Need help building a cnc-cutter

[Blackrat]

why must it be offset from the shank ?

[Boyan Silyavski]

why must it be offset from the shank ?

cause it rotates over the offset point, meanwhile the z is making the corner

[Blackrat]

i understand having it offset from the center point for a drag knife as this acts the same as a castor wheel on a trolley for example

but for a pizza cutter ?

[Boyan Silyavski]

The same, just saves you some cash for motorizing it. I have seen the Donek drag knife with this attachment.

[charlieuk]

you will find it very hard to cut carbon cloth in less it is pre preg, if you are not aware of what pre preg is it cloth that is pre coated with resin on it that you activate by cooking it usualy around 100deg c. Even if you could cut carbon cloth dry it will fall apart as soon as you pick it up or try do anything to it. You can use a method were you use a spray adhesive to stick the carbon to wax paper which you then wet it out on but you will still get distortion and loose any sort of accuracy. Pre preg is nice stuff to work with but it must be stored in a freezer and must be cooked to cure it and it is also expensive.

[Gotty101]

Artic Monkey, im guessing you have already worked with carbon or even glass cloth. As charlieuk said, i think you will have to come up with a plan to cut it if its not prepreg. I use it in another hobby i do and i use the wax paper trick but the final item is trimmed to size anyway.

I Wonder if a rolling cutter or a laser would be better. In any case with out prepreg or a backing the edges will fray like mad depending on the weave.

Trev

[Arctic monkey]

Thanks for every answer so far.
The accuracy is not that much of a concern for us since the cut has to be finished by hand anyway. Basically at our university theres a small lab where one person works with carbon fiber. He coates the fiber as already discussed in this thread. Therefore he needs to cut the fibre with scissors by hand which is suboptimal because the scissors wear out quickly and the carbon irritates the skin.

I have to check which exact material we use but we ran a few tests and the rotatory blade had the best result.

Thanks a lor for the post with the postprocessors thats exactly what were looking for atm. Are there any other postprocessors which work with rotatory blades and how do they interact with mach3 and the triple beast? As far as i know we need an additional hardware for the beast in order to support that.

[charlieuk]

if its only for one person a pair of latex gloves and any form of electric scissors is going to do the job and probably with better results trust me I do this for my day job the only time it would be worth it was if you used pre preg. You have to be so carfullt when cutting carbon that you get every thread other wise it all falls apart as soon as you try lifting it. you will probably have to cheque it manually and go over with a knife anyway and if something catches with a machine you could destroy a hole lot of expensive carbon very quick! Back it on paper like said and then electric scissors or a new shape blade cut on a cutting matt will give quick and easy cutting.

Ps the trick with using scisors on glass carbon and Kevlar is you only have the top blade sharpe. Run a file over the lower blade it booth directions to give it a fine but rough texture which stops the fibers sliding along the shape edge.