# The Charter Oak 12z bed mill discussion thread



## coolidge (Sep 26, 2014)

I'm starting this thread to discuss the Charter Oak 12z bed mill AND to discuss other brand/model mills for comparison purposes. I'm pretty far along in my own research and after speaking with Charter Oak this morning I'm 90% sure I will be opting for their 12z bed mill. 

Here's my price sheet so far...

$2,350 - Charter Oak 12z bed mill
$850 - 3HP VFD upgrade, boosts spindle RPM to 3,600. China motor and custom, you won't find an off the shelf replacement.
$785 - Belt drive upgrade, boosts spindle RPM to 5,000 plus, I think they told me 5,300 rpm. They install bearings good to 7,000 rpm.
$458 - X axis power feed, I still need to track down a picture and some specs on this, I'm hoping its similar to the Bolton Tools power feed.
$562 - Shipping, ouch! Not much to be done there they are about 2,800 miles from my house.

Total - $5,005.00

I'm on the fence at the moment regarding the chip tray and stand. My pals at my local CNC punch press shop can knock out a chip tray for me. The stand is already pricey at $550 the problem is shipping it 2,800 miles will only add to that cost. I'm very likely to make my own stand and enclosure locally.

Before I spoke with CO this morning I was still considering the Grizzly G0722 at $4,045 w/stand w/sales tax minus 10% discount coupon to my door. The Grizzly is turnkey ready to go, has a power Z, uses a brushless DC motor, its a nice little package at $1,000 less than the CO. The things that were spooking me about the Grizzly were the gobs of electronics, my guess is those are China quality and I had some concerns about how long they would last and what a hassle it would be to replace them if they failed. Also the Grizzly max spindle speed is 1,600 which is not acceptable. I found one guy who swapped pulleys and boosted spindle RPM to 3,200 but then are those bearings rated for that I don't know and neither did he. It also has less power than the CO, a smaller work cube. Would it meet my needs...maybe but $1,000 wasn't enough for me to cross the CO off my list and go Grizzly.

So I spoke with CO this morning and obtained some good information. The Grizzly is now crossed off my list in favor of the CO. Here's what I learned about the CO...

1. The Y axis 12" of travel is not from over traveling Y off the saddle, that's 12" of travel fully on the ways. They said its possible to extend Y travel another 2-3 inches to the 14-15" range. I'm familiar with doing that via my early model IH mill years ago. I'm happy with 12" however so I'm good to go there.

2. The belt drive conversion is from Arizona (somebody) I have seen his conversion on the web. I was surprised to learn this boosts spindle RPM to over 5,000 with the 3HP VFD upgrade, that got my attention. I was also pleased to hear they swap the bearings in all these mills with bearings rated for 7,000 rpm. Its a serpentine belt system which I'm fine with. I will sometimes mill composites and aluminum which can benefit from the increase spindle speed. A big problem I had with my old IH mill was the 2,000 top speed it was slow going and LOUD. Noise is one of the other reasons I'm going with a belt drive conversion.

3. The 3hp VFD option, its a China motor and sounds like its heavily modified to for the CO mill, I won't find an off the shelf replacement motor but at the end of the day its just driving a pulley so I'm not concerned with having to adapt another motor one day if ever. I like the variable speed. I like that the VFD electronics is a stand alone unit that could be replaced vs the built in electronics on the Grizzly. If I fry the VFD I like that I wouldn't have to half gut the machine to deal with that.

4. The price of these options includes installation and testing by CO before it ships to me. That eliminated the Grizzly turnkey advantage. 

5. One major gripe with my old IH CNC mill was the crap quality ways. They were loose and sloppy in some spots and would bind up in others and were a constant problem even after ridiculous amounts of lapping by both IH and myself. I'm simply not looking to deal with that crap again period. CO assured me this morning this would not be the case, I would not have to lap the ways and there would be no binding issue. They did say they had to work with the factory on this to get it right. I don't have any experience with Grizzly brand mills but this was also one of the concerns I had about the G0722 or any other brand model mill for that matter.

