4.5 inch grinder abrasive tech

[Gusb]

I recently bought the entry level grinder that Milwaukee makes (or has made in China) and I'm beginning to spend some quality time with it grinding welds.

I used the Milwaukee abrasive wheel that came with the grinder for a while and I've bought a few 4 1/2 - 7/8 inch arbor wheels at various hardware stores, etc. with mixed results as to how well they seem to do at grinding welds. Today I picked up the (now older) wheel that came with the grinder and was surprised to find that it still seems to work better than anything I've bought. A few questions:

1) Does Milwaukee make really good wheels, or is it maybe a coarser grit than the others. The Milwaukee seems to wear away faster but continues to work. The other wheels (Norton, Makita, etc.) seem to plug up really fast.

2) I assume that with a hand-held grinder no one ever uses coolant or wax stick, etc. I also assume there's no way practical way to diamond-dress one of these wheels?

3) What is a good coarse grit for removing lots of weld material (18 ga sheet metal) with minimum heat/wheel plug-up?

4) What is good finer grit (finish-up) for getting closer to the base sheet metal (do those "flapper" things have a place in finish work)?

5) Anyone know where I can order a bunch of Milwaukee wheels online at a good price?

6) What about the 4-1/2" x 1/4" x 7/8" Grinding Wheel A24R Metabo at Lehigh Valley Abrasives (recommended by fj40charles in an earlier thread)? Would this be a good choice for rough grinding welds?

Thanks for any feedback.

 

[justweldit]

well i have good luck with sait 60 grit 5 inch sanding disc. we use it on 16ga metal . get a firm but flexible backer pad , as you all ready know dont dig with the edge of wheel use the whole pad and heat is your enemy on thin metal . i like to bog the grinder down till rpms drop . then look ,never more than ten sec pressing . to much heat can cause the sanding pad to fail early

 

[CruisinGA]

Grinding disks get used up too quick to bother doing anything to them other than using them. Keep a few almost worn out ones handy for the tight spots a new one won't fit.

Flap disks beat the snot out of grinding wheels for removing weld material. Faster material removal and much easier to smooth surfaces together. Unfortunately also 2+x as expensive per unit and don't last as long as a grinding wheel.

 

[justweldit]

hey, i guess you really need the right tool for the job , if you have alot to grind , well you need a bonded wheel , to sand or polish a little weld out of 16ga or thinner i prefere the sanding pad

 

[3_puppies]

I get grinding wheels at a welding supply store. much better than stuff you get at the hardware store.

there is a difference!

 

[Gusb]

I'd also gotten a few from the local Airgas store before. Just a few days ago the Airgas manager gave me a flap disc to try out. He said the flappers cut faster and cooler but wore out sooner than a hard grinding wheel (as CruisinGA also stated). These were "Weiler - Tiger" flap discs and they seem to work great. I used them on a few weld beads/tacks and couldn't believe it. Even at a 120 grit they cut the welds like butter compared to to the hard wheels I've been using. And they seemed much quieter with less heat build up.

So I got a few more from Airgas and then ordered a bunch (flappers, cut-off, hard wheels) from Lehigh Valley Abrasives. They seem OK (Lehigh brand flappers) - have not tried them yet. Shipping (US postal mail) was kind of weird with all the wheels loose and banging around in a box with a few pieces of paper thrown in for padding. And I ordered 3, 4-1/2" Grinding Wheels (A24R Metabo) and they shipped 3 of some other brand (German I think?) instead.

In future I may just take out a bank loan and get a bunch of those Tiger discs.

 

[CruisinGA]

I see Klingspor flapdisks all over the place, and they're what I used to use a shop I worked at. Haven't checked on bulk pricing yet. Sandpaper, Abrasives, Woodworking, Metalworking, Rolls, Automotive, Waterproof, Belts, Discs, Sheets, - KLINGSPOR Abrasives, Inc.

I've been using flap disks from Northern Tool that run about $5 a piece, IIRC. exact same disk at local Airgas store is over $8 ea.

 

[Awl_TEQ]

Flapper disc for sure - I "borrow" mine from work cause they are $7.80 CDN each. I am the purchaser at work and first started getting them at $13-15 each until I shopped around. Of course I buy 30 or 40 at a time. I don't know the brand off hand, likely VSM, but to be honest for all the "our product is better" talk I find they are all the same. Except the super, super cheap crap.

Here's a shot of my welded on wheel arch rib before an 80 grit flapper disc on a 5" Walter variable speed grinder set at speed 5 (out of 6). Someone mentioned keeping it flat and not gouging - a must.



This is the end of the floor ribs in my 45 LBP by the tailgate. I made this panel from flat sheet and had to weld the ends of the ribs and then dress them. I used a 2" angle air grinder with an 80 grit sanding disc (because of the tight spaces), then the 80 grit 5" flapper disc to smooth, then a 80 grit 6" random orbital. All the same grit but different effects.

Also, when you think your flapper disc has about had it - keep going. I find they last longer than you think. Another point to consider is that a new disc will remove material faster than you think because you were used to the old one you just changed out.

 

[Awl_TEQ]

The ribs before grinding

 

[RAYJON]

see the air grinder he has in the above photo, I use one of those for all the small stuff, with everything from a scotbrite pads to 40grit, they are great on small stuff,

I agree with everyone else the flap disc's work great on cleaning up stuff, I keep 3 grinders one with each a flap, grinder and wire wheel when I am welding alot it makes things go faster...

 

[craptabulous]

i personally like flapper wheels way better then grinding disc's .

walter makes good disc's .