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max_imum2000
12-11-2006, 06:15 AM
hello
till now i didnt see any DIY foam cutter or commerical software that make true 3D cuts in foam.
all what i can find is a foam machine that cuts letters and some very basic shapes.
is there anyone or any site , that enable me to build a machine which produce a true 3D prototypes in foam ?

thanks

erase42
12-11-2006, 08:05 AM
do you mean a machine that can produce some free standing statue type item with detailed eyes ears fingers etc? if so you probably need to look at something like a 5 axis mill or router. the best you will get from a hotwire machine is a 3d blank cut to the exact outline of the product you want, without the internal details. this is done by cutting a profile, rotating the blank, cutting another profile etc. each profile being the outline of the item from a different perspective of the original item.

thkoutsidthebox
12-11-2006, 08:26 AM
I dont know anything about this :rolleyes: but I just had an idea. :)

What about making a 5 axis mill/router, but instead of having a router spindle, fit it with some sort of hot point, like a soldering iron. Then as the cnc mill/router moves around the block of foam the soldering iron type tip will melt and shape the foam like a hot wire would, and like a router spindle would carve. Is this practical...

Any thoughts?

erase42
12-11-2006, 10:30 AM
doest really work like you would think, the melted foam has to GO someplace, so it either collects as a liquid on the hot tip then drips and melts a huge deep hole into your piece, or it sticks to the piece in a continuous string. It adheres very well, and trying to sand or chip it off damages the foam underneath. If you make a hot loop that actually removes a section of foam, the results are a little better, however where the cuts overlap there is always a hard ridge of melted foam, or worse and more common, a valley lined with hard melted foam that has been melted twice as the tool makes a second slightly overlapping path.
best bet for that sort of thing is to use very dense foam and remove it with a fine cutter.

Ed Rees
E3 Foam

max_imum2000
12-11-2006, 12:31 PM
thanks for your replies
well i was thinking of something like making a simple shapes, like say a big mobile phone, a big LCD screen shape and things like that.
i dont want to have details on it.

the rotating table holding the foam block is exactly what i need, but its like a 5axis machine , and i cant know any software which will handle that. ??

even if i want it manual
suppose i have a shape in CAD, how can i convert it to outlined shapes and cut them all accuratly at the end ?

erase42
12-11-2006, 03:47 PM
well really its only 3 axis. the x and y on each end are the same motion. true on some machines its independant as mine is, but for this they can be "slaved" together. then the z axis could run the table. however if you mark it out with compass degrees say every 10 or 20 so you can tell where it is, you can operate it manually. example if you have a proifile from 10 angles around the item, you would cut one, rotate 36 degrees (360 degrees / 10 profiles) cut the next and so on. depending on the symmetry of the item, you may be able to get away with far less. also mach 3 software will controll 6 axis.

thkoutsidthebox
12-11-2006, 04:11 PM
doest really work like you would think, the melted foam has to GO someplace, so it either collects as a liquid on the hot tip then drips and melts a huge deep hole into your piece, or it sticks to the piece in a continuous string.

Im not sure if this is going off topic or not, so if it is please tell me and I'll stop, but my mind is working away now. :)

What about making a modified type of soldering iron with a hollow tip, and the tip connected to a vacuum which will suck the melted foam back out through the center of the iron as it is being taken off the block of foam. Is this a good idea?

Would the melted foam be too sticky?...maybe just add more suction and little slots at the tip for extraction....

Unfortunately I dont have the equipment to make a test setup, so just thinking out loud. Also this in no way whatsoever helps with your software questions! ;)

max_imum2000
12-11-2006, 09:27 PM
well, that crossed my mind, actually i was thinking about a stainless steel surgical needle, #12 or #14, connected to a heating source.
maybe someone can discuss this further till i give it a try.

about the software, yes mach3 can control 6 axis, but what will be used to generate the G-code ?

thanks all

erase42
12-11-2006, 10:29 PM
do you know how many years it would take to carve something with a surgical needle :) you might be able to suck the foam away, but it cools and hardens quite fast, ive used this little trick before tho, and its this, always have the tool either cutting on the lower side of the foam, or have it tilting down and away so that the drops travel away and drip off.
as far as writing the g-code if you are talking about cutting multiple profiles with a rotation in between like we spoke of before. if you want to string all the profiles together, any CAM will create the code, then you manually insert a single line to make your rotation at the end of each profile.

thkoutsidthebox
12-12-2006, 05:54 AM
Hmmmm.....maybe just use a stationary hot point sitting vertically and facing upwards. Above the point use one of those robot arms to move the foam block around the stationary tip. The robot arm would only need 3 axis of movement, just like a gantry router...although 4 axis would be better.....

.....or perhaps, why not just make a gantry router with the hot point sitting in a fixed position (Or moving) on the bottom pointing up, Im sure it would be easy to make some sort of 'scraper' or 'scraping sleeve' mechanism that could move up and down quickly on the hot point to scrape it clean, perhaps every few seconds. Or the scraper could be two soft rubber squares mounted either side of the hot tip a few cm from it, every few seconds the squares move in and squeeze the tip then scrape downwards and go out back to the start position.

Of course rubber melts so a good rubber or other material choice would have to be made for the 'scrapers'.....

Soldering iron tips are interchangable, so you could change the size and shape just like router bits depending upon what you need to achieve. You could even grind your own tips!

.....any thoughts ???

erase42
12-12-2006, 10:12 AM
from experience i dont think there would be a need to coninually clean the tip. as long as the hot droplets could flow away from the work you would be ok. you could put a small flange on the tip where the droplets could collect and then drip away without puddling up around your the base of the tip.
if left in contact with the hot metal long enough the melted foam will actually burn itself right away to nothing but a fine coat of ash on the tip. sometimes i will turn the heat on my shaped wire cutters up a bit while i go get a drink, when i come back they are clean bare metal again. by the way cutting or removing foam in this way makes a huge amount of smoke, i have a range hood over mine with a blower on steroids sucking the smoke out. is there a reason why using a spinning cutter is undesireable?
Ed Rees '
E3 Foam

thkoutsidthebox
12-12-2006, 12:46 PM
fis there a reason why using a spinning cutter is undesireable?
Ed Rees '
E3 Foam

I dont think it is undesirable, I was just throwing ideas around. :)

But I think with a 4 axis machine (4th axis rotary) with a stationary hot point it would be possible to do true 3D carving of foam. The only problem is holding the piece in a way that the clamping wouldnt get in the way. Maybe mount the block like a lathe so the 4th axis rotates it as needed.

Could this setup work the same with a router....I think so, but the router would be on top....

What software is used to generate G-Code for 4 axis? I know it exists but dont know what it is...can BobCad do 4 axis?

erase42
12-12-2006, 01:07 PM
bob cad can code for a rotory a axis, but is pretty much the same as fooling it into thinking its cutting linear x that just happenes to be wrapped around something, there are settings in bobcad for 5 axis as well, however i have no experience with it even tho i do use bobcad so anything i say has to be run thru a BS filter first

astatue
12-29-2006, 05:05 AM
Hey Thksoutsidebox cool idea. but foam cools too fast. and would clog your vac line right away. but good Idea.

Everyone else. ROTARY CUTTER, ROTARY TABLE AND X AND Z. will get at 95% of the places you need for most figures. hand finish the rest.

:)

moki
01-05-2007, 08:18 AM
Have a look at this site. They sell these types of machines. Maybe you can get an idea as to how it is done! http://www.foamcutter.pl/index.php?id=239