That's it for now, currently they have the mill and VFD in stock but not the belt drive conversion so its hurry up and wait for a bit. I have no plans to CNC this mill. A DroPro's magnetic scale DRO is likely, love the one on my G4003G lathe. I may power the Z axis for convenience as well. But I know from experience its easy to sink $12k into a CNC project on these mills and that's half the cost of a used Haas Mini Mill that comes with gobs of other goodies like an ATC, programmable coolant, full enclosure, etc. etc. I guess never say never but if I decide I need a CNC mill I'll likely go that route.


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## tmarks11 (Sep 26, 2014)

coolidge said:


> $850 - 3HP VFD upgrade, boosts spindle RPM to 3,600. China motor and custom, you won't find an off the shelf replacement.



That is pretty spendy.  For that kind of money, you can buy a quality Leeson or Baldor motor and a VFD.

I am suspicious of the "custom motor" claim.  At the end of the day, the Chinese factory is buying the motor from another Chinese factory, who is building it to established specifications used around the world.  It might be a somewhat esoteric face mount, but there is no way IMHO that you can't find a US made (or Brazilian made) motor that will be a drop in replacement.  Looks like a standard "C-face" to me.

Worst case is you would have to cut an adaptor plate, but that just requires a drill press. Not rocket science.

The picture makes it look like they have mounted a custom cooling fan on the end (not a bad idea because at low speeds, a VFD operated motor is at risk of overheating)... but you can do the same thing by installing a 110V muffin fan to the end.


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## coolidge (Sep 26, 2014)

I have read similar posts tmarks11, as for the motor being non-standard they tell me it has to do with mounting and the motor shaft size. They have indeed added an electric powered fan to keep the motor cool at lower speeds. Factor in my time, aggravation, chasing down components, and not being able to call CO to sort out any problems and how much am I saving. But your points are duly noted. At the end of the day CO has to turn a profit and I support that as well seeing how the government has their hand out every time you turn around.


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## jumps4 (Sep 26, 2014)

I noticed that the mills work envelope is a lot larger on the Charter Oak 12Z than my zx45 from wholesale tool
the mill table is 7 inches longer and the travel on y is 12" compared to my 9.5
I also checked the g0722 and this mills work envelope is a lot bigger than it also.
If I would have seen this for just $500 more I think I might have bought it instead of my zx45
steve


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## coolidge (Sep 26, 2014)

That's the way it is with machines jumps, for n more you can get y more and pretty soon you are at $68k and telling the wife honey that's really about the cost of a new boat these days. Okay I'm off to group therapy...hi I'm Charles I'm a machine-o-holic, its been 2 hours since I drooled over a Haas super mini mill 2 with a side mount tool changer.


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## dave2176 (Sep 27, 2014)

Not to try and change your mind,  but I think if I were spending $5k on a mill, I think I would look at other options like the G9901. Great work envelope and many other features I would like to have. I would probably update the motor at some point to a 3 phase with VFD for more rpm.

I like the CO, just thinking out loud. 

Dave


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## coolidge (Sep 27, 2014)

Good point Dave, now that I'm at $5k I should take another look around at what I could get for that. I do think a full size 2,500 pound knee mill may be a bit much for my 3 car garage shop though.


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## JimDawson (Sep 27, 2014)

coolidge said:


> Good point Dave, now that I'm at $5k I should take another look around at what I could get for that. I do think a full size 2,500 pound knee mill may be a bit much for my 3 car garage shop though.



I had a Bridgeport clone on my houseboat, along with my lathe, welding and other support equipment in a 12x14 shop.  So compared to a 3 car garage, I had all of that stuff in less than one bay.  The good news was that I could reach everything in 2 or 3 steps.  You don't actually park cars in your garage do you?

well %(&*^%  the smilies seem to have quit working  ^%$(&%^


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## maker of things (Sep 27, 2014)

For a direct comparison though, the G9901 doesn't have variable speed motor or 5000 rpm spindle, so if you can live without those features, the 12Z is $1600 cheaper.  Plus all that room under the machine would let you can make a stand with an intermediate tool chest in it that fits under the 12Z.


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## chuckorlando (Sep 27, 2014)

Bridgeports are tall not wide. Your looking at about 4x4 space more or less long as nothing is in the tables way. And they are more like 1800-2000lb. And I have tools and stock on either side behind the table so the travel space for table is still not wasted. Not to say you should get a BP just clearing up any confusion.

