Sanding fir with the RO 150

[CNSmith]

I've been having problems with softer woods ie fir and cedar and the sander leaving small scratches that I can seem to get out. I've tried different grit progressions, differents papers, different speeds, both modes through the progressions and the small subtle hooks won't go away. I am hooked up to a dust extractor. Is the RO the wrong tool for the job, (the fifty dollar bosch orbital doesn't seem to have the same issue) or is it operation error. I would appreciate any advice that smarter people than I can send my way.

 

[Holmz]

While I am not one of the smarter people....
Scrapers are generally "the go", but they do not work well on softer woods either.
If the $50 Bosch is working, then at least you have a near term solution as a backup plan.

One thing you could try is the FT paper on the Bosch and the Bosch pads/papers on the RO-150.
Then you can understand if it is the papers/pads or the tool/operation, and begin to home in on the problem.

 

[Sparktrician]

You might want to consider your technique. 

http://www.youtube.com/watch?v=rZZyypf-Qqk

Here's a good video that may help you with that.  You don't need to apply pressure to your sander.  Just let the tool do the work, and by all means, turn down the suction on your dust extractor to no more than 25% to keep the DE from pulling the abrasive into the wood. 

 

[Ackyjr]

Scrapers are ok what about an in line sander.

 

[Cheese]

Like [member=7493]Sparktrician[/member] said, go easy on the amount of suction you're using from the vacuum. I'm assuming you're using a vac with variable extraction?

 

[elfick]

I used my RO150 on a piece of doug fir for my test of the Surfix system. I was extremely happy with the results. I used the video Sparktrician posted as the basis of my test. I've had that piece of wood leaning on a wall in my office waiting to be installed and people can't believe it is a

 

[Tinker]

I have sanded pine and fir with my RO 150.  no problem.
I use low speed and turn the vac all the way down.
Tinker

 

[Tinker]

I take back that I had no problem.
When sanding a lazy susan made with pine and locust, I was using a soft pad that came with the sander.  I discovered the pine was being scooped out while the locust was hardly affected.  I found out I could get a hard pad for the toy and was able to level the LS.  It still took care to avoid further scooping of the soft wood, but the hard pad solved the problem. 

I know this reply is a little off topic, but anybody who is not used to a RO sander can run into trouble in many ways. The responder who mentioned using minimum of down pressure with the sander was right on.  That advise takes care of many, if not all. problems with any RO sander.
Tinker

 

[Scott B.]

I've been having problems with softer woods ie fir and cedar and the sander leaving small scratches that I can seem to get out. I've tried different grit progressions, differents papers, different speeds, both modes through the progressions and the small subtle hooks won't go away. I am hooked up to a dust extractor. Is the RO the wrong tool for the job, (the fifty dollar bosch orbital doesn't seem to have the same issue) or is it operation error. I would appreciate any advice that smarter people than I can send my way.

Without knowing exactly what dimensions you are sanding, one quick thought is if you were sanding 1x4 (or even x6) boards with the 150, that could be the problem. If the sander is larger in diameter than the width of the boards being sanded, the dust extraction is not complete, which could leave dust particles at the surface, causing the swirls. It is also tough to balance properly if the sander is oversized.

Just a thought...

 

[CNSmith]

Thanks for the feedback. I'm sanding 4x8 rafters using the rubin sand paper. I'm starting at 80 then 100, 120, 180, 220. Seems to be smoother on rotex but a bit worse on the scratching. I think I might be chasing some of the scratching from early passes when I'm using too much down pressure. I will try tuning my vacuum down and be a lot lighter on my pressure and report back. Would starting with a lower grit help?

 

[nickao]

First make sure you are not going to the next grit to soon.

Even if I start at 36 grit I can work almost all the scratches out by the time  get to 100. BUT on soft woods like fir a 3mm stroke works much better. Get an ETS 150 to finish up with. I just sanded up a project with both Heart Pine and Fir yesterday and I had to go to the ETS 150 form the Rotex to get the scratches out. I never even noticed until  I applied sanding sealer and saw the scratches the Rotex left. The ETS 3mm fixed it right up.

