grinder cut off disks

Dan in North Houston · Feb 10, 2019

I bought some of the thin cut off disks that you use in a 4 1/2" hand held grinder, thinking they would come in handy. The first time I used then, they worked great.
Since that time, I've had no luck at all with them. They get pinched or get in a bind and shatter. No matter how careful I am to have a light touch, avoid any side loads, or avoid getting them pinched in the work, they end up breaking.
Yesterday I had some bolts to cut off, and I broke 4 of them before giving up and using some thicker grinding wheels. The best run I had was maybe 20 seconds, most of them shattered in about 5 seconds.
There must be a trick to using them, anyone have any advice? Maybe that is why you can buy them in packs of 10?

Mike Groom · Feb 10, 2019

It's the quality of the discs,not all discs are created equal,I've had good luck with Dewalt that I buy at Farm and Fleet,I'm a little leary of the packets of 10 in the discount stores because I don't want flying objects in my shop.

kcm.MN · Feb 10, 2019

I'll ONLY buy cutting discs that are made in USA or Germany.

I've been fortunate that what foreign-made discs I've bought have held up well. Have heard from too many folks that the Chinese-made products often fail due to lack of Quality Control and lack of using consistent quality materials.

Bob · Feb 10, 2019

"There must be a trick to using them, anyone have any advice?"

By quality THIN discs, then keep a death grip on the grinder and keep it aligned with the cut so it doesn't catch and jerk and break the wheel.

Oregon Tractor Jack · Feb 10, 2019

There is a big differences in cut off disks. I try to only use the US or German disks also. The cheap ones will shatter to easily. A higher speed grinder also helps. I use either a Metabo or a DeWalt high speed grinder for cut off work. Either way, hang on tight when those disks bind the grinder can take off. Nothing like launching a grinder to wake you up.

OTJ

JD Seller · Feb 10, 2019

I use them all of the time. You have to buy good ones. I rarely have one break. You do have to think about how your cutting to not put too much side force on the disk.

I also have found the flat disk work better. The ones with the raised center look great for cutting flush but they are not near as durable.

The best bang for the buck that I have found is "Benchmark Abrasives Brand" I buy them on EBay and direct. The ones on EBay are 100 disks with shipping included for a price of $65.99. My cutting torch does not get used very often anymore. It is easier and faster to just grab a 4 inch grinder and cut the majority of stuff.

Benchmark wheels on EBay: https://www.ebay.com/itm/100-Pack-5-x-045-x7-8-Professional-Metal-Steel-Cutting-Disc-Cutoff-Wheel/280667005048?hash=item41590ea078:g:Xl0AAOSwgQ9Vt~IO:rk:3

f:0
Benach mark wheels on eBay

David G · Feb 10, 2019

Make sure they are being side stressed when you clamp them down.

Russ from MN · Feb 10, 2019

I've never had a problem with the ones I have, but they're probably .062 thick, I have some .032, but I save them for special jobs, they are a lot more susceptible to breaking. Have yours gotten wet? That can be bad for some.

Dan in North Houston · Feb 10, 2019

Follow-up info:
first, thanks to all who have posted advice. The disks I got were from Home Depot, Diablo brand. Maybe not the best but I figured would be better than Harbor Freight. I've tried all of the thicknesses they sell, with the same breakage results. They've never been wet or thrown around in a tool box.
The regular grinder disks have a raised center, and the washer on the grinders I have (Craftsman heavy duty) is dome shaped to fit the raised center. Since the cut off disks are flat, do I use that dome shaped washer? I've tried drawing them up tight against the washer, which puts a lot of strain on the disks by pulling them up in the dome, and doing them not-so-tight, but have had the same results both ways.
What works better? A light touch or heavy pressure?
thanks again.

Russ from MN · Feb 10, 2019

I think on one of my grinders I turn the washer/nut around so the disc is pinched between 2 flat surfaces. If you distort the disc in any way when tightening it it will prematurely fail.

Jim in N.M. · Feb 10, 2019

Speaking of cut off discs, I'm having a real time trying to find the discs for my 4.5 grinders WITH the 5/8 hole, it seems that all I find is with the 7/8 hole! Does anybody have any great wisdom on this ?? Jim in N.M.

Determined · Feb 10, 2019

(quoted from post at 12:23:46 02/10/19) Speaking of cut off discs, I'm having a real time trying to find the discs for my 4.5 grinders WITH the 5/8 hole, it seems that all I find is with the 7/8 hole! Does anybody have any great wisdom on this ?? Jim in N.M.

A nylon drain plug washer or an o-ring is often the ticket to centering a disk that has a hole larger than the shaft.

It really only needs to hold the disk centered until you tighten up the nut.

kcm.MN · Feb 10, 2019

One other question Dan -- How much do you torque the nut onto your discs??

With cutting discs, I never use the wrench. Just snug it up by hand. Rotation into the workpiece will finish tightening it all it needs.