That being said, I would certainly look at other options at 5k. Maybe you find better maybe not, but look all the same. I know for 5k you can slide into some really really nice used mills.


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## coolidge (Sep 27, 2014)

Chuck - you are reading my mind on used mills. I have been watching my local craigslist but they are smoking crack on prices. I .... you not one guy was asking more for his grizzly than grizzly sells the mill new because...he cleaned off the shipping grease.

Maker - Correct the 9901 top speed is only 2,400 I'd have to jump up another grand to $6k plus add a VFD. The other thing about a knee mill is how do you contain the mess, its relatively easy to build an enclosure around the CO.

Jim - I'm cramped for space and contemplating getting rid of some machines. The Kubota and yard work stuff eats one of the three bays. In the other two I have a big ass 12" table saw, planer, jointer, band saw, cyclone, mortiser, the G4003G lathe, workbench, and a couple rolling tool chests.


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## maker of things (Sep 27, 2014)

Isn't that a terrible problem?  Too many machines, or maybe you need a bigger building.


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## wrmiller (Sep 27, 2014)

chuckorlando said:


> That being said, I would certainly look at other options at 5k. Maybe you find better maybe not, but look all the same. I know for 5k you can slide into some really really nice used mills.



I won't speak for anyone but myself but in my case I don't WANT a one-ton piece of iron in my garage unless I never have to move it again, and given my history, that ain't gonna happen until I retire. Oh, and that phrase of "there are plenty of GOOD used mills out there doesn't apply around here. Sorry. The only ones I've seen locally in that price range are completely worn out POS like that one my friend bought. Back East is probably different, but many of us don't live there. 

When I bought Blue (PM25) that was the biggest machine I wanted to deal with while I'm still working. Same for the SB 8k. Then along comes this 12Z thingie. Very similar work envelope to that PM935 Taiwan machine that I have had in the back of my mind for when I retire, but without 'most' of the weight. And cost. As someone stated in a different thread, the CO 12Z is probably pretty close to the rigidity of a BP clone given they carry the majority their weight in the base and knee. The head of a BP/clone is on a sliding/rotating knuckle for flexibility of usage. I've seen some of those commercial 5-6 thousand pound 'real' mills. Now those give new meaning to the term rigid. The flip side is they are completely unusable for a guy like me. In my life everything seems to be a compromise... *sigh* 

Anyway, I was having some problems with Blue (my fault, I bought a pulley kit that I 'assumed' was properly designed. It wasn't. Now I have to fix it.) and started thinking that there has to be SOMETHING out there that can give me most of the capability of a Boat Anchor (i.e., big arsed knee mill) that I can move without having to have friends with large hulking moving equipment. I talked to Ray C about a 932, but in my envisioned use case I would have to upgrade the motor and install a VFD to get the speed range I want. Matt has 'em, but I'd be putting it on myself and probably voiding my warranty. Probably not a deal killer by itself, but...then there's my biggest personal itch with those machines: the lack of travel in Y. Most of the RF45 variants can't even cover their tables in Y. Then it gets even worse if you install a DRO scale on the back of the table! This is not something I am willing to deal with. Do I need 12-13 inches of travel in Y? Not at the moment, but who knows what I'm doing years from now? Fairly certain I don't.  

So then I get wind of this big hulking (for a hobbyist bench style bed mill) thingie from Charter Oak. After doing some cursory investigation, I find it's a re-hash of a IH(?) mill some of the home CNC types use/used but not without having to upgrade/mod the thing. Great. Another Chinese kit machine. NOT something I'm really into at this point. Then I had a few conversations with the folks at Charter Oak and even a customer of theirs or two. The major flaws of the previous design were addressed. Steps were taken to improve the build process and overall quality. Upgrades are provided for those who would like some of the big-guy features without having to go 'all in' on a boat anchor (oiling system, tool changing system, etc.). But the major selling point for me was that they use the same mill for the basis of their CNC mill. The ways are trued and ground. The machine is already designed for a oiling system. You simply have to drill and tap a few holes to install it (so I'm told. The proof will be when I install that upgrade myself, but NO ONE ELSE offers this as an upgrade). Oh, and the head/column interface was improved/enlarged to increase rigidity and improve longevity: that thing is huge for a mill this size!

