DA Sander VS. Belt Sander

Jason K · Post by **Jason K** » Sat Apr 02, 2005 9:14 pm

OK- ready for a really dumb question?

Is a DA Sander significantly different from a belt sander in terms of efficiency?

I know most of you are rolling your eyes and wondering what I'm even doing on this forum. I am, too! However, belt sanding isn't making much progress and it sands very unevenly - I know there's a better way. Triton381.com indicated Tim used a DA sander and finished with a palm sander - I suppose that should be answer enough. Yet, is it so much better than a belt sander that it justifies the purchase? If so, what models are worth picking up?

bcooke · Post by **bcooke** » Sat Apr 02, 2005 10:10 pm

Yet, is it so much better than a belt sander that it justifies the purchase

Yep! It will become your favorite tool. It will sand much more evenly, it is easier to hold on to hour after hour (after hour after hour...) and with a vacuum attachment (definitely go for this) it will be cleaner too. I copied Tim and picked up the Porter-Cable 5 inch. I have never regretted it. A grinder or high speed disk sander is nice to have too, but be careful where you use this. One false slip and you have a repair on your hands.

And since when do you need to justify a tool purchase anyway? You can never have enough tools. I love tools.

-Britton

Post by **Tim** » Sun Apr 03, 2005 8:24 am

I don't find much use for a belt sander on the boat. In fact, I have never used it on the boat itself, though I occasionally use it on a woodworking project here and there.

Belt sanders are best for bulk stock removal when you are hoping to keep a flat surface. Even then, most 3" belt sanders aren't really wide enough to do a good job and require a special touch and lots of movement to prevent the belt digging in and creating a channel. I am usually annoyed when I use my belt sander; it's just not that useful in the big picture. Most (all) of the jobs I do use it for could be accomplished with another tool.

DAs will remove stock faster than a belt sander in most cases, and are far better suited to the curves of a boat. Belt sanders don't spin fast enough to truly be quick at removing stock, nor can you fine-tune your application point to increase productivity.

To me, there's no comparison between a belt sander and a DA. The two are so far removed that one cannot even consider them to be designed for close to the same purpose. A good DA will work as a grinder for serious stock removal if you want, but is also kind enough to be used as a sort of finishing sander too.

I continue to recommend the Porter Cable 7335. I recently bought a new one, as my trusty 12 year-old, never-maintained, heavily-used one started to show signs of needing immediate motor maintenance. With no time to deal with that, I just bought a new one without thought. (Later, I'll take my ole' faithful somewhere for a spa day.) I never even considered another type or brand; the old one was that good to me.

Check out www.froogle.com and enter "Porter Cable 7335". It will bring up a wide variety of suppliers and prices. I don't think you can get more bang for the buck than from this heavy-duty PC tool. You should be able to get one for around $100.

And when you get your new Porter Cable, look no further for your sanding discs than the supreme ones from McMaster-Carr. Expensive, and worth every tiny cent.

Jason K · Post by **Jason K** » Mon Apr 04, 2005 12:55 pm

Thank you both for your input. On your advice I picked up the 6" Porter Cable (there isn't a 5" for sale in New Orleans - ANYWHERE) Sunday morning. What a difference! I am now using my two belt sanders as ground tackle.

What bothers me though, is my inability to grasp the right tool for the job concept. I learn the same lesson over and over, and forget it just as quickly. Maybe it's a disease?

It started early with my first three tools: I had a grippin' tool, a screwdrivin' tool, and a hammerin' tool. Sometimes my grippin' tool and and my hammerin' tool were different edges of the same tool.

Two of the most egregious symptoms are:
1) "Predrilling" by hammerin' in a nail, then pulling it out with the gripping tool, then screwing in the screw with
2) A one-size-fits-some smallish flat head screwdriver that serves as a flat head and phillips screwdriver, a chisel, a pry bar, and a general purpose poker.

If anyone has exhibited similar symptoms, please let us know...

Figment · Post by **Figment** » Mon Apr 04, 2005 2:39 pm

My father has exhibited a lifetime of similar symptoms. I'm bringing him around, slowly.

His most recent eye-opener was last week when he borrowed my PC 97366 sander (just like the 7335, but with a 6" head and dust extraction) to prep the bottom of his boat for antifouling paint. His usual process involves a 15 pound belt sander (try holding that over your head for a few hours) and an old-style 1/2-sheet "vibrating pad" finishing sander. When he returned my PC at the end of the day, he couldn't stop talking about the difference.
He got the whole boat done in one afternoon.
He could lift his arms to drink a beer at the end of the afternoon.
Because the dust extraction lets you get your face right up into the work, he could actually SEE what he was doing, and as a result he did a much more even job than in years past.
The paper didn't clog every 5 minutes (I supplied him with some good open-coat discs).

