To go all Dual Contact, Standard or both?

[trochoidalpath]

If most say, don't worry about it. I may get dual contact and just keep those for when running harder materials (steel,etc), thoughts?

I think non-dual contact holders work great for drills and taps.

The big advantage of dual-contact toolholders is in increased rigidity. That rigidity only comes into play with lateral loading on the end of the tool/toolholder assembly. Tools that go straight up and down do not load the tool laterally so the rigidity doesn't matter anywhere near as much as it does in, say, a long-reach milling application.

(Yes, there are some arguments about Z reproducibility too, but I have never had a substantial problem with this in real life, so....)

 

[Billy_C]

We run a mix of BT40 dual contact and regular in our Matsuuras. I wish we could do a complete change over to dual contact to keep things consistent but it doesn't really make financial sense. So much of the machining we do doesn't really need it. We rarely push half as hard as we could. It we had a 30 taper dual contact 5 axis that meant business we would probably go dual contact on everything. This becomes a tool length issue where we still need to make similar or the same parts that on running on the 40 taper machines with similar stick-out but the 30 is that much weaker.

 

[gregormarwick]

Depends on what you're doing. From what I've heard from others, HSK is better above about 15K-20K RPM. Steep taper is better below.

According to a whitepaper I received from Sandvik years ago, HSK has higher static and dynamic rigidity than steep taper (including dual contact) across the board. The point of the paper was of course to place Capto at the top of the stack, but the data did show that HSK was simply better than steep taper without exceptions.

 

[BROTHERFRANK]

According to a whitepaper I received from Sandvik years ago, HSK has higher static and dynamic rigidity than steep taper (including dual contact) across the board. The point of the paper was of course to place Capto at the top of the stack, but the data did show that HSK was simply better than steep taper without exceptions.

I have an exception. I think there isn't an apples to apples comparison between HSK and BT or CAT. HSK 40 doesn't compare (less rigid) to BT30 and HSK63 doesn't either (more rigid). Just like 40 tapers and 63 or 100 HSK. I know from experience regarding the HSK 40. Brother offered the HSK40 and BT30 on TC-22A, 32A, 22B and 32B machines until they figured out how to do CTS through the BT pull studs. I have ran both versions of the machines and I could not take the same cuts with the same 1/2" end mill on the hsk 40 machines as I could on the BT30 machines without chattering. I even saw a couple of quality name brand hsk40 tool holders break off in the spindle at the thin clamping area during light cuts. Not confidence inspiring.
Again, not apples to apples. I believe the hsk is more suited to high rpm lighter cuts. 30 taper is good up to 27K maybe 30K. 40 taper 15k to 20k? HSK40 40k plus? HSK63 up to 25K plus?

 

[empower]

Is HSK better than dual contact?
Worth the higher dollar holders?

10000% yes

 

[gregormarwick]

I have an exception. I think there isn't an apples to apples comparison between HSK and BT or CAT. HSK 40 doesn't compare (less rigid) to BT30 and HSK63 doesn't either (more rigid). Just like 40 tapers and 63 or 100 HSK. I know from experience regarding the HSK 40. Brother offered the HSK40 and BT30 on TC-22A, 32A, 22B and 32B machines until they figured out how to do CTS through the BT pull studs. I have ran both versions of the machines and I could not take the same cuts with the same 1/2" end mill on the hsk 40 machines as I could on the BT30 machines without chattering. I even saw a couple of quality name brand hsk40 tool holders break off in the spindle at the thin clamping area during light cuts. Not confidence inspiring.
Again, not apples to apples. I believe the hsk is more suited to high rpm lighter cuts. 30 taper is good up to 27K maybe 30K. 40 taper 15k to 20k? HSK40 40k plus? HSK63 up to 25K plus?

Sandvik's data (and I trust their results) concerned the interface exclusively, not the spindle as a whole. It was not a hastily thrown together report but rather very extensive and backed by a huge amount of engineering and data collection/analysis.

In the past there was always a general consensus that HSK spindles were less rigid than steep taper, and that was probably true, because they were usually designed to operate at significantly higher speeds, which in turn meant lower inertia spindle assemblies and greater bearing clearances etc.

Unless the spindles as a whole were otherwise identical on your Brothers, which is unlikely, then you really can't claim that the comparison was objective.

 

[Vancbiker]

One should follow their builder’s advice when looking HSK versus steep taper. They’re the ones that know what works best with their spindle.

 

[BROTHERFRANK]

Unless the spindles as a whole were otherwise identical on your Brothers, which is unlikely, then you really can't claim that the comparison was objective.

Spindle head castings were the same, spindle bearings were the same, spindle motor same except hsk had rotary joint for cts, taper and clamp mechanism were different. I know because we had people calling to see if they could convert hsk machines they had found used to BT. It was possible but pretty extensive and expensive to change the spindle, magazine pots and tool change arm.

 

[CarbideBob]

Spindle head castings were the same, spindle bearings were the same, spindle motor same except hsk had rotary joint for cts, taper and clamp mechanism were different. .

