Grinding disk vs flap disk?

[Welderpaul]

We go through hundreds! Grinding discs for getting rid of the bulk of the metal, and flap discs for finer finishing. We use 40 grit flap discs, which, when you first start using them cut nearly as fast as a grinding disc, they soon loose they abrasivity. A grinding disc is designed to be used at 45 degrees but as you get close to finishing if you use it nearly flat it gives a tidier finish. As a flap disc starts to get worn it tends to dig a bit so if you are flapping off a weld on a weld bend or a tube for example, it starts to look like a 50P. A quick flash over with a new disc for a final clean makes the difference between an 'ok' job and a professional job.

As Paul says, a man needs to be shot if he leaves a finished job with grinding disc swirls all over it - same for people who clean spatter off with a grinding disc.

 

[Hood]

Depends on the finished job, if it is to look attractive then I agree, if it is functional then no. It can actually help a bit in my line (Alu on fishing boats) as it provides more surface are for the oxide to form and a better key for the paint to adhere to but of course that is just my thoughts.
In fact I try not to grind any welds flat in the things I do as it provides a stronger joint and out at sea in a gale the Alu gets a battering.

 

[Kent]

Gosh it took a long while to get me into flap discs and the later thin slitting discs.
The flap disc does not replace a hard wheel rather it comes after it or on lesser grind down jobs.
You still can't beat a card disc and a hard or soft backing for polishing up stuff a treat, I admit I have little use for course grit ones now though

 

[Sean]

cant have too many grinders

 

[Windy Miller]

I very rarely use a grinding disc. Flap discs are awsome for stock removal and use on unusual shapes and radii. I would do most work with a flap but always use the sanding discs on a backing pad for the final finishing of flats.

Sanding discs I always use a rubber backing pad. You need the flexibility and helps to get more life out of your discs. The nylon pads I find are way too rigid.

sanding discs: the brown aluminium oxide discs don't last 5 minutes. The blue zircon discs last a bit longer but still have nothing on the green ceramic discs. The green discs are more expensive but makes so much more economic sense. I will always go for green given the choice.

Can you give us a link to the green and blue ones?

 

[Tiggy_dorset]

Can you give us a link to the green and blue ones?

I don't buy blue discs anymore. I buy the green ones from the Reca rep. Price escapes me, I'll have to check tomorrow

Quick look on ebay brings this up:
https://www.ebay.co.uk/itm/Klingspo...hash=item465ae96064:m:mGDxYIdk3WxOOOrKZlzkRaw


Something tells me it's about the price I pay, but without the delivery charge.
I also buy the 60 grit not the 36.

 

[outofthefire]

Another vote for ceramic flap disks, I've only used Abracs though

 

[Wallace]

I think it's these 115mm 3M 36+ discs I have used at Pondman's workshop. Unbelievable things for metal removal on a grinder that small and I think they make a grinding disc look stupid in comparison, last well too. Might be a bit pricey for some people though.

 

[Wightsparks]

Cripes how much I have a whole stack of 3m discs from my previous company - mostly stick-it I think but time to have a sort out!

 

[lexi]

I use all of them. For removing metal quick on heavy stuff, you cannot beat a 9" angle grinder with the coarse grinding wheel. It is serious and will outlast any flap disc. So will the small 115mm one for getting into tight spaces end on. Flap discs good, but lose their initial effectiveness quite quickly. They are best on sheet material I think.