[effimos]

i recently built a desktop cnc router, mainly for cutting small parts:
thread-> http://www.cnczone.com/forums/diy-cn...nc_router.html

now being an architecture student it would be nice to have a Hot-Wire cutting option for cutting small parts of foam that then could be used for making study-scale-models.

i now have a hand cutter like this:


and this is a quick sketch of how i can combine this with my cnc:
-> keep in mind i don't want to use the existing hand-cutter because it is not made that strong, it would have to be a new design...


now my question was how you guys should make this?
i don't find many info about this way of doing it.
i only find cnc machines that are made for hot-wire cutting only but not how to make a hot-wire "option' on an existing cnc machine.
also, how would you guys connect the hot-wire itself if the u-shaped bar is made of aluminium? needs some sort of insulation between the hot-wire and the bars.... ?

thanks in advance for your ideas!!

[ssutton]

Since you have already built your CNC router you have conquered 9/10ths of what it takes to understand and construct and operate a CNC foam cutting machine. I have also concluded that it would be nice to have a CNC hot wire machine and have considered making it an attachment for my router, but the reality is that it would be better just to build a CNC hot wire machine dedicated for just that purpose. They can be made for much lower cost than a rigid CNC router and they can be taken down and put away in a small space when not in use.
Hot Wire Foam cutting CNC Machines

[effimos]

Since you have already built your CNC router you have conquered 9/10ths of what it takes to understand and construct and operate a CNC foam cutting machine. I have also concluded that it would be nice to have a CNC hot wire machine and have considered making it an attachment for my router, but the reality is that it would be better just to build a CNC hot wire machine dedicated for just that purpose. They can be made for much lower cost than a rigid CNC router and they can be taken down and put away in a small space when not in use.
Hot Wire Foam cutting CNC Machines

thanks for the link!
but at the moment i don't have the budget to make a 'new' cnc machine for foam cutting only, even if it's cheaper.
and i think my ambition in foam cutting is not that large to make a fully new machine. i will only use it for small pieces, therefore the 'option' to put on my existing machine.

[PaulRowntree]

This is interesting, but I have more questions than help; sorry!

What size of foam (x,y,z) are you thinking of working with? It seems like everything depends on this.
Will you always start at the outside edges, or do you make a hole and insert the wire like a coping/scroll saw?
Do you need a dynamic tensioner (spring?) to keep the wire taut as it heats and expands? Some flex in the wire support may be a good thing.

The need for a 'foot' under the work (if the wire is vertical) makes this look more like a CNC embroidery machine than router.

[effimos]

This is interesting, but I have more questions than help; sorry!

What size of foam (x,y,z) are you thinking of working with? It seems like everything depends on this.
Will you always start at the outside edges, or do you make a hole and insert the wire like a coping/scroll saw?
Do you need a dynamic tensioner (spring?) to keep the wire taut as it heats and expands? Some flex in the wire support may be a good thing.

The need for a 'foot' under the work (if the wire is vertical) makes this look more like a CNC embroidery machine than router.

1. the thickness of the foam would be max 5-6cm (i have 9cm of space under the z-axis).

and the x/y dimensions of my router are 20x40cm at the moment so the max size of the fom would not have to exceed this.

2. for me it's no roblem to always have to start at the outer edges of the foam.

3. i could use a dynamic tensioner but is not necessary. i have a foam cutter and it uses the u-shape to tension the wire. but i will concider using a spring.

4. and if the cnc machine looks like an embroidery machine it wil only be when the foam cutting option is mounted so i dont see anything wrong with that

[PaulRowntree]

Ok, so more questions ...
What do you do when the piece gets cut free? The work has to be floating above the table (for the foot) so does the released piece just rattle around?
Khalid's thread on embroidery machines makes for a good read; these machines have their own hardware and software issues that are quite interesting nuts to crack.

[effimos]

Ok, so more questions ...
What do you do when the piece gets cut free? The work has to be floating above the table (for the foot) so does the released piece just rattle around?
Khalid's thread on embroidery machines makes for a good read; these machines have their own hardware and software issues that are quite interesting nuts to crack.

well, therefore this thread.. so other people can give their advise about how i should do this. because like you say the piece will probably drop down when cut. and might get damaged if it touches the hot wire.
i have seen another guy making something like i did but he made it so the wire was horizontal instead of vertical. but the problem then is that i can then only make pieces that are 40x 9cm max because my z-axis only goes 9cm up and down...

[PaulRowntree]

Do you expect to be mostly cutting waste away from the edges of materials, or are some inside openings expected?

[effimos]

Do you expect to be mostly cutting waste away from the edges of materials, or are some inside openings expected?

it wil be only outside/edge cuts, no openings inside.

[effimos]

got a working design now, thanks for the comments so far.
any improvements will still be appreciated

-> http://www.cnczone.com/forums/diy-cn...ml#post1098877