Long story short, I decided to get it. After all the talk, it's the only way to know for sure.  

(why couldn't I have taken up knitting as a hobby...)


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## dave2176 (Sep 27, 2014)

I don't think the G9901 stand footprint is much  different than my G0755 (rf-45 clone). I use the space on the side under the table for stuff. I realize the CO doesn't come with stand so you can customize it to your heart's content. What it has the CO doesn't is power down feed with automatic stop and reverse, one shot oiler and 2325 pounds vs 700 on the CO. As far as the way quality, my 0755 is smooth full travel. If the G9901 was any less, I would wear out their phone until it was fixed. I don't know how far it is from Battle Ground to Bellingham but I would be tempted to drive there and inspect the machine I was buying. 

Dave

Edit: What would it cost to refit this one with 3HP and VFD and some changes to the pulleys get the speed there? I doubt  the bearings are an issue.


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## wrmiller (Sep 27, 2014)

Guys, Maker of Things posted in my "I ordered a mill" thread with a pic of him standing next to his machine. Maybe I'm too easily impressed...but wow.


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## coolidge (Sep 27, 2014)

maker of things said:


> Isn't that a terrible problem?  Too many machines, or maybe you need a bigger building.



I priced a shop a few months back with my builder, around $35k. I'm not that serious yet.


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## coolidge (Sep 27, 2014)

Dave I'm 250 miles from Grizzly but traffic around Seattle is insane. I was up there a couple weeks ago, left Seattle at 3pm and the stop and go traffic jam was 50 miles long. Also add a 8% sales tax on the Grizzly machines for me. Those box ways are sexy though.


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## coolidge (Sep 27, 2014)

wrmiller19 said:


> Guys, Maker of Things posted in my "I ordered a mill" thread with a pic of him standing next to his machine. Maybe I'm too easily impressed...but wow.



Chips by end of day Monday or you wear women's under garments.


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## wrmiller (Sep 27, 2014)

coolidge said:


> Chips by end of day Monday or you wear women's under garments.



Now how the hell did you know that?  :roflmao:


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## coolidge (Sep 27, 2014)

Why am I already thinking of CNC'ing the 12z...somebody hit me in the head with a large tool. :think1:


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## wrmiller (Sep 27, 2014)

coolidge said:


> Why am I already thinking of CNC'ing the 12z...somebody hit me in the head with a large tool. :think1:



Dunno (why you're thinking that). But if you have the requirement to make multiple pieces of the same design, then I can think of worse machines to do so with.

Fortunately, I am not plagued with that thought as all of the work I do is one-off so spending time to make a drawing/tool path for a CNC makes no sense to me.

For now.


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## JimDawson (Sep 27, 2014)

wrmiller19 said:


> Dunno (why you're thinking that). But if you have the requirement to make multiple pieces of the same design, then I can think of worse machines to do so with.
> 
> Fortunately, I am not plagued with that thought as all of the work I do is one-off so spending time to make a drawing/tool path for a CNC makes no sense to me.
> 
> *For now*.



Bill, up until about a year ago I had the same feelings that you do.  What I found is that even on a one-off part, depending on the complexity, if it has a long cycle time, it allows me on work on something else while the part is running.   For instance, I have a part ready to go in the mill right now that has a 115 minute run time for one operation.  I could do it by hand, but doing with the CNC allows me to work on another project at the same time, so in this case I can double bill my shop hours.  Even if I was working on my own project, I could still be productive doing something else, like surfing H-M


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## coolidge (Sep 27, 2014)

wrmiller19 said:


> Dunno (why you're thinking that). But if you have the requirement to make multiple pieces of the same design, then I can think of worse machines to do so with.
> 
> Fortunately, I am not plagued with that thought as all of the work I do is one-off so spending time to make a drawing/tool path for a CNC makes no sense to me.
> 
> For now.



CNC comes in handy, for example to position the machine for manually drilling a precise bolt hole pattern or for that matter quickly drawing a bolt hole pattern. Time is part of the equation. I have a day job already, director with a bunch of people under me so my time is limited. Of course when it comes to arcs that require concurrent X,Y moves CNC is king, then there's 3D machining. Now I will say this, I already have my multi-thousand dollar 3D OneCNC XR2 Mill CAD/CAM software so that investment is bought and paid for already.

