40 Taper on a Bridge Mill

vmipacman · Apr 16, 2020

Is a 40 taper 15K spindle on a bridge mill silly for a job shop environment?
Should I steer clear of that even if the deal is good?

First choice is a 50 taper gearbox spindle, but a 40 is currently available in the size machine I cam looking at, (used).
I admit I have never reached the max limitations of my CT40 VMC, but I might not even know it if I had...
I am usually not trying to reduce time or push things hard though.
I expect to be cutting some AR steels, Aluminum 7075, stainless, and maybe a TI part in a blue moon.
I worry about not having enough torque. I have never come close to running out on my 15HP VMC, but this is big machine to move and then find its under powered. Big tapped holes I can threadmill instead I guess.

This is billed as a High Speed variant of the standard CT50, so can I make up for the small spindle by employing HSM tactics across the board?
Thanks!

Mtndew · Apr 16, 2020

What brand? What model?

vmipacman · Apr 16, 2020

Mtndew said:
What brand? What model?

I was going to try to leave it generic without getting into machine specifics and brand wars...
Good idea/bad idea?

Red James · Apr 16, 2020

The answer to your question depends entirely on the size / nature of your typical work.

Bridge machines are noted for their accuracy. Do you need that?

Work must fit inside the 'bridge'; is that an issue?

Jashley73 · Apr 16, 2020

I'm assuming that by "Bridge Mill" you mean a BIG machine, and not something sized like an Okuma Genos.

Personally, I don't know about it. Big machines usually end up with long tools to clear/reach around big part features. There is no substitute for a big spindle taper when you have long tools. Having a spindle taper with twice the surface area & twice the clamping force means a lot on a long tool.

That said, you know your work.

A 15k CAT40 spindle on a BIG machine like that suggests that maybe it was an aluminum, or finish-only machine?

I'm curious to know the brand, and what they're asking for it. My gut though, says it's a turkey...

Mtndew · Apr 17, 2020

vmipacman said:
I was going to try to leave it generic without getting into machine specifics and brand wars...
Good idea/bad idea?

The reason I ask about what machine you're looking at is this "I worry about not having enough torque. ......but this is big machine to move and then find its under powered......This is billed as a High Speed variant of the standard CT50,"

So if you have a specific machine in mind you would get better answers as to its capabilities.
:cheers:

Kingbob · Apr 17, 2020

Yeah, when I hear 40 taper / 15k spindle big bridge machine I think large aluminum wing sections, or alu injection molds and the like. Without more details on the machine one must assume that was the intended purpose of this mill and if that is what you want to do with it and it is in good working order you should be happy with it. If you plan or machining big steel weldments or iron castings you may have a bad time.

vmipacman · Apr 17, 2020

Yep. Thats what i was afraid you would say. Espetially pointing out the rigidity difference between 40 to 50 taper.
In a job shop setting, about all I know about future work is that it will be big, about 50 x 80. Some work right now would be aluminum, but also some steel weldments and likely plates. Probably a lot of simple-ish work like plates with pins, tapped holes and bearing counterbores, but who knows what would come through the door.

But then I think that if the plate was 40x20 instead of 80x50 then it would be done perfectly fine on a 40 taper machine... so idk.

Jashley73 · Apr 17, 2020

What is it that makes this "deal" so attractive?

Like I said before, length of tools is what will highlight the biggest difference between 40 & 50 tapers. You can do a lot with a 3" high-feed mill & 4 or 5" face mill if you had to in a 40-taper.

I'd be skeptical of the brand, as far as long-term support for parts & service. Personally, I'd rather roll the dice on an older SNK or similar well-known machine, knowing that I could retrofit the control if I needed to.

cpifer3 · Apr 17, 2020

I have a 40 taper bridge mill, and if I had my choice I would go with a 50 taper , gear box machine, unless all your doing is AL.

cameraman · Apr 17, 2020

Kingbob said:
Yeah, when I hear 40 taper / 15k spindle big bridge machine I think large aluminum wing sections, or alu injection molds and the like. Without more details on the machine one must assume that was the intended purpose of this mill and if that is what you want to do with it and it is in good working order you should be happy with it. If you plan or machining big steel weldments or iron castings you may have a bad time.

