What are you cutting your foam with?

[videographer]

Rookie question, but in all the threads I have been reading I haven't seen an answer to the simplest question - what tools are you cutting your foam with?

I assume a sawzall is far too out of control, so is it a long-blade fine jigsaw blade or what?

Thanks in advance -

[videographer]

Oops, found this thread:

http://tnttt.com/viewtopic.php?f=55&t=64058

Jigsaw blades by hand??

[tac422]

A regular Jigsaw works fine... or a circular saw.
These give a straighter cut than a handheld blade.

[lrrowe]

All of above and a sharp fishing fillet knife.
I also use the table saw if the pieces are manageable. But watch it if you slip a little. Boy will that saw blade take the foam sheet and make a heck of a mess out of it if things are not near perfect.

[GPW]

Our favorite tools for cutting form are a hot wire bow and a good sharp handsaw... and jig saw for curves. We do any small trimming with a cheap serrated steak knife ...

[ghcoe]

I love a hot wire. No foam dust, clean cuts.


viewtopic.php?f=55&t=55323&hilit=hot+wire

[videographer]

I have been experimenting with making slots in 2" foam with a router, and while it makes a TON of dust, the cuts are quite clean. Anything to watch out for there?

[dales133]

I routed some wire chases in mine,also used table saw,circ saw;jig saw box cutter,steak knife..ect ect
All work for differnt aplications

[GPW]

Just be careful with those routers , wear a mask and your safety glasses ...

[KCStudly]

I have used a lot of different techniques, perhaps all of these mentioned and more;
Table saw
Router
Small table top band saw with double guide fences for long narrow (close) ripping
Hot wire cutter
Razor knife (for scratching out irregular areas that the router is ill suited for)
Chisel (for digging out deeper pockets that have been scored with an extending utility knife)
Extending snap style utility knife
Straight edge steak knife (I prefer over serrated, use in a long dragging repetitive motion with straight edge... technique for square edges improves with practice, but leave a little extra for block sanding until you get the technique down).
Sanding blocks for truing up cuts and shaping, usually just 100 grit, but sometimes 220 grit to get it just right or smoother... the 100 grit can pull chunks out sometimes. 80 grit or even 60 on a larger block for knocking down quickly, but allow for tear out (i.e. stop well short and switch to 100 grit).

Probably others that aren't coming to mind at the moment.

For any of the power options you can usually rig up a shop vac to help a lot with dust collection, even if just using painter's tape, but be prepared to service your filter frequently, or consider a cyclone separator.

[GPW]

That says it all eh KC !!!
...the only reason we like the serrated steak knife , is the thin flexible blade is good for trimming and sawing off those GS and GG bumps , drips and protrusions... quickest thing we could find around the house to do the job , then come back with the sanding block to finish ...

[KCStudly]

The serrated knife I have is flat on one side and beveled on the side with the serrations. I did not have the touch to get clean flat cuts when trying to trim fill to a flat surface w/o gouging said surface; and could not make straight cut offs from stock because the bevel forced the blade off line; or just due to the flex in the blade. My straight edged knife blade is beveled on both sides and is a lot stiffer (yet still thin enough) so it tracks much better when doing cut offs. It does okay for shaving fill, too, even though you can't get flush out in the middle of a flat panel due to the lack of flex, but since, like you say, it is better to fair the last bit with a sanding block anyway... po-tae-toe, po-tah-toe, tom-a-toe, tom-ah-toe.

I'll try to remember to take some comparo pic's of my knifes this evening. Heading to mecca now.

[KCStudly]

Okay, here are the knives that I use for foamie work.


From top to bottom they are:
A cheap utility knife that I got free from work when they took all of the std. utility knives away from the masses and issued safety style box cutters. I much prefer my good Stanley which has a superior case design with better detent mechanism. This one won’t extend or retract when the case screw is tightened down all the way.

A cheap plastic snap blade style extending utility knife; couple of bucks at the hdwr store. This is my second one. The blade detent thumb adjusters tend to break, hence the electrical tape to make it a fixed blade. Also, with the long scoring technique, having the full length blade extended out all the way puts a lot of leverage on the plastic pin that goes thru the hole in the blade; the pin sheared off on my first one, so I picked up another, but use the straight edge steak knife for those long slicing cuts now.

The third one is now my go to blade for most operations requiring hand cutting; long straight panel cuts, trimming routed corners square, scoring out pockets, basically anything that I can’t be bothered to set up and/or does not require the accuracy of a power tool. IIRC the cost was under a dollar, something like 30 cents at Goodwill. The wooden handle and full tang feel better in my hand than the plastic handle on the serrated one.

The last one, the classic cheap serrated steak knife, also for a couple of coins at Goodwill, is used very little. I prefer the stiffer blade of the straight edged knife for better control with less incidental gouging.

You can see the serrations better here and how far they ride up the side. Maybe a different style of serration would work better, more like a bread knife with wider but fewer serrations that are more scalloped shaped?


Contrary to what I implied in my previous post, I can flex both of the steak knives enough to flush cut, but the serrated one is more flexible.



I was also mistaking about the serrated not having a bevel on both sides, but the back side is beveled considerably less.


One last pic comparing the steak knives. Hard to see, but the straight edge on the left with full tang is slightly thicker in the blade (even thicker in the tang) and is of much better blade quality. I suspect that when it was newer it wasn't as cheap.

[Mary C]

I used a sawzall to cut some of my foam yep you havent read my Grits build that saw and a jig saw and a few different knives including a electric meat knife, it was mine so I didn't yell at me. The jig saw worked the best. I tried several blades.

Mary C.

[GPW]

Yes, thanks for reminding us Mary , an electric carving knife not only neatly cuts hard foam but foam cushion material too ...