After my early model IH CNC mill fiasco I vowed 'never again'. I vowed if ever I wanted a CNC mill again I'd buy a real one. I have been eyeing a Haas Super Mini Mill 2 for some time. But that's $68k optioned out and that's without tooling, add another $30k for a shop to put it in. I could afford it but if I'm honest its a stupid purchase for hobby work and $98k would buy a lot of CNC time at any local machine shop with mills far larger and faster than a mini mill. So as much as I drool at the thought of a Haas its ridiculous really. Now prototyping on a $12k CO type CNC mill that's a motor cycle, half the cost of a fishing boat, its within the realm of toys.

Two things concern me based on my prior experience, Z axis repeatability and X,Y backlash. The thing is half useless if it can't maintain Z position through multiple Z axis moves. As for X,Y backlash machine a circle, if it looks like two halves of a circle slightly offset that's FAIL!. I have more :think1: to do on this.


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## wrmiller (Sep 27, 2014)

I understand the 'time constraint' thingie. I too manage (bunch of engineers at Micron) and highly value my personal time. I'm just into more hand crafting, which is why I like to do custom work on pistols and revolvers. I was offered a job as a pistolsmith for one of the top guys in the country years back, but the best way to kill a hobby IMO is to turn it into your day job. That and the owner wanted me to submit two guns to the pistolsmith guild within the first year. Sounded too much like work to me. Hobbies are supposed to be FUN. )


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## maker of things (Sep 27, 2014)

wrmiller19 said:


> Guys, Maker of Things posted in my "I ordered a mill" thread with a pic of him standing next to his machine. Maybe I'm too easily impressed...but wow.



Bill, I'm blushing I've been called a lot of things but never... oh you meant the mill.


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## wrmiller (Sep 27, 2014)

:roflmao:


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## chuckorlando (Sep 27, 2014)

Brother I thought the same thing till I seen how fast it works. My teacher could have a drawing and cutter path for bout any shaft ready to run before you could load the stock proper. Really all you need is one done, then change the info to fit. I seen the pics of the 12. It does look like a very fine machine.





wrmiller19 said:


> Dunno (why you're thinking that). But if you have the requirement to make multiple pieces of the same design, then I can think of worse machines to do so with.
> 
> Fortunately, I am not plagued with that thought as all of the work I do is one-off so spending time to make a drawing/tool path for a CNC makes no sense to me.
> 
> For now.


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## tmarks11 (Sep 27, 2014)

coolidge said:


> ...hi I'm Charles I'm a machine-o-holic, its been 2 hours since I drooled over a Haas super mini mill 2 with a side mount tool changer.



and then on your way out the door, you passed by the Haas VF2....


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## tmarks11 (Sep 27, 2014)

coolidge said:


> Also add a 8% sales tax on the Grizzly machines for me. Those box ways are sexy though.


10% off coupon is available at Grizzly until 9/30...

That cancels out the state tax. hew:

You are a brave man to tread the same ground twice after your previous experiences with IH.  That company has been bounced around quite a bit over the past 8 years; hopefully CO settles things down and starts pumping out a good product.  At least you can hear Miller's opinion when he gets his machine on Monday.


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## coolidge (Sep 27, 2014)

tmarks11 said:


> and then on your way out the door, you passed by the Haas VF2....



You meant to say VF2SS, my brother owned one, you want to talk pucker factor let that think rapid at 1400ipm "jawdrop:


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## Chip (Sep 28, 2014)

I initially considered the CNC version of the 12z. That envelope IS quite impressive, but I just couldn't wrap my head around how an outfit that neglects their website so much could possibly be counted on for design quality and support of their CNC mill. I mean...it's their storefront for crying out loud. This initial presence to the customer runs as slow as molasses. Its their business card, their lobby, their receptionist, their eSalesman, and their showroom floor. I'm not driving 2000mi each way to look at one in person. Please, help a brother out with something more substantial to review than a brief sales pitch along side four grainy 267x400 jpegs of your marquis product!

