can you put a 7'' cutoff wheel on a 4.5'' grinder?

[Vern_in_IL]

Originally Posted By: AZjeff
Originally Posted By: motor_oil_madman
I do believe a 7" disc is going to naturally spin slower
because it has to travel farther to make one rotation compared to the smaller wheel.


You would believe wrong. If your grinder spins @ 10,000 rpm it spins at 10,000 rpm. It may take longer to spin up with a bigger wheel but not much. A 4.5" wheel has a diameter of 13", a 7" wheel is 22" diameter. You get 70% more cutting surface per revolution and it's traveling 70% faster but it's going to bog down, think of being in 5th gear when you should be in 2nd.

If you do this make sure the disc isn't overlapping the grip area.

I read this at BITOG! Epic fail. Think of pulleys

 

[Shannow]

Which one are you failing ?

Pulleys have nothing to do with a disk on a spindle...

 

[Trav]

Toss the guard and use the 4.5" disc. I don't own any with an OSHA nanny guard, they all went in the bin years ago. Wear gloves.

 

[Rand]

Originally Posted By: AZjeff
Originally Posted By: motor_oil_madman
I do believe a 7" disc is going to naturally spin slower because it has to travel farther to make one rotation compared to the smaller wheel.


You would believe wrong. If your grinder spins @ 10,000 rpm it spins at 10,000 rpm. It may take longer to spin up with a bigger wheel but not much. A 4.5" wheel has a diameter of 13", a 7" wheel is 22" diameter. You get 70% more cutting surface per revolution and it's traveling 70% faster but it's going to bog down, think of being in 5th gear when you should be in 2nd.

If you do this make sure the disc isn't overlapping the grip area.


While I agree I think you are talking about circumference not diameter.

You should also be able to buy a 5" wheel for the 4.5" grinder.
They come in depressed center to give you more working room.

https://www.amazon.com/Black-Hawk-Depressed-Center-Wheels/dp/B06XKJ8Y39/ref=sr_1_4?ie=UTF8&qid=1518789100&sr=8-4&keywords=5%22+angle+grinder+cutting

link is for a 25pack.

 

[Delta]

You can do it, but if it has a side trigger, yea that's an accident waiting to happen. Co-worker has a rear triggered DeWalt that he uses 7" disk, but it finally bit him the other day. Pinched a weld and the grinder jumped, bounced off the side pan, and got his thumb and pinky. Resulted in 10 stitches. Ironically the guy is our lead tech and is supposed to be teaching us safety. Guess he did, by showing us what NOT to do. Like others said, grab a cheap Harbor Freight 7" and save your hands.

 

[Trav]

If you mess around with tools like this and toss the guard you should be wearing cut resistant gloves for handling sheet metal.

 

[Vern_in_IL]

You can put a 7" on a 4.5, but you loose half your torque.

 

[Shannow]

Originally Posted By: Vern_in_IL
You can put a 7" on a 4.5, but you loose half your torque.


No, torque doesn't change.

Increased surface speed, but lower applied force at the disk edge...torque stays the same.

 

[glitch]

searching "exploding cut off disk" on youtube had some interesting results

a spinning disk goes BANG! when it explodes, it is all over instantly

a hunk of cutoff wheel would just laugh at safety glasses

 

[The motor guy]

I use a face shield in addition to safety glasses. No more gritty eye feeling.

 

[das_peikko]

You'll smoke the motor going oversize.

 

[The motor guy]

I didn't do it. I just cut the bolts 80 percent through then hit them with a hammer.