Prospects of CNC for grizzly knee mill

[spunkrat]

Hi, i'm a noob looking for a good mill that i might CNC in the future. I came accross a grizzly knee mill on sale for $1800 including shipping (which is the absolute maximum that i am willing to spend on a mill), but could not find any reviews on that model. If anyone has any thoughts on it I would greatly appreciate it.

http://www.grizzly.com/products/item...emNumber=G3102

[DDM]

It looks like a nice mill and grizzly is a pretty good brand. But do you really need something that big? I mean it's not big compared to the cincinati manual mill that I use at work but what would be it's intended purpose? The other thing is that when you do retrofit it you'll have to be looking at how to eliminate the backlash if you want to try and figure it out in the software or if you want to convert it to ballscrews or somekind of preloaded nut. If I were looking at a manual mill this would be an option but for a CNC conversion, I might think twice. This is just my opion, I think you might want to decide what you want to make first and then spend the bucks. The other thing is looking for used equipmnet, such as a bridgport series 1, it's all on what you want to do.

Carl

[IJ.]

SpunkRat: I'm just finishing off a Retrofit

It's not for the faint hearted trust me on this .

If you have any questions please ask I'm happy to help out if I can.

[spunkrat]

I dont have a specific use in mind, but it would be nice to have a larger mill should i need one. i currently have to "fabricate" parts in wood with hand tools due to severe lack of metal working equipment, i get kinda nervous when trying to make small parts on the table saw. I have looked at mini mills and i think a larger machine would be better for the stuff i plan on doing because one of the things i would like to do is machine stainless steel. i also need to have the capacity to fit large parts on the table. DDM thx for your recomendations, and i have looked at used mills, but then i have to deal with transporting it once i buy it which is a huge problem for me. I think i'de prefer a new mill that i wouldnt have to do a lot of retrofiting on. IJ. i looked at your project and your craftsmanship is amazing, and i'll deffinately use your project as a guide when i retrofit my mill. I am also considering a different grizzly mill http://www.grizzly.com/products/item...emNumber=G0519

and the sieg x3
http://www.siegind.com/mill/MILL-3.htm

i particularly like this model because of the lead screw on the z axis, and that the entire milling head appears to move rather than the quill for fine adjustment. does this make it any better for CNC conversion? a bit small though....

[IJ.]

SpunkRat: If you don't have access to a well equiped metal working shop it might be better/easier to find a Mill that there is a ready built kit available.

It's a huge ask to do this sort of work without the right gear, there are some amazing Routers being built here from scratch but a retrofit means you have to be very precise as you're locked into the existing specs.

[--colin--]

I have a Grizzly knee mill, similar to the one you are considering. Grizzly now sells the machine I have as "G9959 Wood Mill". When I bought it, it was advertised as a small metal knee mill and has a built-in cooling sump/pump in the cast base, instead of the stand shown for model G3102. Other than that, the main differences are most likely just the max spindle to table distance.

I've been very happy with this small mill and it has served me very well as a manual machine. I plan to convert it to CNC some day, but I elected to build a router first, and I'm still working on it.

You decision to get a knee mill, or dovetail column type machine is wise. Many buy the mill drills and there are setup issues since you loose location when moving the column vertically. As long as all tools are within the range of the spindle travel, it's no problem. However, center drills, mills, drills, reamera and boring tools vary in length considerably. So without a larger range of Z adjustment, setups can be trickier.

The only disappointment I have with the Grizzly machine is that is uses 8 pitch leadscrews so the travel is 1/8 inch per dial revolution, instead of 0.100. I suspect that the machine was designed to accomidate users wanting a fractional dial calibration. Perhaps because the USA is still using the antiquated inch system, whereas the rest of the world has standardized on metric. I further suspect that Grizzly had disatisfied customers as a result of this design and they reintroduced the machine as a "wood" mill", as woodworkers are more apt to want fractional increments. These are only my suspisions, and not based on any facts.

As I said, the Grizzly mill is very nice and except for the screw pitch, I would buy it again. Both of the other machines you are considering look good also. If you need a manual machine now and may do a CNC conversion later, you choices are good, considering you want a smallish size machine and your budget.

Some have suggested that finding an older Bridgeport machine with a dead CNC controller can lead to a less expensive path to a home brewed CNC knee mill. These machines are becoming more available and the old controller can be striped off and the machines already have ball screws and stepper motors installed, making the total time and money invested less. If you want to convert a Grizzly type machine to CNC, it's a big task and good quality ball screws and motors are not inexpensive. Something to think about.

--Colin--

[spunkrat]

thanks colin that realy helped clarify some things.