Sanding dust control - sanding long thin curved things with ROS. Thoughts needed.

[elver]

All,

I routinely sand long skinny kayak paddles with a little 125mm diameter ROS.

I raise the paddle of the bench on some stirrups while I sand, but the ROS with attached vacuum just doesn't catch it all.
I chose my ROS by aiming for lightweight, 125mm diameter (lots of sandpaper in stock limits my desire to change sizes..) and good hand feel with low vibration. Good dust control is also important. But light and east to hold single handed is essential _ the other hand holds and rotates the paddle - each sanding step takes about 5 minutes for all surfaces of the paddle, and with 5 grits rapid readjustment of grips means clamping is out. Single handed sander use is essential.

I've used lots of different ROS in the past. They vary in their ability to kick dust into the dust ports. Currently I'm using a Makita ROS which is actually pretty good for dust capture, and is nice and small.

My dust capture at source is from a 2400W vacuum in a big soundproof(ed) baffle box. It runs about a 40 mm diameter hose, which I keep to a minimum length, through a dust deputy. It sucks pretty well.

I work in a corrugated iron shed - its air permeable. I probably spend a day a week sanding on average.

No matter which sander I use, I end up with fine dust spitting out and settling around me. Just a thin layer. I use PPE as I'm allergic to the fine cedar dust.

I'm over cleaning up all the dust everywhere. I'm thinking about a dust booth / large vent hood / shroud of some sort and downdraft table to eject the fine dust out into a nearby paddock / baffle box IBC or something.. (I have heaps of space to exit the dust away from my shed). I've rigged up my 2HP chip collector to a simplified downdraft table but found it just didn't have the suck to work enough to inspire me to make a proper one. In reality the blocking effect of a shroud was more effective than the air movements.

Has anyone got any suggestions on how to:
1) catch dust from a ROS at source when sanding rounded things. (their extraction is made for flat things)
2) examples of good dust extraction / downdraft tables that work well enough to bother with?


I'm hoping for a portable solution that I can pack up after use rather than needing a sanding room. Currently I'm imagining a 2.4m long open box that fits on the table, and connects to a dedicated externally mounted blower to pull the dust down and shoot it out into the long grass outside well away from humans.

Thoughts?

Tom

[aldav]

Are you using mesh sanding discs? If not, that change alone will probably solve all your problems. It may seem unpalatable to sell off the stock of paper sanding discs and upgrade, but once done you wouldn't regret it.

[elver]

Hmm not mesh. Mostly nice Alox discs from Sandpaperman.
Actually my stock of pads is getting low at this time of year, so changeover is least painless now.

I was also wondering about using a flexible backing disc/ foam too. Maybe that and mesh might be a good starting point.

[Chris Parks]

I can't see any way an ROS can capture the dust and I have had the same problem lately. For production purposes and to speed things up I would make a fixture to spin the paddle and use hand held paper to sand with and it would give a far better finish. All that is needed for DE is a long hood with multiple outlets in the hood hooked up to a DC. You could make the hood and the fixture to spin it in all in the same fixture with it all closed on three sides and only open enough to get the hand and sandpaper into. Drive the paddle from one end with an electric motor and the paddle would rest on a support at the other end or even clamp to the blade. You could get fancy and use a 3 phase motor and a VFD to vary the speed as needed if you want.

[aldav]

Hmm not mesh. Mostly nice Alox discs from Sandpaperman.
Actually my stock of pads is getting low at this time of year, so changeover is least painless now.

I was also wondering about using a flexible backing disc/ foam too. Maybe that and mesh might be a good starting point.

A sacrificial backing pad is definitely the way to go. The mesh allows the suction of the vac to collect so much more of the dust and the problem of the sanding material clogging is virtually eliminated. The finish is better too because of the lack of clogging. Hopefully you won't need to take any other steps to bring your problem under control.

[elver]

Aldav - Mesh sheets ordered just now. :2tsup: Cant see a backing pad that fits my current sander 8 hole configuration now so will do that later.

Chris - my paddles are more flat bits than round bits, so spinning won't work for me. The hood with multiple dust ports to create extraction I think might be step 2 after trying the mesh sheets. I think reducing volume inside the space will be important as will reducing the number of open sides, so as to create a path of air ingress with a little velocity.

[Chris Parks]

I honestly doubt that mesh sheets will make any substantial difference but the proof is in the making and it may make enough difference to be good enough.

[pippin88]

Look at BobL's posts about bell mouth hoods. He has posted some nice photos showing the effects.

[elver]

I honestly doubt that mesh sheets will make any substantial difference but the proof is in the making and it may make enough difference to be good enough.

