Cutting straight with angle grinder

[Newsmoke]

IS there a trick or tips to cut perfectly straight with an angle grinder? My last build many of the cuts weren't perfectly straight. Should i use a metal ruler of plate to use as a guide?

[JKalchik]

Hah.... my experience as well.

The shop where I bought my stock for my double pan GF rather highly recommended a handheld metal cutting circular saw (I can go dig out their product if you'd like.) It will be noisy, but you'll get both a much straighter cut, and much faster, but at the expense of being pretty noisy.

[Chromeski]

I think the main thing is practice. I haven't got enough practice to be good at it either. I have seen tools that hold a 4" grinder to use as a chop saw although kinda neat they only help for small cuts and those are not the difficult ones. Just be safe a broken wheel is scary.

[Dirtytires]

Hard to do straight with an angle grinder. I used to do a lot of dressing on a bench grinder.

I ditched the grinder method and upgraded to a carbide tipped cold cut chop saw. Works a heck of a lot better than a handheld and allows you to dial in angles. I don’t use it anymore now that I have the Ellis tho so if you are near Phoenix....

[Newsmoke]

so if you are near Phoenix....

Do you ship to France?! I guess I will stick to angle grinder cutting...

Is there a thread for insulation of a square FB?

[ajfoxy]

Of course he ships to France.... if you pay the packaging and freight

To cut steel sheet you could buy a budget plasma cutter and use a straight edge to keep the thing on track.

As for insulating the firebox if not already build... look at the Mack build thread. There was quite a bit of info in there.

[Dirtytires]

100 ways to do it. Most difficult part for me was building out all the vents and door. Take your time. Plan it out.

[Enrgizerbunny]

IS there a trick or tips to cut perfectly straight with an angle grinder? My last build many of the cuts weren't perfectly straight. Should i use a metal ruler of plate to use as a guide?

Iron worker here. Mark your lines with soap stone or bright paint marker. Clamp a straight edge a couple inches away as parallel as possible(or use the factory edge if you're close), but doesn't have to be perfect. Hold grinder with wheel on line, motor toward the clamped guide. With the hand up near the wheel, drag your fingers on your guide and follow your line. The hand holding the switch supports the weight and the top hand does the driving. Don't rush, you'll eat up fewer wheels that way too.

[McBroom]

I think the main thing is practice. I haven't got enough practice to be good at it either. I have seen tools that hold a 4" grinder to use as a chop saw although kinda neat they only help for small cuts and those are not the difficult ones. Just be safe a broken wheel is scary.

I can vouch for the broke wheel being dangerous.
I have a scar on my leg about 5” long from a cut off wheel that shattered. I spent 9 days in the hospital and 2 surgeries to get all the debris out. And another 4 months with a vacuum patch over it to make it heal up.
Use serious caution with cut off wheels.


I love my truck!
Blue Mule 18 Ram 4x4 C/C
Tradesman Power Wagon

[Stewart]

I make my cuts long and flap disc em to the line. Takes a few minutes longer but works accurately every time.

[Chromeski]

I think the main thing is practice. I haven't got enough practice to be good at it either. I have seen tools that hold a 4" grinder to use as a chop saw although kinda neat they only help for small cuts and those are not the difficult ones. Just be safe a broken wheel is scary.

I can vouch for the broke wheel being dangerous.
I have a scar on my leg about 5” long from a cut off wheel that shattered. I spent 9 days in the hospital and 2 surgeries to get all the debris out. And another 4 months with a vacuum patch over it to make it heal up.
Use serious caution with cut off wheels.


I love my truck!
Blue Mule 18 Ram 4x4 C/C
Tradesman Power Wagon

Wow not good. I knew a guy that took one to the head and he wasn't the one with the grinder. I've had them break , but avoided injuries thus far.

[Dirtytires]

Ouch....safety glasses are your friend tho they won’t save the rest of your face.

[Chromeski]

Ouch....safety glasses are your friend tho they won’t save the rest of your face.

I usually wear my electronic welding hood in grind mode. I admit I sometimes make the quick cuts without a full face shield even tho i know better.

[McBroom]

This is the scar from 7 years ago.


I love my truck!
Blue Mule 18 Ram 4x4 C/C
Tradesman Power Wagon

[Pete Mazz]

Wow!

[JKalchik]

I try to learn from other people's mistakes.... and I really don't want to do that. I make it a point to 1) Wear PPE, and don't work in shorts, 2) keep out of the plane of the spinning disc, and don't put sideways stress on the disc (strongest in the spinning plane.) Safety glasses are no replacement for full face coverage.