And as far as thin stock it's just not the cause of scratches. I  sand 2" wide strips easily with an RO 150 and hard pad and get a smooth scratchless finishes in hard woods. It's more a soft wood issue than a thin stock issue. On the softer woods going to a 2.5 or 3mm stroke makes all the difference in the world. An RO 150 just isn't going to make scrathless finishes on soft wood very easily, for some woods at all.

I sand a lot and have to sand soft woods next to really hard woods as part of my work.  Although the Rote 150 is my go to sander without an ETS 150/3 I just couldn't make the woods scrathless. Flat and smooth yes, scratchless no. It's not necessarily the same thing.

 

[Scott B.]

Thanks for the feedback. I'm sanding 4x8 rafters using the rubin sand paper. I'm starting at 80 then 100, 120, 180, 220. Seems to be smoother on rotex but a bit worse on the scratching. I think I might be chasing some of the scratching from early passes when I'm using too much down pressure. I will try tuning my vacuum down and be a lot lighter on my pressure and report back. Would starting with a lower grit help?

If the rafters are rough, I'd try starting at 60 and keep the extraction cranked to remove all the wood fiber. If smooth, I'd stay at 80. Even when in the low grit removal stage, keep it floating in long smooth passes.

 

[Sparktrician]

Thanks for the feedback. I'm sanding 4x8 rafters using the rubin sand paper. I'm starting at 80 then 100, 120, 180, 220. Seems to be smoother on rotex but a bit worse on the scratching. I think I might be chasing some of the scratching from early passes when I'm using too much down pressure. I will try tuning my vacuum down and be a lot lighter on my pressure and report back. Would starting with a lower grit help?

One thing you should do without fail is to wipe down the sanded surface between grit escalations to get rid of any remaining particles of material at the old (previous) grit.  If you don't, you'll have coarser particles in with the finer grit of the new abrasive, and that will lead to scratching. 

 

[nickao]

I totally disagree. I don't find that necessary at all. There is little reason to wipe down in between sanding grits if that collector is working right.

If enough suction is being used there should be no dust there, at least not enough for sanding the next grit. After the finest grit and before sanding sealer, but that's it. If a wipe down is needed between grits I propose not enough suction is being used .

Unlike some here my system is full power 100% of the time. Years ago we had many threads here on it, I gave up. Even from way back then my CT's still have never seen anything less than full pull all the time and I get fantastic results on all my projects. If I ever run into something where I need to lessen the suction I'll post, but it hasn't happened in 8 years. I guess my type of work work doesn't warrant it, that's all I can say.

 

[Scott B.]

I do the damp wipe at times because it simulates clear finish and helps me to better see the level of sanding I am achieving.

There really is no right or wrong on a lot of this stuff, and there is some variation from person to person. Even using the same tools and settings, the human factor is always in play. So it is a matter of finding what works for you.

 

[nickao]

Now that is a very good reason. I agree with that 100%. If you are looking for scratches nothing is better than damping up the wood for sure. Had I done that yesterday I would not have had to sand off a bunch of sanding sealer.  That can help prevent jumping to the next grit too soon as well. Of course water can raise the grain so alcohol works too. And of course there are tons of ways to do stuff. My way is just that, my way, that all. I need to focus on time as a huge factor.

 

[elfick]

Oh, I did use a hard pad. When I was researching the RO150, many here recommended it so I bought it the same time I got the RO150. I rarely take it off.

 

[Holmz]

... Get an ETS 150 to finish up with ...

Buying another multi hundred dollar sander? After the first one does not work?
That is the last thing I would recommend.

I would be returning that sander and going back to your $50 Bosch.
or
I would be returning that sander for a hand plane.

 

[Worm Drive]

Now that is a very good reason. I agree with that 100%. If you are looking for scratches nothing is better than damping up the wood for sure. Had I done that yesterday I would not have had to sand off a bunch of sanding sealer.  That can help prevent jumping to the next grit too soon as well. Of course water can raise the grain so alcohol works too. And of course there are tons of ways to do stuff. My way is just that, my way, that all. I need to focus on time as a huge factor.

Naphtha works well for this purpose. It won't raise the grain and evaporates slowly, giving you time to look things over.

 

[Tinker]

Quote from Dovetail65 >>>And of course there are tons of ways to do stuff. My way is just that, my way, that all.