DC Revamp

[Jared Greenberg]

Looking at redoing some duct work as I know what I have now just isn't cutting the mustard.

In the pictures you will see that we use a trash can to catch the shavings off of the lathe. The shavings on the lathe are caught (mostly) by a funnel that we rigged up that travels with the lathe knives. This makes it difficult when sanding to have it suck the dust particles since the bed finishes on the far left of the machine and there needs to be sanding down by the tail stock.

I would like to get some suggestions on how we should install the hard duct runs, where to use the flex hose, and generally how to make the system we have more efficient and to catch as much as possible.

I would also like to install a floor sweep in behind the lathe to make clean up a little easier.

I look forward to the responses and suggestions.



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[Bruce Seidner]

Looks like you too have been suffering from the volcanic fallout plaguing Europe.

No one would mistake me for an engineer. So this is just some hunches and ideas as I too am in the process of revamping my approach to dust.

First I am concerned about what looks to be maybe a 2hp motor/blower that is clearly not cutting the mustard. You don't bring a knife to a gunfight. My needs are truly amateur and modest relative to the lifting you appear to be doing. I found a 5hp 220v motor turning, if memory serves, a 17" impeller. It will suck the chrome of a trailer hitch.

Second you are being stolen blind by that flexible hose. I can't afford metal so I have been working on sewer/drain grade 6"pvc that will preserve the vacuum of the blower.

Third from my reading you loose much less power and gain dust cleaning efficacy using a true cyclone and not a separator. I see no shavings but the shop has been hit by a sirocco. I am concerned about your health. See if you can borrow a Dylos meter to check air quality.

Fourth, i wonder if a secondary collector tube, something like a 2" pvc pipe with a 3/8" slit, capped on the end and going the length of the lathe would pull enough air and dust plankton to supplement the hood that is catching the bigger fish.

Fifth if you check out industrial blowers and become familiar with trade names and product you will find the $5k blower/motor you want but can not afford. But, if you are patient and scope Ebay and Craigslist I bet you find what you need in a few months.

In the meantime I trust you wear a full pro dust mask and have learned about Indian neti pots to irrigate your sinus.

Best wishes,

Bruce

[Jared Greenberg]

We are going to be moving shops in a few months, so I don't want to invest a lot of time/money into a whole new system only to have to redo it again.

What I am looking for is to use what I have , and revamp it so it works better.


Do I run ducting from the DC to the trash can?

I am defiantly going to be running ducting from the trash can to the lathe, with some flex hose that is a necessity.

The inlets on on the trash can separator are 4". From my readings 5" would be better.

Any suggestions on the 5" hose going from the DC to the trash can separator?

Will reducers going from 4" to 5" be a problem?

One problem with this lathe/DC set up is there are 3 knives that run at once. The one knife cuts the wood so it fits into the bushing and "sprays" the wood chips in no particular direction of the hood we built.

[Bruce Seidner]

what is the size of the motor (HP) and what is the size of the impeller in your blower (inches)? Better yet do you know or can you find the Operation Air Suction Capacity usually expressed in CFM or the Max Static Pressure of the unit usually expressed in inches?

You may be underpowered for the demand of your work. You could benefit from smooth rigid ducts between the blower and separater but increasing the size of the pipe or changing the pipe is not going to substantively change what might be expecting too much from a unit that is not up to the task. That unit might keep up with a table saw but that lathe is a very impressive beast.

So I would propose that people could be more helpful knowing the parameters of your motor/blower.

[Jared Greenberg]

Impeller is 12"

I believe it is 1600 CFM and 2HP.

Max static pressure is 12"

[David Hostetler]

Jared,

While I am no expert in dust collection, I have done a LOT of research on the subject. I see a LOT going on here that can be fixed up to help you out with your dust collection.

I am unsure of what DC that is, but if the photo of the unit is somehow reversed, I would say that is a Harbor Freight 2HP DC, which is a good unit, with a lousy bag. No worries, that can be easily fixed. And I am going to have to make that assumption not knowing anything really about specificity of your setup...

First things first. If that bag is a stock bag and filters at a level coarser than 1 micron, that DC is doing more harm than good by taking the ultra fine stuff and simple spewing it back into the air. Judging from the amount of dust coating everything, I would suspect that is the case. A cheap fix would be replacing the stock say 5 micron bag with a 1 micron bag from Highland Woodworking.

For better results, but also greater cost, you could likewise upgrade to a cartridge filter. The advantage there is higher air flow for the same filtration rating due to greater surface area.

