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Depth limitations with BT30

A

andehe

Plastic
Joined
Jul 4, 2014
Location
MI, USA
We are looking at buying a machine for a range of Aluminium components in a small established business. Small volume (5-50pcs), mostly a mix of fairly complicated and simple prismatic. The two machines styles I am looking at are a VMC Brother with 4th or Kitamura HMC HX300IG.

Regarding the brother, I am concerned about the depth limitations of the BT30 spindle for a part that requires deep pocketing. The current design has a 3.5" pocket as shown in the attached image with some threads on the inside. Any comments as to whether we can machine this feature on this machine? I'm not after productivity, just capability with a good finish. Internal accuracy is not important as there are not fit-up considerations for this part. I am aware we will benefit from higher speeds and through tool cooling for chip evacuation.

deep pockets.jpg
 
With 1/2"-5/8" Maritool side locks your limitation would be the endmill, not the BT30 taper.

Or the integrated shank holders with end mill ends that screw in, way cool tools.

What about the baby Kitamura BT30 horizontal with a 4 step 30k spindle and what, 2400 ipm rapids?
 
Easy money.

Yes, it is on the long end of optimal BT30 applications, but with Big+, it is definitely in the envelope. I do work with that kind of reach on my Speedio (standard, not Big+) somewhat occasionally and it goes just fine, but you definitely want the Big+ option.

- The Maritool .5" side lock holders are your friend, as they add almost no gauge length and maximize rigidity (BT3 Dual Contact End Mill Holder .5-1.2 Made in USA MariTool)

- I would pre-drill a plunge hole. I've found long tools especially hate ramping.

- TSC is your friend here, and SwiftCarb makes their ramp mill with a center TSC hole that would be quite helpful with chip evac.

Your concerns are understandable though, but it sounds like these are occasional parts and BT30 is going to dominate the cycle time on everything else that doesn't have this long a reach.

The Kitamura's siren song is very high and I briefly considered one over my Speedio. Problem is; you get the rigidity/power limitations of BT30, but only about half the speed gain compared to a dedicated BT30 machine like a Robodrill or Speedio. You do get more tools + the horizontal benefits, but you need to be in a high-mix environment where 20 minutes of SKU changeover is a really critical problem. Quick change fixtures and a little planning can get you 85% of that on a VMC BT30 machine, for one half the price. The Kitamura is a super nice machine, but I don't think it really takes a specialized environment to really see the benefits. There are reasons HMCs have fallen out of favor in pass production of small parts and been replaced by Speedios/Robodrills...

There is that HSK40E option for the Kitamura, but the feedback I've seen says it's not much more rigid than a BBT30, and you're stuck in the world of exotic $450+ tool holders.
 
Ugh, I wouldn't want to do those pockets with my 30-taper Speedio. Not sure from the attached pics, but it looks like you could use a 3/4" endmill to make the deepest pockets, but that big + long of an endmill will not work well in 30-taper.

Can you machine it with 30-taper, sure, but it will IMO be a struggle. My enthusiasm falls off quickly when depth exceeds 2".

Regards.

Mike
 
gkoenig said:
Easy money.

Yes, it is on the long end of optimal BT30 applications, but with Big+, it is definitely in the envelope. I do work with that kind of reach on my Speedio (standard, not Big+) somewhat occasionally and it goes just fine, but you definitely want the Big+ option.

- The Maritool .5" side lock holders are your friend, as they add almost no gauge length and maximize rigidity (BT3 Dual Contact End Mill Holder .5-1.2 Made in USA MariTool)

- I would pre-drill a plunge hole. I've found long tools especially hate ramping.

- TSC is your friend here, and SwiftCarb makes their ramp mill with a center TSC hole that would be quite helpful with chip evac.

Your concerns are understandable though, but it sounds like these are occasional parts and BT30 is going to dominate the cycle time on everything else that doesn't have this long a reach.

The Kitamura's siren song is very high and I briefly considered one over my Speedio. Problem is; you get the rigidity/power limitations of BT30, but only about half the speed gain compared to a dedicated BT30 machine like a Robodrill or Speedio. You do get more tools + the horizontal benefits, but you need to be in a high-mix environment where 20 minutes of SKU changeover is a really critical problem. Quick change fixtures and a little planning can get you 85% of that on a VMC BT30 machine, for one half the price. The Kitamura is a super nice machine, but I don't think it really takes a specialized environment to really see the benefits. There are reasons HMCs have fallen out of favor in pass production of small parts and been replaced by Speedios/Robodrills...

There is that HSK40E option for the Kitamura, but the feedback I've seen says it's not much more rigid than a BBT30, and you're stuck in the world of exotic $450+ tool holders.
Click to expand...
Having a Kitamura BT30 mill I am willing to bet the Kitamura BT30 is going to be a lot stouter than a Brother BT30, way more to it than just the tool holder. I bet the Kit spindle weighs a lot more than the Brothers.

If the extra tool pots would allow you to keep all your tools loaded that would be pretty valuable.

The 300 is a 40 taper, the 250 is the 30 taper.
 
With through-tool to prevent double cutting of chips I would cut that in a heartbeat on our Speedios. That said, I'd prefer to put it on a 4th to dump chips in anything but plastic.
 
