Question re Dust collection system blowing to the outside

[David Metzman]

Does anyone have a dust collection system that instead of blowing into a bag filter or other type of filter blows outside? Is this more effective than blowing into the bag since there would be less or no back pressure?

I turn in my garage - it is about 2.5 cars and everything is covered in dust from power sanding. I have one of those cheap 1hp blowing into a filter bag system and am thinking about upgrading.

I once saw a turners shop that blew everything outside.

If anyone does this, I am wondering:
Does the outlet of the blower need to be near the outlet of the house? I assume the closer the better.

In order for me to do this, I will have to drill a 4 inch hole through a poured concrete wall that is than faced in brick. I am assuming that I will use a dryer vent as the outlet and aluminum dryer tubing to hook everything up.

Any advice would be appreciated.

Thanks,
David

[David Walser]

David -- The Workshop forum here on Saw Mill Creek has had a number of threads on this topic. You might go there if you want to hear a lot of opinions on the subject. Let me summarize:

You are correct in your assumption that the DC's performance will be improved by venting to the outside. The shorter the run to the outside, the better.

There are potentially two downsides to such an arrangement: First, the neighbors (which would include the local government) might object. You'll be venting noise and dust into the air outside your shop. Depending on how close the neighbors are that are downstream, the dust now accumulating on you cars might soon be covering theirs. This could be a very big deal, or it may not even be a consideration.

Second, if your garage is heated or cooled, you'll be pumping a lot of heated or cooled air outside! Again, this may not be an issue for you. It's the reason my DC is NOT vented outside. I live in Mesa, AZ. The stand alone shop behind our house, about the size of single car garage, has a mini-split installed. During our 115 degree days, the mini-split can keep the temperature in the shop down to about 80 degrees -- as long as I don't go in and out the man-door several times an hour. Or, tragedy, I have to open the overhead door. When that happens, the mini-split is overtaxed and temperature inside the shop will flirt with 90 degrees. Venting my DC outside would make it like trying to cool the shop with both doors open!

HTH

[Keith Outten]

I have been using an exterior chip box for over 20 years in three locations. Over a hundred people have visited my current shop for training sessions and have seen my system work.
I have made a number of posts concerning my setup, check our archived threads for my input.

[Brice Rogers]

I bought a 2 HP Harbor Fright DC attached to a home made separator (more on this later) and vent outside through a 5" dryer vent. I chose to use a 5" vent because it has about 50% more cross-sectional area. It works great. I live in a temperate climate (North San Diego county inland) where it can reach 110 F and get down to the 40's ... occasionally. But most of the time it is between about 60 and 90 F.

I think that a separator is mandatory unless you are only pulling through sawdust. But if you are pulling through planer shavings, use a floor sweep (great idea but you'll pick up "chunks"), jointer shavings, you'll want a separator. Otherwise all of the chunks and shavings will be either flying through the impeller or just stuffing it up. The cyclone separators work well but they are a bit tough to make yourself. So they are a purchase item. Check out the Super Dust Deputy. There are some super simple separators that you fit over a drum or bucket that separate out the chunks and perhaps a lot of shavings. BTW, if the shavings get past the separator, they'll quickly plug up the DC impeller. I chose to build a Thien baffle for my separator. It is easy to do, there are lots of plans on-line plus Youtube videos. I used the metal section of the Harbor Fright DC for part of the separator plus a metal garbage can and some plywood. It works reasonably well. If I cram the pickup hose into a pile of sawdust/chips it will temporarily overload the separator - - meaning that I can visually see "some" dust going outside for a few seconds. But if I am not so aggressive (I do a bunch of sanding on my lathe), I suspect that perhaps 98 plus % of the dust and chips goes into the garbage can.

A plus of venting outside is the sound level in the shop is cut down quite a bit. I've been running my DC and separator for 5 years and there is no noticeable build up of dust/chips outside. The noise outside isn't too bad either - - less than a gardener's blower or a shop vac.

[Steven Cooper2]

I don't have much to add here, no filter could potentially substantially reduce your pressure drop.

I'm just jealous that venting outside is something worth considering elsewhere on the planet

[Timothy Thorpe Allen]

Hmm.... just thinking of a Y diverter downstream from the blower that could give one the option of venting outside (unfiltered) or keep the exhaust inside through the normal filter, so you could choose depending on the weather (e.g., heating/cooling loads) or other factors (e.g. seasonal neighbors?). Wonder how well traditional blast gates would work under pressure (as opposed to under suction as per normal when upstream of the blower)....?