No matter your filtration media, bag, or canister, you need to keep it clean to keep it flowing. Most of those basic trash can lid separators simply become a bypass for dust that gets sucked back up and through to your bag as they get past about 1/3. I would strongly suggest you do a Google search for "Thien Cyclone". Look for a thread in Phil's forum there called "here's the plans", that is an excellent set of directions on just how to build a Thien trash can separator. The difference is in the port locations, and the baffle. They make a HUGE difference. You can fill a Thien separator to just below the baffle before they start to bypass. I've only managed to do it once...

You are running an awful lot of flex hose there as well. Think of air flow, like a car going down a road. You can drive that car much faster if you aren't bashing into a ton of potholes, and curves right? Smooth the path for the air flow out by using only as much flex hose as is absolutely neccesary to make your connection, and keep the connection working. So for example a connection to a lathe hood that moved back and forth should have enough hose to allow that movement, but a connection to a TS belly pan might have no flex hose at all...

IF your budget can handle it, I would make an impeller face plate for that DC that will accept 6" hose / duct, and run it to a single 6" main trunk, with 6x6x4" wyes to get to 4" branch circuits for each major station. I didn't do that, and wish I had now...)

Now I am sure I missed something here, hopefully I will remember, and post up an update here. But look at Phil's site. You also might want to look at Bill Pentz' web site. He has a great site, a bit OCD on dust collection, but that isn't a bad thing. He's been in the trenches as it were. And although he's a bit extreme, I think he has a LOT of very valid points on setup of a DC system.

Long story short, yeah you can work with what you have, but to make it work the way you will really want it to, you will have to put some work into it...

[David Hostetler]

Jared,

To answer your questions more directly...

Do I run ducting from the DC to the trash can?

You can, but you should reduce the amount of flex between the trash can and the DC. Every ridge in that hose is robbing you of air flow. I put my DC on a stand to get the inlet level with the separator outlet. I haven't put duct in there because the distance between the two is less than 2'.

I am defiantly going to be running ducting from the trash can to the lathe, with some flex hose that is a necessity.

You are on the right track there. Mind you, flex hose is sort of a necessary evil. Eliminate it as much as you can.

The inlets on on the trash can separator are 4". From my readings 5" would be better.

5" would be ideal, but a ROYAL PITA to get. Most folks upsize to 6". BUT... If you are willing to spend the $$ to get 5" metal pipe (plastic is just about impossible) you can have a great system...

Any suggestions on the 5" hose going from the DC to the trash can separator?

Build a Thien separator with 5" ports if you want to go 5". Wynn Environmental, and I believe Kencraft have 5" flex hose at reasonable prices.

Will reducers going from 4" to 5" be a problem?

Going from 5" duct to 4" separator and back up is sort of pointless, and will rob you further of performance. Don't do it.

One problem with this lathe/DC set up is there are 3 knives that run at once. The one knife cuts the wood so it fits into the bushing and "sprays" the wood chips in no particular direction of the hood we built.

I'm not even sure how to address the dust hood design complexities. Honestly as far as my lathe is concerned, I am not all that worried about catching the chips, but rather the fine sanding dust. A split PVC tube capped one end, running the length of the lathe bed just behind where the sanding is happening, assuming you sand underhanded, overhand just shoots sanding dust in your face...

You have a real dust collection challenge, and I am curious to see how you address this. Good luck, and keep us posted!

[Jared Greenberg]

Thanks for the responses.


My plans after looking at my set up (the lathe is a challenge to move) and space and how these two are used and where we need to be able to get to in relation of everything are these. Also knowing that we will be moving shops shortly, and upgrading our system and building it properly (with a cyclone):

- Get a cartridge as a replacement for the top bag.

- Run metal ducting (I found some @ HD) from the DC to the trash can, and from the trash can to the lathe along the wall with some straps and use the least amount possible of flex hose. Unfortunately the lathe has a contraption that we built the hood around that is meant for a 4" hose, so it'll have to be 4" running to it.

- Rig up a PVC tube with a slit or holes that is capped at one end above where the hood runs to a smaller DC located on the other side that can run when sanding, this will allow it to catch the dust particles, and will keep the set up simple (since we need to be able to walk behind the lathe and running another duct for this application; there simply isn't enough room).

- Build a different hood, that "wraps" the turning better. Hopefully with the increased airflow, there will be

As far as as that trash can separator, I simply don't have enough time/expertise/patience/tools to make the Thien separator. I'd be willing to pay someone to make it though (any takers?) So I'm forced at this point to use it and deal with the 4" inlets.

Two questions:

1) Would the metal furnace ducting be OK for this application after wrapping where you put it together with duct or aluminum tape? Or would it collapse? If it would collapse, I'll just go with the HD PVC pipe.

2) Would an Air Cleaner that is a suitable size of the garage be useful?

Let me know if anyone wants to build me a Thien separtor via PM and we can discuss details/compensation etc.

Thanks again for the help; I feel I have some sort of direction as it is a bad problem.