Any rule-of-thumb for replacing 4.5" cutoff wheels?

[i7win7]

i7win7 - what is your tractor pulling in your avatar? Is that a dirt pan? Do you have a bigger picture?

RB-6R

Hoelscher Commercial Products - RB Scraper

Hoelscher is a Bushton, Kansas hay baling equipment and earth moving equipment manufacturer.

www.hoelscherinc.com

 

[amhicks21]

Ive used many hundreds of cutoffs over the years with only very few incidents. When possible I run em right down to nothing. The problem with cutting roofing is the metal will start to vibrate and will destroy the disc in seconds if you let the blade get in too deep or bind. The other problem with thin metal is it gets hot quick and expands and pinches the side of the disk. You can mostly avoid this by keeping the blade very shallow and do whatever possible to keep the blade from pinching. Maybe try rotating the guard into a position that acts as a depth gauge and only let the blade come 1/4" through the bottom and, as everyone knows but it always bears repeating let the disk do the work and only guide it along without pushing.

 

[California]

FWIW, Project Farm did a comparison of cutoff blades. DeWalt took 2.5 times longer than the majority of them.

See the 7:29 point in this video.

There are other conclusions a few seconds either side of that point.

I ordered a pack of Makita blades yesterday after studying the video. He showed that these aren't consumed as fast, while taking the same time to cut as most others.

Back when I was a carpenter it was common practice to mount a Skilsaw blade backward to cut sheet metal.

 

[ArlyA]

I love my 4.5 Porter cable grinder, but I'd not use it for cutting tin. And like others have pointed out, cheap wheels are just that. Cheap!

 

[PILOON]

Back when I was a carpenter it was common practice to mount a Skilsaw blade backward to cut sheet metal.

Sort of like what I posted earlier.
A friction blade is very similar to a regular saw blade but without teeth, just all the slits.
Rare to find but sure does a great job.

 

[rangerfredbob]

I bought some new Milwaukee tin snips for doing the siding on my shop, like a hot knife through butter... I used those over an electric double cut shear I had borrowed and an air nibbler... If the metal is just currogated and not the one rib per 9" like I have they would be a pain though...

 

[aviator411]

Manufacturers of steel roofing, paneling, siding do not approve of cutting their panels with any kind of saw blade or abrasive disc due to heat produced degrading finish and accelerating rust process. Power or manual shears only if you possibly can. Not always an easy option.

 

[nknelsen]

I've read of them shattering and I'm apprehensive of getting shards in my body even though I wear PPE.
But presently the roofing metal I'm cutting is eating about 1 Dewalt DW8062 wheel per panel width.

I find that the cutting wheels generate too much heat when cutting and that will affect the paint and possibly cause corrosion later on. When I did my metal roof it was suggested that I not use a grinder for that reason.

I used a Dewalt Sawzall with a 6"metal blade that worked very well for cutting. On my average size house I think I cut it all with 2 or 3 blades. Much safer too in my opinion.

 

[Bullwinkle123]

Don't buy harbor freight cutting wheels...stick with diablo or dewalt.

I happen to like my HF cutting wheels. They're cost effective and have a thin kerf that I prefer when cutting.

That said, I suppose the thinner disks are even more likely to shatter, though I haven't had any shatter. Always something to worry about with any brand.

 

[v908]

Project Farm did a great evaluation. You might want to consider his testing/results: