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

Status
Not open for further replies.
Joined
Nov 29, 2009
Messages
7,217
I'm cutting some bolts off with my 4.5in handheld dewalt grinder and I'm having trouble cutting all the way through because I keep hitting either the guard or the center washer that holds the wheel on. I don't see any reason why it wouldn't work, just have to take the guard off and make sure my fingers don't get close.
 
The diameter of the wheel will greatly rob the grinder of the torque needed to perform, but if the center diameter of the wheel/arbor is the same, give it a try.
 
Last edited:
Most will have a different size hole, but it isn't a good idea if they did fit. It kind of sounds like you are using a worn out disk. How big are the bolts you are trying to cut?
 
I wouldn't do it. RPM for the 4.5 is higher than the 7 in grinder. The 7 in disc may not be designed for the higher RPM. There's about 3000 RPM difference between my 4.5 vs the 7 in.
 
Last edited:
Originally Posted By: tig1
I wouldn't do it. RPM for the 4.5 is higher than the 7 in grinder. The 7 in disc may not be designed for the higher RPM. There's about 3000 RPM difference between my 4.5 vs the 7 in.


Once he puts that 7 inch disc on anything, it won't be spining very fast at all.

lol, I must be dangerous, only my chop saw and miter saw have guards!
 
Last edited:
I feel like it's more dangerous with the guard getting in the way making me go crooked with the wheel. I'd rather have a larger wheel on it so I can cut straight.
 
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.
 
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.
 
It will work.
The hazards presented by such a configuration are generally self-correcting. I've done it plenty. Prefer not to.
 
Yes, they even make "spacers" to help do it.

Take off the guard, apply big disk, and off you go.

How attached are you to your fingers ?
 
https://images.google.ca/imgres?imgurl=http%3A%2F%2Fi.imgur.com%2FzOAyZxU.jpg&imgrefurl=https%3A%2F%2Fwww.reddit.com%2Fr%2FWelding%2Fcomments%2F1sq6v7%2Fwear_your_faceshields_folks_theres_no_reason_that%2F&docid=xi5ti2KEKtbi9M&tbnid=2lPMfZ76zgVH0M%3A&vet=1&w=960&h=720&source=sh%2Fx%2Fim
 
Originally Posted By: tig1
I wouldn't do it. RPM for the 4.5 is higher than the 7 in grinder. The 7 in disc may not be designed for the higher RPM. There's about 3000 RPM difference between my 4.5 vs the 7 in.
This
 
Nope, 100% do not do this. Your 4.5" Grinder will exceed the speed limitation of the 7" disk and its very likely to explode. Google grinding disc injury's Im sure you wont want to try it.

If a 4.5" disk will work without the guard go for it, wear thick gloves, but 100% do not put a bigger disk on it.
 
Originally Posted By: thescreensavers
Nope, 100% do not do this. Your 4.5" Grinder will exceed the speed limitation of the 7" disk and its very likely to explode. Google grinding disc injury's Im sure you wont want to try it.

If a 4.5" disk will work without the guard go for it, wear thick gloves, but 100% do not put a bigger disk on it.



This +1

Don't use a bigger disk. Buy a larger grinder with the correct rated speed for a 7" disk from Harbor Freight.
 
If you run the numbers, a 1 ounce chunk off a 7" disc spinning at 11k rpm on 4.5" grinder would be moving at 230mph and has 110ftlbs of energy, about the same as .22 shot out of a rifle...
Better wear your safety glasses...
 
My step-dad had a grinder come apart and it hurt him pretty bad. That same day in (as I recall) an off-set grinder came apart in another city and killed 2 people.
 
Status
Not open for further replies.
Back
Top