Bench Top Mill CNC Conversion

[jamiedaugherty]

Hi guys, new member here....

I've got a bench top mill similar to a Grizzly G3358 (http://www.grizzly.com/products/2-HP-Mill-Drill/G1006). I bought it from Homiers but it appears to be the exact same thing (Chinese of course). What I'm working on doing is converting this over to full 3-axis CNC controls. I've already got the motors, drives and the Microkinetics OptiStep Plus card and software. I thought at one time I saw some drawings for the brackets to mount the steppers to the X- and Y-axes as well as a design for the Z-axis. The X and Y aren't too much trouble, I really want a belt drive with a reduction to add resolution. The Z-axis looks to be the biggest chore.

Anyone know if there are some plans out there specifically for this mill? Any help would be greatly appreciated. Thanks!

[jhowelb]

Harbor Freight mill conversion to cnc

[ataxy]

the disadvantage with those machine is the fact that the head is mounted on a round column wich mean that if you use the z axis from the column you will have a hard time retaining your x,y 0, if you know for sure that most of the tool you will need will have mostly the same lenght the the quill can be used as a z axis but it will limit your travel to ~5 inchs i know that some user here have modded the column installing a square attachement to the head&column assembly thus preventing up to a certain point the rotation of the head around the column

[Bubba]

jamiedaugherty
Just to give you some encourgement, I have a RongFu RF31 that is very similar to the one you have. I used servos instead of steppers and have been VERY happy with the results.
Yes, I have to PLAN ahead with the tool situation so I don't have to move the head up or down during the process. One thing I did was to get a straight shank ER collet setup and this will help by allowing me to move it in and out. Yes, I have to take lighter cuts, but then again this is not the most rigid machine out there.
Hang in there and I think you will enjoy the results.

[jamiedaugherty]

I like servos too, but I already have the steppers and drives and not a lot of money! I'm also not worried about the round column, it will work just fine. I'm not even going to change out the lead screws at first because I can take care of those using the backlash compensation. Later on I'll probably upgrade to ball screws. Again, money will decide this.

I thought there were some plans around somewhere that showed details of all the components necessary and a full parts list. Maybe I'm going crazy. I have not problem making the stuff myself (Mechanical Engineering is what I do for a living) I'd just rather not reinvent the wheel if I don't have to.

Thanks guys!

[Bubba]

Jamie,
Some words to think about.
As for using the existing screws, "been there done that" and was VERY disappointed. It got so bad that my backlash exceeded .125" and finally I was able to "walk" the nut down the screw without even turning it. Also, if you think you are going to make round circles (g02 03) and not have problems, forget it. Part of the circle will be climb milling and it will make a big mess of the part, possibly break the tool etc. (Don't ask how I know:{(

Just some food for thought.

[jamiedaugherty]

Originally Posted by Bubba Jamie, Some words to think about. As for using the existing screws, "been there done that" and was VERY disappointed. It got so bad that my backlash exceeded .125" and finally I was able to "walk" the nut down the screw without even turning it. Also, if you think you are going to make round circles (g02 03) and not have problems, forget it. Part of the circle will be climb milling and it will make a big mess of the part, possibly break the tool etc. (Don't ask how I know:{( Just some food for thought.

My mill is almost brand new, so the screws are still tight. I'm guessing that it will last a long time, by then maybe I'll update to ball screws. Circle interpolating should not be a problem with this machine. Keep in mind that I'm not going to try and make accurate holes. Profile tolerances of .005in+ at minimum, usually more on the order of .015in. For accurate work I'll run a boring bar down through the roughed out hole. Mostly I'm looking to make parts with intricate outside profiles. i'm currently sending this out to another guy and I want this machine to make prototypes and test parts.