9" discs on 5" grinder

[naughtyboy]

not as bad as title sounds.
got a load of 9" cutting discs that have worn down through use ( about 50 at mo ).
they are tad under 5" now would it be safe to use them on a 5" grinder or is it a big no-no?
boss says i can bring them home if i want them.
have been kept flat in dry area.

 

[Wozzaaah]

It has been mentioned on here before but I believe you'll find they won't fit as the spindles are usually different sizes.
I think one of the questions raised was running speed, look at a 5" one and a 9" one and you'll see they're rated at very different speeds.

 

[naughtyboy]

ill bin em then when i go back on sun.

cheers

 

[Wozzaaah]

I've tried worn out chopsaw discs on my 9" grinder as the running speed was similar and tbh, they wore out so quickly it was hardly worth bothering.

 

[sean-1]

I always run worn 9 incher's on a 7 inch angle grinder and when they are small enough on a 4 1/2". I do use flexovit zirconium discs which are a bit on the pricier side but they use the same abraisive material for the entire disc. A lot of disc manufacturers only have the abaisive on the outer inch or so which is why they wear out very quickly when you are past a certain point.
Waste not want not.

 

[Hitch]

I think most 9" and 4.5" grinders use the same size centre, 7/8" (22.2mm)

Although 9" discs are rated for about 6600 rpm, that takes into account the speed at full sizes, some are marked also in metres per second.
Theoreticaly, the smaller the disc becomes, the faster (rpm) it can go. Providing the periphial speed isn't exceeded.

 

[Welderpaul]

Being Yorkshire men we regularly use the old 9" discs on 5" grinders. The trick is to wear them down sufficiently until they fit inside the guard.

 

[pedrobedro]

I used to recycle mine to the next size down but I don't use many 9" now. My 9", 5" and 4.5" all have the same spindle size. My abrasive chopsaw uses larger centres and has a spacer as well so they are binned when two thirds used as per the instructions as they don't go all the way through.

 

[rocketron]

I often use worn down 9" to fit a 5" grinder, but they don't last long. Perhaps I should give them away and get some brownie points?

 

[s410man]

as said as long as they fit and you dont exceed the speed it is fine

i have always done it

 

[KemppiFrog]

Me too, as said, it is the speed (&therefore the centrifugal force) at the edge of the disc. My cut off is a mounted 9" and when they are too worn they fit my 5" nicely. Same quality of grit all the way through.
A

 

[outofthefire]

Another tight yorkshireman here, I do the same 9" to 4.5"

 

[s410man]

I always run worn 9 incher's on a 7 inch angle grinder and when they are small enough on a 4 1/2". I do use flexovit zirconium discs which are a bit on the pricier side but they use the same abraisive material for the entire disc. A lot of disc manufacturers only have the abaisive on the outer inch or so which is why they wear out very quickly when you are past a certain point.
Waste not want not.

ive noticed cheap discs wear down faster when you get to the centre but never realized that was the reason why

having always bought cheapish discs i am now starting to think expensive may be better as less time grinding, less time changing disc if they last longer and more safety

 

[brightspark]

the other reason is the smaller the disk as it wears the slower the surface speed and aeria of cut which makes them inificient and wear quicker

 

[Dov]

Being Yorkshire men we regularly use the old 9" discs on 5" grinders. The trick is to wear them down sufficiently until they fit inside the guard.

Yip, being doing this for years, they are too expensive to bin and do the job.