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Toolholder type for 3D finishing

trochoidalpath

Cast Iron
Joined
Jan 17, 2016
Thought I'd solicit some advice on toolholding for a BT30 machine doing 3D finishing. We usually run these with 1/4", 3/16", or 1/8" ball nose end mills, depending on the part, stepovers around a thou, in either 7075 or A2.

Hydraulic chuck with a reducing sleeve? SK? Stick with ER because it's good enough? (We're not set up for shrink fit, so that's off the table.)
 
Is this a Brother or a Roku-Roku? Best tooling in the world won't gain you much is the machine's not optimal for surfacing (a Brother in good shape won't be bad, but it's not a high-end surfacing machine).

Are you having issues currently? If so, what?
 
If shrink fit is not an option then my vote would be SK with precision collets. But I doubt you will gain much over good ER, maybe .0002" or so?
 
Is this a Brother or a Roku-Roku? Best tooling in the world won't gain you much is the machine's not optimal for surfacing (a Brother in good shape won't be bad, but it's not a high-end surfacing machine).

Are you having issues currently? If so, what?

It'll be a Brother. We don't run these parts all that often.

I am in absolute agreement that the best tooling in the world won't help if the machine sucks, since right now they're running on a Tormach. :) It's tough to pin down what's to blame for, say, poor surface finish, when there are so many variables at play. Right now we just baby the hell out of it until the parts come out okay.
 
When I was evaluating shrink fit I ran them with a MAPP gas torch. A bit slow, but worked great. Then I got Maritool's induction machine which is priced very competitively.
 
To add to this, ISCAR has a line of thin nose shrink holders they call "SRK" (they call their thicker ones "SRKIN") and it seems they need less heat to expand them enough to get a tool in compared to thicker ones.

Probably not as rigid but for finishing they work good in my experience, and the clearance is great.
 
It'll be a Brother. We don't run these parts all that often.

I am in absolute agreement that the best tooling in the world won't help if the machine sucks, since right now they're running on a Tormach. :) It's tough to pin down what's to blame for, say, poor surface finish, when there are so many variables at play. Right now we just baby the hell out of it until the parts come out okay.

[Points to engine laying on garage floor] Ayup, that's your problem right there...

Tormach's a marginal machine tool. A Brother in good shape is a big step up, but start with decent ER or SK tooling, no point YET getting the big-buck holders.

Something to keep in mind - most cutting tools have good, but not perfect registration between shank and cutting edges, and the best holder in the world will not make up for that. In fact, you're better off with a holder than can be "knocked about" such that you can push the cutting edges into concentricity with the holder shank. But that takes careful work at the machine or in a dummy spindle, not a quick process.
 
[Points to engine laying on garage floor] Ayup, that's your problem right there...

Tormach's a marginal machine tool. A Brother in good shape is a big step up, but start with decent ER or SK tooling, no point YET getting the big-buck holders.

Tell me something I didn't learn the hard way :)

Once we get set up, we'll try this part with both ER and SK chucks, and see if it makes a difference. Thanks much!
 
FWIW, I only mention this because you mentioned reducing sleeves... Pretty much any of the big manufacturers will happily make you those smaller endmills with larger shanks, at about the same price as standards... Figure that way you don't have the added error of a reducing sleeve.
 
If the machine is a Speedio, the High Accuracy settings are probably way more important than the marginal differences between high quality holders. Have Yamazen install firmware V10, use the new Quick Setting codes (M298 Lx/M299), and input the book rates they have.
 
Something to keep in mind - most cutting tools have good, but not perfect registration between shank and cutting edges, and the best holder in the world will not make up for that. In fact, you're better off with a holder than can be "knocked about" such that you can push the cutting edges into concentricity with the holder shank. But that takes careful work at the machine or in a dummy spindle, not a quick process.

This is a great point that many people overlook or forget. CNC tool and cutter grinders don't have some special magical collet system that have zero runout. Some of the newer machines actually probe every part and can compensate for any runout during the clamping process. But even then you can easily have .0001-.0002 runout from the shank to the cutting edges. For good 3D surfacing you need everything to be on par. Good machine with a good spindle. Properly tuned servos and post processer that gives efficient code. Proper workholding. Good quality tool holder and collet ( if using a collet chuck) and good cutting tools.
 
Pretty much any of the big manufacturers will happily make you those smaller endmills with larger shanks, at about the same price as standards... Figure that way you don't have the added error of a reducing sleeve.

I do this all the time for tooling that I use for my production. 4mm ball endmill with a 1/4" shank, 7/16 ball endmill with a 1/2 shank, 3/8 5 flute finisher with a 1/2 shank. You get better runout and less deflection. Helps a lot.
 
I do this all the time for tooling that I use for my production. 4mm ball endmill with a 1/4" shank, 7/16 ball endmill with a 1/2 shank, 3/8 5 flute finisher with a 1/2 shank. You get better runout and less deflection. Helps a lot.

Hi Frank,
What's your estimate for the extra cost to do this? There's more grind time, wheel wear, and blank cost, so it's not insignificant, is it?
 








 
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