What's this Carbide coating.

[gavztheouch]

http://www.mycncuk.com/threads/6770-...r-milling-foam

Here is a thread I started when I was looking for a simlier tool. I also looked into the frog tools but the cost was too high when I was unsure if I even had the ability to mill the foam parts I needed. After completing the job I would say that the vast amount of running time is actually in the final finishing passes and the rough cuts take very little time in comparision. I don't know what sort of finish and step over res you are going to use but I would suggest starting out with some cheap tools to get a feel for what you need to complete the job in an acceptable time.

I bought some cheap indexable insert mills and also some pricey ballnosed mills but half way through the job I relised I could use the endmill to 3d profile and rough the part so the ballmill became redundant. Condsidering the ball mill was twice the price of the endmill it was a costly mistake.

I also think you spindle and machine may not be man enough to take a large frog tool but I could be wrong. I just know even on my thermwood the larger tools cause a hell of a lot of vibration due to off balance tools and jerky machine movement. Burrs dont look like the most balanced tools available with all that carbide glued onto a blank at random angles.

[charlieuk]

Cheers many thanks I took a look at the thread. The burrs I have seam pretty well balanced there's certainly no noticeable vibrations and cut well at around 6-7000rpm I think the way to start is going to be getting a collet extender which luckily come in er 20 1/2" and relatively cheap and will allow me to use the burrs I have all be it having to do a few more passes and get me going then try a few other cheaper bits and and hopefully in the mean time save up for something a bit more specific when I know what works best.

[charlieuk]

I have been playing with a variety of end mills slot bits and standard router bits and the pics are bellow. It seams unless you run at very slow feed rates you get a large amount of tear out with any of the conventional bits and that was with a variety of feeds and speeds.however with the burrs the spindle speed could be significantly lower and feed rate a lot higher and still giving a very clean cut with minimal tear out which is why I have been trying to persue them.

[Boyan Silyavski]

Truth is I am not s specialist concerning foam. I cut only once before a couple of weeks when I was demonstrating some 3 d job setting to my friend on the yellow machine I made for him.
So without knowing anything I started at 4500mm/min with 3 flute straight 6mm carbide bit. The cut was perfect. Spindle was 16000rpm. I pushed it somewhere to 8000 mm/min where was still acceptable the finish.
Now I have to tell you that the machine is extremely sturdy. I suppose that with the proper bits for foam , some air stream at the bit, 10000 mm/min will be no problem at all . And this cheap construction foam.
what I want to say that the bits you use must be good, SHARP, and the not sturdy frame and z can and will play you tricks there, so take it slow and concentrate on making back some cash.

But it would be interesting to hear what speeds and feeds others and you are cutting foam at?
I'm very interested in this discussion cause one of the things I would do on the big machine I am making right now will be molds from foam. Not to speak of the paddle board I have a plan to make and some other stuff. Plus foam is nice for casting aluminum, molds or directly