Shark Guard and Dust Collection

[alex wetmore]

I have a pretty basic BT3100 setup, but it does have the addition of a Shark Guard.

I also have a Jet DC-650K dust collector (650CFM, 4" connection).

I mostly use a ZCTP with the saw.

My dust collection plumbing right now is very simple. A 2.5" to 4" reducer is plugged directly into the saw's dust port. This is connected with 1' of tubing to a 4" Y, which is then connected with 5' of tubing to the dust collector. On the other end of the Y is a 4" to 2.5" reducer with 10' of tubing going up to a coat hanger hanging from the ceiling and then back down to the Shark Guard.

I think my Shark Guard is a 3.0 model (it is a bit over a year old). The dust port is about 2" and came with a shim to make it work with 2.5" tubing.

Dust collection is good, but not great. A fair amount of dust is usually flung out of the front of the Shark Guard onto the front of the saw. When I'm making dado's (I do this with the regular blade and just make many nibbles) dust collection is awful.

I think that my Dust collector is somewhat starved for air. When I run it without the Y (so there just 4" tubing) the dust in the collection bag makes a nice swirl. When hooked up to the saw as described above there appears to be a lot less air movement inside the collection bag.

What can I do to maximize my dust collection with the SG? Is there a way to add a larger port to it to get additional air flow. I've noticed that some users are drilling a hole into the front of the ZTCP which looks like it could help a lot with making dados. Where is this hole located?

I'd be interested in seeing how other people plumb their dust collection from the SG and combine this with the dust port on the saw. My solution (a coat hanger) is probably not ideal and might result in a sharper than ideal bend in the 2.5" hose.

alex

[drumpriest]

Alex, my setup is almost identical to yours. ZCTP are great for chipout, but the limit the amount of dust that will go under the table, leaving more for the shark guard connectin to grab. When making a dado, the only dust collection there is the under table part. You might want to consider a blast gate to the guard, maybe taking it out will improve the air flow to the belly pan when making dado cuts.

Also, make sure that your Y connection isn't a T connection, as a 90 degree bend is BAD BAD BAD.

Also, when making a cut, make sure that your blade isn't too high. The guard will have gaps on either side of the blade if it's higher than needed. Just slide the stock under the guard beside to blade to see how high you need it to be in order to clear the shark at the back.

I am also eagerly awaiting anyone else's thoughts on this one.

[Tom Miller]

quote:Originally posted by alex wetmore

My solution (a coat hanger) is probably not ideal and might result in a sharper than ideal bend in the 2.5" hose.

It's not the coat hanger, it's the 10' of 2.5" hose. You might want to try plumbing 4" rigid pipe up and over, or at least 4" hose. (The pipe is way cheaper, though.

That's how I have my DC plumbed to the shark. I have a 4" S&D (sewer and drain PVC) drop with a 4 to 2.5 reducer and a couple feet of 2.5" hose to the SG.

Regards,
Tom

[alex wetmore]

My problem with rigid piping is that I'm working in a small space (this is also why I have a small DC). I need to be able to put the table saw away when I'm not using it. I also want to be able to use the DC with other tools. Flexible tubing makes it much easier for me to do these things.

I am using a Y, not a T.

Basement space is competing for 3 different hobbies: the wood workshop, the bicycle workshop, and beer brewing. I have to push the tablesaw out of the way when I need the floorspace for other projects.

It sounds like things might improve if I can make the tubing shorter and make sure that there are no sharp bends in it. Right now I think there is a sharp 180 and another semi-sharp 90.

alex

[lrogers]

I currently do not have make dust collector hooked up. I recently moved and I'm using the garage as a temporary shop. Bigger on space, but very under powered/lighted. Once the new shop is built I'll get the Dc out of the old shop and hooked up. The old shop was a small 12'x15' building. I had the collector in the corner, and had it hard piped to just before the center on the shop. It came out of my collector 8" reduced to 6", made a turn at the center of the shop and came forward about 4'. There it reduced to 4" and wyed. I attached my blast gates (shop built) right to the ends and a attached a 10' section of 4" hose to one gate. That served the saw and everything on the right side of the shop. The other wye had a quick connect for the 4" hose attached to the band saw. I also made an adapter that fit into the quick connect that I could attach a small hose that went to the Shark port. I used bungie to suspend the hose and the hard piping. This worked out very well for me. If you click on the link under my name, there are some pictures of the old set up that might give you some ideas.
Definetly limit the length of the smaller hose.

[alex wetmore]

Thanks for the links to your photos, they gave me some good ideas. I enjoyed looking at your ultimate tool stand. I've been thinking about trying to make a similar workbench/miter saw table.

alex

[Stytooner]

Welcome aboard, Alex. Not only did you buy the best blade guard on the market, but you just found the best Forum on the internet. Period!
I think you will find that there aren't any overhead guards that will be able to get the dust for the type of cut you mention. It will pretty much be left to the table collection area. I think the suggestion for blast gates is a particularly good suggestion. This will allow you to regulate the amount of suction between both the bottom and the Shark. You can close off the bottom some and then the Shark would collect more. Not on dado's but on other standard cuts.
Another thingthat may be beneficial during dado cuts like you describe is using the standard throat plate. Now it won't help for chip out, but you can scribe it first with a utility knife if its critical that you have fine crisp dado's. The standard throat plate will collect more dust under the table than a ZCTP.
I look forward to hearing more from you, Alex.

[LCHIEN]

I think dust collection varies by type of cut.

I often use a finishing pass with the saw where I rip off 1/16th-1/8th of an inch. This tends to blow a lot of material out the side and all over the table top and SMT.

Dados by nature have the blade buried so virtually all the cuttings go down. I think regardless of whether its a ZCTP or the factory dado plate. If you think about it, there's no other place to go.