[William C Rogers]

I vent outside. I wouldn’t do it without a cyclone separator. I have the Escarda cyclone (around $300) and use a 3 hp DC. However don’t think you will eliminate the dust in the shop. There just isn’t a good dust collection system for a lathe.

[David Metzman]

Thank you for the advise.

I forgot to mention that I do have a separator - I think it is from woodstock and fits on the lid of a metal trash can. I hear they are not the best but OK- there is a woodwhisperer youtube comparing something like this to an Oneida cyclone and some dust gets through and it probably adds up over time. (they especially don't work well, apparently, when you hook the hoses up in reverse like I seem to have done when moving it as some point!). So I will give it another try.

My filter bag was really coated in fine dust. I cleaned it. It is very heavy felt like fabric with a heavy plastic zipper. Can I wash it or hose it down?

I have a PennState 1.5hp blower (dated 1989!).

My garage wall seems to be 10 inches of poured concrete plus a layer of brick. A lot to drill through. So I will try the current system a bit now that I have adjusted some of my errors.

Someone mentioned that the filter bag should not reduce air flow - is that correct? It seems if the flow is unobstructed you should have much more flow - maybe I will test my suction level with and without the bag to see.

I checked out the workshop forum - they do feel strongly about their dust!

Unless I build something like Reed shows on youtube it is hard for me to see sucking up a great majority of the dust when power sanding. It seems to fly in all directions. And certainly when you are doing normal turning some dust is generated with the chips and that goes all over the place. I assume this is more so with dried wood. I was thinking about hanging plastic sheeting around my main woodworking area to keep the dust and chips in. I wonder if a 3hp blower really increases the pick up of dust versus a 1.5hp if both run through the same system to a big gulp catch. for example.

Thanks for the help, David

[Prashun Patel]

I vent my lathe dc outside. I use a super dust deputy under a Harbor Freight 2hp motor. I also use a big gulp (Powertek version) that I clip to the back of the ways. It works, but is a pain to adjust. Am in the process of hanging the hood from a ceiling trolley that runs parallel to the lathe.

The SDD is so good at catching most material, there's no evidence of the exhaust outside.

I also have a secondary air cleaner hanging from the ceiling. My entire lathe is surrounded by several clear plastic shower curtains. All of this contains the dust (and flying chips) fairly well, but as has been noted, the dust is smarter than I am and Shawshanks its way outside of the booth despite my best attempts.

[David Sochar]

DSCN0937.jpgWell, It is sideways isn't it?

This is a small 4' x4' x10' room on the side of my shop. Looking closely, you can see the fan motor on a deck high in the room. The cyclone is just behind it. It is air tight, including the doors. The pipes pick up shavings at the source and they go to the cyclone where 95% of the dust drops into the room. The rest go thru the fan and then thru filters back into the shop. The fabric filters have a collection point at the bottom of the manifold that holds them.

This way, the pressure inside the shop and outside are irrelevant to the collection process. As the bin fills, it can be emptied into a tractor wagon or a pick-up truck.

The key is to isolate the high pressure zone from the normal pressure zones. I designed this with Oneida in 1994. It has worked very well ever since.

This design is superior since most of the noise of the collector is outside.

But you said you were sanding to create dust. There is one solution to this, and only one. Festool sanders with the matching vacuum. Transformed the way we work, and improved the shop environment 100%.

[Reed Gray]

There are many ways to improve dust collection, or at least contain it. Getting it at the source is the first step. While my hood is a bit of over kill, it does get all of the sanding dust. I have seen variations, and one was a cardboard box.

To contain the dust, you might wall off the section of the garage where your lathe is. I have seen some jacks and plastic set ups that are used when the sheet rock people are working. You could even frame it in with door and window.

Also, if you can get a pleated paper filter for your DC system, they are far better than the cloth bags, if for no other reason, they offer several times the surface area for the air to vent through.

robo hippy

[David Walser]

...

But you said you were sanding to create dust. There is one solution to this, and only one. Festool sanders with the matching vacuum. Transformed the way we work, and improved the shop environment 100%.

The Festool sander/vacuum combo, and the even more expensive Mirka combo, are not the only way to address sanding dust. They work well, but an even better approach is to avoid creating dust in the first place. For several years, I wet sand virtually everything I turn at the lathe. I use a number of sanding lubricants -- depending on the material and the final finish. For resins (including stabilized wood), I use water. For most woods, I use walnut oil (my typical finish). If I'm not going to be using walnut oil and/or want to preserve the natural color of the wood, I'll use mineral spirits. I know a number of turners who use a mineral oil/wax mixture as their sanding lubricant. I keep meaning to try the wax mixture, but have not.

