Tag Archives: Foam

The Problem with Foam: Thoughts on our new foam cutter

A housing treatment that I have recently taken on led me to getting some hands-on experience with one of the newer tools to arrive at the lab: The Hercules Cordless-Battery Operated Hot Wire Table from Hercules Cutters.

Image of Hercules Cordless battery operated foam cutter
Figure 1: The Hercules Cordless-Battery Operated Hot Wire Table

The Difficulties of Cutting Foam

We have typically performed foam cutting at the lab using either a hand-held blade like an Olfa or scalpel, a board shear, or in some cases a hand-held saw. While these methods can be somewhat satisfactory, they are none without their limitations. Cuts with a hand-held blade often look sloppy, especially if the foam needs to be stacked; the compressible nature of foam makes it very difficult to make accurately measured cuts this way, and the inaccuracies become glaringly obvious when trying to stack multiple seemingly same sized pieces for thick fills inside an enclosure (something I often need to achieve!).

Stack of foam sheets with emphasis on their imperfect cut edges.
Figure 2: The minor inaccuracies of hand-cut foam become obvious when the pieces are stacked. Notice the unevenness along the edge of this stack of Plastazote foam. Plastazote, as well as a thinner foam called Volara, are among the most commonly used foams we utilize at The Preservation Lab.

A board shear is quick and offers a measuring guide to provide accurately measured cuts, but the edges where the blade slices through the foam often end up rounded or otherwise distorted.

Image of foam with rough edge from being cut on a board shear.
Figure 3: The downward cutting motion of a board shear can often leave the edge of foam looking rounded or otherwise distorted, as can be seen on this piece of Plastazote.

Finally, cuts with a saw can leave a mess and the teeth can leave a sloppy looking edge on the foam.

Stack of foam roughly cut with a saw.
Figure 4: This stack of Plastazote was cut with a saw. A saw’s teeth can leave a very messy edge when cutting through foam.

The Hercules Foam Cutter: Basic Features and Operation

                The Hercules foam cutter uses a different approach. It heats up a filament wire that is pulled taught vertically through the device. While the wire it hot, foam is drawn through the wire to accurately and cleanly (with a little practice) slice through it.

Image of foam plank being cut by a the hot filament of the Hercules foam cutter.
Figure 5: A stack of Plastazote is pulled through the hot filament wire to make a clean cut.

The heat can be engaged in one of two ways: with the power switch turned to “On” mode, the wire stays hot until it is turned off; when the switch is set to “Foot pedal mode”, the wire only heats up while the included foot pedal is pressed. There is an adjustment knob allowing the user to control the temperature of the wire. In general, after experimenting a bit it seems that the thicker the foam, the hotter the wire needs to be.

Image highlighting controls of the Hercules foam cutter.
Figure 6: The Hercules Cutter’s heat controls.

The cutter includes an adjustable guide rail to aid in accurate cutting. The position of the spool that holds the wire is also adjustable, allowing for angled cuts to be made.

Image of Hercules foam cutter with adjustments labeled.
Figure 7: Cutting position adjustments of the Hercules Cutter.

Finally, there is an attachment that can be placed onto the guide rail allowing for circular cuts to be made.

Image of circle cutting attachment on the Hercules foam cutter.
Figure 8: The circle cutting attachment: the foam piece is impaled by the point of the attachment at the center point of the desired circle. The distance from the point to the wire will be the circles radius. Once the attachment is in position for the desired size of circle, the foam piece is rotated as the wire cuts through the foam until a complete circle is made.

Advantages

                The Hercules Foam Cutter’s ability to cut stacked pieces of foam is by far my favorite and the most practical of its uses in my opinion. As previously mentioned, cutting inaccuracies become very noticeable when trying to stack multiple same sized pre-cut pieces of foam. With the Hercules Cutter, the foam pieces can be stacked/attached to each other before hand, and then cut to a uniform size. I was pleased to discover that the heated wire doesn’t seem to have any trouble cutting through multiple layers of foam that have been adhered together using double-sided tape and/or PVA. With a bit of practice, I was able to achieve neat, uniform chunks of foam that were several layers thick. I have found, however, that when cutting foam adhered together using double sided tape it is important to be mindful of where your points of adhesion are inside the stack of foam. It is possible to end up with a stack of foam that doesn’t have any tape holding it together after cutting.