Started doing that, as one time I was torquing on a cutting disc and heard a sound like the disc cracking; threw that disc away unused. Never "torqued" one since. That was many years ago and "likely" a cheap disc, but can't remember. I don't use cutting discs a whole lot.

JD Seller · Feb 10, 2019

You need to flip the nut over so your using the entire flat side of the nut to hold the disk against the backing nut. If you have been using the side with the flange that centers wider grinding disks that is your problem. Diablo disks are good enough quality.

So your disk should fit the backing nut shoulder. Then the flat side of the clamp nut will hold the disk secure while supporting it out form the center hub.

Oliver 500 Wa · Feb 10, 2019

I've pretty much used nothing but the HF cheapies for the past 10 or so years. I don't recall one ever breaking and they last as long as any others I've tried. I mainly use them to cut out rusted floors and walls from wood chip trucks when overhauling those.

They usually do get a bad rap here, but that does not line up with my experience.

I use Hitachi and Metabo grinders with them. Both of those use machined drive spacers and mounting nuts. Maybe that's part of why they hold up. The grip is very even and solid.

jniolon · Feb 10, 2019

(quoted from post at 13:38:34 02/10/19)

I use a 6" Metabo grinder and several name brands of cut off disk (.040 dia) and never had one break. You do need to (as mentioned) snug them up between two flat surfaces and don't side load. Another consideration is don't bear down too much, let the disk work at it's own speed, they last a lot longer. I have seen pictures of people breaking the and they end up in a wall or arm or whatever.. I consider that operator problem. Only time I ever broke one was when I knocked the grinder off the bench and the floor broke the disk.

Buy good quality and don't mistreat it AND WEAR SAFETY GLASSES OR FULL FACE SHIELD OR BOTH !!

JOHN

grizz02 · Feb 10, 2019

like has been said flip the outside nut over for thin disc's

MarkB_MI · Feb 10, 2019

Ya need one of these.
Backing flange

GEO-TH, In · Feb 10, 2019

I buy 4.5 and 6 inch Dewalt cutoffs from Rural King when on sale for a buck each. I buy a box of each. 6 inch will work on 4.5 inch grinder. YES they are fragile. Sometimes I'll use 18v grinder and it's slower, easier to handle, less likely to break.

Jim.ME · Feb 10, 2019

This is the backing washer and clamp washer on my 4-1/2" Craftsman grinder and I use them with all grinding and cut off discs with no problems. I have a light "tin" washer for recessed discs but I don't use it. Says right on it "For depressed center wheels only". If you were using one like that I would say that is why your cutting discs break.

jeffcat · Feb 10, 2019

First off stop buying JUNK. Now here is my opinion about cut off wheels. The ones you named are all from the half right land. They are very brittle and have crummy internal structural reinforcement. I wear safety glasses ALL of the time. Had one of the dewalt ones shred and actually puncture my skin. This brand is a bit more expensive but more than worth the extra cost. Also last longer. I use .045 wheels all over the place. Now here is my recommendation. SAIT wheels are made in the USA. You can find them on Ebay for almost the same price as the store price for junk. There is an industrial supply place not that far from me and I buy ten or fifteen at a time. Please buy some and try them.

jeffcat · Feb 10, 2019

Yes...Bob and Mark you reminded me. Forgot to mention the backer disk. Needed for the .45 disks. Sorry about that. You really need to use one. This one is three inches across. This is on my Sears 4 1/4 inch grinder. This is a cupped disk and fits the contours of a drop center disk perfectly. I also add one used up cutting disk as a little extra reinforcement. Also keeps the disks from spinning on the arbour. My Dewalt grinder I made a backer from the hold down plate used on truck body hold downs. Fits very well.

tn terry t · Feb 10, 2019

I have run hundreds if not more of the sait Blades. we only buy the ones for the larger grinders untill used down then they are about right for the small grinder

jeffcat · Feb 10, 2019

You need to use the tightening nut from another grinder that has the larger ring. Far as I know they are all 5/8 thread but the nuts are different. Any repair center or even try Ebay. Also check out a local rental center where they rent tools. Usually have a junk box full of odds and ends. Take your grinder and all of your washers, brackets, disks, etc. They should be able to fit you up. My Dewalt has a nut you need to flip over just for that.

bison · Feb 10, 2019

(quoted from post at 11:38:34 02/10/19) I've pretty much used nothing but the HF cheapies for the past 10 or so years. I don't recall one ever breaking and they last as long as any others I've tried. I mainly use them to cut out rusted floors and walls from wood chip trucks when overhauling those.

They usually do get a bad rap here, but that does not line up with my experience.

I use Hitachi and Metabo grinders with them. Both of those use machined drive spacers and mounting nuts. Maybe that's part of why they hold up. The grip is very even and solid.

Same here, I use these 4.5"cutoff discs a lot,I use them more than I use the chop saw. I seldom break one and when I do it is usually when I happen to drop the grinder on the floor or lay it down to hard.