For wet sanding, I use whichever paper I have handy. I suppose some papers wouldn't hold up to extensive wet sanding. However, I've not had a problem with any I've already had in stock. My favorites are Abranet and clones. These woven abrasives rinse out easily and can be reused several times. The rolls of J-weight sandpapers I also use can be used several times, too. However, I generally toss them after one use.

As suggested, one of the advantages of wet sanding is that it prevents the creation of dust. Other advantages are that each grit of sandpaper works faster and lasts longer. The lubricant carries away most of the heat generated by sanding. It also carries away much of the swarf from sanding. The combination of cooler temps and cleaner paper is what allows the abrasive to simply work better. The downside is the mess. My turning smock has a stripe of walnut oil staining from where the oil was spun-off while sanding. Even with the mess, I much prefer the results I get by wet sanding. I also enjoy the lack of dust in the air!

One more thing: Since I started wet sanding, I've all-but given up power sanding. I had gone through two cheap Harbor Freight angle drills sanding at the lathe in about five year's time. The last of the two drills gave up on me about the time I started wet sanding. Wet sanding is so fast I don't see the need to power sand anymore. That's true even on large bowls and platters.

[Alex Zeller]

A good friend owns a sprinkler business. I've used his core drill to make large holes in cement. It's a bit of a process. For a wall the drill needs to have small holes with anchors to attach the drill roughly in place. Then it gets fine tuned to the correct location to drill. It can be kind of messy. I think a 4" hole would be too small for anything other than a 1hp dust collector. Often he's running main pipes for a whole building that are 10" or so in diameter. It's not unusual to hit rebar while doing it. It leaves a nice clean hole (vs just making tons of 1/4" holes and connecting them). I think you can rent the drill and the correct size bit.

I grew up next to a mill. They only did softwood but everything they planed was blown out the back of the building through a pipe about 100' long and into a pile. The pile would get 30' or so high at times. As kids we would play on it jumping off the piles. My mother would get so mad when I came home with chips stuck everywhere on me. Now there's a wood burning electrical plant not too far from the mill and they buy up almost everything.

[tom lucas]

The Festool sander/vacuum combo, and the even more expensive Mirka combo, are not the only way to address sanding dust. They work well, but an even better approach is to avoid creating dust in the first place. For several years, I wet sand virtually everything I turn at the lathe. I use a number of sanding lubricants -- depending on the material and the final finish. For resins (including stabilized wood), I use water. For most woods, I use walnut oil (my typical finish). If I'm not going to be using walnut oil and/or want to preserve the natural color of the wood, I'll use mineral spirits. I know a number of turners who use a mineral oil/wax mixture as their sanding lubricant. I keep meaning to try the wax mixture, but have not.

For wet sanding, I use whichever paper I have handy. I suppose some papers wouldn't hold up to extensive wet sanding. However, I've not had a problem with any I've already had in stock. My favorites are Abranet and clones. These woven abrasives rinse out easily and can be reused several times. The rolls of J-weight sandpapers I also use can be used several times, too. However, I generally toss them after one use.

As suggested, one of the advantages of wet sanding is that it prevents the creation of dust. Other advantages are that each grit of sandpaper works faster and lasts longer. The lubricant carries away most of the heat generated by sanding. It also carries away much of the swarf from sanding. The combination of cooler temps and cleaner paper is what allows the abrasive to simply work better. The downside is the mess. My turning smock has a stripe of walnut oil staining from where the oil was spun-off while sanding. Even with the mess, I much prefer the results I get by wet sanding. I also enjoy the lack of dust in the air!

One more thing: Since I started wet sanding, I've all-but given up power sanding. I had gone through two cheap Harbor Freight angle drills sanding at the lathe in about five year's time. The last of the two drills gave up on me about the time I started wet sanding. Wet sanding is so fast I don't see the need to power sand anymore. That's true even on large bowls and platters.

I like the idea of wet sanding, and the results I've received when doing. I've mostly used mineral spirits. My problem is that it seems the sandpaper clogs up pretty quickly, especially on the first two or three passes. I've tried a lot of different papers, including abranet. They all clog. Yes, I can clean the abranet. I guess I'll just have to use 2 or 3 pieces so I can finish sanding before stopping to clean the abranet. I'd love to hear suggestions on making this work better for me (less clogging).

[Mike Nathal]

I also heartily endorse wet sanding. I use walnut oil on wood and soapy water for wet sanding between coats of finish. If your sandpaper is getting clogged, use more oil. You want a slurry and not a sludge. Also here is an excellent video on designing a dust collection system, including answering the above question on cleaning filter bags: https://www.youtube.com/watch?v=qjI5l4nF9AM