Some might poo-poo that opinion as irrelevant to the machine, and indeed that could well be the case, but from the perspective of a customer with cash-in-hand hundreds of miles away looking at making a $12,000+ investment in his future, it is sorely un-reassuring to say the least. Would you buy from a new car dealer that doesn't bother to mow the lawn or sweep the showroom floor? (perhaps, if the price reflected that omission and you knew you could take it somewhere else for service)

Truly, I wish CO the best and hope that if they do read this that they would consider this post as intended; honest constructive criticism from this customer's perspective.


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## coolidge (Sep 28, 2014)

Chip I don't disagree the CO web site is lacking and slow. I don't see the belt drive conversion listed on their site at all or that fact that it boosts spindle speed to 5,000+ rpm which to me is a big selling point. So they are shooting themselves in the foot a bit. That said some of the major auto manufacturers web sites are pathetic. Haas has a great web site...when it works I can't tell you how frequently their build a Haas has been broken. So point taken but not sure I would call it a deal breaker. Just my 2 cents worth.


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## coolidge (Sep 28, 2014)

Here's a couple video's of the belt drive conversion by the guy who builds them for CO. Top spindle speed 5,300 rpm. Looks like he has a 2 speed belt drive conversion out now also.

[video=youtube;4dmfP5i2syQ]https://www.youtube.com/watch?v=4dmfP5i2syQ[/video]

[video=youtube;HeoKGTWeBEU]https://www.youtube.com/watch?v=HeoKGTWeBEU&list=UUOtPHVL6Qi-LuJp17ASrBww[/video]


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## wrmiller (Sep 28, 2014)

Wow. Looks like a pulley drive is in my future as well.

I too have been frustrated with their website, but it is getting better (content) and faster over the last few days. Maybe I should have stipulated that some of the money I paid them goes to their website.  

None of these machine sites are perfect. Grizzly has the wrong thumbnails under some machines and the site occasionally hangs. PM just changed the 'updated' date on their home page, but most of the sub pages are still the same. I could go on, but I'm just making a point not digging on websites as a whole.

I wasn't convinced to put my money down until I had a few conversations with Paul and one of the support guys there at CO. I've been burned by pretty websites with lots of glitz and inaccuracies or omissions before. So I 'window shop' the company's website, but I want to talk to someone and even get a email history trail before I plunk down any money. But I can even point to a very recent case where NONE of this helped. So at some point, the talk stops and a leap of faith (for lack of a better phrase) is needed. If you think that a cool website is going to prevent post sale problems in the future, I wish you luck.

So, I just jumped off a cliff. Again. We'll see how it turns out over the next few weeks.  )


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## coolidge (Sep 28, 2014)

WR I predict after you experience a few hours of 100+ decibel WHAAAAAAAAAAAAAAAAAAA from the gear head a belt conversion will be in your future. I do still need to speak with both Arizonavideo and CO about torque as typically you don't get something for nothing.


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## coolidge (Sep 28, 2014)

Get some! Note he's using a 4hp motor...

[video=youtube;hwCsD10Fwtg]https://www.youtube.com/watch?v=hwCsD10Fwtg&amp;feature=player_embedded[/video]


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## wrmiller (Sep 28, 2014)

coolidge said:


> WR I predict after you experience a few hours of 100+ decibel WHAAAAAAAAAAAAAAAAAAA from the gear head a belt conversion will be in your future. I do still need to speak with both Arizonavideo and CO about torque as typically you don't get something for nothing.



Maybe I'll have to wrap the head in a blanket for the short term.  :lmao:

What are you hearing about the torque issue? You are correct of course. There are tradeoffs to any power transmission system. I won't be stressing this machine like some will, so I doubt I will need that full 3HP. I will be curious as to what you find out though.


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## coolidge (Sep 28, 2014)

Dave's here's a pretty good in depth review of the 9901

[video=youtube;kyDuqwuczts]https://www.youtube.com/watch?v=kyDuqwuczts[/video]


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## dave2176 (Sep 29, 2014)

coolidge said:


> Dave's here's a pretty good in depth review of the 9901



okay, I'm sold. 
Dave


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## maker of things (Sep 29, 2014)

Maybe each mill is different, or maybe I just have different expectations than many.  I don't find the stock mill to be "loud".  Seems about on par with a sewing machine to me, just the sound come from a bit higher off the ground.  I don't find it uncomfortable, unlike my craftsman 26 gallon air compressor, I can't even think when that thing is running.


