Round Column Mill/Drill motor sizing

[APD_CNC]

Im about to make the plunge into a CNC conversion of my old Jet mill drill. It is essentially the same an RF-31 or a Grizzly 3358...over 600 Lbs, round column, R8 spindle, 9x24 table.
Im looking at the Keling kit with 495 oz in. steppers, 4030 driver, 24v power supply.
I plan on using ball screws (7/8" x 0.200") and gear reduction (only if I need it for the torque).

Ive done lots of reading and searching here, and found all the sites (I think)and threads with these conversions.

From what Ive seen, I estimate these to be powerful enough for milling aluminum and steel on this machine, but just want some reassurance before dropping the money.
Rapid travel is nice, but with only 24" of table, I wont be going far.
Those motors seem so small, its hard to believe they will be strong enough.

Do you think that kit is a good selection for this application? Do I need better drivers or Power supply?

[vulcom1]

I have basically the same mill/drill from Busy Bee. When checking on the table feed motor from them it is listed at 200 oz. I have bought 300 oz steppers for mine and am going to gear it 2 to 1 to start with. I am hoping that I can do what you are doing before too long. My spindle motor is 2 hp and I don't see any problems unless I get carried away with to deep of cuts.
Keep us updated on your progress as I am interested.
John

[burner303]

I know this is an old thread, but I am in the beginnings of converting my craftex mill drill to cnc and would like to know if anyone has any advice, information, plans, drawings photos or anything of the like when it comes to a column conversion.

Just want to know what to expect once I start pulling the bed off and such.

Cheers

[arizonavideo]

I have a RF-31 apart but I don't understand the question.

The table CNC's like any other but the guy above said 7/8' ball screw which is nuts.

What exact machine do you have and what are you trying to do?

[burner303]

Originally Posted by arizonavideo I have a RF-31 apart but I don't understand the question. The table CNC's like any other but the guy above said 7/8' ball screw which is nuts. What exact machine do you have and what are you trying to do?

I have a B1977 craftex 30 Mill Drill.

What is wrong with 7/8 ball screws? I have ordered 25mm Ball screws with 5mm lead.

[arizonavideo]

The problem is fitting the nut under the table. Some nuts have a larger flange and you will have to grind it off to allow for the clearance needed.

For a 24" table a 3/4" screw is fine and a 5/8" would be OK too.

[burner303]

well the screws showed up with the nuts yesterday, looking at them they are only slightly larger than the screws i removed from the mill so they will fit with some minor modification for the x screw the y should not need any modification. The nuts have flats ground in the top and bottom of the flanges which is a plus.

Does anyone have any good information on how to go about mounting them?
Like bearing support blocks, and how to make sure everything is straight and aligned properly? I have the mill in about 6 pieces and I am ready to start fabricating the bearing blocks but some ideas would definatly help.

I already have the stepper system figured out, and motors and everything ready to go so the screws are #1 priority at the moment.

Cheers