Random Orbital Sander Q.

[zapdafish]

How am I supposed to startup a ROS and then start sanding? I've been experimenting on some scrap and it seems like when it first starts up, if it is already on the surface I want to sand it makes some marks that take abit to sand out. If i start it up then lower it to the surface, I sort get the same thing with the first edge that hits even if I am trying to keep it flat.

Once I am over the hump of getting it started, everything goes real well. Sorta like driving a manual transmission and getting past 1st gear for me :icon_scra

 

[froglips]

Steve,

I've found starting the sander off the work and gently lowering it while letting it sort of pull itself along. I also tend to start the sander in motion. Sort of like a plane coming in for a landing (of course without the flight attendants, complimentary peanuts and in-flight movie)....

I'm in the camp that believes ROS should be only guided and let the weight of the sander be all thats applied. Also, I work the sander very slowly along the grain of the part. At most a foot in 5 seconds.

I think you see more trouble if you put downward pressure on the sander, more so at the start.

Hope that helps.

Jim

 

[RayH]

complimentary peanuts
Jim

What complimentary peanuts?:gar-Cr

 

[LeftyTom]

:icon_thum What Jim said.

 

[Joe Scharle]

Never had that happen, but it does make me wonder if the brake band is broken and allowing the pad to spin.
Anyway, it's best to practice things on scrap. After all these years, I never use a belt sander (hand) on good wood without getting the feel again on scrap. And that doesn't help much!

 

[JimD]

I generally turn it on and put it on the wood as it is coming up to speed. I am also moving it while I am lowering it. I still create some noticable scratches sometimes but I remove them before moving to the next grit. It takes a little practice IMHO. I find a belt sander easier to use and my old Rockwell pad sander the easiest of all.

Jim

 

[Gofor]

With most electric ROS that have the brake, starting and stopping with the sander off the wood is the recommended practice. Moving laterally when settling onto the surface will give the best results rather than plopping it down flat (i.e. what Jim said). With pneumatic ROS (usually called DA for dual action), there is no brake system, and so should be both started and stopped on the surface. If the brake is defective on yours (you can tell if it starts spinning wildly when held in the air), starting with the sander setting (not pressed) on the surface is your best bet. If it slings the sanding disk off when in the air, the brake is non-existent!!

Go

 

[ehpoole]

I'm puzzled, I'm still pretty much an amateur and I have never encountered this behavior with my DeWalt ROS -- what am I doing wrong??? :rolf:

Did I really just luck out that much when I made my selection a couple years back? I have a pneumatic ROS I have not yet had a chance to try, have to wait until I get a larger compressor for that, so I don't have anything to compare my DeWalt with.

In all seriousness, though, I'm just curious if this is really a common issue for everyone?

Now, if I can just get used to the aggressiveness of a ROS with Norton 3x sandpaper -- not as aggressive as my band sander, but much more aggressive than the 1/4 and 1/3-sheet orbital pad sanders I was accustomed to in the past. I replaced most of my powered sanding gear a couple years back because my older (10-25 year old) orbital sanders lacked any meaningful dust collection.

 

[zapdafish]

i didnt find a brake on mine but I'll give the airplane coming in for a landing method a try in a few days. I got painted things drying so don't want to generate any dust. 24hr complete dry/cure times kinda suck.

thnx for the tips

 

[Bill Clemmons]

Steve,

I've found starting the sander off the work and gently lowering it while letting it sort of pull itself along. I also tend to start the sander in motion. Sort of like a plane coming in for a landing (of course without the flight attendants, complimentary peanuts and in-flight movie)....

I'm in the camp that believes ROS should be only guided and let the weight of the sander be all thats applied. Also, I work the sander very slowly along the grain of the part. At most a foot in 5 seconds.

I think you see more trouble if you put downward pressure on the sander, more so at the start.

Hope that helps.

Jim

I'll second what Jim said (except for the complimentary peanuts, which are no longer complimentary :no. The only thing I would add is to never let the sander stop moving over the wood. Slow is good, but letting it sit stationary will cause swirls. Like belt sanders, succes w/ a ROS is more art than science. You just have to learn to "feel" your way over the wood.

Bill

 

[Gofor]

The brake isn't much on some. On my older DeWalt, it is simply a thin plastic skirt that drags on the edges of the disc enough to keep it from spinning up when lifted. It can wear out to the point that there is no longer any friction, which means more spin, which will tend to gouge into the wood when it first hits it.

Go

 

[DaveD]

Never thought much about it. Just turned them on, slapped it down on the wood and had at it. Let the weight of the tool do the work.