Tools for builds

Pipe? what size and thickness?

I am not a builder or a welder......but whenever I see videos from Shirley Fabrication of work being done on cookers in their Shop......they are always using larger grinders.

If you send a PM to Paul Shirley, "tuscaloosaq" here, I'm sure he'd be glad to discuss the equipment that they use in the Shirley Fab shop.

I have 6) 4.5 angle head grinders, Dewalt and Metabo. I use them a lot as a garage fabricator. But I normally don't cut anything or grind anything with them that's more than 3/16 thick. They are a great size for tight spots, quick cutting without using the chop saw, lightweight enough for one handed use if needed.
I also have a 7" Rigid angle head that I don't use that often, but it's a beast if you want to grind anything that's thicker material. 1/4" and up.
I use a the plasma to 3/8" - 1/2" for cutting and the oxy torch anything thicker than 1/2" that needs cut.

You didn't mention what diameter and thickness of pipe, nor the type of cuts.... but not teaching Oxy Acetylene cutting seems odd to me. As far as safety and accuracy goes, using a grinder for all of your cutting tasks is not a good option. Does the school have a band saw?

I have done almost everything with a 4.5” with no issues. Yes takes longer cut for thicker stuff but its smaller and can maneuver in tighter spots. I would have few larger ones and a lot of smaller


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After over 30 years using grinders at work, not metal but concrete I can say this the smaller ones were much easier to use, and control. Plus you actually get more done because they are not as tiring to hold and work with. The Metabo grinders are very good. They held up best in the conditions we use them in. Far better than Hilti, Dewalt, or any of the others.

I'd go 4.5. They are handier, and cheaper. Plus after my stent in the petrochemical industry a long time ago, it wasn't the heavy machinery that hurt people it was grinders and drills. the 4.5 are easier to control, and theoretically less likely to injury your students if they mishandle them to some degree.

I own and use both sizes you referenced as choices.
Since you in a teaching situation, I would stay with the 4.5".

I consider the 7" as more of a production size, compared to a 4.5, where production speed is required.

If you are teaching inexperienced students how to properly and safely operate a grinder, in my opinion, the 4.5 would be easier to learn on.

Any grinder can cause serious injuries in inexperienced hands. And in experienced hands as well sometimes. Their reputation for potentially causing injury is well earned and real.

I see no need to teach technique, with a larger, heavier, and more powerful 7" unit, when the 4.5 will be far easier to gain both experience and confidence.

I am assuming this choice is based on students with very limited grinder experience.
Learn on a starter size, then after gaining experience, perhaps graduate to a larger size grinder as production needs mandate speed.

Bill

I'd go 4.5" all day long, for the reasons mentioned above. A 7" grinder is quite heavy and powerful and can do a lot of damage in the wrong hands.