dressing a cutoff wheel

Submitted by DadOfFan t3_y7mx85 in DIY

I have been doing a bit of cutting of angle iron lately and have found the cutting disc to relatively quickly stop cutting.

Normally I find that the disc will continue to cut wearing down as it goes. But in this case I found that the edge of the disk had become smooth and full of metal swarf.

I plan to do a lot more cutting of angle iron for several projects I have coming up and this is going to chew through my supply of disks.

Looking online all I find is people asking about dressing to remove damaged edges (chunks missing) on the disk and I agree that that is unsafe because what ever damaged the disk may have affected the structural integrity of the disk.

No-one I could find was talking about dressing a disk to remove swarf.

Is it safe to use a dressing stone on a cutoff disk (125mm / 5") so that I can keep it cutting (sharp)?

Similar with a 300mm cut off disk as I will be using that a lot too for larger pieces of metal.

UPDATE:

Some people have asked for some pictures. I don't have any of the actual project as its finished and gone but here is what has been asked for

Update 2:

For anybody that thinks I am trying to sharpen the cut off wheel, please look at what dressing is and what a dressing stone is used for.

UPDATE 3

The consensus seems to be not enough pressure when cutting.

I'll try to see if more pressure will do the job next week when I start the next project.

Failing that trying different disks and keeping these for sheet metal work

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Comments

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h0dgep0dge t1_isvfjyn wrote

It sounds like you're using the wrong wheel, and trying to dress a wheel on an angle grinder sounds pretty dangerous

12

Sudzkng t1_isvfk8s wrote

How thick is your wheel? It sounds almost like your cutting with a grinding wheel.

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DadOfFan OP t1_isvg7yw wrote

Replying to Sudzkng (#137,914)

About 1.2 mm they are definitely cutting disks (Makita brand). one difference between what I am doing now and what I have done previously is I bought a cheap cutoff mount for the grinder so I can get more accurate cuts. I doubt that would have any effect and no I am not running it too lightly or too heavily.

The angle is 3mm. normally I only cut sheet metal so that is another difference.

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CoconutJeff t1_isvilqw wrote

There is nothing to sharpen. Its abrasive.

If you have a bit more to do, look into a hand band saw.

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Sensitive-Alarm2954 t1_isvj3e0 wrote

My God that sounds dangerous. I moved to metal cutting discs because I always break them in the absolute most dangerous ways

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mlaffs63 t1_isvl8ix wrote

If you're determined to dress that wheel, I would use a vertical sander and and just touch your cut off wheel to it ever so slightly. If you don't have a vertical sander I would mount a grinding wheel or a handheld sander with the face vertical and do the same thing. Make sure the sparks are not going towards you and of course use eye protection. I work with these things all the time and you sometimes have to do things that are unconventional. I would suggest that if this makes you nervous, don't do it and just suck up the cost. Be careful!

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Syndicofberyl t1_isvm4c9 wrote

I've never heard of a cut off wheel becoming clogged with swarf except when used on the wrong material. Maybe you got some bum wheels?

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dominus_aranearum t1_isvm5xa wrote

Replying to DadOfFan (#137,969)

What angle are you cutting the material at with your grinder? You should be as close to a 90° as possible to minimize the cross section at your cut. Trying to cut much longer areas will cause your problem where cuts seem to take forever.

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Blue_Sail t1_isvmg36 wrote

Can you share some pictures of the angle iron and the cutoff wheel?

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Dr_Poofist t1_isvmhyq wrote

You don't dress cut off wheels. You cut with them carefully and if there are chunks missing the disc is garbage.

I've only ever had a disk clog when I tried it on non ferrous metals when it wasn't meant for them.

You only ever dress grinding stones.

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steelgeek2 t1_isvogo6 wrote

If it's the right disk, then it's your technique that's flawed.

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j_bus t1_isvpear wrote

Are you sure its iron? This would make a ton of sense if it was a soft metal like aluminum, which really shouldn't be cut with a grinder.

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APLJaKaT t1_isvpsn3 wrote

Replying to PsychoEngineer (#138,382)

Yeah same here. Been using them forever and never had one clog up. Make sure it's for ferrous use if steel and for aluminum if aluminum.

Otherwise, toss it out and use a new one. They're cheap. Certainly cheap enough to not risk blowing one up.

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chuckfr t1_isvqksg wrote

What model angle grinder are you using and what was the cheap cutoff mount you got for it?

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mad_science t1_isvtxws wrote

Just gonna join the chorus telling you something doesn't add up.

Cutoff wheels don't clog unless you're using them on aluminum or similar non-ferrous metals.

I think this would get a lot clearer if you could share pictures.

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Reelplayer t1_isvuhws wrote

Get a handheld bandsaw. Harbor Freight $130.

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darrellbear t1_isvyyac wrote

Sounds like you're using a grinding wheel as a cutoff wheel.

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Can-DontAttitude t1_isw14mn wrote

If you’re cutting steel/iron, you should be using an aluminium oxide wheel. If you’re certain that you’ve got the correct abrasive, throw it away and buy a different brand. Defective wheels aren’t something you take chances with, even with proper PPE

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Kanyouseethecheese t1_isw3yo8 wrote

STOP. I’ve used more cutting/grinding discs then trump has lied. You never dress a cutting disk. If it’s cracked or missing a chunk it’s tossed. Anything else and it’s a great way to meet your local ER staff.

Don’t push the grinder, let it do the work and make small straight passes. If getting a good cut is key get a bandsaw. Much better and safer.

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Dr_Poofist t1_isw988g wrote

Replying to DadOfFan (#139,447)

I've probably gone through hundreds of these cut off discs over the years and never had one "clog" and stop cutting. These are abrasive discs that abrade as they cut - they dress themsleves as you go.

