The Secrets of Tangential

[scogre]

So, as I have been searching for a Graphtec cutter, I keep coming across the feature that is listed - Tangential Cutting. I've asked three different sellers and each of them just say, "It helps with very detailed cuts."

Does anyone actually know what "Tangential Cutting" does?

Thanks. Soon, a mystery of the universe will be solved for me.

 

[Letterbox Mike]

A tangential cutting heat has a motor that "steers" the knife blade, instead of a more typical dragknife blade that just rotates in the holder as the head and media move around. Typically at a sharp corner the knife is lifted , turned while up, and then dropped back down. Cuts are very accurate, and tangential plotters are great for cutting thicker materials like sandblast stencil or reflective.

I may be wrong on this, but I don't think Graphtec makes a tangential plotter. They may offer "tangential emulation" which is just a software option on a drag knife plotter that makes the head pick the blade up and rop it back down at corners like a Tangential plotter does, but if it doesn't physically steer the blade, it's not a tangential plotter.

If you're just cutting vinyl, I wouldn't bother with tangential, it's not worth the extra money, even though they do cut really nicely. That is unless you cut alot of really small text, then it may be more justifiable.

If you are looking for a tangential plotter, consider Summa, they've been the industry leader in that area for a long time. Excellent products, we've had 4 of them over the years.

 

[bob]

So, as I have been searching for a Graphtec cutter, I keep coming across the feature that is listed - Tangential Cutting. I've asked three different sellers and each of them just say, "It helps with very detailed cuts."

Does anyone actually know what "Tangential Cutting" does?

Thanks. Soon, a mystery of the universe will be solved for me.

True tangential cutting, as seen on some Summa machines, means that that blade is physically rotated to be pointing in the proper direction before each cut.

Tangential emulation, such as that used by Graphtec, means that the machine relies on various positioning techniques to try to make sure that the blade is pointing in the right direction before making a cut. Just how effective this is is summed up in the words of Dan George "Sometimes the magic works and sometimes it doesn't."

The point being that when making a continuous cut in various directions, each time the cut changes direction the blade must rotate so that it's pointing in the same direction as the cut. Without tangential cutting, this rotation is accomplished merely by moving the blade along the desired path thus the blade has covered some hopefully small distance before it's facing the right way. This is fine for most everything except small detailed objects. Then the distance the blade must travel to properly align itself to the cut may be a substantial percentage of the cut.

 

[Fred Weiss]

True tangential cutting is provided by having motor driven theta axis rotation of the blade while cutting. It was available on all the older Gerber plotters and some Summa plotters. Not only does the blade lift, turn and come back down at a 90 degree corner, it also if physically rotated without lifting through any change in direction rather than swiveling as a drag knife does.

The benefit is that there is no offset from center of the point of the blade resulting in the most accurate form of plotting possible. Swivel or drag knife systems depend on the tip for the blade being slightly offset from center in order to take the path of least resistance when cutting. The amount of that offset is an inherent inaccuracy and is compensated for by adjustments in the firmware of the plotter.

In addition to being more accurate, tangential cutting also remains accurate with thicker materials while swivel technology requires greater offset correction to be accurate.

The downside of tangential cutting is that it adds cost to the plotter and production of most work in noticeably slower.

This animation illustrates what a tangential cutter does along a vector cutpath.

 

[Do-Over]

Using that cut method results in nice cuts, but it is extremely slow, and I mean painfully slow.

Kevin

 

[scogre]

Awesome Information

Thanks everyone. This is great info.

So how much slower will the cutting be? And is it worth slowing down or are Graphtec Plotters just better at cutting anyway?

 

[Service Sign Co]

Speed doesn't prove to be as valuable as one may expect. I havs a Gerber HS 15 Plus that cuts True tangential and use it at 10% of it's speed,which is slower than the old 4B's, and have no problems with production time.

 

[Fred Weiss]

I have to agree that plotter cut speed is a highly overrated feature.

 

[visualeyez]

We rock a Summa T1010 Plus (something like that) and it's a 40some inch tangential cutter made in the early 90's. It's very loud and finicky, but with enough practice, this thing will still cut 1/4" letters beautifully. Unfortunately our Roland SP540v cuts 10x nicer and it is non tangential.

 

[Tel]

We have 2 original gerber supersprints and a GS15 Gerber plotter all true tangential cutters and the supersprints are maybe 25 years old. They work great.
regards
Tel

 

[animenick65]

I'd take crisp vector lines and better weeding over cut speed anyday.