I'll report back on whether I can tell the difference.
Given the low quality feedback many give downdraft tables I'm not keen to go there (or to a 'fume hood style box' without being able to move heaps and heaps of air.
I doubt my little 2HP chip collector will cut it. To make it work I think I'll need to keep it more boxed in than I can tolerate and still do the job well.

[elver]

Pippin,

I've seen the benefits of the BMH. I might be missing something, but I'm not sure that they will assist enough given my little dusty. I sand over about a 1.5m sweep as I work. That might take a lot of CFM and hoods to be effective. My little 2hp dusty just wont cope?

[BobL]

If it was an oft repeated task I would go for a different approach.

Position and fix the ROS upside down with a BMH on 6" duct about 300mm directly above or at a slight angle away from directly above the ROS.

Then move the wood over the ROS rather the the ROS over the wood.

A modified 2HP DC on 6" ducting should be able to cope with this amount of dust.

Might even experiment with that some time and run the particle counters to see what happens.

[elver]

Interesting thought Bob. Not sure I'd have the same control, only because I've been doing it the same way for a decade or more.. but it might be worth me giving it a crack.

[QC Inspector]

My last job had downdraft tables for the metal finishers. They had 4' x 8' tops with 5hp motors moving 3,000cfm and they didn't get it all. I doubt you will ever get your 2hp to do the job you need.

I suggest you look into ventilation fans. I set a couple up beside my fathers lathe that I salvaged from ceiling mounted heaters in the plant. They were 16" across and had 1/4hp or 1/3hp motors. The fans were mounted just below waist level and when turned on were able to grab all the dust and a good deal of the shavings and blow them out into the woods behind the shop from a few feet away. They were great in the summer but not so much when the snows were on their way. If you can get a good sized fan or two and mount them just above bench height opposite you in the wall or in a window opening They will pull all the sanding dust you produce and when not sanding will ventilate the shed when doing other operations. They will pull enough air that you won't need PPE when you sand. The ones with self closing louvers would help keep the weather out. Example below.

ECOtronic EC Square Plate Axial Fan Series - fans - Fantech (https://www.fantech.com.au/FanRange.aspx?MountingID=WE&RangeID=2052)

Pete

[BobL]

Interesting thought Bob. Not sure I'd have the same control, only because I've been doing it the same way for a decade or more.. but it might be worth me giving it a crack.

It will take some getting used to but eventually you might find get more control??
Anyway, I usually prefer to handle the wood especially if its lighterthan the tool.

This is how I set up a belt sander to do what I'm taking about some 15 years ago.
I was surprised to see what level of control I could get.
No BMH those days and only a 1 HP DC. Dust everywhere!
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On long stock you'll have to learn to sand from each end so you'll have to flip the work but that's no biggie.

These days I have this 1000 x 150mm belt sander and I handle stock the same way.
I've sanded stock up to 2.4m long with this machine.
It now also has a BHM on the end of the belt
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Vids of BMHs in action
150mm on lathe

https://youtu.be/xjtHCmR-N3M

100mm on DP

https://youtu.be/usk3qWv-8Yc

[elver]

Bob, I did start off making my paddles just like that with a belt sander. Upside down in a bench, spurting a fine mist of dust _everywhere_.
I moved to finishing up the other way so I can see what I'm doing for fine work. Seeing the pass assists me in pace of work. I've not tried it with the ROS. The sweet spot on the ROS is smaller and clamping will take a little more thought than a belts ander, but I'll try and give it a crack.

What do you think of using large axial fans exhausting dust laden air? If there is room for large diameters are axial fans more efficient at moving air to evacuate dust, compared to our centrifugal systems used in dust blowers, or is the velocity too low to manage the speed at which the dust is exiting a 10000 RPM tool head?

Seems like these large fans are used in spray booths. Per m3/hr they seem more energy efficient, if your not trying to achieve large pressures to push air through a filter.

[BobL]

do you think of using large axial fans exhausting dust laden air? If there is room for large diameters are axial fans more efficient at moving air to evacuate dust, compared to our centrifugal systems used in dust blowers, or is the velocity too low to manage the speed at which the dust is exiting a 10000 RPM tool head?

Seems like these large fans are used in spray booths. Per m3/hr they seem more energy efficient, if your not trying to achieve large pressures to push air through a filter.

Correct - Axial fans are fine when there is no back pressure from restricted tools, cyclones or filters. When there is back pressure the axial fans fail badly whereas centrifugal blowers will at least keep moving some air. Just like manufacturers claimed DC flows, I would take all claimed axial fan flows with a few grains of salt.

Even more efficient, compact, and quieter than axial are squirrel cage fans but they cost more. I have variable speed two squirrel cage fans in my shed for ventilation. One is up to 1600 cfm on my fume/welding bay/booth. The other is a 1200 CFM fan that vents at the top of the ceiling.

