Angle Grinder Wheels - Type 27 vs Type 1

[gsmith22]

For a 4.5" right angle grinder, is one wheel type better than the other? Grinding and cutting discs are available in both Type 27 (depressed center) and Type 1 (flat) versions. Is one style (depressed center or flat) better for the other at a particular task? I can't seem to find any information or prior discussion anywhere on the web. And before anyone asks, yes, I own and use the correct guards (type 27 for grinding and type 1 for cutting) so it really comes down to is one type/style better than the other at a particular task? Thanks in advance for shedding some light on this for me.

 

[gsmith22]

Really? No one knows or at least has any ideas where there might be two seemingly interchangeable grinding and cutting discs?

 

[Hot Rod Grampa]

Logic dictates that if you are cutting or grinding on an adage or a circular profile it would not matter. If you are cutting off a whatever flush or grinding flush to an existing surface then the depressed center would be the better choice. Do I win? Is there a prize?

 

[bcradio]

Personal preference

 

[crab]

Personally I prefer a flap wheel anyway.

 

[Wamsutta]

Type 1 is a cut-off blade.

 

[toplessHO]

be careful of those thin ones
they will shatter and explode

 

[MJD1]

Type 1 are usually less expensive than type 27. Type 1 works well for most things, except trying to cut the head of a bolt or rivit that isn't close to the edge of a plate or bracket. I go thru 200 or more 6" cutting discs in a year, and have never had one shatter or explode. With that being said, I only use quality cutting discs, no HF or other no name ****.

 

[gsmith22]

For Wamsutta "Type 1 is a cut-off blade" isn't strictly true which led to my question. I initially thought the same but then found grinding discs in type 1 style and cutoff discs in type 27 style. I'm wondering if there is a historical artifact here. The instruction manual for my grinder wants me to use a type 27 guard for all grinding actions (using a type 27 or type 1 grinding wheel) and a type 1 guard for all cutting actions (using a type 27 or type 1 cutoff wheel). Maybe someone can confirm, but I am strarting to think that angle griders where developed for (!) grinding using depressed center wheels (type 27). then flat (type 1) cutting discs came a long and so a different guard was developed. then later, grinding wheels in type 1 and cutting wheels in type 27 came along and the naming of disc type, guard type, and purpose of disc got all confused. or maybe I am just confused and this seems logical to everyone else

 

[LXCam]

I prefer the recessed so I can get a flush cut in some instances. But I own plenty of both since both styles have their strong points. Still my preference is the 27.

 

[Wamsutta]

Are you saying there's a Type 1 guard available for your grinder? Who's the manufacturer of the grinder?

 

[LXCam]

Are you saying there's a Type 1 guard available for your grinder? Who's the manufacturer of the grinder?

Is that questions for me? If so I don't use a guard.

 

[Wamsutta]

Is that questions for me? If so I don't use a guard.

I was asking gsmith22.

 

[tarbellb]

Type 27 v 1 is only referring to the depression vs non depression (flat).

Mostly personal preference but I feel like you get more cutting life from a 27 and the ability to cut nearly flush.

Also, no guards for me either. Just quality disc and smart practices.

 

[sberry]

I use gaurds, I can make it work. When I started in this biz it seems like I was always jammed up in a corner, now very rarely.

 

[gsmith22]

Wamsutta - dewalt dwe402. it came with a type 27 guard (like every other angle grinder) but they also sell the type 1 guard as an accessory online. Reading through the instruction manual (I guess no one else does this?), it says that if I want to use a cutoff disc (type 1 or type 27), I have to use the type 1 guard. For everything else (grinding with type 1, type 27, type 29, wire wheel, flap disc, etc.) it says to use a type 27 guard that it came with. So I got the type 1 guard for cutting and it works fine (same with type 27 for grinding).

But this led me to my original question which was if one style of cutting (or grinding) disc better than the other.

I also find it odd that you use a type 1 guard with all types of cutoff discs (type 27 or type 1) and a type 27 guard with all grinding discs (type 27, type 1, type 29, flap, wire wheel, etc.) so that led me to wondering if all of the guard naming was a historical anomaly.

 

[Dozerhand]

My red cordless grinder came with two guards, clearly marked type 1 and type 27