still trouble with collecting sanding dust

[Don Jeansonne]

I have a Delta 50-760 with a Thein Baffle installed onthe inlet. I connect my tools with 4" pvc and flex and only run machine at a time.
The baffle works well on the normal table saw and larger particles but I feel that the dust from my Delta 18x36 drum sander ( about 18-20 ft run) and 6" belt sander is getting through. The filter bag is clogging and seeing more and more in the plastic collection bag. Still see fine dust all over shop. I tried adjusting the baffle inlet elbow angle with little change noticed.

Considering discharging outdoors.... loss of shop air is not a problem in Louisiana,
Or upgrading to larger collector,
Or purchasing a cyclone system.

Any suggestions?

[ian maybury]

Don't know a lot about drum sanders and/or your dust set up, but based on the 4in hose it's probably not much bigger than about 1kW.

There's numerous likely issues:

1. That size of fan isn't going to move all that much air.
2. Sanders because they can't easily be tightly hooded/shrouded tend to need big air flows to collect dust. Even then they are likely to need careful setting up.
3. A 20ft run of flexible is equivalent to about 50ft of smooth ducting. Smaller fans don't really have the grunt to pull through ducting, it's better to run a very short hose and to place the collector beside the machine.
4. Use of a separator will further step up the pressure drop, and make the marginal fan situation even worse.
5. Fine wood dust like what you get from a sander is right down at the limit of what separators can deal with (if at all), and to do so they rely on having enough airflow to provide the kinetic energy needed to drive the separation process. Marginal airflow means minimal chances of it working on fines.
6. Chances are if the collector uses filter bags that they are not going to be fine enough to stop the very fine stuff anyway. Certainly not when the bag is fresh (before it seasons), and once it seasons the resistance will step up and further drop the airflow.

It seems likely that you just need a much larger dust collector - either exhausting outside, or with close to HEPA cartridge filters. Probably also with a cyclone to maximise filter life.

If you can keep the hose runs below 10ft you should do OK with say 3HP, but if you definitely have to run much further then a 5HP unit is likely to be advisable. I'm not sure how big the drum sander is, but chances are that even then the sanders will need some care in setting up hooding/shrouding/dust collection arrangements....

ian

[Clint Olver]

You have several options Don.

The biggest limiting factor with that machine is the 5" inlet. The second is the filter bag. For optimum performance you need 6" or 7" ducting - you're somewhat limited with the 5". Flex hose triples the static pressure over straight pipe - it's a killer, so limit it as much as possible. The easiest thing to do would be to run 5" straight pipe as close to your drum sander as possible, then use the 5"-4"-4" Y that came with your 50-760 to split to two 4" into the drum sander. Make a new dust hood for your edge sander using 1/4" ply and run a direct 5" into it. Lastly, put your felt bag on the bottom, and put a canister filter on the top.

This will work well. It won't be a 5hp cyclone, but it will drastically improve your performance.

Just remember to aim for larger diameter pipe, short runs, less flex, more filter area (or just shoot the fines outside).

A 1 1/2hp motor with an 11 1/2" impeller will move a lot more air than a 4" pipe and little bag filter will allow.


C

[David Kumm]

Don, unless you change out the system your best bet is to exhaust outdoors when sanding. Even cyclones have trouble separating fine dust and 1.5 hp 11.5diameter doesn't give you much room for error.. Reducing flex and larger diameter pipe may help some but if the restriction is on the outlet side due to clogging it won't help at all. I'm not sure a cartridge filter is the answer either. Cartridges are almost never run with drum or belt sanders unless real light use as they clog quickly and are harder to keep clean than felt bags. An oversize bag might help but your system will be just adequate without filter restriction due to the lack of velocity at the sander. A sander needs lots of velocity through the ports to pick up the dust at the source. I don't know if you have one or two ports but sanders are tough. I run 1800 cfm to my edge sander and it isn't perfect by any means, and over 6000fpm through both the ports on my Performax which is barely adequate. Dave.

[Jim Andrew]

I have a Grizzly wide belt sander, the smallest one, and a 2hp cyclone with 6" pipe, and I don't understand why they put a 5"dust fitting on the sander. It creats a lot of dust, and no way you can get it all with a 5" fitting. Probably wouldn't get every bit with a 6", but it would be a big improvement. Considered cutting it out and adding a 6", but the way it's designed, not very practical. Love the sander, though. Just plane my boards down to 13/16", and then sand the panels and they come out at 3/4".

[Don Jeansonne]

Thanks for the replies. Just about everything you all said are the things I suspected. I guess I need to chnage my duct run size to 5 or 6" and minimize the flex. I think I will experiment with discharging outside also to see if the filter plugging is really impacting me. I will probably try this first and still be on the lookout for a used larger collector or cyclone.

[Michael W. Clark]

You have two issues, one is getting the dust at the sander, which takes a better hood and more airflow. Assuming you collect the dust at the sander, now you have to separate it from the airstream. A single stage collector with baffle is not going to be very good at this due to the small size of the dust. A cyclone will improve the separation of the fine dust, but most hobby cyclones are still relatively inefficient at separating fine particulate. However, they will buy you some time before plugging the filters. Exhausting outside is your best bet, but if you want to keep it inside, you will want to increase your filter area, clean them often, and minimize your duct run using the largest duct practical. Two 4" ducts on the sander hood may do a better job than a single 6", depending on the hood configuration.

Mike