Evap AC units make excellent ventilation fans

[elver]

Correct - Axial fans are fine when there is no back pressure from restricted tools, cyclones or filters. When there is back pressure the axial fans fail badly whereas centrifugal blowers will at least keep moving some air. J

Ok so maybe then an axial fan might cut it for a drawdown table or extractor hood- just fitted to pump all the fine dust laden air straight out of the shed into the paddock. Should I still be aiming for 1000CFM or more or do I need to chase a minimum velocity? (maybe adding a fudge factor of 0.7 for manufacturer lies)

[BobL]

Ok so maybe then an axial fan might cut it for a drawdown table or extractor hood- just fitted to pump all the fine dust laden air straight out of the shed into the paddock. Should I still be aiming for 1000CFM or more or do I need to chase a minimum velocity? (maybe adding a fudge factor of 0.7 for manufacturer lies)
More suited to a basic hood - less so for a draw down table - the holes will stymie the flow.

[elver]

Got the mesh discs today from SandpaperMan.

They look amazing! Almost see through.

Might get a chance to trial later in the weekend.

[aldav]

Got the mesh discs today from SandpaperMan.

They look amazing! Almost see through.

Might get a chance to trial later in the weekend.

Sunday delivery. :oo:

[elver]

Hmm - slack with my terminology: It was a Saturday delivery, but I got home Sunday to the package. However, a Saturday delivery in itself is a marvel too!

[aldav]

Hmm - slack with my terminology: It was a Saturday delivery, but I got home Sunday to the package. However, a Saturday delivery in itself is a marvel too!

You won't get any argument from me. :D

[elver]

Updating my own thread:

I got a bunch of mesh sanding dics. While excellent on flat materials, and they do let the machine suck up heap more dust, they don't work so well on long skinny things or profiles.
It seems the loop side of the discs doesn't have enough stiffness to hang onto the sanding pad when I sand curved things. This means without warning the pads slip off and you tear into the wood with the hook side. Not great on soft timber when your up to 600 grit, at the end of a job..

So I'm back to better dust extraction with a whopping great big sucking machine and a custom hood / box as well as using a connected at source vacuum.

With respect to sucking fine dust - i did some experiments with straight through bag less blowers (*just shoot it out the shed into the paddock with a little flap of shade cloth to slow the exit velocity / reduce spread.) The results were pleasantly surprising - a 0.5hp machine doing this was waaaaay more effective at collecting visible dust when sanding on my lathe than my 2HP machine with clean pleated filter, so I think I will pursue this approach for my sanding box/hood. <Yes I know this is not a real test, and I just used a torch and low light to look at dust being sucked into the BMH, and it doesn't mean much> Hosing down the grass after each sanding session seems to bed the dust down into the soil, so not much dust lifts off on a the next windy day.

Other than a dedicated sanding booth, I think this is the best I can do for now. The trade off is that this needs heaps of power. To run this I'll use:
1500w on the 2HP dusty
750w on the 0.5hp dusty
2000w on the shop vac
400w on the sander.

Luckily I can run all this when the sun is shining and the solar on my shed pumping out power in excess of my export limits.

[markharrison]

What about a delta sander? I have a Metabo DSE 300 (https://sydneytools.com.au/product/metabo-dse-300-intec-300w-electronic-triangular-base-plate-delta-sander?gclid=CjwKCAjwiOv7BRBREiwAXHbv3PGyeZmWpwDTGqQ8g4kf2TPLVyNtbof8aLZGE1sH6XUPAv5y4ndzrhoCoJoQAvD_BwE). I don't use it that much but when you need it, there is nothing else like it!

You can hook up a vacuum with the included (well, mine was) dust collector port that replaces the stupid little dust filter cartridge that is utterly useless.

[elver]

Im not sure a delta would assist much. I still need to remove a bunch of timber as dust, and my little makita 125mm ros with vacuum attachment seems to work pretty well.
Maybe the delta miight not fling the dust out sideways so fast, but Im not sure. And I did just buy another years supply of discs for my 125mm sander. Like 5 mins ago!

Once I did look at going festool, and was committed to a little small ROS, but then at the counter, I was about to pay for it and I got a price for the little custom clip on vac hose connector, and my $$ tolerance tipped over a little cliff. After mentally preparing for the cost of the sander, the extra was too much. I put it down on the counter and walked out a case of completed "purchase interuptus". I'm scared forever and never even looking sideways at the fancy grey and green stuff in the corner of the shop.

[markharrison]

Im not sure a delta would assist much. I still need to remove a bunch of timber as dust, and my little makita 125mm ros with vacuum attachment seems to work pretty well.
Maybe the delta miight not fling the dust out sideways so fast, but Im not sure. And I did just buy another years supply of discs for my 125mm sander. Like 5 mins ago!