Not as extreme...

We cut a 4.5in x 4.5in x 2.25in deep pocket in 6061 aluminum on Brother S1000x1 (4/5axis setup) with Big+ coolant thru 16K spindle. Drill hole, plunge 1/2in 3fl Helical end mill to 2.225in deep and use HSM style tool path to remove material at full depth of cut. Tilt to dump residual chips and finish wall/floor. 30-40pcs per run with excellent finish and dimensional fidelity. Definitely agree with gkoenig that Big+ is desirable, if not necessity, to get consistently good result.

If we were in the same position as you are, we'd invest in the end mill (and possibly holder) and have Yamazen cut 3.5in deep pocket on Brother you are looking at. If they are interested in impressing you with what a 30 taper machine can do for current and future purchases, I would expect they would demonstrate it.

Fred
 
If you have the budget, go Kitamura for the better chip evacuation of a HMC. Maybe even go HSK over BT30 due to weak pullstuds on through spindle coolant setups. Expensive holders, but as long as the retention fingers were designed well should be more reliable. Look into this to ensure peace of mind...
 
Milland said:
If you have the budget, go Kitamura for the better chip evacuation of a HMC. Maybe even go HSK over BT30 due to weak pullstuds on through spindle coolant setups. Expensive holders, but as long as the retention fingers were designed well should be more reliable. Look into this to ensure peace of mind...
Click to expand...
Like everything else, Kitamura pull studs are beefy. No worries there.
 
I didn't know there was a pocket depth limit with taper number.
I've gone 8 inches deep profile on a B-port and on 30 machines so how does one know?
What prevents you from going 16 inches if you have a tool to do it other than the tool defection which will not care about the spindle taper?
School me please.
Bob
 
CarbideBob said:
I didn't know there was a pocket depth limit with taper number.
I've gone 8 inches deep profile on a B-port and on 30 machines so how does one know?
What prevents you from going 16 inches if you have a tool to do it other than the tool defection which will not care about the spindle taper?
School me please.
Click to expand...

It isn't the physics that prevents you from doing this, it's the profit margin.

In my experience, a standard BT30 spindle is in the happy zone up till about 1.5" tool reach. Dampen the speeds/feeds, and you can hit 2.25" in tool reach and be OK, but beyond that? You're in the zone of babysitting, and very slow feed rates that's OK for one-off, prototype, get a couple parts out the door kinda situations.

Frank's super stubby side lock holders effectively lop off about .5" from that equation by eliminating the extra leverage from the gauge length of a standard collet arrangement, and Big+ gives you a further rigidity boost of about 30%. In the end, a Big+ BT30 with the stubby tooling is going to be running OK - but not great - at about 3.575" of reach. Compared to a CAT40 machine, you're probably giving up 25-35% productivity on this one operation.

So this is an ROI game for the OP. He says he has a family of parts and this is the only one that's outside of the BT30 comfort zone. Have Yamazen do a test cut and see where this is in the real world, and I'm guessing the productivity on the other SKUs will swamp the losses on this one area.
 
gkoenig said:
Easy money.

Yes, it is on the long end of optimal BT30 applications, but with Big+, it is definitely in the envelope. I do work with that kind of reach on my Speedio (standard, not Big+) somewhat occasionally and it goes just fine, but you definitely want the Big+ option.
Click to expand...

What endmill?

Regards.

Mike
 
Did this cut in Titanium with a 3/8" 5 flute neck style EM hanging out about 5.5" with a Big Plus S1000. Roughed it out in 6 minutes using Dynamic milling then did a finish pass and chamfered. As has been mentioned previously, you should consider your overall needs. If the Brother will be doing this type of work occasionally and you have a majority of work that does not require long reaches, you will probably be ahead in the game. Eagle Mike has a fairly regular job he does where he takes around a 3" deep side cut in 6061 with a standard non Big Plus S500!


20170126_115654.jpg
20170126_122954.jpg
 
Take this with a hefty grain of salt, because I do not do production. I ran a HUGE production run the other day of 150 pcs. :willy_nilly:

I also don't do any work in Aluminum (hoping to? maybe this year?) everything is steel, and most of it tool steel.

But I regularly go over 2" depth without any major issues or concerns. I have a 2 1/2" depth part coming up in tool steel that I will be interested to see how it runs. I do alter my feeds and speeds some for the longer endmills.

If I were doing the part, on my machine(S1000, std 16k)), I would pocket the corners with a drill, hog the interior with an inserted TSC tool, and skim the exterior. Depending on the surface finish requirements, you may be able to step down the wall, then take a real light skim pass to clean up. Low RPM high Feed.

Make sure you get TSC. It wasn't in the budget at initial purchase for me and it is a REAL DRAG. :cryin:
 
Finegrain said:
What endmill?

Regards.

Mike
Click to expand...

For this stuff, I keep a couple of relatively inexpensive Onsrud/WAM series cutters around in 3/8 and 1/2. These are Western Tool’s house brand- very nice, but not exotic.

The more important thing is the holder- I’ve got SK25, Schunk hydraulic and Frank’s stubby side locks... the side locks are the only ones that actually work. SK25 gauge length is massive and the Schunks have some weird resonance deal where they run like trash at long gauge lengths.
 
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