Author Topic: Help with sanding please  (Read 4366 times)

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Offline ocd

  • Posts: 7
Help with sanding please
« on: September 30, 2014, 10:35 AM »
Hi,
I have the Rotex 125.  Have never really studied it.  I am a novice WW.  Now, am making a mahogany blanket chest for my niece, and since spent all this $ on wood, would prefer to do the sanding right.  It is a great tool, and a shame I am likely not using it correctly.

Have had swirl marks in past.

Can someone help me out with using my 125?  My concern is dealing with the cross grain in the mahogany; it is pretty rough right now, and I think I'm gonna have to take it down some to get a really smooth surface.  I have a nice high angle hand plane that I could have used to negate this problem, but I didn't. [embarassed]

I have read in a thread here to use lower CT settings with larger grit(?)

Dust/sweep in between grits(?)  Finish off with hand sanding block(?)

How do I know when to use the mode that just hogs off material?

Maybe a beginner's tutorial on YouTube?
 
Thank You, David

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Offline waho6o9

  • Posts: 1472
    • Garage Door Handyman.com
Re: Help with sanding please
« Reply #1 on: September 30, 2014, 10:58 AM »
Maybe practice on some scraps and go

hog wild, that way you can dial it in

and use your experience on your expense

lumber.

Good luck on your project.


Offline Sal LiVecchi

  • Posts: 1377
Re: Help with sanding please
« Reply #2 on: September 30, 2014, 11:07 AM »
I would not go past 100 grit in Rotex mode, they switch out to RO mode and move up in grits from there, also let the machine do the work, by that I mean you do not have to apply a lot of pressure in either mode, the paper will do its job for sure.
The advise on practice first on some scrap is also advisable for sure
Life is too short and the road is too long to drive anything less than a Festool

Offline abgoto

  • Posts: 85
Re: Help with sanding please
« Reply #3 on: September 30, 2014, 11:11 AM »
Generally speaking, you don't want to use a 125mm sander to flatten large panels.

For sanding technique using a Rotex, here is a great instructional video:

Offline leakyroof

  • Posts: 2280
Re: Help with sanding please
« Reply #4 on: September 30, 2014, 11:12 AM »
There are Foggers who use the Rotex Mode into way higher grits than I do, and they are successful at it with no swirl marks claimed to be left.
 For me, I use the Rotex mode for rougher sanding with abrasive grits below 150 or 120, and use the Random Orbit Mode for all sanding above 150.  You can also polish or burnish with your Rotex Sander if you want that kind of finish for your work.
 Rubin 2 will work well with bare/raw wood.  I've also followed some Rotex sanding with Random Orbit Mode using the same grit when I wasn't happy with a scratch pattern or other visible sanding mark left using Rotex Mode. But that's a rare thing for me.
  tons of videos on YouTube about using your Festool Sander, also good info here on FOG.
Not as many Sanders as PA Floor guy.....

Offline RL

  • Posts: 3040
Re: Help with sanding please
« Reply #5 on: September 30, 2014, 11:25 AM »
Is the mahogany sapele? If so, you're going to have a tough time planing it due to the reversing grain. I'll tell you what I would do, and it perhaps differs from the way others do it.

With sapele, I use my Rotex 125 in geared rotex mode all the way to 180 grit. I usually start at 100 (granat) if I have any tear-out, then 120 (rubin 2) and finish at 180 (rubin). If the surface is already quite smooth I may only start at 180. Then I switch to my ETS 125 and sand at (Brilliant) 220 (random orbit). You could use the Rotex 125 in random orbit mode too. The vac is set to about half-power, and I use a hard sanding pad on the rotex sander to keep everything flat.

This will get you a finish-ready surface. The wood does not need to be sanded any more than this, and this is key. If you sand it further, you are actually making your finishing process more difficult in most cases.

I don't bother to sweep off the dust between grits, and I let the sander float across the surface. I'm just there to steer it. If you are getting swirl marks, it is usually because of either i) the suction is too high ii) you are bearing down on the sander iii) the sander is not lying flat on the surface iv) you switched to a higher grit too soon.

Good luck.

Offline ocd

  • Posts: 7
Re: Help with sanding please
« Reply #6 on: September 30, 2014, 11:54 AM »
That is great!

