The Charter Oak 12z bed mill discussion thread

[coolidge]

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.

 

[tmarks11]

$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.

 

[coolidge]

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.

 

[jumps4]

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

 

[coolidge]

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.

 

[dave2176]

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

 

[coolidge]

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.

 

[JimDawson]

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 ^%$(&%^

 

[maker of things]

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.

 

[chuckorlando]

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.