Need Advice Ball nose CNC Bits

[Robert166]

First let be begin to say that I am new to the cnc. I purchased some Spetool ball nose bits. Because of the price and concerned I would make numerous mistakes. My feeds and speeds are averaging around 120-150 ipm at 15000-18000rpm, with 10-12% stepover, pass depth normally 1/2 of the diameter.

Shank size is 1/4 inch. The 1/4 inch down cut bit is much louder and leaves fibers compared to the 1/32 or 1/8 bit. I assume this is because of the amount of material being removed?
Will purchasing more expensive bits like Amana dramatically improve the cut quality?

How many hours should the average lower end/ lower priced bit last compared to the more expensive ones?

Staying with one brand/manufacturer makes the tool database easier to navigate in my opinion. I tend to be brand loyal if I can settle on a good quality without breaking the bank. $100 bits are not in my budget.

 

[ptt49er]

We run 3 commercial CNC routers full time at work, they use onsrud bits almost exclusively.

We ordered some of bits and bits cutters and the operators were very happy with their performance. I need to go check on them long term.

We're cutting HDPE, so I know the life expectancy is different but if I was running a CNC at home I'd start with some of their stuff. Looks like the 1/4" ball nose is less than $50. Seems like the discounts stack the more you order.

 

[mkepke]

I am by no means an expert, but it seems to me a downcut bit is not a good choice for every application.

So what are you using the bit for?

Are you, for example, using the downcut (DC) bullnose for bulk material removal (vs finishing)? How’s your chip removal?

-Mark

 

[Robert166]

Material removal on 3D carves like this.

 

[riggsp]

I use Whiteside bits almost exclusively…for 3D carving, tapered ballnose upcut bits are the best choice I can recommend…diameter is your choice, but 1/8” dia and 1/16” dia with 1/4” shank are the two I use most depending on the detail desired…Adjust feeds and speeds to get a chipload of about .003” per tooth, and depth of cut to about .040” for the 1/8” bit, and a depth of cut of .020” for the 1/16” bit.
Downcut ballnose bits tend to push down and twist the wood fibers and make a rougher cut, adding too much depth of cut just makes for more misery.
Spindle speeds too high can cause the bit to rub instead of cutting, and that generates heat which dulls the bit.
Remember that all this is dependent on your machines capability.