Picture of Cut Off Saw from an Angle Head Grinder
It is difficult to cut a straight line by hand with thin cut off wheel in an angle head grinder. I had an angle head grinder and wanted to make a mount for it to convert it to a cut off saw. I know you can buy a mount at Harbor Freight Tools, but I have a bias against most of their tools and wanted to make my own. I also have a welder. I used scraps of steel I already had.

Step 1: Basic piece for a start

Picture of Basic piece for a start
A friend gave me some scrap pieces of steel. One of these was a piece of 1 inch square tubing about 22 inches long with a 90 degree bend at one end. For a long time I had no idea how I would make use of this piece. If you choose to make a saw like mine, you probably will not have a piece like I had, but you can use other things. You could even weld a couple of pieces of square tubing together to make an "L" shaped piece.
NeuroStorm made it!6 months ago

I noticed that when I cut slightly larger square tube the blade of my small grinder isn't big enough to cut all the way through (especially when slightly worn). This is fine for 90 degree cuts as you can just turn the work and keep cutting, but for 45 degree cuts it is a problem. So I added 2x 45 degree guides to help with this. I had to raise the 2nd one so that it does not interfere with the 90 degree guide. It all works very well and the only change I'd still like to make is to add a spring which will auto return the grinder to the "up" position.

GillerUK1 year ago

Hi great instructable, am looking into making one for myself but with the added benefit of being able to change between 90 and 45 degrees easily. My idea would be to add a pivoting fence made out of angle-iron and bolted at the grinder end and a series of pre-set hole at the other end of the fence and base up-to 45 degrees held either with a loosely assembled bolt of pin.

Phil B (author)  GillerUK1 year ago
Good idea! Thank you for looking. Please post a photo when you have completed it.

Another excellent and practical 'ible - thanks Phil!

Phil B (author)  Pat Pending1 year ago
Thank you.
I_StarkGuy1 year ago
This is just what I was looking for. Thanks fo posting. Just a question: the guy that was worried about safety perhaps exaggerated a bit but, in your experience, is tinkering with power tools such a bad idea?
Phil B (author)  I_StarkGuy1 year ago
I have never had a problem or even felt at risk from something like this project. Follow all of the safety precautions you can, especially for safe usage. Use good sense and try to anticipate what could happen so you can avoid all such things.

What I think of as dangerous with a grinder such as these handheld units is: a) I have heard of a cutting wheel that shatters and flying pieces of it sever an artery so that the user bleeds to death in a few minutes, or b) the cutting wheel catches in a piece of steel so that the wheel jerks and badly cuts into the users leg. Both of those scenarios could happen with a tool out of the box. Neither is more likely to happen because of the modification I showed here. Thank you for looking.
And I think you can avoid the two bad scenarios by simply making a straight cut and allowing enough time for the wheel to cut through the material. Also wearing a face shield improves safety exponentially.

I don't have a welder so I will have to make my saw in another way but using yours as a basis. Would you mind if I post an Instructable of my model while giving you credit for the original idea?

I'm following you.
Phil B (author)  I_StarkGuy1 year ago
Please do publish your idea. I actually got the idea from something I saw at Harbor Freight.
Great 'ible! I'm hoping you'll take it to the next stage where you can cut up to 45 degree angles - that would be perfect for me! lol! Maybe it could turn on it's axis with a bearing of some sort?
Phil B (author)  bricabracwizard2 years ago
Commercial cut off saws for steel do not tilt the arbor like a power miter box does, but they have an adjustable fence on the table that angles to 45 degrees. It is very easy with the saw presented here to angle the fence so the steel is cut at 45 degrees.

Thank you for looking and for commenting.
the cut dust and sparks are very open. this is sedentry so use is dangerous as we have to move the object to cut. no use is machine stays. pls make it more different. but good concept keep it up dear sir
Phil B (author)  bannutechniclor3 years ago
I am not sure what you are talking about. I do not move the steel, but the grinder is hinged and the steel is stationary. Further, I can use this with the factory guard, but usually the sheet metal deflector for the sparks is more than sufficient. I wear a face guard, too, when I use it.

I saw your design. I notice the grinder is held in place with only one bolt. It appears to me the grinder could twist on its mount and bind against the steel being cut. It also appears to me you have no fence to hold the steel from moving as it is being cut. My grinder is held very firmly in place and cannot twist or move in its mount.

My design is an adaptation of a design once sold by a tool company (Harbor Freight) in the USA. Thank you for your comments, but after about ten years of use, I do not see any safety problems with the unit I built.
Cooldeal4 years ago
Nice design and all but I really see lots of possible danger here for a serious accident. Modifications of tools often lack of properly engineered safety design and lead to horrible accidents. Yes I have witnessed lots of modified tools especially powered ones that harmed or killed people. Upside down bandsaws, skilsaw attached to a table upside down, unguarded blades and methods of attaching rotating power equipment that can bind or be thrown off and where improper access to switches were improvised.

Go ahead and curse me for wanting people safe from dangerous and improperly designed tool modifications. When your finger or hand gets cut off then you'll stop. This can throw a chip off the blade, loosen in the vice you made for it which is squeezing the motor chassis. Just as bad mixing electricity with water, mixing power tools with modifications FAR FROM THE INTENDED AND LICENSED SAFETY ORIGINAL DESIGN...

How would you feel Phil B if someone looked you up and told you that one of your improvised safety power tool modifications caused them to lose a limb? Or a life of a family member? Just looking at your skills and placement of the tool cutting blades lets me know you are not qualified to design and scary configurations of your contraptions are DANGEROUS!!!!!!!!!

Can you show us a way to put safety guards on your devices and a way to insure clamps at motor casings and switches can be operated properly as to the tools' original safety design? I don't want anyone hurt. Especially not you.
Phil B (author)  Cooldeal3 years ago
After some thought, I checked and it can be operated as shown with the original guard in place.
harvey6396 years ago
you should use a cable tie to hold down the grinders switch and make a a foot operated momeruntry switch and plug the grinder into that
Phil B (author)  harvey6396 years ago
If I used this tool more regularly I would probably do that. Thanks.
rimar20006 years ago
Very useful tool.
prestux6 years ago
Excellent idea! I just happen to have a extra angle head grinder that could be converted into one of these. Just the thing for those smaller cut-off projects.
Phil B (author)  prestux6 years ago
Even though I have a big (230 volt, 200 amp) welder, I find most of what I do are fairly small projects. A small cut off saw works fine for cutting 3/4 inch square tubing or 1/8 inch strap iron. Sometimes I cut something too big for a single cut, but it is easy to stop and roll a piece of pie for another cut until I get all of the way through the piece. The tapped holes on this grinder are 180 degrees opposite one another. The second grinder I bought has angled holes in the head. It would still be possible to make one of these for angled holes, but it would present a couple extra little challenges.
Lftndbt6 years ago
"Angle Head Grinder" Got to love it! ;) Preparing for Zombie wars anyone?