RusselAZ · Feb 10, 2019

How thin? The biggest error people do when using them is put to much pressure on them. They need to just make sparks not actual contact. Same with a chop saw. I am not good at explaining the science behind them but it is what makes them work. Last Christmas Home Depot had a promo set of steel disc with diamond on them. Two disc for 14.00. I got two packs and am still on my first one in a 4 1/2 inch angle grinder. Pretty fantastic.

catalina0029 · Feb 10, 2019

We had to cut some bearings off a shaft not too long ago. 4" shaft or something like that. One guy had a Metabo from his truck, the other guy had the Dewalt off my truck. The Metabo out cut the dewalt like nothing. I was impressed. He was using Metabo wheels and mine had Dewalt wheels.

hd6gtom · Feb 10, 2019

I bought some from Harbor Freight, junk. I bought some from Menards. They work well for me.

Hobo,NC · Feb 11, 2019

Splurge one time and try a metal diamond tipped cut off wheel they will spoil ya...

Keith Molden · Feb 11, 2019

I read all the post and am surprised that nobody has said anything about the rpms of the grinder. If your disc is rated at lower rpms than your grinder, they can and sometimes will fly apart. On a Metabo, which is a higher than most others, use only ones that are rated for them. Pinching and forcing the blade is the worst thing a person can do with a cut off disc. Guys, I see on here all the time folks using a grinder without the guard. I've seen and investigated several accidents where the guard was either not on the grinder of was positioned in the wrong place resulting in bodily injury. I'm not a YT police and it is up to you whether you use them or not, but I had a friend that was running a 7" grinder. The blade shattered and cut into his stomach. Several operations later, he now uses a guard on all his grinders. I have 2 Metabos and 3 Dewalt grinders in our shop, the Metabos use SAIT wheels and the Dewalts use wheels rated for them.

Jim.ME · Feb 11, 2019

What brand grinder do you have? I would think you should be able to get the back up and clamping washers to fit a 5/8" spindle so the 7/8" discs fit properly.

Jim.ME · Feb 11, 2019

Sorry my question was to Jim in N.M. regarding "Speaking of cut off discs, I'm having a real time trying to find the discs for my 4.5 grinders WITH the 5/8 hole, it seems that all I find is with the 7/8 hole! Does anybody have any great wisdom on this ?? Jim in N.M."

Dale in ND · Feb 12, 2019

I get mine from NNP tool people that are at all the farm shows,seen them in ND and Colo Dale

Bill in IL · Feb 12, 2019

The only discs i had luck with were dewalt discs. Never broke one and they wear well.

I have tried several brands but the last ones i bought were the diablo?s and i was not happy with them. Have not exploded one but have chipped them beyond use on about every wheel i have used.

Leroy · Feb 13, 2019

I have had good luck with the Harbor freight ones. I think it was dewalt thar did not want to cut, tried the Harbor freight one and it whent right through what the other just sat on.

1948CaseVAI · Feb 13, 2019

(quoted from post at 14:38:34 02/10/19) I've pretty much used nothing but the HF cheapies for the past 10 or so years. I don't recall one ever breaking and they last as long as any others I've tried. I mainly use them to cut out rusted floors and walls from wood chip trucks when overhauling those.

They usually do get a bad rap here, but that does not line up with my experience.

I use Hitachi and Metabo grinders with them. Both of those use machined drive spacers and mounting nuts. Maybe that's part of why they hold up. The grip is very even and solid.

This. I had to throw away a box of DeWalt junk because they shattered like eggs. The HF disks never break for me and I use the heck out of them.

Traditional Farmer · Feb 14, 2019

I buy the cheapie cutoff wheels from the tool guy at the Marion PA auction,they work great for me using them on a high speed air tool.Just make sure you wear eye protection.

Brad Buchanan · Feb 15, 2019

Ken(Ark) · Feb 15, 2019

Splurge one time and try a metal diamond tipped cut off wheel they will spoil ya...

I have not tried one but think I will . $13.56 delivered to my mail box and lasts 30 times longer than abrasive . You can't get 30 cheap cut off disks for .50 cents each ($15) They also will not wear down to 2" - 3" or explode .

I use them all the time building iron rail , driveway gates , spiral stairs , etc . Once on the job I got in a hurry and the cut off wheel got in a bind and propelled it between my index and middle finger , 7 stitches and very deep . Got lucky and missed tendons , veins , bones , etc . 100% user error . Now I think , is buying a 25 pack of cheap disks for $19.99 worth saving $10 - 15 when I could have gotten higher quality .

I have AFLAC now but I really don't want to sell a finger for $500 plus the $50 a year I saved on disks .

[i:283113147a]Advanced diamond technology provides 30X longer life than thin bonded cutoff wheels in metal cutting applications* *Average performance in 1" carbon steel square tube vs. thin bonded abrasive cutoff wheels. [/i:283113147a]

When it comes to sawzall blades for cutting metal I only buy Lenox . There are probably a few other good brands but I am 100% satisfied with Lenox .

https://www.ebay.com/itm/Lenox-Meta...h=item4b5c975eaf:g:5r0AAOSwaEdcVEh1:rk:8:pf:0

grinder cut off disks

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