Dust collection: enlarging machine dust ports.

[Dan Forman]

I have been studying up on dust collection systems, learned lots. According to Bill Pentz's site, one should enlarge all existing 4" ports in our machines to at least 5", if we are to capture the really fine dust which is most damaging. Apparently even a short neckdown to 4" will kill the airflow to the point that the fine dust will not be captured. Has anyone here actually modified their machines to expand the dust port to 5"?

[Terry Hatfield]

Dan,

I have modified quite a few of my machines to 6" ports using mostly readily available and cheap HVAC fittings. It does make a tremendous difference in the performance.

There are lots of pics and such on my site in the "Shop Tour" if you would like to check it out.

Terry

[Jeff Sudmeier]

The neck down does cause a big drop in air flow, so if you are running 6 inch ducts, it is best to have a 6 inch port on whatever you are collecting from. If you are able to upgrade all of them, you will get better performance.

[Steven Wilson]

This is one area where I disagree somewhat with Bill Pentz. You don't need 800 CFM to every tool. Some of the smaller tools are effectively evacuated with smaller DC ports. For example a 4" DC port is appropriate for a 6" jointer and would be for an 8" jointer if it didn't clog on chips so much (5" or 6" port not so much for dust but to keep from gloging with larger chips). IMNO the 12" lunch box planers are reasonably served by a 4" DC port although a 5" port would be handy. Port size depends on the machine.

[Bill Arnold]

I have been studying up on dust collection systems, learned lots. According to Bill Pentz's site, one should enlarge all existing 4" ports in our machines to at least 5", if we are to capture the really fine dust which is most damaging. ...

I've read through a lot of the data on Bill's site and can't disagree with most of it. But, when a vendor preaches a 'doomsday' message, then tries to sell something, I look elsewhere.

I get decent dust/chip collection on my equipment with the 4" ports built into them. Would a 5" or 6" port be better for my tablesaw? Maybe, but the major issue with my tablesaw is that I don't have top collection and haven't decided how to approach it since I have a router in the extension.

Regards,

[Bill Lewis]

Almost all of my ports are 5". After the gate, I use 5" flex hose then reduce down at the machine with a 5x4 HVAC reducer. It absolutely works just fine with my DW733 planer. The PM 54A jointer is also reduced this way. It has some spillage, but I think there are other issues, like an open bottom base cabinet, that need to be addressed first. Ultimately I may upsize to a 5", but not after fixing the leaks first. I have even reduced the 5" to 2.5" for the CMS, then reducing the 2.5" to 1.5" at the saw. It works with at least 80-90% efficiency.
So I'd have to say that, in general, the reduction at the machine is probably not as much of an issue as with the size of the DC pipe leading up to it.

[eugeniusz luzar]

I have been studying up on dust collector systems, learned lots. According to Bill Pentz's site, one should enlarge all existing 4" ports in our machines to at least 5", if we are to capture the really fine dust which is most damaging. Apparently even a short neckdown to 4" will kill the airflow to the point that the fine dust will not be captured. Has anyone here actually modified their machines to expand the dust port to 5"?

My first accessory mistake was buying a transition that mated my 4" dust collection hoses to the tiny 1.25" port on my band saw. So little air was moved I went back to using my powerful shop vacuum on all tools with small ports. I also bought the 5" replacement port for my band saw lower port.

[Mike Chalmers]

If 6" ports were so essential, why do most machines come with 5" or smaller, mostly 4"? Why do most machines seen on woodworking shows have 5" or smaller? I am not saying that 6" openings would not be better, I do not have the data to support such a position, however, we can't all afford a purist approach. Nor, in my opinion, is such an approach necessary for most people.

[Robert Engel]

What are the big dust producers? TS, BS, DS. That's where it matters.
The only one I could possibly change to 6" ports is the DS.
Very difficult on the BS and TS I would have to cut new holes somewhere.

Planers and jointers produce shavings almost entirely don't worry about them.

Bottom line I don't think it will make a noticeable diff.

I still use a respirator messing with Chinese ply or MDF.