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## coolidge (Sep 29, 2014)

Maker when you CNC one of those gear head mills and it runs full blast for hours on end trust me you will long for something more quiet. I also think a good point for us who have garage shops attached to our house is the noise others in the house will have to put up with. I had my old one in my basement and the noise came right up through the floor into the living room. Just my observations and 2 cents worth.


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## coolidge (Oct 2, 2014)

UPDATE: The Charter Oak mill still tops the list after pouring over umpteen mill choices the last week. Only found one that tempted me, a used Grizzly knee mill similar to the 9901 that is absolutely mint sitting in a guys garage for $2k but the price was the only temptation, it really doesn't meet my needs. I considered again going with a used Haas but damn they are smoking crack on their prices, not far off what the things cost new and its pretty easy to rack up thousands in repair costs on those things. A new Haas is out of the question.

THEN I got some information on the new improved Charter Oak CNC kit. I was already familiar with the old style kit, belt drive and problem prone been there and done that on my early IH CNC mill. The new style kit uses brushless servos with integrated drives and direct drive connection to the ball screws e.g. no belts. I'll need more information on this kit before I'm ready to pull the trigger on that but I'd order the mill today if the belt drive option was in stock, I'm waiting for an ETA on that.


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## wrmiller (Oct 2, 2014)

When you get an ETA on that belt drive could you pass that along? It's on my upgrade list.


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## coolidge (Oct 9, 2014)

Update: In no particular order...

Manual mill...

1. Belt drive kits are still on back order.
2. 3hp VFD motor confirmed at 3,600 rpm, the shaft size is some custom metric size from the factory so retrofitting a Baldor, Leeson, Marathon may require turning the motor shaft. On the other hand if converting to belt drive you just machine the pulley to fit.
3. I did look around for inverter duty alternative motors, not cheap about $500 and up and nothing with the wide base mounting frame of the China motor.
4. They insure the mill for shipping with an outside company (not the freight company) and CO will deal with any insurance matters, if they can just send a replacement part they will, if the mill is half destroyed they will ship out a new mill.
5. The VFD is a Danfoss 3hp Micro drive, I checked pricing looks to be $380 to $420 for that unit. Of the $850 they charge for the VFD upgrade which includes installation, control pot, etc. that only leaves $450 to put towards another motor plus having the shaft turned down, machining an adaptor plate, bah I just decided to go with the China motor CO provides. If I upgrade to a better quality motor later I'm only out a few hundred. Also I have yet to find a better quality inverter duty motor that was 3,600 rpm like the China motor, they were all 1,800.


CNC Kit...

1. The newly designed kit includes servo motors that are pretty cool, but are not yet IP rated. CO thinks they are good to go for flood coolant but I pointed out the electrical connection which clearly is not, bottom line I would need to confirm this with the servo manufacturer.
 2. All three ball screws are 20mm and rated P3.
3. The Y axis servo is now mounted on the back of the base vs the front. They machine the back of the base flat at the factory in prep for the servo so if you purchase the kit and install yourself is bolt on, you do have the drill/tap the holes.
4. CO assures me backlash is zero, if you machine a circle you won't see issues at the quadrant changes in axis direction it should be a smooth circle.


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## wrmiller (Oct 9, 2014)

I wondered what that hole in the back of the base was for (as I was lifting it off the floor with the hoist). Figured it was for the CNC upgrade and it looks like I guessed correctly.

Oh, and the VFD has a RS485 cable coming out of it. I assume this for spindle control via CNC software?





coolidge said:


> Update: In no particular order...
> 
> Manual mill...
> 
> ...


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## zr8cnc (Jan 8, 2015)

is the belt drive kit sold through CO or ArizonaDave?



coolidge said:


> Update: In no particular order...
> 
> Manual mill...
> 
> ...


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## wrmiller (Jan 8, 2015)

Yes!  

Dave makes them for CO as well as direct customers. Coolidge and I are getting ours from Dave (Coolidge did all the leg work). Not sure one is better/quicker than the other.


