# Talk me in or out of a 12z mill



## Chip (Sep 12, 2014)

The 12z looks like a good alternative that has a pathway to CNC. Is this a wise choice for a manual under $4,000?


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## stupoty (Sep 12, 2014)

Just googled them as i hadnt heard of the company, it has a realy wide table for its size, ive always wondered how that stands up to heavey stuff on the table.

Stuart


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## dave2176 (Sep 12, 2014)

Do it! I double dog dare you. 

Actually, i think will be nice mill.
Dave


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## wrmiller (Sep 12, 2014)

Well, I can't talk you out of it, because I just put a down payment on mine...  :whistle:

While everyone's requirements and desires are different, I'll share why I went ahead and picked this over the others I was looking at.

Size and weight:
This thing basically has the X, Y and Z travel (26", 12" and 22") of a small BP or other small knee mill with a 10x40 table, but without the extra weight. At the hobby level, everything is a trade off (well, for most of us). For some it's size, others weight, for some it's both. I fall into the latter category. But...this machine is also the basis for their $10k CNC mill that, according to one I spoke with, functions fine in a full production environment. I won't stress this machine anywhere near that hard, so until proven otherwise I am not worried about capability or longevity.

Availability of proven upgrades:
This machine in it's CNC form is pretty impressive. And most of those upgrades can be applied to the manual version. I paid for the 3 HP sensor less vector VFD which provides good torque across the entire rpm range of 0-3600 rpm. Planned future upgrades will include the one-shot oiling system which only requires that I drill and tap a few holes. The oil paths are already there because this is the base machine for their CNC mill. Really cool. I will also add a X-axis power feed later as if I ever have to crank back and forth through 26" on X I will build some rather massive forearms... They also offer things like a quick change tooling system and a NT30 spindle, but I doubt I'd ever need that. But then I also said some time ago that I'd never need a machine this large too... The last thing I might put in would be their two-speed pulley system, but as they have hardened steel gears in the head, I'll just see how they (gears) do for a while before I make a decision in this regard.

Custom stand:
Two stands are options, one that has wheels and one that doesn't. Either can be built to your specifications for no extra cost. I ordered the wheeled one at plus 4" of height. Really cool...

Larger head to column interface:
This thing is just plain massive. It will better distribute load across the column and 'should' enhance rigidity. It has to if it's being used in a production CNC environment. Or at least that's my reasoning.

Just my $0.02,
Bill

EDIT: I can't speak to the wise part...  )

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stupoty said:


> Just googled them as i hadnt heard of the company, it has a realy wide table for its size, ive always wondered how that stands up to heavey stuff on the table.
> 
> Stuart



According to the GM, it will handle up to 500 lbs on the table.

Bill


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## Chip (Sep 12, 2014)

Thanks for the feedback. Thats a lot of good info.

You mentioned "most of those upgrades can be applied to the manual version."

Which upgrades are given up by not going full CNC from the start?


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## wrmiller (Sep 12, 2014)

Chip said:


> Thanks for the feedback. Thats a lot of good info.
> 
> You mentioned "most of those upgrades can be applied to the manual version."
> 
> Which upgrades are given up by not going full CNC from the start?



Sorry, I misspoke.

I believe what I was thinking when I typed that was that 'some' of the upgrades you wouldn't want to do if your ultimate goal was to CNC: power feed and DRO was what I was likely thinking of.

Or I may have just confused myself as I cannot type as fast as I think.  

All of the upgrades can be applied to the manual in any combination, except the pulley conversion. That must be done after, or in conjunction with the VFD upgrade.

Bill


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## stupoty (Sep 13, 2014)

wrmiller19 said:


> According to the GM, it will handle up to 500 lbs on the table.
> 
> Bill



Wow thats pritty nifty, that extra 100kg of mass over the smaller bench mills must really beef it up.

Stuart


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## wrmiller (Sep 13, 2014)

stupoty said:


> Wow thats pritty nifty, that extra 100kg of mass over the smaller bench mills must really beef it up.
> 
> Stuart



What I was told is that there is "extra ribbing" that adds to the machine's rigidity. I doubt it's any different/better than anyone else's offerings in this size range, as I would bet that these castings all come from the same foundry.

In smaller machines, you need structural design to garner sufficient stiffness for the machine's design/intended usage, whereas for a commercial machine you just start with a 5000 lb lump of iron and whittle away. Or so that's my belief. )

Bill


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## Chip (Sep 13, 2014)

More good info!

Did you get a price on the v4.0 3 axis CNC conversion kit? Do you know if it will be 4th axis upgradeable? Do they sell a one shot oiler kit or are you going to source your own?


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## wrmiller (Sep 13, 2014)

Chip said:


> More good info!
> 
> Did you get a price on the v4.0 3 axis CNC conversion kit? Do you know if it will be 4th axis upgradeable? Do they sell a one shot oiler kit or are you going to source your own?



I didn't price the CNC conversion, as I'm not currently interested in CNC (but never say never). I really do like the fact that they use closed-loop servos instead of steppers (appreciated from the perspective of an embedded engineer who's written way too many lines of code for motion control systems).

Yes, there is a 4th axis option. For both manual and CNC machines

They do sell a one-shot oiling system upgrade for the manual (CNC comes with it) and the 2014 price list I have has it at $690. (ouch!) Might be cheaper to source/make my own as the mill is already set up for a oiling system. But then again I'd have to figure out how to design/build my own. Always tradeoffs...