McBroom, thanks for posting the picture and the reminder.

[jadstar]

This is a topic that comes up often in our home..... Better half is manager of optical store. I have to admit I have cut and without protection more than once . The pics she shows me of eye /facial injury are hard to look at but, that's the point....I still can look at them she hammmers home eye protection and face shield Everytime she knows I'm headed to shop . Having said all that when you think of RPM cut off wheels grinders run it is not surprising they can fail catastrophically pretty much anytime.

Sent from my Moto Z (2) using Tapatalk

[Newsmoke]

Has someone ever cut the doors with a jig saw? It seems they do sell blades for thick metals in France.

[Newsmoke]

And how would you cut the doors out for the CC?

[McBroom]

I try to learn from other people's mistakes.... and I really don't want to do that. I make it a point to 1) Wear PPE, and don't work in shorts, 2) keep out of the plane of the spinning disc, and don't put sideways stress on the disc (strongest in the spinning plane.) Safety glasses are no replacement for full face coverage.

McBroom, thanks for posting the picture and the reminder.

My pleasure brother

Claud

[McBroom]

Has someone ever cut the doors with a jig saw? It seems they do sell blades for thick metals in France.

Yes I do when the cutoff or die grinder can't get in the spot. I use cutting oil with my jigsaw and occasionally with the 7 1/4" skilsaw blade that's made for cutting metal. It helps clean the teeth and keep it cool too

Claud

[Tigit]

In the previous responses, you got a ton of great info. Wear a face shield, safety glasses and gloves that allow you to have a good feel of the grinder and the cut you’re making. Mark your line with a soapstone or some other means. Cut out side of that line and give yourself a little wiggle room to flap disc back to. When you make the initial cut, use only light pressure to scribe in the cut and go slow, set yourself up for success when you go back to cut through. Don’t force the cutoff wheel, it will break and send shrapnel everywhere.

If you are cutting the door out, will you be using some flat stock to create a lip on the outside to create a seal so to speak? If so you could cover a wild cut with the flat stock and nobody would know but you!

Do you have access to a oxy acetylene torch, that could work, but would generate a lot more heat...and could cause warpage in the door.

Good luck and keep us posted!

[hogaboomer]

Has someone ever cut the doors with a jig saw? It seems they do sell blades for thick metals in France.

I cut the doors for my latest build with a metal circular saw. It's like a wood circular saw, but it has a guard that catches most of the chips. You could use a wood circular saw, you just need a blade for metal.
Took 15 minutes and the cuts are beautiful. The tank is about 1/4 inch thick. 6.35 mm?
It started out this long, I ended up cutting it shorter. I won't cut doors with anything else in the future.




This is what it looks like at the moment, still got a little ways to go.

[tinspark]

A trick I have shown a few apprentices in the past in the Sheet Metal Workers Industry. If you need a straight line and only have access to an angle grinder is... get a wide black ink marker (Or even paint), and lay out the line (1/4" wide to the centerline of the cut). Then come back with a tungsten scribe, or a sharp ice pick, or anything that can give an accurate and deep (shiny) line. The black is only for a contrast to help the scribe line stand out (can be any color, but I like the contrast of black and shiny metal) If you are blind like me from many years of welding and middle age, you may need magnifying lens glasses. I keep a few cheap pairs from the 99 cent store lying around for welding and detail work, including accurate cutting. You must wear a face shield of some sort! I have a couple of high dollar auto welding hoods, but I don't use them for this because I want to see my scribe line and My lens' on both welding hoods are a little too dark for my liking for accurate line cutting.I use a clear $10 face shield..
Start the cut to the inside of the shiny line and take your time. I always push my angle grinder instead of pulling it. By push, I mean that I cut in the direction that the wheel wants to pull away from me. It is easier to control, and I am not working against the wheel rotation and fighting the motor. I let it work for me. when you see the cut moving off the shiny scribed line, adjust your cut. Also, I start with a 6" wheel if possible. The longer straight edge of the larger diameter wheel seems to make it easier to keep the cutting wheel running straight. Once your cutting wheel starts getting too short, (for me that is between 3"-4") its harder to keep things straight. Take the short wheel off and save it for non-critical cuts. I often have a stack of a half dozen wheels at a time that am working on to get rid of.. You may use a coupe of wheels per door if you are cutting 1/4".
My 2 cents.
Regards, DM