1/2 Sheet Sander Question(s)

[Scott Young]

Hey guys, first time posting and hoping you can clue me in on an issue I'm having. I've used a 1/2 sheet orbital sander pretty much for my whole woodworking life, since its what my dad had. It's one of the massive and well built Milwaukee ones from the.. 90's? Anyways- after using that for well over a decade, I came to want to purchase my own recently and was sad to see how the half sheets are a dying breed.

Makita and Festool seemed to have the best reviews of current manufacturers and still just doing this for a hobby and partly for my job of building cabinets for our rental property- I opted for the Makita. Several people had compared the two with favor falling both ways. My issue, is one I've never had before- however. This sander jumps around like crazy when I use it, and it's definitely something I don't get. At the low speeds its terrible and the only real workable speed is the upper end one (still about 1000 opm under our milwaukee). Is there anyone who knows what the issue could be? I've tried adding a lot of pressure, I've tried no pressure. Our Milwaukee was so great it could float on top of the piece of ply that was being sanded but if this was left alone it would river dance. I did read there could be a break in period for the bushings to set during which time full power isn't obtained but this is ridiculous. The sander IS super quiet in comparison with a very smooth start stop and vibration control- no numbness :) so they get credit for that. I just don't get this bouncing/jumping issue. I tried a search but either there isn't much on the subject or I don't know the proper terms. Any advice would be greatly appreciated. If it keeps up as annoying as it is- I'm thinking about upping it to festool quality (assuming that is the issue...). Thanks guys! (Also- sorry for bad formatting, on my iPhone at the moment but I had to get this out while I was thinking about it at the job site.)

[Ole Anderson]

Which Makita did you get? I used to have a Sears 1/2 sheet sander gotten from my FIL. It had the same problem you are describing. Take a look at the 5" round ROS sanders as an alternate, don't need Festool quality to get a good one. PC makes a fine sander at around $100 as do others. If you need to get into square corners once in a while, add a 1/4 sheet sander at $50 or a multi-tool with a sanding pad.

[Jim Andrew]

I wore out a couple of old Black and Deckers, back in the late 70's and 80's, and was happy to find how great the random orbit sanders work. I got the Bosch with the side handle, makes them easier to keep a hold onto, and also got the fittings so I can hook my vacuum to it. Makes sanding much more tolerable. I just sand the pieces before putting them together, then you can cover the entire piece without worrying about corners.

[John Hollaway]

Scott, I experienced the very same problem with the Bosch 1/2 sheet sander I recently bought. Turned out the problem was caused by the vacuum suction. I even put a speed controller on my vac to cut the suction way back, but that didn't help much. So, I ended up using the included dust collection container, and no more jumping around. Actually, the dust collection container for the Bosch works really well. Kinda makes you worder why they even produce a vac hose connector for the sander.

[Charles McClain]

Scott,
I have the Festool and it will bounce if I have the vacum turned up and I get some bounceing on the first grit if the board isn't straight edge flat. As the pad makes contact with the board again after comming across a dip it will cause bounceing. I'm not looking at it now but I belive this is in the festool RS2E manual (which may be online) and it has more to do with how hard the pad is than orbital vs ROS. A softer pad will follow the dips and doesn't loose contact with the board. In fact, I have hard pads for my RO90 and RO150 and they will bounce for the same reason. My solution is to turn down the vac until I see sawdust then back up just a touch, if that isn't the problem I lift on the sander just enough to take some of the weight off it until I work out the dips in the board.

[Scott Young]

I can't tell if its the vac or not. I forgot to say I tried both methods (granted I didn't have the punch plate yet, it's being delivered). I punched out some holes with a nail for the vents and tried that way (didn't hook the bag or my vac up yet) and I tried sanding both with and without holes, on new and old sheets of sandpaper.

The one thing I haven't tried yet is seeing if they have alternate pads. I know our milwaukee has really soft padding and this Makita (BO4900V) has a significantly stiffer, flatter pad. I read or heard the festool half sheet when using standard paper, needs a different pad to work with said paper. Thought that could be an issue so when I get home tonight I'm going to look into that.

As to why I insist on going with a half sheet sander- I've used quarter sheets in the past, always with a jumping problem. Never used a random or it but then- I've never had the need to. Honestly- it pretty much stems from the fact that a very large amount of my sanding is large, flat surfaces where 1/2 sheet sanders have a tendency to excel (larger surface area, aiding in not creating dips so easy etc). Could also be ignorance since many of the quarter sheets I've used had next to no padding, basically flat rubber or something. We did have a quarter sheet PC which wasn't bad, had good padding but it just was too small for 80-90% of what we do so it got less use.

I watched a video of someone using the festool with the same amount of care I gave our milwaukee (doesn't need a significant mount of a soft touch to work right) and that was where I thought the rigidity of the pad may be an issue. Once I find out more, will let ya know.

[Scott Young]

So a quick temporary update- I've been using the sander more (fixing a bondo situation I really screwed up... Hah) for like the last 30-60m and it seems the 'break-in' hypothesis might not be wrong. It's skipping far less (still there on a couple areas of my plywood workspace, however it's significantly better on what I've been doing (at least without holes punched for dust collection). I also checked and it puts out a little over 3 amps of power for a max of 10,000 orbits per min vs the milwaukee which does 12000 at 5amps. I have a feeling the extra 2000 orbits really aids the milwaukee at floating on the surface, however the 10000 seems to knock down an equal amount of at least the bondo I was sanding.

[John TenEyck]

Never had any bouncing issues with either my old B&D or new Makita 1/4 sheet sanders, or my Bosch 1/2 sheet sander. I use all of them only with their attached dust collector bags. My new little Makita 1/4 sheet is so smooth, though not really quiet, I just can't imagine it bouncing around. If it's not your vacuum causing the problem, I'd have to guess it's either the sandpaper or, more likely, your technique. I have no idea what you could possibly be doing wrong, but I just can't think of any other reasons. Try it w/o the vacuum. If it still does it, have someone else try it - someone who wasn't watching you first. If it does it for the other person, take it back and get a refund.

John

[Scott Young]

It would appear to be true. Either I had to get used to this new half sheet sander compared to our 15-20 year old one, or this had about a half hour to an hour break-in period. At least without punching holes for dust extraction, the sander is significantly better. Once my punch plate for the dust extraction arrives, I'll do more testing. Thanks a lot for your guys' input. It was helpful. Looking forward to really getting into woodworking as a much more serious hobby/part-time job so hopefully I won't stop learning. Great site and advice.

[scott vroom]

If you ever get lonley for an old Milwaukee half sheet, I'll sell you mine...all 8 lbs of it. Haven't touched it in years....make an offer. :D

[Scott Young]

Hehehe.. Nope. My dad is about 63, his sander is approaching (if not at) 20, and to my knowledge- only replaced the brushes once when I was doing some massive sanding of our wood paneled garage doors (16'x8'x2doors.. Fun). Don't think it's going to die. Thanks for the offer though. The Mak wanted me to break her in. Now she's a sanding machine. Literally :). Thanks again for the advice guys. Now back to the game.