One can not fix stupid. I know it was a cost thing. Shortcut and not the best effort.
File this under Duh and we need to keep the price down.
There is a lot of bias in reports so how to know?
This single taper, dual contact, HSK, Capto is so full of bullshit and "scientific" proof.
I could argue that any of these better and show real world feed and speed numbers to prove my point in one application or another.
Bob

 

[gregormarwick]

Spindle head castings were the same, spindle bearings were the same, spindle motor same except hsk had rotary joint for cts, taper and clamp mechanism were different. I know because we had people calling to see if they could convert hsk machines they had found used to BT. It was possible but pretty extensive and expensive to change the spindle, magazine pots and tool change arm.

I'm afraid I remain unconvinced.

One can not fix stupid. I know it was a cost thing. Shortcut and not the best effort.
File this under Duh and we need to keep the price down.
There is a lot of bias in reports so how to know?
This single taper, dual contact, HSK, Capto is so full of bullshit and "scientific" proof.
I could argue that any of these better and show real world feed and speed numbers to prove my point in one application or another.
Bob

You're wrong, and your post is ignorant.

You could never prove in real world applications that steep taper is better than HSK, and especially not Capto, because it just isnt, not by any metric.

Any claim to the contrary is just wishful thinking and I don't know why people are so quick to deny it.

 

[gkoenig]

Any claim to the contrary is just wishful thinking and I don't know why people are so quick to deny it.

Because everyone has different experiences, about matters with literally thousands of variables, and we value our experience over anecdotes from others almost all the time, and often above vigorously collected data.

What it really comes down to is that a lot of our entire industry acts on gut feelings and experience, with near zero well collected, totally independent, and meaningful data comparisons. What we need is a Consumer Reports of machine tools, but the nature of things (i.e. the massive capital costs and small overall market) make that virtually impossible.

 

[Mtndew]

You could never prove in real world applications that steep taper is better than HSK

Not even if you have 2 identical machines, 1 with HSK and the other with CatV?

I've never ran an HSK or a Capto so I'm just playing devil's advocate.

 

[BROTHERFRANK]

I'm afraid I remain unconvinced.

Here is a guy having trouble with a 3/16 end mill cutting brass on his HSK40:

End mill recomendations for naval brass

 

[fmari --MariTool-]

Just had a customer with a similar problem. Was running an ISO20 and trying to use a 5/16 endmill. These tools helped. They are free cutting and keep the loads and vibration down.

Tool Holders, Collets and Machine Accessories 3 Flute Carbide 45 deg Helix - MariTool

oops, meant to post this on the naval brass topic, sorry.

 

[empower]

Here is a guy having trouble with a 3/16 end mill cutting brass on his HSK40:

End mill recomendations for naval brass

does that automatically mean its the spindle-tool-interface fault?

 

[DavidScott]

There is way more to how well a tool holder works than just the taper interface, like the rest of the machine. Drawbar force also has a huge impact on how stable the holder to spindle interface is. With these tales of unstable cuts being blamed on the tool holder interface my first question is how much drawbar tension does it have? Next will be machine stability. The actual taper is not the first thing I think of.

I think an important aspect of the OPs question is the spindle itself and just how robust it is. If it is on the small side then I wonder if it would be advisable to use only dual contact to protect the spindle taper. Will the non dual contact holders open up the taper over the years as they get pulled deeper and deeper until the dual contact holders don't get proper taper support at high RPMs?

As for the Brother dual contact spindles not supporting the tapers at high RPMs that sounds like the tool holders are not preloaded enough when held in the spindle. If this is an issue with a newer spindle what will it be like with one with 15-20,000 hours on it that has seen a lot of non dual contact tool holder use at high RPMs?

 

[CarbideBob]

...
You could never prove in real world applications that steep taper is better than HSK, and especially not Capto, because it just isnt, not by any metric.
.

Sure I can. It is done in the cutting tool world and magazine articles all the time.
This world is full of "selective" information based on small samples or one off runs.
Run a new perfect steep taper against a poorly made or used up HSK. Write up the results and send the "hard numbers" off to the tool engineer.
Capto has one huge problem. Even if you are licensed it is just about impossible to make a fully correct part.

More than once I've had test runs come back showing my tool winning by a huge amount and I just look at it and say this is not possible.
Never doubt the magic power of free donuts, coffee, and friendly chat with the operator on a tool test.

Nobody in the tooling business makes a video or publishes something showing their tool or spindle failing against the competition yet it happens all the time.
It is hard to go to the tool/process engineer and say "I got my ass kicked" with your tail between your legs.
Other side on a big win sometimes it best to tell the customer "I don't really trust this number and let's see if it holds up". One gets strange looks here.
Bob

 

[JMC]

You could never prove in real world applications that steep taper is better than HSK, and especially not Capto, because it just isnt, not by any metric.

Any claim to the contrary is just wishful thinking and I don't know why people are so quick to deny it.

Steep taper is better in the most important metric....availability. They are more brands, styles & configurations that one could imagine in steep taper.
HSK is slowly catching up. Capto not so much.

 

[fmari --MariTool-]

CarbideBob is 100% correct. Moving lots of carbide in the past few years i've been exposed to some interesting stuff.

 

[empower]

Steep taper is better in the most important metric....availability. They are more brands, styles & configurations that one could imagine in steep taper.
HSK is slowly catching up. Capto not so much.

HSK has PLENTY of availability. you've got brands like techniks etc selling HSK holders, and IIRC frank@maritool is getting ready to make HSK stuff as well

edit: maritool already makes/sells HSK50/63 holders. at a price very close to 40 taper.
if you have the choice, HSK is a no brainer 100000000%