Now if I can just get him to quit using screwdrivers as chisels, we'll really be getting somewhere!! ;)

Shark · Post by **Shark** » Mon Apr 04, 2005 8:40 pm

I just purchased a Porter Cable 7336 6" random orbit sander too. I bought it mostly on the strength of Tim's recommendation in the Project Tools and Spare Parts section of his website and the many pictures of Nathan "happily" sanding away on Dasein.

I don't understand why you guys refer to these sanders at "DA" sanders. Mine is not "dual action." It only has one mode of operation, random orbital, but with variable speeds from 2500 to 6000 opm.

"DA"??

Lyman

P.S. Porter Cable owes you a commission, Tim.

Post by **dasein668** » Mon Apr 04, 2005 9:11 pm

I have always used Dual Action and Random Orbital interchangeably. Is that not the case? Note it's dual "action" not dual mode. The two actions would be the primary rotation and the secondary tiny circles...

bcooke · Post by **bcooke** » Mon Apr 04, 2005 9:40 pm

Okay techno geeks. I think the correct description of the model 7335/7336 (since we are all agreed that it is the best) is a dual action random orbital sander. That is, the tool has the same motion as a random orbital - it vibrates (essentially)- but also incorporates a secondary rotating motion (dual action) for even quicker sanding and more complete paper usage.

Besides the DA, Porter Cable makes a whole range of great hand tools. I can recomend any of the ten or so I have under my work bench.

-Britton

Jason K · Post by **Jason K** » Mon Apr 04, 2005 9:44 pm

My interpretation was that dual action refers to a dual mode sander - circular and random orbit. However, on reflection you may be right, Nathan. The Porter Cable 7336 is certainly not dual mode - though it's not labeled as Dual Action either...

Just pulled the manual - it says Lijadora de 5"/pulidora de.. oh wait, wrong side.

- Random Orbit 5" sander/6" Polisher

Perhaps Dual Function is what they mean. Of course that seems rather limiting - I guarantee I can come up with at least another 8 or so other handy dandy functions for it.

-- Just read Britton's post belatedly...Ohhhh, I get it. I assume you aren't refering to me as a techno geek; that suggests an aptitude I certainly don't possess!

Post by **Tim** » Tue Apr 05, 2005 7:19 am

Nathan and Britton are right on the mark. Don't confuse dual "action" with dual "operation", or dual "mode".

The motion is indeed "dual action": the pad moves in two (dual) ways, all at the same time and invisibly to the user. In addition to the pad spinning in a circular motion around its shaft, the head of the shaft also moves around an eccentric orbit. This is the dual action that is referred to. It's this eccentric oblong motion that allows the tool to sand smoothly without leaving the circular marks that a true grinder or disc tool ("single action", if you will) would.

If observation of the tool in use doesn't convince you, remove the pad and look at the mechanism beneath. You'll easily see that "hidden" second action that is so important to the quality of the finish left behind; spin the shaft and you'll see how it moves in a sort of parabolic orbit around its centerline, thanks to a sort of cam setup (going from memory here...). Or, leave the pad there and, with the tool off, watch how you can push the pad around a small distance along all axes of the shaft. It'll move a small amount in all directions. Note that it's a very small amount, which is why you can't see it when it's in use.

Random Orbital and DA are often used interchangeably to describe the same tool. However, the right-angle tools like the PC 7335 are more accurately called a DA, to me, since that term differentiates between thse tools and the circular finishing sanders (usually called "random orbit") that are a totally different animal.

A "real" DA is a lightweight automotive sander (air-powered) that uses the exact same motion as our electric versions. The electric version, pioneered by Porter Cable in about 1990, is a relatively new animal. My original PC was the first generation; I bought it in 1990 when it was new on the shelves. The new 7335 is the same tool, other than the variable speed function, which my older one did not have.

Air DAs are excellent, but few tools require a higher CFM rate than these, which makes it harder (expensive, that is) to buy a compressor that is up to the task. The air DA weighs far less than the electric version and is much more enjoyable to use as a result.

Lacking a $2000 compressor, the electric versions work extremely well. It's definitely the one of the most-used tools in any serious boat restoration. Note that for the best finishes, you still need a good palm sander, or any true finishing (vibrating) sander.

Post by **dasein668** » Tue Apr 05, 2005 8:17 am

Regardless of what you call it, it's a killer tool and the only tool that rivals it for usefulness is my DeWalt cordless drill. But that's another thread!

