard.

Dust collection is very good with short runs of flex and a 1.5 HP cyclone.

Regards, Rod.

[Ole Anderson]

Bigger is better? Not always. IMHO a 4" SharkGuard is just too big, visually and practically. I went with the 3" and it is more than enough for topside collection, as it is, I still pull offcuts up the hose. I went with a 5" bottom and 3" top and not just because Mr. Pentz said those were the optimal sizes. In your case where you are restricted to a 4" main hose, I would go with a 4" on the bottom and a 2.5" on top. You won't reach the optimal velocities for a perfect solution, but it will be the best you can do with what you have, and if in the future you upsize to a cyclone with larger pipe, you can keep the 2.5" SharkGuard and still have a good topside solution. Here is what a 3" looks like (now imagine it with a honkin 4" hose):
(The extra hose is needed as I slide my saw back if I need to rip an eight footer in my tight basement shop) 3" hose into a 4" blast gate into a 5" duct, and it works fine.