[Rod Sheridan]

If 6" ports were so essential, why do most machines come with 5" or smaller, mostly 4"? Why do most machines seen on woodworking shows have 5" or smaller? I am not saying that 6" openings would not be better, I do not have the data to support such a position, however, we can't all afford a purist approach. Nor, in my opinion, is such an approach necessary for most people.

Hi Mike, it's because the manufacturers don't have to meet a standard for dust collection performance in NA.

Buy a Euro machine and you'll find that the ports start at 120mm, and the machines come with a performance statement as to how much dust they emit at rated airflow. The airflow is also specified in the equipment manual.

In addition, they're designed for dust collection, for example the saw will have a shroud below the blade, and there will collection above the blade.

Regards, Rod.

[Phil Thien]

Hi Mike, it's because the manufacturers don't have to meet a standard for dust collection performance in NA.

Buy a Euro machine and you'll find that the ports start at 120mm, and the machines come with a performance statement as to how much dust they emit at rated airflow. The airflow is also specified in the equipment manual.

In addition, they're designed for dust collection, for example the saw will have a shroud below the blade, and there will collection above the blade.

Regards, Rod.

What does the statement for your machine indicate it emits for the various functions?

[Jim Andrew]

It seems to vary by machine. My 15" Grizzly planer works fine with a 4" port. I planned to change it, but it works so well see no need. My G9983 widebelt had a 5" opening, and saw dust on the belt falling off on the discharge side of the sander. Looked at the port, and it had a round pipe welded onto a flat plate on top of a 5" square. So I cut the round pipe off, and made a 5" square to 6" round adapter. Less saw dust now. If I had a bigger dust collector, could cut down on that. Planning to make a under table port for my mm16. Already has a 4", so another 4" would work just fine. When I got my K3 Hammer tablesaw, was surprised to find the guard had a 2" port. Hooked it up, and it works fine for over the blade dust collection. The cabinet is just 4", and it seems fine as well, except when several thin strips plug it up. Hard to get the strips out of that 4" flex hose.

[Rod Sheridan]

What does the statement for your machine indicate it emits for the various functions?

Hi Phil, I'm working in Virginia this week, I'll send you the info next week.

If I remember correctly it was X number of milligrams per hour during a standard test.................Rod.

[Phil Thien]

Hi Phil, I'm working in Virginia this week, I'll send you the info next week.

If I remember correctly it was X number of milligrams per hour during a standard test.................Rod.

That would be interesting to see, thanks Rod!

[James Gunning]

Based on the difference I saw in collection with my machines, upsizing the ports is the way to go. Admittedly, on some smaller machines such as ROS, hand held routers, biscuit joiners, etc. even a 4" hose wouldn't be practical, let alone larger. Those tools are better served by a good shop vac, and if you don't want to clean filters all the time, put a small cyclone in line with the vac. For the larger machines, upsizing the ports will make a big difference. Here is a thread where I showed the modifications I made to my machines to adapt them to 6" hose. http://www.sawmillcreek.org/showthre...se-6-quot-pipe Making the changes wasn't difficult, and in my case no major surgery was required on the machines, but WMMV. In addition to the larger ports, I used sealing and baffles in a few places to help direct the chips and dust to the pickup points.

I think the point that is missed concerning the Bill Pentz findings is about ensuring that your machines are not blowing out the small particles that could possibly endanger your health. The whole idea is to maximize the airflow so the very small particles we can't even see are being captured. I don't know why the manufacturers settled on 4" ports. Probably, because years ago that was considered adequate to collect the chips, and health concerns weren't on the radar. It became the de-facto standard in the US and using something larger would possibly hurt sales since most folks were already equipped with 4' piping. In general, the European view is that health and safety are paramount, and doing what is necessary to safeguard that is something the manufacturers had to do. A major case in point would be their use of riving knives long before they were required in the US.

The number Bill Pentz arrived at that was adequate to collect the harmful dust was 800 CFM at the machine. It's physically not possible to get that much airflow through a 4" pipe without a massive blower that would be impractical for nearly all of us. However, the Clearvue, Oneida, Penn State and other cyclones plus many large single stage DC's can move that much through a 6" pipe.

There is a difference between what seems to work adequately (chip collection) and what you can't see escaping (very fine dust-that carries a real health risk).