I need to watch the video(s), but from what I see, the deal is:
-use the rotex mode only grits below 100, usually
-The less vacuum is better sometimes cause higher suction causes the sander to dig into the surface

RL: What is ETS?
       Why would sanding to higher than 220 make the process more difficult?

I am pretty unsophisticated on the type of abrasive.  I have an assortment right now, mostly Rubin and Brilliant-all appropriate for wood, but am @ work right now for sure what the names are of all the diffo grits.

abgoto:  I milled the wood before glue-up-but, as we all know, it has some edge unevenness, and of course the cross grain tear-out.   I have lots of L-N planes, frogs, blades, and all that-but I mostly admire them instead of using them [embarassed]  As I have gotten older, I have am using machines more.   So, the panel is pretty flat already.   If someone examines it in a raking light will it by nice and all that?  Probably not....then, they will say, in 50 years........Gee, this is hand made [cool]

So, I will get a piece and experiment with the geared mode and 100 or 120.

I need to watch those videos. 

I welcome all advice.  Thank you all much!!  David 


Offline ocd

  • Posts: 7
Re: Help with sanding please
« Reply #7 on: September 30, 2014, 12:22 PM »
Wow.  I watched that video that abgoto sent.   

Is it possible that I been spending way too much time on sanding (using the Rotex wrong)?   Is it really as quick as he depicts?   He uses only the gear driven mode.   Is that what you all do?

Do any of you use the 1500, and then polish?  I have some of that Micro-Mesh, what is used to rub out scratches on airplane windshields.....a lot of trouble, though.   Leaves a finish like a wax has been applied.   A lot of work.   The Festool polish is just as good?

David

Offline RL

  • Posts: 3040
Re: Help with sanding please
« Reply #8 on: September 30, 2014, 12:29 PM »
That is great!

I need to watch the video(s), but from what I see, the deal is:
-use the rotex mode only grits below 100, usually
-The less vacuum is better sometimes cause higher suction causes the sander to dig into the surface

RL: What is ETS?
       Why would sanding to higher than 220 make the process more difficult?

I am pretty unsophisticated on the type of abrasive.  I have an assortment right now, mostly Rubin and Brilliant-all appropriate for wood, but am @ work right now for sure what the names are of all the diffo grits.

abgoto:  I milled the wood before glue-up-but, as we all know, it has some edge unevenness, and of course the cross grain tear-out.   I have lots of L-N planes, frogs, blades, and all that-but I mostly admire them instead of using them [embarassed]  As I have gotten older, I have am using machines more.   So, the panel is pretty flat already.   If someone examines it in a raking light will it by nice and all that?  Probably not....then, they will say, in 50 years........Gee, this is hand made [cool]

So, I will get a piece and experiment with the geared mode and 100 or 120.

I need to watch those videos. 

I welcome all advice.  Thank you all much!!  David

I use the rotex mode well above 100 grit, and also when polishing (above 500 or so). It's totally untrue that you have to stop using it after 100.

The ETS 125 is Festool's 5" random orbit sander with a 2mm stroke. It is for very fine sanding. The Rotex 125 has a 3mm stroke for example.

Rubin and Brilliant work very well for sanding wood; you can also try Granat.

Offline SRSemenza

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  • Posts: 8956
  • Finger Lakes Region, NY State , USA
Re: Help with sanding please
« Reply #9 on: September 30, 2014, 12:36 PM »
    Personally I wouldn't be using the aggressive mode at all unless you actually need to remove material or strip something or polish. When I say remove material I mean rough boards that haven't been planed, glue lines,  actually reducing  thickness by 1 /32" or more, removing mill marks, etc. To me this isn't really sanding. I think that if you are sanding a planed, flat, mill mark free board you are just asking for problems to be introduced by using the aggressive mode. If you have used the aggressive mode and are transitioning to the random orbit mode, sand very thoroughly with the same last grit used in aggressive or even one grit lower in random orbit before moving forward to higher random orbit grits. You need to really make sure all the aggressive mode marks are removed or they will plague the surface all the way to the final grit.