Through cuts tend to throw material both up and down, making above and below capturing necessary for a real clean operation.

I think I'm a long way from capturing all the dust from my table saw.
My broom and shop vac still earn their keep.

[alex wetmore]

On a related subject does anyone have a good suggestion for dust collection from a SCMS?

I was thinking about copying the cardboard venturi design found in "Woodshop Dust Control" by Sandor Nagyszalanczy. Has anyone else built this and found it to be effective?

I have an extra ZCTP so I might try drilling an extra hold near the end to pull down dust when making dado's. This sounds better than using the larger throat plate. In the past I've also made dado's on the router table, but that is a huge mess.

alex

[JimD]

I have a 1 hp Delta DC connected to the BT3100 with a 4 inch flexible line to a Y right at the saw. One side of the Y goes to the stock connection to the blade surround through a 4 to 2 1/2 adapter (or whatever size this is, I forget). The other side of the Y goes to a port in the movable base that sucks up under the saw. I added the second port because I noticed I built up dust under the saw even with the port on the blade. I also block off unnecessary openings on the saw to force the air to come mainly past the blade (some with tape, some with wooden blocks, some with sheet magnets). Lastly, I experimented with openings around the blade in the zero clearance throat plate. If you open things up around the front of the blade, you defeat the purpose of the zero clearance - control of chip out. I did not find drilling holes to make much difference. I got slightly better results by using a router to make the slot for the blade wider on the back half of the blade. A slot width around 3/8 to perhaps 1/2 inch seemed to work best. My experimentation was to make rips in a piece of 2x4 and take a picture with a digital camera of the dust on the top of the saw. I tried making the back half of the opening anywhere from 3/16 inch (barely wider than the blade) all the way up to 3/4 inch. The biggest opening may have been the best but I was uncomfortable with that large an opening around the blade - offcuts could go into the blade. I never got to zero dust on the top of the saw. I convinced myself that a modified zctp was about as good as the stock throat plate at controlling dust, however. I now use a wooden throat plate where the front half of the opening is blade width but the back part is 1/2 inch wide (with the blade in the middle). My next one will probably be the same except 3/8 wide with the extra opening all on the left side of the blade. This also seemed to make a slight difference - probably because the blade surround is open on the left so the normal suction path is better on the right.

Jim

[drumpriest]

There is a discussion going on related in the shop layout forum, where it's been stated that moving to a 2.5" hose at the Y may be a good idea because it is closer to a consistent air flow volume. 2.5 up and down make 5, moving from 4 at the DC.

As to the SCMS, I have NO idea. that thing is the messiest tool in my shop.

When I make dados, I tend to do it with a hand router outside.

[alex wetmore]

Do you know of a source for a tapered Y? The "Woodshop Dust Control" book suggests that these are more effective than using a standard Y along with reducers.

I've been hoping to find a Y that goes from 4" down to 2 2.5" hoses with a nice taper, but haven't found one.

2.5" and 2.5" don't make 5" since we are working with diameter, not area. A 2.5" hose has a cross section area of about 4.9 in^2. A 4" hose has a cross section of about 12" in^2. So a single 4" hose should be able to move more air than two 2.5" hoses.

alex

[drumpriest]

Alex, you are correct, we are actually talking about a circle cross section. So for a 4"

12.56636 square inch area

for a 2.5" pipe

4.908734375 square inch area.

therefore for 2, it's right around 10" vs 12.5". You are restricting it slightly, but it's much closer the the 12.5" than a Y into 2 4" pipes, which would yeild 25" area. That's the theory anyway.

The test is what matters, I havn't tried it yet, but I will and let you know what I find.

Ken (kwgeorge) thinks it's working better for him.
I'd also like to know where to get a tapers fitting, I looked and looked and couldn't find any.

[vaking]

Alex,
I have a similar situation and problem. I have a DC very similar to yours, it is also Jet, but it is JSL-610DC (610 CFM; 3/4hp; 4" connection). I have a small basement shop, so I use the DC with one machine at a time by just connecting the hose. Until now I had a reducer installed right on DC and a shopvac hose was connecting from DC to a machine. It worked OK but I just got a shark for BT3100 and I made router table with dust collection from the fence and below the table, so now 2 machines in my shop could use the Y-split hose. My next project is to take a 10 gallon metal can and make a lid for it to turn it into dust separator. The lid will have 1 4" connection for the hose going to DC and 2 2-1/2" connections for hoses going to the machine. One of the 2-1/2" connections will have a blast gate so I shall be able to use the setup with 1 or with 2 hoses. I don't know yet how it will work, many people say dust separator helps managing the dust and I think eliminating the Y-connector completely by splitting hoses at the lid of separator might help too. Only time and test will tell.

[JimD]

Cross sectional area is a good first cut at looking at airflow but there are many other factors. Pipes with smooth sides move more air, for instance, than pipes with irregular sides (like flexible pipe). The resistance comes from the outside of the pipe, mainly, so small pipes have more resistance than is suggested by the ratio of the open area. They have a different ratio of circumference to area. (While two 2.5 pipes have 80% of the cross sectional area of a 4 inch pipe, they also have 125% of the surface area so the airflow will actually be less than 80%).

The practical thing I get from facts like these is to run as little smaller diameter pipe (like 2.5 inches) as possible if I want to maximize airflow. Do the area reduction as close to the source of dust as possible. Keep runs of flexible pipe, regardless of diameter, as short as reasonably possible.

DCs are different from vacumns in that any restriction in the piping has a much larger effect on the airflow than it would with a vacumn cleaner. They move much more air than a shop vacumn or home vacumn cleaner but only if you give them a big area to move it through. We need to keep their general operating principals in mind as we design the piping runs.

Jim