Thursday, August 14, 2014

Beginners Fab Episode 8: Straight Cuts W/ An Angle Grinder

That's right... If you're just starting out in the metal working hobby, or vehicle fabrication scene, more than likely, you've not been able to justify the purchase of a precision metal cutting tool. So, you're probably using an angle grinder or a reciprocating saw. While both work well, the challenge is always getting a straight cut. Well... here's what I've learned to do and why.

Over the years, I've tried to cut straight lines using the angle grinder a number of different ways. Still, my edges have always needed a little working after the cut. Because of this, I've tested different methods to produce a better cut.

A few things that I've considered when choosing my form for of cutting a line w/ my angle grinder are....

Time vs Time
At first glance it can seem that measuring out the lines and adjusting the metal, the straight edge, and the clamps can all be time consuming for just one line. Even more so if you're cutting multiple strips or pieces.

While it's true that setting up a straight edge can be time consuming, the reality is, I've found it to be faster to set up the straight edge, than to have to re-work a less than straight edge by grinding, and sanding.

Materials used for Straight edge guide.
In the video below, I use a 1/4" piece of flat bar. However, a 1/2" or 1/4" piece of square tube or angle can be used with equal effectiveness. Using steel instead of aluminum, wood, or plastic is important. Aluminum, wood, and plastic all have a tendency to melt, or gauge easily. This wears on the straight edge and then you have a non straight guide after one or 2 cuts.

Steel also wears with repeated use. Still, it tends to last much longer without gauging, or wearing down to a point were the edge is no longer straight.

A Few Things To Think About.
When you prepare your materials to cut a straight edge, there are few things to consider. Here are few.

1) Think carefully about what you're about to use as your straight edge.  If this material needs to be pristine and unmarred, it's probably not a good idea for you to use it as a straight edge.

2)Even after just one cut, the straight edge will be slightly modified. So, always think about the straight edge material and if it will work for your needs even after just one cut.

3)Cutting wheel selection is important. While thinner cutting wheels cut faster, they also warp, and walk easier. So, if you get lax in your control, you could easily cut an unstraight line and even cut into your straight edge.
Thicker cutoff wheels heat and tend to warp metal more, but they will typically follow the straight edge with less difficulty. It will take longer to cut thru thicker material with a thicker cutoff wheel. So, be patient no matter what wheel you choose.

4)Marking your line for cutting is important to pre-think. A number of factors come into play when you are preparing your straight edge and line for cutting parts for your fab work or metal work. Never forget to line up you straight edge on the same side of the line, or in the center. Also, don't forget to make the needed adjustments for the thickness of the line drawn, or the thickness of wheel used. Factors such as these can make the difference between a fairly square, or completely unsquare product.

Enough of the talking, and on to the demonstration in video form. So, here you go...

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