Foam XL hot wire cutter

[charlieuk]

i wasn't talking about the motors or the price just the simple drive system, and if it does the job then ....

I cant see the point in the printed carriages they will never last under any sort of load and ether the plastic will fail or the surface of the aluminium will deteriorate. I would rather just use something like a cheap set of skateboard bearings and make a arrangement that runs down the groves of the aluminum that way at least the have a larger contact area and the aluminum should not deteriorate

8 x 4 eps blocks are not light but if your frame is not supporting the foam and on a solid floor you can probably get away with a smaller frame I wouldn't even consider anything lighter than 40x40. you need a relatively high tension in the wire to reduce sag and drag if you want straight lines and want any sort of reasonable speed without to much curf. and if you are ever going to do 4 or 5 axis you will need stiffness in the frame to get that, unless you build a complex frame that will likely cost as much.

[Boyan Silyavski]

any idea of the force needed to tighten the wire for radiation cutting? i think its less than 1 kg in mass, if weight is used. i cut now using 0.16mm wire and a small spring, for sure less than 1kg pull.


I see the benefit of the big aluminum profile and 20 size rail, as that was my initial design, using 3060 profile. But that's more for industrial use where somebody will work for you and will not take care of the machine. Doing it for myself, i think 2040 is enough. Still have not bought either yet. And have a day or 2 to think it over. Price wise will be just a bit more expensive.


By the way cages could be printed from Delrin, so they will be ok for the job. I have read reports on a printer after 1500h was perfectly fine

[charlieuk]

any idea of the force needed to tighten the wire for radiation cutting? i think its less than 1 kg in mass, if weight is used. i cut now using 0.16mm wire and a small spring, for sure less than 1kg pull.


I see the benefit of the big aluminum profile and 20 size rail, as that was my initial design, using 3060 profile. But that's more for industrial use where somebody will work for you and will not take care of the machine. Doing it for myself, i think 2040 is enough. Still have not bought either yet. And have a day or 2 to think it over. Price wise will be just a bit more expensive.


By the way cages could be printed from Delrin, so they will be ok for the job. I have read reports on a printer after 1500h was perfectly fine

I'll see if I can figure it out, it's more than you think as with a manual one you are normally pressing down on to templates which tenshions it further. The larger the block your cutting the more tension you need or the slower you have to go. It's a combanation of having the right temperature, the right tenshion and the right cutting speed so as to get a clean cut and not too much burn back

At a guess I would say mine is probably 2-3kg tension but I'm cutting relatively slow and and not too hot.

The cost saving is minimal on the Ali, I know what I would do..

I see less of a problem with the printed cages than I do with the balls them self. If using steel ball on Ali you don't need to be a materials scientist to know which will be the winner!

[Boyan Silyavski]

The balls are Delrin, so would be the printed cages. There is no steel on aluminum.

Agree about the aluminum profile, there is false economy there.

I have cut till now at most 100mm thick. I cut at 200 mm/min and i don't push the hot wire in the block, rather the heat makes the cut, so no stretching or effort at that speed. I am not in a production environment, but even when i would be, what matters is the cut quality, not the speed. And it seems at that speed all details cut well.

[charlieuk]

that's incredibly slow for such thin material and no use if you want to cut big blocks you will be there all day. With a cnc and no templates you obviously have to be very carful not to push the wire as if you do you will not get a straight cut when it comes to curves this is also where tension is very important so the higher the tension the less likely you are to get problems. I think with time even hard plastic would start to leave a mark on aluminium but by all means try it, personally I don't see it being accurate or stiff or durable enough.

If there is a slightly cheaper linniar rail option for the long axis I would be happy to pay for it the vertical axis could probably get away with maybe something like v bearings certainly if its only two axis but like you say you need smoothness or else it shows up very clearly in the surface finnish

[Boyan Silyavski]

" Incredibly slow" ??? I have no previous experience with foam and was trying to find info on internet what is the normal speed to no avail. So i did some experiments heating more the wire and going faster, slower and so on. 200mm/min gave me the best quality/speed relation .

What you say is the normal speed for this?

Why i have to push the wire into the foam, this means the cut will lose precision? I will not be cutting big blocks all day, i am cutting intricate shapes. if i would be cutting big blocks all day i will make a cutter with 20 wires heated at once, not one wire.

[Clive S]

. if i would be cutting big blocks all day i will make a cutter with 20 wires heated at once, not one wire.

Good luck with the power supply then you would need about say 36V at 100A

[charlieuk]

If I can't find some linniar rail at the right price I will probably go for a aragement like this but with a deralin caridge that houses the bearing but allso as a guide even though the bearings are almost a perfect fit width wise. I will find it hard to find the cost saving of linniar rail viable over the time it will take to design build and set up my own method

[Boyan Silyavski]

No, no, i have prepared the money for the Hiwins or the chinese MGNs. I was just exploring options as its a low demand machine.


As i said quality is the Top priority, not speed. So i will not use a thicker wire than i use now 0.16mm. I could go even 0.10mm. I am using constantan wire. As when you cut only and mainly letters, later you need to repair the cut on an A for example. So thats time, and time is money. When i cut so much letters that 200mm will take me all day , that will mean i make money enough to make a second machine

[charlieuk]

I will be interested to hear which rails you go for then, it seams crazy to use genuine hiwin for the amount of use it will get compared to my cnc but it's hard to know what you are geting from Chinese suppliers