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A_Plumber2020 t1_isw9hqp wrote

Go buy a cheap portable bandsaw and a decent blade. You will get way more cuts on things like angle iron. Save the angle grinder and cutoff discs for cutting out shapes, cleaning up corners or cutting off of large pieces.

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Grunblau t1_isweobm wrote

If I had to guess, might need a bit more pressure. I know if you limp wrist a flap wheel it will glaze right up.

That said, look into getting a portable steel bandsaw. I like my corded Milwaukee and have used it for countless projects.

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racefapery t1_isweuzt wrote

Dude… cutoff discs are like less than $1 each at harbor freight, I just toss them when they start wearing. Too paranoid about it starting to throw chunks as it deteriorates or develop uneven wear or a dozen other things I don’t want to have to worry about with something that’s cheaper than tissue paper.

Here’s a link to a 10 pack for $5.99, use the coupon code and it’s even cheaper.

https://www.harborfreight.com/power-tools/grinding-cutting-wheels/cut-off-wheels/3-in-x-116-in-x-38-in-metal-cut-off-wheels-10-pack-61354.html

They’re consumable, just toss them once they wear out

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DadOfFan OP t1_iswr73k wrote

Replying to racefapery (#139,822)

My problem is they aren't wearing out. I am only getting a few cuts per disk.

And they are much more expensive in Aus where I am from.

The point of this post is to ask the question, to not make assumptions.

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DadOfFan OP t1_iswrajr wrote

Replying to Grunblau (#139,817)

I have lusted over a bandsaw, but if I bought everything I wanted for the odd project or two I would quickly run out of room and funds (and a partner) :(

1

blinkybilloce t1_iswvrho wrote

What's happening is you are not pushing hard enough to wear iut the fibers on the "cutting edge" .

Note this diesnt mean slam the fucker down lie a drop saw on balsa wood. Just firm constant pressure. Could also just be that as the radius decreases with use itdiesnt have sufficient speed at the edge to cut.

Probably just need more pressure tho

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paulmarchant t1_isx00wf wrote

Replying to DadOfFan (#139,446)

You are using the wrong disc, based on your links.

The discs you've linked are for stainless, not mild steel.

Basically the different types of disc use a different binder (glue) which holds the abrasive particles together. The idea is for the disc to wear down just slightly faster than it builds up metal particles, so it doesn't clog.

You might recover the disc if you did a heavy (push hard) series of cuts on a couple of bits of scrap metal. It'll clog again though.

Continuing to use it as-is is dangerous as the heat generated by the rubbing action of the clogged disc will eventually cause the binder to break down and chunks of the edge of the disc will be ejected at high speed.

Whatever you decide to do, in terms of trying to recover the disc you have, you must have the guard in place (and correctly positioned) because there's a non-zero risk of bits of the disc coming off.

There's a reasonable argument that can be made for binning that disc (because it'll only clog again) and buying the right type for the metal you're cutting.

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nikniuq t1_isxa8v4 wrote

Glazing often means not enough pressure.

I have a pack of those same discs I believe and have no issues with them generally but did have issues with cutting an old barrel.

I grabbed some much cheaper and softer discs I had lying around and they cut it no problem but I did use a bunch of them.

Don't keep struggling with this combo, change something.

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TheSloshGivesMeBoner t1_isxqbft wrote

If it’s a thin disk let it do the work. If you lean too hard it’s just turn to dust. The swarf being stuck on the disk is weird? I’d buy a different and new pack for your grinder!

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TheSloshGivesMeBoner t1_isxqcjo wrote

If it’s a thin disk let it do the work. If you lean too hard it’s just turn to dust. The swarf being stuck on the disk is weird? I’d buy a different and new pack for your grinder!

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DadOfFan OP t1_it03i0g wrote

Replying to NotObviouslyARobot (#142,714)

the problem is they are not wearing, just clogging up. The consensus seems to be not enough pressure when cutting.

I'll try to see if more pressure will do the job next week when I start the next project.

1

lostdad75 t1_it07lqr wrote

Do not stay in one place; keep the wheel moving. Staying in one place and simply pushing can create too much heat which in turn loads up the wheel. Just move the wheel slowly back and forth along the cut line. Keep an eye on the spark plume, you should always see a good shower of sparks.

I have cut huge sections with abrasive wheels and the trick is not to sit in one place.

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DadOfFan OP t1_it08wq9 wrote

Replying to lostdad75 (#148,395)

Hmmm, Good advice, but it negates the purpose of the angle grinder stand, which is to make repeatable accurate(ish) cuts.

Not being flush with funds I couldn't afford a band saw nor have the space for it. tools seem a lot cheaper in the US than we have here in Australia :(

1

CarloCustom t1_it0hfpn wrote

this is what i'm thinking, it's the "Bond" of the abrasive that's too strong, i.e. not letting the wheel break down as you are describing. as it breaks down it keeps it sharp. if the bond of the abrasive is too strong, it doesn't release the grains as they are used, and hence clogs up or heats up. A softer bond does provide certain advantages — it sheds its grains more rapidly to provide a faster cut. With a stronger bond, the bond may hold the grains in place after they have become worn. A softer bond releases them faster to reveal fresh, sharp grains more often and increase the wheel's cut rate.

the abrasive type seems to be correct, aluminum oxide. but i dont' see the bond listed. you'll need a technical spec for that

i'd suggest simply trying a different brand of cutoff wheel, and look to see if there is something in the spec about the bond.

stainless is another animal, and this wheel states it specifically. i'd try something different.

hope i've helped a little

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