tell me about flap discs

[mrjaw14]

I've recently got into welding and am getting supplies. never used a flap disc before. Used plenty of grinding, cutting, and wire wheels. I'm curious what grit if flap disc is used most often in welding, and which brand(s) you guys like, where to buy etc. I've heard good things about Walter flap discs, the ones you can trim the backing and get more life out of. What say ye about flap discs?

 

[FakeNewsRealHP]

40grit to removed welds, 120 to finish a surface. The Walters are pretty awesome and i use 4.5” or 5” on a metabo. ABN 2” discs off amazon are nice for the coin but I’m spoiled and all consumables from work are free and we get 3M Cubitron for flaps and cutoff wheels.


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[sqznby]

I prefer a flapper over a hard wheel. The noise reduction alone is worth it.

Its always good to have a few on hand.

Grinding, blending, deburring, chamfering, material removal, spatter removal etc,,,,,,, They even have a corner wheels for grinding out/down welds.

Walter makes great products. There's plenty to choose from.
3M, Norton, Benchmark Abrasives, DeWalt, Metabo the list goes on and on.

Give Benchmark a try, they have great prices and usually sell in bulk for far less than most stores. Start with a 40 grit. After its worn in some it'll be more like an 60, 80 or 120 depending on how hard you are with it.

 

[Bigblue&Goldie]

I buy Benchmark in bulk. They are cheap and seem to work well enough.

 

[Natemade]

Yeah...flap wheels over grinding wheels for pretty much every thing. I keep 40grit and 80grit in the shop all the time. I use Roark supply, they have good prices and hi quality wheels. I have not tried the ceramic ones yet but even if they work half as good as ceramic belts on the belt sanders they will be awesome.

 

[TTMotorsports]

I've been using benchmark jumbo flap discs for years. Buy 100 or so at a time. 40 grit here.

 

[dr_clyde]

Flap discs are for people who haven't discovered resin fiber discs.

Seriously, I don't understand why everyone uses flap discs when resin fiber discs exist.

A fraction of the cost, and are way, way more long lived. I buy VSM ceramic 36 grit and 80 grit discs, and they are the best I've found. 36 grit moves some metal fast, and 80 grit blends a little finer for the next set of abrasives. I use 5" on a 4.5" backer pad.

They are less than $1.50 on amazon. I get them for about a buck a pop from my welding supply. They outlast a flap disc by about double.

I run a professional welding shop, and we might use one or two flap discs a year. I can't remember the last time I bought some. The are ok for blending and the occasional corner blend, but for general grinding, fiber discs all the way.

 

[American Locomotive]

The resin fiber discs are okay for certain tasks, but I prefer flap discs for others. There's a lot of overlap between hard grinding wheels, flexible grinding wheels, flap discs and flat resin fiber discs, but they all have areas they excel in compared to others.

For the stuff I do, I like using the flexible grinding discs to remove material, and then blend and clean with flap disc.

 

[KBigg]

Ive never seen a resin fiber disc at my local hardware so i use flap discs. They're nice for removing scale and surface rust quickly as well without actually cutting into the material.

Edit: Nevermind i have seen resin fiber discs, i just didnt know thats what they were called or how they worked.

 

[mike1956]

Flappers are awesome. Great for prepping metal for welds. Most brands last long and with 40 grit you take metal down as fast as a grind disk

 

[TTMotorsports]

I use flap disc to cope tubing and stuff like that. I've used resin but if you catch an edge with those they blow apart.

 

[shoot summ]

I buy Benchmark in bulk. They are cheap and seem to work well enough.

This, great company, and great products.

 

[slodat]

Thanks for the recommendations! I ordered a few things mentioned in this thread. I have a new variable speed Metabo 5" grinder coming, too

 

[rvieceli]

Dr Clyde what backer pad do you use for the fiber discs? i can't seem to find one that I like.

Thanks

 

[tarbellb]

Flap discs are for people who haven't discovered resin fiber discs.

Seriously, I don't understand why everyone uses flap discs when resin fiber discs exist.

A fraction of the cost, .......

This ^^^

I jumped on the flap disc a while back, and they are great, but also expensive, especially if you dont know how to dress them.

I now mostly run fiber disc. My experience is that fiber disc give you a more consistent removal rate over the life of the abrasive. Where as a flapper has stages of removal.

btw Benchmark is your typical cheap Chinese stuff, not bad, but def not great. My favorites are: Walter, Pferd, 3M, SAIT, United Abrasive, Weiler, Mercer, Metabo, Norton.

 

[dr_clyde]

Dr Clyde what backer pad do you use for the fiber discs? i can't seem to find one that I like.

Thanks

I use one from Milwaukee. Cheap and lasts about 100 discs or so before I damage it or something.

 

[Marctrees]

drClyde suggested "Resin fiber discs"

Can someone link to an example clearly showing exactly what they are / look like ?

Marc

 

[Wanna Ride]

I buy Benchmark in bulk. They are cheap and seem to work well enough.

Same here, got an online coupon a while back for something crazy like, 10 for $10. Well worth it and I’ll always buy from them now.

 

[slodat]

drClyde suggested "Resin fiber discs"

Can someone link to an example clearly showing exactly what they are / look like ?

Marc

These are the ones he mentioned.

https://www.amazon.com/dp/B072JGMCQJ/?tag=atomicindus08-20

 

[slodat]

I jumped on the flap disc a while back, and they are great, but also expensive, especially if you dont know how to dress them.

How do you dress them?

 

[Marctrees]

slodat - OK, yup I use that type.

Thank you, Marc

 

[74cj5]

Haven’t tried those, are they similar to the smaller ones for the air grinders?

 

[Kaizen]

How do you dress them?

