Machining tough steel on a Tormach

[keen]

Hi folks. I thought a thread discussing ways to machine tough materials on a Tormach would be useful.

I start the ball rolling with this video. Cliff



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[Tigster]

On an 1100?? They seem very capable. Now I have to do SS and Ti on a 440, I have done SS so far and have seen videos of Ti on the 440. Tormach sells the 440 being able to handle these materials...that might be questionable, but the 1100? They should have no issues...no?

[keen]

Hi Tigster. Tormachs are "Capable" if you take light cuts. But they are not VMC's

Have a look at the comments under the YouTube video if you doubt me eg " Recently I have been doing mild steel and stainless on my pcnc 1100, everything Cliff says is accurate."

Cliff

[mountaindew]

Couple questions?
Did your spindle bearings get hot?
Would a 3 or 4 insert cutter with reduced shank mitigate some of the hammering with more engagement?
Could the part be machined from each side "looks like less depth" to reduce tool over hang? "might help a little"
Would a 4+ flute helix end mill cut with less stress on the machine? "Guess it would not last long in any case"
I wonder how many parts would the Tormach make running like that before the spindle bearings cook or some control connection bridges and the magic smoke comes out.
As you mentioned it was making some strange noises.
Anyway good video! It shows just how tough some of these tools are even when working outside their design comfort zone.

[TurboStep]

Hi Cliff
Just wondering, are you using the standard Tormach R8 collet? Have you checked the contact area between the collet and spindle tapers? I've just replaced my collet and the contact pattern of the old one leaves a lot to be desired. Unfortunately I forgot to check the new one and I don't really want to remove it right now.
The 3/4 bore of the collet is only ground for the first 35mm and beyond that the diameter widens slightly. Using this particular collet with your tool would mean it would only be held for the first 35mm, in the area of the R8 taper, and wouldn't benefit from the interface between the parallel section at the other end of the collet and the spindle ID. This could lead to rigidity issues because you don't have benefit of the TTS flange resting on the spindle nose.
How's the runout of your tool just above the inserts?
Steü

[jwatte]

Now I have to do SS and Ti on a 440,

I do that with some frequency. 303 and Grade 2 are pretty easy, just use smallish tools. 304 and 6-4 is a bit tougher, but only broke one end mill because I got good recipes. You have to have some patience, though!

[keen]

Couple questions?
Did your spindle bearings get hot?
Would a 3 or 4 insert cutter with reduced shank mitigate some of the hammering with more engagement?
Could the part be machined from each side "looks like less depth" to reduce tool over hang? "might help a little"
Would a 4+ flute helix end mill cut with less stress on the machine? "Guess it would not last long in any case"
I wonder how many parts would the Tormach make running like that before the spindle bearings cook or some control connection bridges and the magic smoke comes out.
As you mentioned it was making some strange noises.
Anyway good video! It shows just how tough some of these tools are even when working outside their design comfort zone.

Hi - Spindle bearings not too hot.
I think more inserts would help in theory - but only if they were very concentric, otherwise with run out one does all the work anyway.
I agree an endmill would be better, but I have found with that depth of removal, tough steel and some ship eating the vibes shorten the tool life and cost more in tooling than inserts.
Cheers Cliff

[keen]

Hi Cliff
Just wondering, are you using the standard Tormach R8 collet? Have you checked the contact area between the collet and spindle tapers? I've just replaced my collet and the contact pattern of the old one leaves a lot to be desired. Unfortunately I forgot to check the new one and I don't really want to remove it right now.
The 3/4 bore of the collet is only ground for the first 35mm and beyond that the diameter widens slightly. Using this particular collet with your tool would mean it would only be held for the first 35mm, in the area of the R8 taper, and wouldn't benefit from the interface between the parallel section at the other end of the collet and the spindle ID. This could lead to rigidity issues because you don't have benefit of the TTS flange resting on the spindle nose.
How's the runout of your tool just above the inserts?
Steü

Hi Step. Yes good points from you as usual. I use a non TTS collet for that heavy work, but I think they are all relieved internally as you described.

I had not thought of a special non relieved collet with a close upper OD/spindle bore fit to give better support - that might be worth trialing!

Cheers Cliff

[Tigster]

I don't have even dozens of hours under my belt with the 440, but it seems to do fine with SS and Ti. Good cutters and patience for sure. Do those of you that cut the more challenging materials lean toward larger axial versus radial? I've kind experimented as I really don't know the better approach, but I lean towards axial DOC over radial DOC. Does this seem like the better way to go?

[jwatte]

Deeper is generally better for me, because it wears more of the cutting edges. If I creep it down 20 thou at a time, I will only wear a very short part of the edge. "Adaptive" / hypocycloidal tool paths, deep and narrow all the way!

[MFchief]

Hey Cliff,

I know I'm a little late to the party here, but I was wondering if, when you were contemplating tools, if you considered direct R8 shanked indexable end mills? I know you are aware that they are available, and I have never personally used one, so maybe you know they wouldn't help?

Terry

[keen]

Hey Cliff,

I know I'm a little late to the party here, but I was wondering if, when you were contemplating tools, if you considered direct R8 shanked indexable end mills? I know you are aware that they are available, and I have never personally used one, so maybe you know they wouldn't help?

Terry

Hi Terry - Yes a good point. I needed to make that indexable tool to get the best size for the job, but I could have made it direct R8 and it probably would be more rigid than collet mounted because it would avoid some of the issues Step pointed out. One downside though, is that the projection length is fixed and can't be optimized to suit each job. Cliff