You are right about the dust not being flung about with as much vigour. That, and the amount of suction with an attached vacuum, at the business end does not tend to leave a lot of dust. That number is not zero though.

With the right grit abrasive, you can get quite aggressive. These are variable speed too.

I bought mine many years ago to assist me with the restoring of windows in my house. The house had been left in bad repair and there was so much rot in the wooden windows I almost ended up making totally new ones in some cases. On others there were patches of dry rot that did not structurally impair the window and putting in a graving piece was just too difficult, so the use of polyester resin was appropriate. I used this in shaping hardened resin and graving pieces. 40 grit paper ripped through that stuff and the Merbau graving pieces I made.



Once I did look at going festool, and was committed to a little small ROS, but then at the counter, I was about to pay for it and I got a price for the little custom clip on vac hose connector, and my $$ tolerance tipped over a little cliff. After mentally preparing for the cost of the sander, the extra was too much. I put it down on the counter and walked out a case of completed "purchase interuptus". I'm scared forever and never even looking sideways at the fancy grey and green stuff in the corner of the shop.

Understood! I don't think the 90mm ROS would be materially better than what you already have in terms of dust collection in this particular use-case. The Metabo is definitely not on that same shelf price wise!

[BobL]

Other than a dedicated sanding booth, I think this is the best I can do for now. The trade off is that this needs heaps of power. To run this I'll use:
1500w on the 2HP dusty
750w on the 0.5hp dusty
2000w on the shop vac
400w on the sander.

Luckily I can run all this when the sun is shining and the solar on my shed pumping out power in excess of my export limits.

If it's just for sanding, I would replace the dusties with a couple of bathroom vans venting the shed. A lot less noise too.

[woodPixel]

For round things, perhaps try the Festool LS130 sander (https://www.festool.com.au/ls-130-linear-sander_567770.html).

Its linear and useful for doing stair rails and banisters. VERY useful! Back and forth, not ROS.

Paddles are like these things. :)

The pads can be exchanged for different shapes, or make your own custom shape (they sell blanks). I've also seen the pads for sale on AliExpress.


I see them for sale all the time on Gumtree and Ebay, for they are rather specialised. They go quite cheaply.

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[elver]

Oooh that does look interesting. Second hand seems about $400 or so I think.

I did make a downdraft box last night its got a hood at the back, partial sides and as small an area as possible. Connected to my 2HP chip collector with a hose that's too long and with unfinished (unrounded) holes in the table it was a good start. Its got lights in it to allow better illumination of defects and is quite nice.

Certainly fugitive dust was much less than normal, but it was still underwhelming.

When I round over the holes and pretty it up a bit I'll post some pics.

Next steps:

Round over the holes in the table and experiment with covering some up some holes to see if higher velocity airflow will help catch more dust.
Shorten the connecting hose and pump the dusty hose straight out of the shed (after I move a bee hive from the flow path) bypassing chip collection completely
Get a sander that doesn't spin at crazy speeds with a smaller / better directed fan, so that dust velocities are reduced. (Linear or delta perhaps - this is last on my list as I've just ordered a heap of new ROS discs..)

[woodPixel]

Another idea might be to use part of BobLs designs with a twist. His ideas are good.

He suggested a belt sander, plus the BMH.

I think his BMH's are the bees knees. I LOVE MINE! Its magic - not science :)


I once saw a company in Sydney that made all sorts of mouldings. Rather than fart around with a hundred different profile sanding things, they used a machine that seemed to have brushes. One fed the object into it and it used a thousand fingers rotating to brush the thing silky smooth, regardless of shape.

I've seen them once on thickness sanders for one pro model (name defies me now). It replaced the drum.....

AANNYYWWAAYY..... the idea is you could hack together a box (to capture dust) and place one of these brushes onto an angle grinder, drill or other rotating-device-of-choice (such as... a motor!!) and make your own Low Cost Hack.

Some cheapo thing like this off AliExpress (in a custom dust box) --> Emery Abrasive Brush Sanding Wheel used on Air Polisher (https://www.aliexpress.com/item/32865881477.html)


Edit - This mob also sell add-ons for angle grinders (cowlings, handles and whatnot) as well as brushes of various size..... Hand held Linear Polisher Parts, Angle Grinder Adapter, Protective Cover, Bulgarian Extension Handle (https://www.aliexpress.com/item/33051328256.html)


Edit 2 - Apparently these things are called LINEAR POLISHERS (https://duckduckgo.com/?t=ffab&q=linear+polisher&atb=v214-1&iax=images&ia=images). These things are fantastic! Metal, timber, strip paint, fine sand, the works! All sorts of add-ons. Making up a dust box to capture the exhaust should be dead easy.
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[Dirk J]

Have a look at how a dust extractor works on a CNC machine. With a fine brush running around your sander . A little like a drywall sander.