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## johnwell (Jan 8, 2015)

Damn, it must be a tough life to constantly figure out how to throw big money around...hehheh :lmao::lmao:
 Although it's good food for thought though reading about you rich folks...)

Anywho...provided I get a response to email I think most interesting to me is a 932M....
Give or take listing for 2500 and have less Y-travel than the CO, but for that money I do have power-just-about-anything. All that is lacking is my (obvious) brainpower!
 I can live quite comfortably with (only) 8 inches Y and the wife agrees wholeheartedly with that....:whistle::whistle:
On my 1640 I don't have much Y-travel and that didn't bother me so far....:nuts:
I can't argue a VFD though..that's super nice.

In my defence...coming from a Littlemachineshop mini mill...everything looks better when it weighs a bunch!

Feel free to call me a mentally challenged Dutchie now...I can take it....

John


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## wrmiller (Jan 8, 2015)

John,

There are guys here throwing a lot more money around than I!  

As I've said before here (and will continue to until someone tells me to shut up) you get what you can afford/fit/justify and to heck with everyone else. This isn't a contest (I hope).

I was inches away from getting a 932 as I've had pretty good success with it's little brother my PM25 (had a LMS mini-mill before that), but I don't need power down feed and what I really needed was the ability to work to a 12"x12" work envelope without having to reset the workpiece. Having 26" of X doesn't hurt either... :whistle:

So I popped for the slightly bigger machine. I really do like the VFD upgrade and use it a lot so can't complain about spending the $$ for that upgrade. )


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## johnwell (Jan 9, 2015)

wrmiller19 said:


> John,
> 
> There are guys here throwing a lot more money around than I!
> 
> ...



And I think you've made exactly the right decision, Bill.
In my case I already went a tad 'overboard' with my 1640 lathe and not that I don't have a specific budget for me it's, as of now, more messing around with the machines making a thingie here and there while others have alot of 'stuff' to produce, with an actual plan! I do not...)
I do want a mill that doesn't try to walk over to my neighbour like most mini mills probably do so I'm going for lbs and nice colors....hehheh
I don't need powerdown feed either, no matter how professional that looks...:lmao:
Just looking at the 932 cuz of the price shipped and the table feed and head feed. Not getting any younger here and even though I pull levers for a living...don't wanna pull anything at home except my wife!
The table "work envelope" is absolutely no issue for me in my situation.
I would stay jealous about the VFD though....

John


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## coolidge (Jan 10, 2015)

wrmiller19 said:


> Yes!
> 
> Dave makes them for CO as well as direct customers. Coolidge and I are getting ours from Dave (Coolidge did all the leg work). Not sure one is better/quicker than the other.



ArizonaDave manufactures the belt drive kits for CO, whether you get your kit from CO or directly from David its the exact same kit. CO will install it for you however for a fee I feel is quite fair given the task.


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## zr8cnc (Jan 29, 2015)

does anyone know if Arizonadave custom makes the kits to fit your specific motor shaft diameter?


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## wrmiller (Jan 29, 2015)

I would say yes to that, as he wrote me to specifically ask what motor I had. He has all the shaft specs for the motors that Charter Oak sells, but if you have a different motor he will want/need the specs on it so he can make it to fit your motor.


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## zr8cnc (Jan 29, 2015)

awesome thanks for the quick feedback. Also I am looking forward to hearing your review on the belt conversion and how it cuts



wrmiller19 said:


> I would say yes to that, as he wrote me to specifically ask what motor I had. He has all the shaft specs for the motors that Charter Oak sells, but if you have a different motor he will want/need the specs on it so he can make it to fit your motor.


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## coolidge (Jan 31, 2015)

zr8cnc said:


> awesome thanks for the quick feedback. Also I am looking forward to hearing your review on the belt conversion and how it cuts



Yeah speaking of that Bill if you don't post some pics or video of this belt drive in action soon I'm going to photoshop your Avatar wearing a dress and cheap Walmart make up and use it as my Avatar, you have been warned!


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## zr8cnc (Jan 31, 2015)

Perfect! I couldn't have said it better my self



coolidge said:


> Yeah speaking of that Bill if you don't post some pics or video of this belt drive in action soon I'm going to photoshop your Avatar wearing a dress and cheap Walmart make up and use it as my Avatar, you have been warned!


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