Seth

Offline ocd

  • Posts: 7
When to change abrasive-same grit
« Reply #10 on: September 30, 2014, 01:17 PM »
I went to YouTube, and am looking around for some videos, but the one posted already seems to be most specific to my issues.

Any easy way to tell when a pad needs to be replaced (same grit)?  Am I alone when I use a pad until it obviously is no good?   My guess is that if I were to change them out more often, maybe just after the microscopic exposed cutting edges of the abrasives were used up/worn off, etc, that it may cost a little more, but save me a lot of time?

Offline leakyroof

  • Posts: 2280
Re: When to change abrasive-same grit
« Reply #11 on: October 02, 2014, 08:58 AM »
I went to YouTube, and am looking around for some videos, but the one posted already seems to be most specific to my issues.

Any easy way to tell when a pad needs to be replaced (same grit)?  Am I alone when I use a pad until it obviously is no good?   My guess is that if I were to change them out more often, maybe just after the microscopic exposed cutting edges of the abrasives were used up/worn off, etc, that it may cost a little more, but save me a lot of time?
  I'm guessing you mean the actual Abrasive Disc, not the sander pad itself?
 With DC collection, the discs will last much longer, and while a worn disc may not cut as fast as a new one, it can still be working for you. I tend to leave them on[ sanding bare/raw wood] until either the outer edges are really showing wear and I don't want the Velcro pad hooks damaged, or I'm sure I'm working with a worn, non-cutting disc and it's not worth keeping it on the sander[time for a new one]
 With refinishing work or stripping a finish off, this would be totally different since you get into a different type of sanding/stripping than bare wood sanding.
Not as many Sanders as PA Floor guy.....

Offline mcooley

  • Posts: 239
Re: Help with sanding please
« Reply #12 on: December 08, 2014, 01:25 PM »
I'll add my two cents here.

I have always struggled with swirl marks in the finer random orbital mode. I tried all the usual recommendations for avoiding them etc. But today I tried this method of leaving the Rotex in the aggressive all the way up through the grits. Maybe I am being too quick to judge but this method has kind of changed my life (well, my life with regards to sanding!).

We'll see how it does with some other pieces of wood but I never thought to try the aggressive mode from start to finish. No swirls and just as smooth as in the fine mode. Amazing it took me so long to try this.


Offline sae

  • Posts: 842
Re: Help with sanding please
« Reply #13 on: December 08, 2014, 01:41 PM »
I use Rotex almost exclusively as well.

The only caveat is to watch your sander speed if you're doing this between finish coats, because you may melt your finish if you introduce too much heat.

Offline jnbgtr

  • Posts: 1
Re: Help with sanding please
« Reply #14 on: December 11, 2014, 11:03 PM »
Hey OCD,

New to the tools myself but after a week of working on a living edge table top (Cherry), I can at least add to what others have said.  Seth commented above (correctly), that if you're taking down too much material you're really planning and not sanding and can introduce unevenness.
I had to manually plane down the stock (built a makeshift router guide table) to take out a bad twist.  Once I was left with a relatively even board I had to even off the router passes.
I have a Rotex 150 and the ETS 125. 
I moved through the early stages with the Rotex 150 with Granat 40-60-80-150-180 grits.  All the preceding passes in the aggressive mode.  As others point out you will get swirls but that is not an issue this early on.  I then alternated and experimented with the random orbit more/ Rotex mode on 220 grit and this seemed to remove most swirls.  You'll have to also experiment with the vacuum suction as others pointed out.  With a machine as heavy as the RO150 it's not too much an issue but with the lighter 125 the high suction will draw the sander into the stock and it won't rotate the random orbit head as freely as it should.

I then moved through higher grits with the ETS 125 (340-400-800).  Then back to the RO150 with the interchangeable buffing head for Platin S1000 - S2000, then felt and finished with the lambswool.  Results are impressive and you'll learn (as I did) as you go.

One thing I noticed is that I had to back down to a lower grit to remove swirls (340 from 400).  Sometimes you can only see it once you sand as the fine particulates expose defects in the sanding and settle into the swirls.  One user commented that he didn't wipe between sandings.  BIG MISTAKE.  The machine cannot remove all the sanded material and should not be treated as a vacuum.  Always wipe between coats.  So far, quite happy with the machines.