A comment about the course:

[fergy]

Just wanted to post here that the intent of the course will be more than just creating a calcium reactor. The reactor will be used as a case study in acrylic fabrication. I chose the reactor because I felt it had the most different fabrication techniques used in making it.

For those of you who have already dabbled in acrylic, you have some ideas of what worked and what didn't. I would like to get some input from you, as to any questions you might have, or problem areas you encountered in your endeavors. It will help me to make the course as well-rounded as possible.

BRIAN

 

[hfmann]

Hi Brian,

I built my first acrylic item over the weekend after much thought and research about how to do it. It was an acrylic internal 3 sided overflow. Here's the lessons I learned.

1) Always test the process on a piece of scrap first. Three processes failed on my first attempt on the scrap. Evaluating what happened and how to modify the process, enabled me to successfully apply the technique on the "real" item.

2) In bending the acrylic using a heat tape, my bends never came out at 90 degrees. Seems like you have to bend slightly more than that and it'll relax back to 90?

3) You may build the item square, but if what it's mating to isn't square you'll be chasing your tail. The back of my tank where I wanted to glue the overflow, was out of square with the bottom by 3/16" at the top. I ended up having to angle cut my eges so they fit snug.

4) Depending on how you feed the acrylic into the router bit, the router will try to pull the acrylic away from you, possibly causing the piece to get away from you.

Questions so far:
a) Using heat tape, I had the tape on top of the acrylic with a flat board and weight on top of that. I think I overheated the plastic a couple of times. How do you tell how long to heat it?

b) How to precisely bend the piece to the exact angle you want?

There'll be more.

In advance, thanks for all the help.
Hal

 

[fergy]

I'll make sure I cover all of these questions in the course. The short answer regarding bending is to use a jig or form. I'll make sure to show you how to build those. Also, heat tapes are notoriously bad at bending, as they are in contact with the material, and can heat unevenly. I'm assuming you got some sort of bubbles in the joint, or the tape left marks?

The router tried to pull the material away because you were "climb cutting". Cut the other way, always. Climb cutting is very dangerous, as it can pull your hands into the bit, and it never gives as nice of a cut. I'll show you pics of what can happen if your hand gets sucked into a router bit, too, under "Safety". :?

BRIAN

 

[firefish151]

What is climb cutting :?:

 

[fergy]

Climb cutting is when you move the object along the bit in the same direction that the cutter is moving, instead of pushing into the cutter. When climb cutting, it can grab the object you are routing, and tear it out of your hands, fling it across the room, or even pull your fingers into the bit. In everything we'll be doing, you want to move your object into the cutter, not with it.

I had the luck of having a router tear something out of my hands, and suck three fingers into the bit. I was using a fluting bit, which you would use to machine oring grooves into the side of something. It was a 1/4" radius bit, and grooved three fingers 1/4" deep for about 1". Needless to say, you don't want to do that. Almost a year now, and it still hurts.

BRIAN
_________________
Honda 1300

 

[agiacosa]

Fergy,

I, like the others, am very excited about the course. Thanks for sharing your knowledge and experience.

I would ask that you assume that some of us do not have any experience working with a router or drill press. Therefore, tips on how to hold, push through, and avoid getting hurt are appreciated.

Thanks.

Art

 

[fergy]

Don't worry, Art, I'll make sure we do everything safely, and give tips for all the techniques. Most of it will be pretty straight-forward, once you get a feel for it. And the more careful you are, the better quality you'll end up with.

BRIAN
_________________
Honda Magna