Bill


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## Chip (Sep 13, 2014)

So closed loop servos is good. Learned something new today!


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## JimDawson (Sep 13, 2014)

Where possible a closed loop servo system is always the best.  And in my opinion, feedback directly from the load (the table in the case of a mill) is the best way to go.  Unless you are buying a 6 figure machine, relying on the encoder/leadscrew for positioning accuracy introduces too many variables into the equation.  I use magnetic readers on my mill that replaced the original encoders.

Open loop stepper systems tend to loose pulses, especially at higher speeds and/or heavy loads.  It is possible to close the loop with stepper systems by programming in on-the-fly error correction, if you have a feedback device on the axis.


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## wrmiller (Sep 13, 2014)

JimDawson said:


> Where possible a closed loop servo system is always the best.  And in my opinion, feedback directly from the load (the table in the case of a mill) is the best way to go.  Unless you are buying a 6 figure machine, relying on the encoder/leadscrew for positioning accuracy introduces too many variables into the equation.  I use magnetic readers on my mill that replaced the original encoders.
> 
> Open loop stepper systems tend to loose pulses, especially at higher speeds and/or heavy loads.  It is possible to close the loop with stepper systems by programming in on-the-fly error correction, if you have a feedback device on the axis.



I once designed a 6-DOF system for a Darpa project that used high precision linear motors and laser interferometers for absolute positional data. Don't remember precisely, but repeatability of this system was in the millionths of an inch. We had to have real-time meteorological data for our error correction algorithms.

I'm pretty sure that during that project was when I lost all my hair...  

Bill


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## jeff_g1137 (Sep 15, 2014)

Hi
Is this mill made in the USA.

It looks like the one from Grizzly

http://www.grizzly.com/products/Heavy-Duty-Mill-Drill-with-Stand-and-Power-Feed/G0755

or the one in the UK

http://www.amadeal.co.uk/acatalog/AMA45A.html

what is the difference in the mills, they all look the same, just the specifications,
in the speeds & motors. Is this one any better ????

The one in the UK look nearly the same.

ps
is tooling for the *NT30 Spindle *inexpensive and easily obtained in the UK


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## tmarks11 (Sep 15, 2014)

jeff_g1137 said:


> Hi
> Is this mill made in the USA. It looks like the one from Grizzly



Both the Industrial Hobbies and the Grizzly mill are made in China.  The UK mill you linked is probably made there too.

There is some variation between the mills, but they all started life as clones built following the pattern of the Rong Fu 45 (RF45) square column mill.  

The Industrial Hobbies mill received quite a few upgrades over the last decade at the behest of IH, gaining larger table, larger base, thicker cooler on the head, etc.

I would look a little more carefully at the specs when you buy a mill; the UK mill comes with an MT4 taper, which I would rather not deal with in a mill.  You should be able to look around and find an R8 RF45 square column mill from an importer in the UK.  Try here:

http://www.axminster.co.uk/metal-working/milling


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## wrmiller (Sep 15, 2014)

jeff_g1137 said:


> Hi
> Is this mill made in the USA.
> 
> It looks like the one from Grizzly
> ...



No, the mill is made in China.

The Griz isn't even close to the same table size or travel. Head mount to column is different too. Same for the UK one. As for the NT30, I can't say. It's more expensive here, at least the ones I've priced, and for much larger tooling than what I will be running. Don't know about across the pond.  

When I talked to Paul (Ops Mgr) about this he told me that they hired a British company to inspect the machines in various places during the build process. A statistic sample was done, and the machines that were inspected showed up here in good shape spec wise. The others though, were hit-and-miss on the quality. So, they (Charter) decided to have the Brits inspect every machine intended for Charter Oak. But the cost increased. Always tradeoffs...

Given the story and the fact that they use these machines for the basis for their CNC mills, I decided to buy in. The proof will be in machine that I get I guess. Good or bad, I will report my findings to those interested.

Bill


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## jeff_g1137 (Sep 15, 2014)

tmarks11 said:


> Both the Industrial Hobbies and the Grizzly mill are made in China.  The UK mill you linked is probably made there too.
> 
> There is some variation between the mills, but they all started life as clones built following the pattern of the Rong Fu 45 (RF45) square column mill.
> 
> ...



Hi
Thanks for the info, will get a mill next year, still looking around.
I think the the UK mill can be got with a R8, but up to now it is the best i have seen in specs & cost.

Are all the parts interchangeable between the makes.

 I think it is made in China.


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## grantj (Oct 26, 2015)

wrmiller19,
Can you post pictures of the Stand you received from IH/Charter Oak and comment on it, I'm on the fence about buying the one with wheels.

Thank you,
Grant


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## brav65 (Oct 26, 2015)

Reach out to Bill Miller of Coolidge as they both purchased 12Z's this year.


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## wrmiller (Oct 26, 2015)

Brooks: Coolidge didn't buy a stand, he built his. And I think I've had mine for a year now. Time flies?

Here's a couple of pics of mine from when I was initially setting up the mill. Initial impressions were not great with regard to the appearance of the welds, but it's still standing and I've been up on the stand with the mill in place working on the top of the head (about an additional 300 lbs. at that time), and nothing broke so I would say it's strong enough. I don't have welding capability to make my own stand so I popped for theirs and had them add 4" to the height.







I did make one change since these pics. I put some aluminum blocks under the levers to get them further back into the stand. I didn't like the look of them sticking out so far.


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