Random orbital sander and dust collection

[Paul F Mills]

I have been using a ROS with a shop vac for dust collection with good results overall. Occasionally I will get swirl marks and one of the local guys says it is due to too using the shop vac and that it is sucking the sander to the surface. It does feel that way sometimes but does not always leave swirls. He says the solution is to use a Festool, Fein, or something with adjustable air flow, or maybe a smaller shop vac.

Do any any of you use a specific dust collection system for sanding or do you just make due with a standard shop vac or DC system?

[Phil Mueller]

I use a festool dust collector and ROS. The dust collector has variable suction adjustment and the ROS has variable speed adjustment. Even with that, I always hand sand in the direction of the grain to ensure removal of any swirl marks. I also have a festool hand sander that can connect to the dust collector. Using the hand sander, I set the vacuum power for low and keep the venturi open to avoid it being sucked to the work piece. These have been a great improvement to keeping my small basement shop fairly dust free.

[Charles Lent]

A ROS is not intended to be the final sanding step, even if you have used several sandpaper grits. Each finer grit is needed to remove the scratches left by the previous sanding grit, but then hand sanding needs to be done, in the grain direction, to remove the scratches left by the final grit used on the ROS. In most cases, I start with 80 or 100 on the ROS, then switch to 150, and then to usually 180. My final hand sanding is then usually 180 or 220 attached to a padded sanding block. This final sanding is to remove the last of the swirl marks left by the ROS. You have to be careful with each sanding step not to leave scratches left by the previous sanding step, or you will need to spend more than a usual amount of time trying to get those scratches out with the final sanding. Don't skip a step, or you will spend more time sanding too. The quality of the sanding will show in your finished project. Always vacuum off your project when about to switch sandpaper grits. If you don't, you will be sanding with two sizes of grit and it will be impossible to completely remove the scratches created by the previous grit.

I've never had a problem with excessive vacuum, but I suppose it's possible. Just create a leak in your vacuum hose connection and vary the size of this leak to adjust the vacuum level. A short piece of PVC pipe with a hole in it can be used for this. Use a short piece of the same pipe, with a slit in it and slide it over the piece with the hole. Now you can move this short piece to partially cover the hole and adjust your vacuum leak to attain the vacuum level desired. You may want to apply a piece of tape to prevent this sliding piece from moving once you have it adjusted to your satisfaction.

Charley

[Prashun Patel]

In fact, not using a Shop vac can also cause swirls because of trapped grit and dust.

The shop vac cools the pad, saves your lungs, and makes the paper last a tad longer.

Keep using it.

The swirls will be mitigated several ways:

1) don't press the sander at all; let it glide. Pressing reduces the ability of the pad to move freely and randomly.
2) don't move it fast; go slow. The swirls stay tighter this way and have a chance to scratch themselves out more evenly. Moving fast leaves pig tails
3) start at a higher grit. if you have done a great job flattening before beginning to sand, you may be able to start at 150 or 220 - instead of 60-100. The higher grit swirls are easier to remove.
4) finish at a higher grit. Contrary to popular literature, there is a HUGE aesthetic benefit to sanding almost anything to 400 or even 600 grit. You'll remove the lower grit swirls and highlight other imperfections you woulnd't normally see until finishing. The swirls imparted by 400-600 are way less visible to the eye. The smoother raw surface also makes initial finish coats go on more evenly. This is a big benefit on porous woods. The only downside is a little more up front effort vis a vis stopping at 180-220. But it pays dividends in the end. I dare you to try it.

[Paul F Mills]

Thanks for the input guys.

I have been starting at 60 grit and going until it feels smooth, then moving to 80, 120, and sometime 180. I have sanded with Festool 125 ROS until the swirls go away, never thought about hand sanding at the end but will try that on my next project. It makes sense.

I always brush and towel the surface between grits, I will try vacuuming too as I can see it being helpful to get the small dust out from cracks.

During my sanding session tonight, and with the sander off, I placed the sander directly on the workpiece and could tell it was sticking slightly, but probably not enough to matter. I like the the idea of creating a leak in the hose, and it is cheaper than a Festool DC. I will try it. I just want to be as dust free as possible.

I have have yet to flatten anything well enough to start with a 150 or higher. I usually run through a planer when it is small enough and even then I am not sure it is smooth enough to start that high. And the planer is only two months old and has not been used that much.

I may try sanding to a 400 grit on a test piece. As you alluded to, I have always read that too much sanding will not allow the wood to take a finish but your experience is different. Time to expirement.

[David Buchhauser]

Paul,
You might try using a blast gate inline with your shop vac to adjust the amount of suction. Or - you could install a T-fitting inline with your shop vac hose and use the blast gate to regulate the size of the "leak".

David

https://www.amazon.com/Big-Horn-1125...sr=1-1-catcorr

https://www.amazon.com/Big-Horn-11259-2-Inch-Plastic/dp/B003NE59D8/ref=sr_1_1?keywords=blast+gate+2+1%2F4&qid=1556162 217&s=hi&sr=1-1-catcorr



Blast Gate for Shop Vac.jpg Shop Vac T-Fitting.jpg

[Steve Eure]

I noticed that when I used the 2 1/2" Shop Vac hose connected straight to my sander, it would do the same and leave swirl marks. It was also a challenge with the weight of the hose on my Bosch ROS. I found the solution, at least in my case, was to take an old Bi-Pap hose that I had and use it between the sander and Shop Vac hose. It is 1" and it restricts the airflow enough that it doesn't suck down to the wood as much. It still works fine and collects just as much dust as before. It's also much easier to handle without the bulky 2 1/2" hose pulling on it.
Someone told me that it would cause issues with my Shop Vac, but I haven't noticed any problems. I told them that Shop Vac sells small hose kits for those vacuums, so if there was a problem, they wouldn't recommend them. Six years and still running strong. Noisy, but strong.