Steve480 · Post by **Steve480** » Tue Apr 05, 2005 9:38 am

Any recollections on materials and quantities used with the 7335 on their boat projects? I'm at the deck panel seams grinding stage on our Triton recore project. Fairing and paint prep for deck and hull will follow.

Post by **dasein668** » Tue Apr 05, 2005 11:19 am

For my deck job including prep, glassing, and fairing I used about 50-60 40-grit discs, 75 80-grit discs, and 50 120-grit discs. Discs were the open coat fabric discs from McMaster-Carr. Very expensive and very good.

Sanding of the finish primer was done by hand using different materials. 220- and 320-grit.

george · Post by **george** » Tue Apr 05, 2005 11:44 am

Can you better define "expensive?"

How much for all of that sandpaper? I see Tim spent $500!

Post by **dasein668** » Tue Apr 05, 2005 11:51 am

I spent a little over 100 on paper, I think. That doesn't include the hand-sanding paper. I'm more stingy with the discs than Tim, mostly because I'm kind of poor at the moment. Changing discs more frequently is certainly a more efficient and more expensive way to work.

Click here for the appropriate McMaster-Carr catalog page. I used the "Clog-resistant" discs, 5-inch.

Figment · Post by **Figment** » Tue Apr 05, 2005 11:56 am

Steve480, for the seam-grinding stage (a.k.a. "digging a trench for the tape") of a recore job, I'd suggest something with a bit more muscle than the random-orbit sanders we're discussing here.

That's a job for an angle-grinder, or some other simple-orbit disc sander. I started with 40grit 6" discs, but quickly changed to the smaller (3-1/2" or so?) size, as they offered better control while cutting just as quickly. I must say, even my heavy old disc grinder was barely up to the task. I had to give it a break every couple of hours when the gearbox grew alarmingly hot to the touch.

Save the RO units for the subsequent fairing.

Figment · Post by **Figment** » Tue Apr 05, 2005 11:59 am

dasein668 wrote:Changing discs more frequently is certainly a more efficient and more expensive way to work.

Only if you don't assign any dollar-value to your time!

(just teasing. I'm right there with you, deep deep in the dark dark hole.)

Post by **dasein668** » Tue Apr 05, 2005 12:06 pm

Figment wrote:
dasein668 wrote:Changing discs more frequently is certainly a more efficient and more expensive way to work.
Only if you don't assign any dollar-value to your time!

(just teasing. I'm right there with you, deep deep in the dark dark hole.)

True! Many studies have shown that over-working consumables is more expensive in the long run. Assuming that you are paying someone!

Post by **Tim** » Tue Apr 05, 2005 12:18 pm

Good sandpaper is expensive--and worth it. These discs we're talking about have cloth backing and are very heavy-duty. Forget the lame ones at the home center in the little 5-packs, or the flimsy gold ones on the rolls. You can't do any serious work with those, though they're OK once you get past 120 grit (the rolls, that is; forget the homeowner 5 packs for good).

It's best not to fight the cost of sandpaper. You'll spend it one way or another, so just buy the bulk packs of the good stuff. If you think you need one package, buy two; you'll need it. Yes, sandpaper adds up to a significant cost, but you need it.

Steve 480, if you don't have an angle grinder, rest assured that you can "trench out" with the DA and some 40 grit discs from McMaster. It will definitely take longer than with an angle grinder, which is much more aggressive for sure. Still, it can be done successfully. When you tip a DA on edge, it cuts quite aggressively. I hardly ever use an angle grinder myself, except for the heaviest cutting. This all depends on how much material you actually have to remove--it's back to the "right tool for the job" thing again.

If you use the angle grinder, just be careful with it! One can create quite a mess for themselves if not careful. I've seen more damage to fiberglass and wooden boats as a result of improper grinder use...so be careful!

Post by **Tim** » Tue Apr 05, 2005 12:20 pm

dasein668 wrote:I'm more stingy with the discs than Tim...

Plus, you know that I always have a supply on hand, should you run low one day! The discs from my supply are really cheap...hehe ;<)

Post by **dasein668** » Tue Apr 05, 2005 12:33 pm

Tim wrote:
dasein668 wrote:I'm more stingy with the discs than Tim...
Plus, you know that I always have a supply on hand, should you run low one day! The discs from my supply are really cheap...hehe ;<)

True, I suppose. Though I seem to remember someone needing some of MY discs a few weeks back, too! hehe

Shark · Post by **Shark** » Tue Apr 05, 2005 2:42 pm

Thanks for clearing up the "DA" term. I was aware that the PC 7336 spins around the central shaft and also moves around as Tim described but I thought I was missing something else OR that some how I had purchased the wrong or different sander, as the 7334 is no longer available.

