What's this Carbide coating.

[IanS1]

This seems to be the manufacturer http://www.saburr-tooth.com/index.htm can't seem to find any info on longer shanks on their site though. Do you need the whole burr to be 3 inches or just the shank? If you're happy with a longer shank perhaps you can have an adapter made, to give the effect of a longer shank, to fit your spindle

[charlieuk]

Yes those are the ones I got, a longer shank would be a start but ideally the cutting edge wants to be longer . Many thanks

[Beone]

What you are looking for is called a rotary rasp.
Dave

[Boyan Silyavski]

Thats definetely non stick teflon coating, similar to Freud .

Now i i don't have something clear. Why use burs instead of some ultra sharp sharp micro grain carbide router bit, say 3 flute straight long reach?

I don't see how you will route faster with these compared to normal router bit. Also if you insist on burrr just buy roughing bits.

What size bit, depth of cut, speed and step over? lets do the calc here. cause i dont see it right using these bits on foam.

[njhussey]

there's these ones from France....http://www.hand-stitched-rasp-riffle...tre-25-mm.html

Or this, I know it's only a ball but it's 30mm diameter? http://www.clasohlson.com/uk/Rotary-Rasp/30-9512

[charlieuk]

The burr style is a prity standard practice when working on surfboards. From experience I have had in the past normal fluted bits can tend to heat up after a long duration and coolant is not a option and on eps this can end up melting the foam which can make a right mess. The burrs also give a great surface Finnish.

im open to ideas ?

I played with the two burrs I have today and even the fine one seams good.

No idea how hard or I fit would be posable but would it be posable to make a blank bit on a lathe and then coat it in some sort of abrasive grit? I'm assuming balancing would be the major problem?

[Boyan Silyavski]

i would give you tons of ideas but you have to give me some data to work with

What size burr, depth of cut, speed and step over you use now? Do you pocket or slot cut? What is your collet size ? Spindle kw and rpm? What speeds your machine is capable of? What rails and ballscrew ?

[charlieuk]

The two burrs I have are 33mm cutting depth and 21dia 64mm overall The ideal would be something around 25mm dia 75-90 mm cutting depth 130mm over all
I have a 2.2kw water cooled huanyang spindle so er20 collet so 13mm max using hywin 20 rails x is on mod 1 rack geared 3.2-1 rapid is set at 10,000 mm/min but capable of a lot more but to scared to set higher at the moment. y and z are 1610 ball screw set at 2500mm min and it is quite happy cutting at 2500mm/min. When cutting a surfboard it is basically just running up and down the length with very small y and z movements most of the time

[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.