minicell questions

Two questions- Has anyone fooled with drilling minicell? I need to fabricate some blocks to slide on my yakima racks to get my canoe higher so it won’t clunk around on the cab of my truck. Spade bits or twist bits? Drill press or jig with cordless drill?

Also, has anyone found a product that could be used to coat minicell so it doesn’t absorb water over time. I’m looking for something to spray or brush on the foam kayak seats I make for myself. I’ve heard that the minicell holds water and so makes the boat heavier, which I would rather not lift over my head if I can avoid it. Thanks------------Kevin

Liquid Electrical Tape
You could coat the foam with this stuff, available at hardware stores in your choice of basic colors. However, minicell is waterproof and doesn’t need a coating.

I don’t know about drilling minicell. I’ve molested it in lots of ways but not that one. I’d avoid large twisting bits, though. I think the stuff is too elastic to work well with those–but again, I have not tried that.

you can use a dremel with
the round sanding disk and actually carve many things with minicell…

Never had a problem drilling it, but
I’m not fussy. Spade bits will work. Eric’s mention of an auger bit is right on. If you had a Forstner bit in your prefered diameter, I think it would work too.

We have mincell pillars in whitewater boats, and when I have pulled them out to get at the stern, I have not seen any sign whatsoever that the minicell has absorbed water or degenerated in any way.

hole saw works
you must be thinking of something else because minicell is closed cell,it does not absorb water

What you want to do will work but
minicell has a short lifespan when used for tie down blocks. I know that most stores sell them (at an high price for what they are) just for that purpose but I think you can do better springing for the Yakima gunwale brackets. you can glue a small piece of minicell on the pads if you need more heigth.

It’s easy to drill and no it does not…
absorb water.


I drilled that hole using a drill press, but I have also drilled holes in it with a portable electric one.

If you are using the hole to put a rope through to tie it to your racks, I would advise glueing a piece of PVC pipe in the hole like I did so the hole won’t get torn through by a tightly tied rope.



Spade bits work
I’ve drilled it with spade bits.

Augers would probably be better if you have them.

I don’t recommend power tools…

– Last Updated: Jun-16-08 8:35 PM EST –

...for making a half inch or larger diameter hole in plastic foam, like minicell. Get a scrap of EMT (metal electrical conduit) about a foot and a half long, "sharpen" one end with a file or bench grinder (the sharper and smoother, the better) and use it to core holes by hand, working slowly, twisting as you push. This method allows precise control and is much safer than using power tools, which, to my mind, is like using a Skilsaw to cut birthday cake.

I probably shouldn’t pick you up on it,
But I highly recommend it for the dense gray minicel foam.

A drill press goes through it like butter and it stays just as secure as a block of wood.

Also a band saw makes the neatest cut going with absolutely no grabbing.

I have cut it many times with my table saw to, but the band saw makes the smoothest cut.

Are you sure you are not thinking of foam rubber or some less dense stuff?



Admittedly, it does take strength…
…to core a hole in thick EVA foam, as it isn’t as slippery as PE, and I’ve filed little teeth on some of my hole-makers for use on higher density foams. Yes, Jackl, you are right that a properly set up drill press, with workpiece adequately clamped in place, is an option. I just can’t, in good concience, recommend it to someone whose level of experience is unknown to me. As I’m sure you know, making a large diameter hole in any material with any power tool is rife with risk of injury. After rereading responses to the original post, I like Eric Nyre’s suggestion of an old fashioned auger bit in a brace the most. It’s not common, these days, to find those items in your average tool collection, however. Oh, and Jackl, I agree that the bandsaw is the way to make straight cuts in foam. You should try a knife blade for the smoothest cut (with NO dust)! I think you can get them ready-made for typical Delta-clone 14 inch saws. Another nice feature of the knife blade; it stops at the bone!

Couple of thoughts
I too believe the “coring” method using an appropriately sized conduit, or even a section of Yakima bar would work. Taking the time to file teeth will make the cut go faster and truer.

As for sealing the surface, I have heard of folks using a heat gun or a torch (carefully!) to sear teh surface, thereby melting the thousands of sliced-in-half bubbles into a smooth skin.


Heat Sealing
I’ve had mixed results putting a skin on PE using a heat gun and even using a regular iron with a sheet of silicon-release paper between. EVA’s tended to scorch rather than melt. If a flexible smooth surface is what you’re after, I’d advise laminating a vinyl sheet.

Simple punch…
you can make a punch from the appropriate size/length of electrical EMT (conduit). Use a bench grinder to form the sharp edge on one end of your pipe and hone it smooth with a file. Use soapy water to lubricate. It should gently twist right through the foam.