Just to add to the confusion, I also have an old half sheet sander that actually has two modes of operation, in-line finishing & orbital, ie dual mode.

I'm glad I bought the right tool!! I'll let you know how I like it once I get the cover off my boat and start work.

Lyman

bcooke · Post by **bcooke** » Tue Apr 05, 2005 7:41 pm

Just read Britton's post belatedly...Ohhhh, I get it. I assume you aren't refering to me as a techno geek; that suggests an aptitude I certainly don't possess

If you are on this forum then you probably have the aptitude. It can reside dormant in the unconcious id for years and years before revealing itself. Keep a watch out. Once it emerges your social life is doomed.

And I realize I just used the term "id" improperly and I expect our resident philosopher is going to feel obliged to correct me now...

-Britton

Post by **dasein668** » Tue Apr 05, 2005 7:43 pm

bcooke wrote:And I realize I just used the term "id" improperly and I expect our resident philosopher is going to feel obliged to correct me now...

Nah, I'll let you off easy...

'sides, metaphysics was more my area of interest....

;-P

Post by **Tim** » Wed Apr 06, 2005 6:31 am

bcooke wrote:... in the unconcious id ...

And I don't even know what the heck you guys are talking about! I guess that means my social life is far past the "doomed" stage and into some other dimension.

Jedediah · Post by **Jedediah** » Sat Nov 26, 2005 2:27 pm

Reading this post has been very insightful. However, I can't help but wonder how much more helpful (and thus should I purchase one) the DA part of the sander is. I'm currently using a regular 7" polisher/sander for heavy inside paint removal with a 36-grit flap wheel. I've found at slow speeds the removal rate isn't too fast to follow and the wheel is lasting forever. Is it worth the $200 for the Porter Cable 7335 and a bunch of sanding pads? Or is the PC just a very nice right-angle variable speed sander which I already have a cheaper version of. It seems like everyone else I'm on the budget crunch and thought I'd ask.

Jason K · Post by **Jason K** » Sat Nov 26, 2005 3:09 pm

When I started this post, I had no idea how dramatic the difference would be when I purchased the Porter Cable. It really is an incredible tool. The difference would, of course, be less dramatic if you switched from your sander, but I have yet to use or hear of a more effective and versatile tool for paint preparation.

I've already had a number of them. The one failing these tools have is the power switch is a bit unreliable - so save your receipts. I bought two of the 7336 at Lowes for only $100 each. When I had to replace them recently, I bought a couple of the 97336 (the vacuum attachment model) online from Coastal Tool for about $150 each.

I definitely recognize the need to maintain some semblance of remaining within a couple of factors of a budget. In this case, I think the Porter Cable is a tool you should have.

Post by **Tim** » Sat Nov 26, 2005 4:48 pm

The 7335 (5") and 7336 (6") Porter Cable sanders are readily available for $100. For that price, anyone doing fiberglass, wood, and painting projects can't afford not to have one, or one just like it. Other brands are available; prices vary.

I prefer the smaller 5" pad, possibly because that's the size of the first of these tools that I ever used. But the smaller pad will help the tool be more versatile, I believe, as it fits in areas where the 6" won't. And the discs are probably less expensive, too. I think there's also the ability to better control the tool, and to finesse the sanding/grinding rate with the smaller disc.

The DA sanders are quite a bit more aggressive (if you want them to be) than a so-called "polisher/sander" might be. With proper technique, one can accomplish heavy stock removal with a DA sander. Or the tool will also do near finish-quality sanding if used differently.

CharlieJ · Post by **CharlieJ** » Sat Nov 26, 2005 8:44 pm

We have had a pair of the PC 7335's in the woodshop for about 10 years or so now. One of them finally shelled a segment from the armature, so it's toast, but the other still pounds away.

In all that time I've replaced the brushes in both sanders, one of them twice. Costs 10 bucks and takes 10 minutes. I HAVE worn out dozens of pads, but new ones run from 12.50 - 19.50. I ocnsider them consumable anyway.

Very soon now I'll be purchasing another as a replacement for the crapped one.

These sanders have been POUNDED, on a day in day out basis, to the tune of about two 150 sheet boxes of discs a month for much of that time. They've done all the sanding on the construction of 7 new boats, and three interior gut-out rebuilds.

I wouldn't want any other machine.

BY the way, both of mine are PSA disc, not hook and loop. You pretty much have to order the PSA ones anymore since all the "Box" stores seem to only sell Hook and loop anymore. The PSA's are cheaper and I seldom reuse a disc anyway, so what do I care if they are reusable.

Plastic Classic Forum

DA Sander VS. Belt Sander

DA Sander VS. Belt Sander

DA?

DA

DA vs non-DA