Image of a cleanly cut block of Plastazote using the Hercules foam cutter.
Figure 9: A cleanly cut chunk of Plastazote 4 layers thick. Notice that the section that was cut off has fallen apart due to not having any double-sided tape in this section. Fortunately, this is not the piece I needed from this cut!

Also remember that the thicker the foam, the hotter the wire needs to be. There is a decal attached to the cutter with heat setting recommendations based on how thick the foam is, but the instructions (and also myself) recommend doing a few test cuts with scrap foam first to see what works, as different types of foam will respond differently to various heat settings. It shouldn’t require much pressure from the user to push the foam piece through the wire, and too much pressure will cause the wire to bend or even break; if this happens, the wire isn’t hot enough!

Image of a snapped cutting wire caused by applying to much pressure, and not enough heat, while cutting a foam block.
Figure 10: It is difficult to see as the wire is so thin, but it has snapped. The wire wasn’t hot enough and I had to apply too much pressure to pass this stack of Plastazote through it. Fortunately, there was plenty of wire remaining on the spool, and it was easily threaded back into its port.

I found the foot pedal to be a beneficial feature as well. Some types of cuts require the user to adjust their hand position mid-cut, and it is helpful to have the option to stop the flow of heat into the wire if such an adjustment needs to be made. The wire both heats and cools down almost instantaneously, which is also a nice touch.

Finally, the circle cutting attachment proved to be useful during a recent housing treatment. I needed to create a compartment in a piece of foam to store a commemorative medallion, and my attempts to cut a circle using a hand-held blade did not look good. I was very pleased with the results I achieved using the attachment, although it took several attempts to get my circle to have the correct diameter.

Two images - a hand cut circle into foam and a circle cut with the Hercules foam cutter.
Figure 11: A circle cut into Volara foam using the circle cutting attachment with my previous attempts to make the cut by hand using a scalpal in the corner of the image.

Drawbacks

                It should be noted that many components of the Hercules Cutter are made of plastic. While this makes it lightweight and portable, it causes some problems. The guide rail feels rather cheap, and even with all the screws secured tightly, the rail still has the potential to wiggle around a bit. This can make getting accurate cuts difficult. I did find that cuts still look better using the rail than doing them free hand, though.

Image of adjustable guides on the Hercules foam cutter.
Figure 12: Most of the components of the adjustable guide rail are made of plastic, giving them the potential to move slightly during use, even when tightly screwed down.

Another issue I had with the cutter lies in its cutting platform. There is centimeter grid on it for measuring/setting the guide rail which is a nice idea; however, I feel it would have been much more helpful to have millimeters indicated somewhere like board shears often do, as precision cuts rarely fall exactly on nice round centimeter measurements. The user is forced into one of three solutions: 1) measuring the foam and adding a tick mark to it, which is not as easy and one would think as foam isn’t very easy to make discreet marks in; 2) using a ruler or other measuring device to set the guide rail, which defeats the purpose of the cutting surface containing a measuring grid to begin with; 3) eyeballing the correct measurement between the grid marks. This parred with the already wobbly nature of the guide rail makes it somewhat challenging to make precision cuts.

Image of the measurement grid in millimeters on the base of the Hercules foam cutter.
Figure 13: Although the numbers represent millimeters, the grid lines on the cutting platform appear only every centimeter.

Finally, as the Hercules Cutter operates through a wire essentially melting foam, it can produce a somewhat unpleasant burnt-plastic smell while in use. It is recommended to use under a fume hood, outside, or in another well-ventilated area if possible.

Final Thoughts

As with all other methods of cutting foam, the Hercules Foam Cutter is not perfect. For making simple cuts in a single layer of foam, I still find using a board shear to be my preferred method; it is quick, easy, and the rounded edges left by the blade don’t bother me much if it is only a single layer of foam.  However, the Hercules Cutter has become the default tool I use to cut stacked foam and to make circular cuts. It has been a fun tool to test out, and it is always possible that more practical uses for it will arise as I continue to make more custom and specialized enclosures.

Matt McCoy — Senior Library Conservation Specialist