Curious as well. I had seen something about running it on a sharp edge like a welding table renews it but unsure if it’s true?


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[red94chev]

Another fan of Benchmark Abrasives.

 

[sberry]

I am going to order some of the resin doc talks of. I got a flap or 2 I bought for field work, never used one. I am an absolute master of the 1/4 hardwheel, so used to it that I can do 95% of it with that and even some sanding as it coasts down.
I am going to get some 7 inch resins though, should get a pack as I put on my last 6 the other day. I have a 5 inch, I should turn the air down some when I use it but can cut a worn 7 down with old snips to use it on 5 but I don't like it as well as the bigger one.

 

[rattle_snake]

Flap discs are great for some jobs but not all as already said. I have a grinders set up with flaps, fibers and abrasives so I can use whatever works best without changing wheels.

or at least it is a good excuse for another tool.

 

[tarbellb]

Curious as well. I had seen something about running it on a sharp edge like a welding table renews it but unsure if it’s ok

Essentially. When the outside edge gets gummed up or slick you cut it down. I do this by finding a sharp edge, sheet metal, etc... And cut it back till you see new fresh abrasive. Some are made for it, Walter, SAIT, have a poly backing, but all can be dressed.

 

[sberry]

My basic and number 1 is electric 1/4x 4 1/2. I have most of the specialty items on air. Electric and hard wheels are so much cheaper to operate and use light cord. It saves a lot on air comp, I use them quite a bit.
If I didn't have the air would probably use flaps.

 

[jeepinerdeep]

I use the 40 grit high density Benchmarks. Great performance for the cost. Easy buy on Amazon.

I have run exactly 4 resin fiber discs and the all blew apart. Threw the box and backer in the trash before someone got hurt. Seems like 1940's technology to me.

 

[dr_clyde]

I use the 40 grit high density Benchmarks. Great performance for the cost. Easy buy on Amazon.

I have run exactly 4 resin fiber discs and the all blew apart. Threw the box and backer in the trash before someone got hurt. Seems like 1940's technology to me.

You must have had some real **** ones, because I literally have run hundreds and hundreds with no problems.

 

[Marctrees]

I use the 40 grit high density Benchmarks. Great performance for the cost. Easy buy on Amazon.

I have run exactly 4 resin fiber discs and the all blew apart. Threw the box and backer in the trash before someone got hurt. Seems like 1940's technology to me.

Now I am confused.

Will someone clarify exactly what product is being talked about in the above two apparently opposite paragraphs ????????

And link to the recommended SPECIFIC ? "Benchmark" ? product(s) on Amazon please ?

Marc

 

[slodat]

https://www.amazon.com/Premium-High-Density-Jumbo-Zirconia

I searched for "benchmark flap disc 40 high" on Amazon. They were the first result. Same with the others.

The resin fiber discs are in the previous post where I answered your question about them.

 

[jeepinerdeep]

You must have had some real **** ones, because I literally have run hundreds and hundreds with no problems.

I had these, just hated them for my application. If I were deburring the outside corner of plate all day they would have worked. Anything with an edge or inside corner meant immediate destruction. Life is too short for that.

https://www.amazon.com/gp/product/B00C0LT8UU/?tag=atomicindus08-20

Now I am confused.

Will someone clarify exactly what product is being talked about in the above two apparently opposite paragraphs ????????

And link to the recommended SPECIFIC ? "Benchmark" ? product(s) on Amazon please ?

Marc

Easy now. Benchmark ( El Cheapo ) Discs are all over Amazon

https://www.amazon.com/gp/product/B01D0HA3LK/?tag=atomicindus08-20

 

[Marctrees]

The thing is it is often unclear in posts above if someone is talking about flap or non flap resin at that moment.

Example right below - Only your link showed me if it was a flap DISK or a resin DISC to be used w backer.

Thank you.

Marc

 

[slodat]

Marc, I linked to two specific products. The first was the resin disc dr_clyde mentioned. The second the flap disc jeepinerdeep mentioned..

 

[xjfish]

Interesting thread. I switched to (and prefer) conventional flap-disks for mower blade sharpening and dirty metal cleanup. I've always used cheap conventional grinder discs for weld clean up... I'm NOT a pro welder

 

[BryceW]

I'll be the tenth person to recommend Benchmark abrasives. Are they the best/longest lasting? No. They are however quite good and the best I've been able to find at a reasonable price. As far as grit I use 40 for dressing welds and rough blending and 120 if I need to put a finer finish on something or work an edge. I go through about 3 times as many 40s as 120s. I can't remember the last time I used a traditional grinding disc. I get about the same rate of removal from a 40 grit flap disc with half the noise and vibration.

 

[dr_clyde]

I will say the resin fiber disc isn’t intended to grind inside corners or fillets. I can see how it would be poor at that.

I do primarily flat and OD work. Seams and corners and such.

Grooves and fillets tend to be ground out with a hard 6” pipeline stringer disc.

Flap discs have their place, don’t get me wrong, but for a general grinding wheel, they’re very expensive and don’t last very long compared to a hard disc or a resin fiber disc.

 

[sberry]

I got to clean a little rust from used steel where welds go and square cuts some, 95% hard disc and mostly fillet welds that never get ground. Some spatter cleaning and I can sand quite well with a hard disk. I weld a little flat on the bench mostly vertical on equipment with some overhead which is really my favorite most of the time.

 

[mrjaw14]

Lots of great info here, just what I was looking for. I didn't know about the resin fiber discs, that seems like a great way to keep costs lower than using just flap discs. Thanks as well for the benchmark recommendations. I'm usually not one to try the brands like that unless I hear good things about it. I'll probably pick a few of those up as well.

For those that use Flap discs, do you prefer type 27 or 29?