Basic Question - ROS vs Finish Sander

[ejstefl]

Hello,

I have what I think is an easy question. When do you use a Random Orbit Sander, and when do you use a Finish Sander? I assume that they are designed for different jobs, but I'm not sure what the advantages/disadvantages of each of them are. I was sort of under the impression that a ROS would be bad for wood, as it would sand across the grain, which you're not supposed to do.

Also, to tack a bonus question on here, what is the best way to smooth a glued-up panel? Using a sander? A hand plane? Something else?

Thanks guys!!

Eric

[scorrpio]

A ROS, especially variable speed, will create a uniform scratch pattern. The only real advantage of a quartersheet finish sander is that being square, it can get into those tight corners where ROS can't. However, most people do their sanding before assembly, which means there are no tight inside corners yet. I have both, and I use finish sander very rarely.

Far as glued up panel goes - well, you should try to get it flat to begin with - by using caulls during glue up. But once glued, the best way would probably be a drum sander - but those can be costly. A belt sander works well too.

[Tom Miller]

I'm not sure how specific the term "finish sander" is -- obviously I don't have one. But I do have an ROS, and can tell you that it's perfect for sanding wood to whatever level you desire. It's the "random" motion that reduces the swirl marks to nearly negligible levels.

With 80 grit paper, it'll remove stock, such as a ridge line at the seam of a panel glue up (not that that's the best technique). And with 220 grit or higher, you can get a very nice, smooth surface ready for finish.

Re: panel glue up --

Depends how severe the problem is. If the boards are misaligned, I'd probably go at the high one with a handplane. Before I had handplanes, I used to go at them with 80 grit on the ROS. But you have to be careful, and you probably won't end up with as flat a surface.

Now, I tend to use biscuits purely for vertical alignment. It makes clamp time a lot less hectic, while giving better results.

If you're just dealing with a little ridge and/or glue squeeze out, you may only need a card scraper.

Either way, don't do any of this for several days after glue up, as that area around the seams will be swollen from the glue moisture. If you planarize the area when swollen, you'll have a depression when it dries.

Regards,
Tom

[vaking]

ROS is a woodworker's workhorse. If you only have enough money to buy one sander - make it ROS. It is aggressive enough to get the job done quickly and yet is leaves the surface very smooth because of the "Random orbit" style - it produces no residual marks.
It has 2 disadvantages:
It does not get into corners.
It needs specialized round sanding disks and those disks come in grits up to 220. There is nothing finer than that.
Don't get me wrong - 220 grit is plenty for any raw wood. Finer grits can only be used on top of some already applied finish - between coats. It is also unclear how much you need sander between coats - this stage is supposed to need very light sanding only.
Finish sander is much slower than ROS. But it can get into corners and you can use standard sand paper including high grits.
As for smoothing the glue-up panel - there are many different opinions. It is a matter of personal choice. Some say smoothing plane is best, others prefer scrapers and some use sanding. I have seen a magazine article with test results and the conclusion of tests was that after typical finishes are applied - all methods produce basically same results. Sanding is probably the quickest and the dirtiest of all. Planing is physically hard but morally satisfying. Scraping takes some skill and time but is clean and not hard on you physically.
Chose what you like.

[RayintheUK]

I agree that a ROS is the most practical form of sanding nowadays. My Makita has two choices of orbit, so it will really remove stock fast if desired, otherwise it's a pussycat and leaves a glass-like finish with the appropriate grits. I like its heavy construction - the weight of the machine does most of the work for you.

.... needs specialized round sanding disks and those disks come in grits up to 220. There is nothing finer than that.

Sorry to disagree, Vaking, but aside from 240 grit, there's 320 grit here and 400 grit here

I rarely go above 320, although you can feel the difference if you go that extra (400) step on some timbers.

I have a "finish sander" too, but it hasn't seen the light of day since I bought the ROS.

Ray.

[mschrank]

Sorry to disagree, Vaking, but aside from 240 grit, there's 320 grit here and 400 grit here

Ray.

And Grizzly has some 600 grit. Actually, they also sell 1500 grit, but I don't know where you would need that in woodworking.

[scorrpio]

It needs specialized round sanding disks and those disks come in grits up to 220. There is nothing finer than that.

That is, BORG and Lowe's won't have anything finer.

Grizzly has H&L Silver discs In both 5" and 6" with 5 and 8 holes up to 400 grit. ($26 per pack of 100 5"/8hole discs). And H&L Gold discs up to 600 grit, $30 per 100-pack.

[vaking]

Thanks guys,
I stand corrected. There are disks finer than 220. I usually limit raw wood sanding to 220, so I did not investigate properly. For me sanding above 220 is usually manual although I also have a finish sander and could have done it with this sander even before. I guess I am afraid this work is too delicate for any machine. As for 1500 grit disks, I used rottenstone when I wanted mirror finish on laquer. I believe this is in the same league.

[LarryG]

I have what I think is an easy question. When do you use a Random Orbit Sander, and when do you use a Finish Sander?

That IS an easy question.

A random-orbit sander is used for all woodworking projects.

A finish sander is used when it's a windy day and you need something small and semi-weighty to hold the shop door open.

[bigsteel15]

Another source for fine grit discs
http://www.stockroomsupply.com/prices/HLDchartcU.php

That said, I don't own a handplane (please don't chastise me) so tend to use my cabinet or card scrapers for minor touch-ups after sanding the big problems.

[ejstefl]

I already own a finish sander, and have been using it up until this point. Bascially, it sounds like the advantage to a ROS is speed. Sounds like the finish sander will do the same job, just take more time... Thanks for all the replies!

[ke4rdb]

ROS is used for almost all projects, a 1/4" sander for getting in square corners.

I did a 12"x24" glue-up panel the other night and rushed it. I jointed the edges but did not thickness plane (using BORG dim. 3/4"x 4" lumber) after putting in clamps noticed that 2 of the boards were appox 1/16" higher than the others. No problem says I, I'll just run them thru my Ryobi AP1300 planer (mistake) to flatten. When I did so the planer had a issue pulling the panel thru. I did get-r-done but it was a pain and I had snipe that I will need to sand out (ROS).

Has anyone else tried to use a planer to flatten out glue-up panels or was I having problems because of the size of the glue-up. I have planed 12" wide lumber (solid) before with this planer and had no problems with it pulling the boards thru and giving me a great finish.

JW

[Tom Miller]

Has anyone else tried to use a planer to flatten out glue-up panels or was I having problems because of the size of the glue-up. I have planed 12" wide lumber (solid) before with this planer and had no problems with it pulling the boards thru and giving me a great finish.

Using a planer is a perfectly reasonable approach to flatten 12" wide (or less) panel glue ups. I'm not sure why you had trouble with the feed, but it could be due to friction between the stock and the planer bed; maybe due to glue squeeze out(?).

I can't think of any reason that snipe would be more prevalent with a glue up, either.

Keep in mind that glue is very hard on planer (and jointer) blades. Scrape off as much as you can, first. Then, if possible, feed your stock at a slight angle to spread out the affected area of the blade.

Regards,
Tom

[Ken Weaver]

In addition to what Tom said, clean the rollers - they lose grip when dirty.

[John Hunter]

And Grizzly has some 600 grit. Actually, they also sell 1500 grit, but I don't know where you would need that in woodworking.

I use all the way up to and including 12,000 grit. https://www.micro-surface.com/defaul...95LV&storeid=1 Gives finishes like polished glass.