I'm with Kingbob on this one in terms of "design intent".

Rigidity is the biggest factor and there are no standardized "Metrics" for rigidity …

Flicking through a spec sheet or brochure it doesn't say "Scores 25 wibbles on the ISO/ANSI woblotron scale" .

Some of these styles of machine can be crazy beasts or conversely floppy noodles and have to be driven accordingly without wrecking them or going broke 'cuz the machine literally can't cut the parts for the jobs you are trying to score.

There are some really interesting bridge / gantry* style machines that have 40 taper / HSK 63 type spindles that do very precise and intricate work. Mitsubishi have some smaller gantry/ bridge machines , even Kitamura...

As to @Vmipacman's question ~ Massive can of worms for what random machine that takes up a lot floor space can you charge a premium for doing oversized parts … Like "@Kingbob" I'm thinking aerospace.

@Vmipacman what do you want to do, what are the intended markets you want to serve ? (I'm not job shop so I can't say how a big mill will transform your business, but seems you run this machine hard to eventually buy the machine of your dreams when you get to "Step-up".) [Not everyone in manufacturing wants to buy "Giant" machines and will need to farm stuff out. ].

We have some oversized parts that we in essence have yet to buy machines for... So your idea @Vmipacman might be a good business move (in an abstract sense.).
There are a number of job shops that have done quite well specializing in Big components, you may have a good niche there for affordable structural components without being a race to the bottom kind of thing.

_________________________________________________________________________________________

* When does a bridge become a gantry ? Gantry has the rails mounted high ? Bridge has the table move through ?

cameraman · Apr 17, 2020

Jashley73 said:
What is it that makes this "deal" so attractive?

I'd be skeptical of the brand, as far as long-term support for parts & service. Personally, I'd rather roll the dice on an older SNK or similar well-known machine, knowing that I could retrofit the control if I needed to.

I like that "thinking" ~ retrofit.

vmipacman · Apr 17, 2020

I am not opposed to retrofit. Its a fanuc machine and I have some experience breathing life into old machines with new servos and controller. Fact is that for such a big piece of equipment that I want to shoehorn in here, its going to stay a while. This size machine fits nicely becasue it us not much bigger than i know I need. In my area, and looking at some parts that may come up, I need 53" in Y, So a 1.6m Y axis seems right, But I don't need much X, nor do I want to take up a single foot more than I have to. Literally its going to be a tight fit. So this machine is about the right year to put it in my range, travels and compactness are pretty good (just big enough to do everything I've seen, but no bigger than needed), reputation and support are OK, atleast for the 50 taper version. Its this 40 taper that has me stumped.

I had considered the idea of running this until I step up... its just a PITA to move.

And beggars cant be choosers.

Talking about retrofits, I'd be more inclined to try to figure out a 50 taper spindle retrofit. It might even be the same head casting for both tapers?? But that's just brainstorming.

Kingbob · Apr 17, 2020

vmipacman said:
Yep. Thats what i was afraid you would say. Espetially pointing out the rigidity difference between 40 to 50 taper.
In a job shop setting, about all I know about future work is that it will be big, about 50 x 80. Some work right now would be aluminum, but also some steel weldments and likely plates. Probably a lot of simple-ish work like plates with pins, tapped holes and bearing counterbores, but who knows what would come through the door.

But then I think that if the plate was 40x20 instead of 80x50 then it would be done perfectly fine on a 40 taper machine... so idk.

I agree with your thinking about if it were a 40x20 plate on say a vf3 with a 40 taper no one would bat an eye. The specific reason for my concern with a large bridge machine is the Z height of the spindle. On the vf3 you have what 24" or so of z travel with about 4" of clearance (spindle nose to table) on the bridge machine you are likely to have a more travel with more clearance (a greater nose to table length) that would have to be made up for by blocking up the work if it is thin or running longer gage length tools which is the concern with the machine as configured.

