Is there any such thing as too large of a mill?

[GT-6 Racer]

Looking at your other machines it looks like you are kind of headed the way I have gone, only on a different scale. I have a small Sherline 5400 mill 3.5x12" and a Clausing 8520 mill 6x24". Both get used, as small parts often use small tooling so the much higher speeds available on the Sherline do offer some advantage. It is also much quieter to run. The Clausing while a small mill in the big picture is just a completely different class of mill from a mini-mill, bigger, heavier and a knee mill. I like having the bigger mill very much, and I have no urge to get rid of the little Sherline, they both have a place for me.

I have no concept of the practical differences between working with a mill the size of a typical Bridgeport and a larger mill.

People have mentioned that the smaller mills are more comfortable when running them manually. I find that especially true when hand cranking x axis on along table 50”. Pretty far away and difficult to see the cutter. If following DRO not such an issue but I still like to see. So much more comfy on the 32” Bridgeport or the FP3 which has all the controls in close proximity. Whatever size, really consider the quality and rigidity in relation to the work you want to do. This is an interesting discussion that probably doesn’t happen enough.

 

[m1kemex]

I find that especially true when hand cranking x axis on along table 50”.

On small machines it's typically the nut fixed and the screw turning. But I've seen many large machines with the screw fixed and the nut turning, thus making it possible for handwheels for all axis to be located in the front.

 

[Aaron_W]

People have mentioned that the smaller mills are more comfortable when running them manually. I find that especially true when hand cranking x axis on along table 50”. Pretty far away and difficult to see the cutter. If following DRO not such an issue but I still like to see. So much more comfy on the 32” Bridgeport or the FP3 which has all the controls in close proximity. Whatever size, really consider the quality and rigidity in relation to the work you want to do. This is an interesting discussion that probably doesn’t happen enough.

I didn't even think about that. My mills are small enough that there is no need to shift position even if running the extremes of travel. While to some degree the weight is off set through mechanical advantage I'm certain the difference between raising and lowering the knee is quite noticeable between my Clausing where the knee / table weighs maybe 150lbs and a mill where they weigh 1000lbs+

 

[GT-6 Racer]

Remember once you get beyond the Bridgeport and clones into the more complex machines ( K&T, Cincinnati, Van Norman, Deckel, Maho, etc.) they have power on all the axis. Some are separate motors, some are geared, some servos. Full power with rapids is pretty sweet. So cranking is really for setup and very small moves. The smallest of the heavy US iron is interesting but they become huge fast.

 

[FOMOGO]

I have three at the moment. The BP is 9 x 42, and is my go to as it is the only one up and running. The Acra is 10 x 54, 3hp with servos on all three axis, and is around 3500lbs. I installed the the Y&Z units, and it is waiting on me to finish up the VFD install. The big one coming in at 11k is a 14 x 62 horizontal/vertical Gorton mill that has been patiently waiting for a big enough RPC to run the 10hp main, and 3hp axis drive motors. I was going to build the RPC, but recently came across a very nice commercial unit for $600, so That one will be up and running this winter when I get more time in the shop. I doubt I will be parting with any of them. I realize many have neither the room, or the need for a large mill, but I tend to work on some larger stuff, so big will be good for me when they are up and running. Mike

Here's a pic of the Acra near completion.