[David Buchhauser]

Steve,
I like your suggestion. Using the "Bi-Pap" hose sounds like the best solution.
David

[Art Mann]

I don't know what type of planer you are using, but the finish left by my planer is good enough that I normally start with 150 or 180 grit. If you need to start with 60, 80 or even 120 grit then I think there is something wrong with your planing operation. I can't imagine having to sand out the swirls caused by using 60 or 80 grit paper. I'm guessing that is the real source of your problem.

My opinion of sanding bare wood with 400 grit is that it is a useless endeavor. After you apply a finish, you won't be able to tell the difference between 400 and 220 grit. It only makes a difference when you are applying stain. If you don't believe me, just try it. After the first coat, you will be sanding finish and not wood. That is the point at which you should use 400 grit and up.

Thanks for the input guys.

I have been starting at 60 grit and going until it feels smooth, then moving to 80, 120, and sometime 180. I have sanded with Festool 125 ROS until the swirls go away, never thought about hand sanding at the end but will try that on my next project. It makes sense.

I always brush and towel the surface between grits, I will try vacuuming too as I can see it being helpful to get the small dust out from cracks.

During my sanding session tonight, and with the sander off, I placed the sander directly on the workpiece and could tell it was sticking slightly, but probably not enough to matter. I like the the idea of creating a leak in the hose, and it is cheaper than a Festool DC. I will try it. I just want to be as dust free as possible.

I have have yet to flatten anything well enough to start with a 150 or higher. I usually run through a planer when it is small enough and even then I am not sure it is smooth enough to start that high. And the planer is only two months old and has not been used that much.

I may try sanding to a 400 grit on a test piece. As you alluded to, I have always read that too much sanding will not allow the wood to take a finish but your experience is different. Time to expirement.

[Prashun Patel]

"My opinion of sanding bare wood with 400 grit is that it is a useless endeavor. After you apply a finish, you won't be able to tell the difference between 400 and 220 grit. It only makes a difference when you are applying stain. If you don't believe me, just try it. After the first coat, you will be sanding finish and not wood. That is the point at which you should use 400 grit and up."

We agree to disagree on this point. It makes a huge difference in how that first coat goes on. I agree that if you are brushing on or spraying on thicker coats, it makes no difference. But if you are wiping on thin coats or doing an oil-varnish finish, it makes a noticeable and tangible difference. I encourage anyone to try it for themselves and make their own determination on this.

[Jim Becker]

The wood species will have an effect on the relative merit of sanding to finer levels on the "bare" wood as well as what kind of finish will be used. Hard, closed grain woods like cherry, maple, etc., benefit more from sanding to finer levels than some other species, IMHO. So I'm with Prashun on this for sure, both in agreement on the theory and in my personal practices.

[Frank Drackman]

Nice to find another in the "Its worthwhile to sand to higher grits club"

I never hand sand after the ROS. I routinely sand to 800 with the ROS, sometimes much higher.

The only times I have swirl marks is when I don't adequately clean the previous grits before going to the next grit.

I agree, it s a wonderful thing when you apply the first coat of finish.

In fact, not using a Shop vac can also cause swirls because of trapped grit and dust.

The shop vac cools the pad, saves your lungs, and makes the paper last a tad longer.

Keep using it.

The swirls will be mitigated several ways:

1) don't press the sander at all; let it glide. Pressing reduces the ability of the pad to move freely and randomly.
2) don't move it fast; go slow. The swirls stay tighter this way and have a chance to scratch themselves out more evenly. Moving fast leaves pig tails
3) start at a higher grit. if you have done a great job flattening before beginning to sand, you may be able to start at 150 or 220 - instead of 60-100. The higher grit swirls are easier to remove.
4) finish at a higher grit. Contrary to popular literature, there is a HUGE aesthetic benefit to sanding almost anything to 400 or even 600 grit. You'll remove the lower grit swirls and highlight other imperfections you woulnd't normally see until finishing. The swirls imparted by 400-600 are way less visible to the eye. The smoother raw surface also makes initial finish coats go on more evenly. This is a big benefit on porous woods. The only downside is a little more up front effort vis a vis stopping at 180-220. But it pays dividends in the end. I dare you to try it.

[Edwin Santos]

Sorry if I'm taking this off topic, but would one of you aficionados of high grit sanding care to suggest a good source for high grit hook and loop sanding discs?

I usually get my sanding supplies from a place called Industrial Abrasives. But they seem to top out at 320 grit for the 9 hole festool pattern in 5" which is what I need.
I used to stock Mirka bought from Amazon but no luck with the higher grits there either.

Thanks, Edwin

[Frank Drackman]

I get all of my sandpaper at Klingspor's Woodworking. Not cheap but I think that their sandpaper is an excellent value.

https://www.woodworkingshop.com/abrasive-discs/

[Prashun Patel]

I get 400 and 600 indasa rhynigrip from 2sand. They also have 800 and 1000 abranet but 600 is where I usually stop.

They also have 800 and 1200 rhynosoft pads which I have been impressed with for contour sanding between coats