Jashley73 · Apr 17, 2020

Another thing to think about is 5-sided cutting. A lot of times, these bridge mills will come with programmable right-angle heads, and there's a good reason for that. Say you're working on a big press platen, but it has some holes on the edges that need drilled or drilled/tapped. Are you going to move this to a HBM to put the holes in the edges, or use a right-angle head & do it on the same machine?

The 40-taper is a head-scratcher really. IF this truly was an aerospace alum-monster machine, then I'd expect it to be HSK and 20k+ spindle. Full enclosure, tons of coolant, etc. Is it even dual-contact CAT40?

vmipacman · Apr 17, 2020

Def. need to be able to do right angle work. The 5 side heads are sweet but too much a “feature” to justify now. But drilling/tapping on a 90deg is a must. I should be able to do that well enough with 40 taper tooling (I think)
Hardest thing I see with that is programming. Telling it to treat y axis like z for drilling etc.
True 5 side machines will switch coordinates on the fly (so I have heard)

2outof3 · Apr 17, 2020

vmipacman said:
Def. need to be able to do right angle work. The 5 side heads are sweet but too much a “feature” to justify now. But drilling/tapping on a 90deg is a must. I should be able to do that well enough with 40 taper tooling (I think)
Hardest thing I see with that is programming. Telling it to treat y axis like z for drilling etc.
True 5 side machines will switch coordinates on the fly (so I have heard)

The Mitsubishi Heavy Industries machine move from Vertical function to Horizontal function when the right angle head is engaged. Z follows the function and so does the other properties like rigid tapping. The problem with making half the investment on a machine like this is you find new obstacles in your way that with the right machine are not obstacles but benefits. Right angle heads that actually mill like the vertical. High accuracy over larger space because the construction is set up to move large pieces and to attack them from 5 sides. All using scales. Let alone the metal removal rates that are pretty fun. All on a base spindle that is 8,000 RPM and 50 BBT.

Andy

Andy

Jashley73 · Apr 20, 2020

2outof3 said:
The Mitsubishi Heavy Industries machine move from Vertical function to Horizontal function when the right angle head is engaged. Z follows the function and so does the other properties like rigid tapping.

The MVR I ran in the past didn't have auto coordinate/axis swapping, or if it did, no one was aware of it. (97' model I think, with a Fanuc 15M) We would switch to G18 or G19 mode for drilling & milling. Possible, but requires you to slow down & *THINK* before cutting. Cut some air to verify, then move in to the metal.

To the OP - Right angle heads aren't cheap. They also may not go through the toolchanger, which would require them to be hand-loaded. Just something to consider.

2outof3 · Apr 20, 2020

Jashley73 said:
The MVR I ran in the past didn't have auto coordinate/axis swapping, or if it did, no one was aware of it. (97' model I think, with a Fanuc 15M) We would switch to G18 or G19 mode for drilling & milling. Possible, but requires you to slow down & *THINK* before cutting. Cut some air to verify, then move in to the metal.

To the OP - Right angle heads aren't cheap. They also may not go through the toolchanger, which would require them to be hand-loaded. Just something to consider.

All the machines with right angles actually change the head and the toolchanger will load in the vertical and horizontal mode. No need for a special tool holder when going to the horizontal position.

Andy

Jashley73 · Apr 20, 2020

2outof3 said:
All the machines with right angles actually change the head and the toolchanger will load in the vertical and horizontal mode. No need for a special tool holder when going to the horizontal position.

Andy

Yes, your MHI bridge-mills, and most any machine designed for right-angle heads, the tool-changer will accomodate the standard vertical, or the auxiliary horizontal spindle automatically.

My comment about right-angle heads not going through the toolchanger - Specific to the OP's situation. Assuming his machine doesn't have an auto-right angle head, he'd have to use an aftermarket right-angle head from Lyndex-Nikken, Alberti, etc... These may not fit through his tool-changer door, fit within toolchanger weight or dimension requirements.

40 Taper on a Bridge Mill

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