Hey guys,
I finally am getting around to starting the work on my RF45 Lathemaster mill conversion. I got the Gecko G320s here, got my ballscrews and nuts and I am about to start machining them. I tore apart the whole mill now since I have another small mill here ready to do backup duty. I had one helluva time getting the z original screw assembly out of the machine's column. I noticed it has a lower bearing mount and it might even be a place to lift from but I did not investigate it all that well. I figured it all was gonna be replaced anyways. I am using a 3/4 inch screw for the z axis and I am gonna machine my own plates to mount motor and fix the ballscrew end. Just wondering of those on here with this same type of machine did you fellas remove this lower bearing mount or use it to steady the ballscrews end and fix the top and drive the top from the top of the column? The lower mount on my machine is cast iron and pretty heavy duty so it would be alright to use it but I suppose I would still drive from the top and support the weight of the head from the top plate as well. I would think of the bottom mount much the way the undriven end of the x axis will be with just a snug fit of the ballscrew thru a bearing to add support to keep it from wobbling around. Is this the correct thinking on this or am I way the hell off? I am really excited and I experimented with the ballscrew stock yesterday in the lathe and despite the hardness of the screws outer area my 12x36 lathe and my favorite carbide cutter made short work of the screw material and I am now gonna be machining them once I receive my bearings in from the supplier. My kit is gonna be loosely based on the Homecnc conversion but I want to try to beef things up wherever possible. Not that the original designs are weak just that I think they were designed with a little smaller machine in mind.
I took off the millhead by myself yesterday and I gotta tell you that baby is no joke!! A lot heavier than I thought it would be and if you met me you would not think me a wimp!! About blew a gasket taking it from the mill to the table next to it to get to the column stuff behind it. I gotta rig up some kinda crane in here someday.
This should be some kinda adventure I think and hopefully at the end will yield a nice machine that is capable and accurate but we will see. The machining of the z axis lift block I will call it to accept the ballnuts I am supposing I will do in my lathe on the four jaw and attempt to center the threaded original hole with the lathes centerline as best I can and then machine thru with the boring bar followed by a single point thread operation to get the ballnuts to fit. That should be interesting...
Any ideas as to the best way to center the ballscrew stock in the lathe for machining. It looks like I am gonna have to machine for about 1 3/4 inches of screw area to get the bearing surface, the threaded area, and the little shank to accept my rotary encoders. That is gonna certainly need to be machined with a center in the tailstock and with as little of it stickin out the jaws as possible for this hard stuff. I heard someone say that they would zero it in the four jaw off the grooves in the screw not the outer edge to ensure that it was concentric with the actual centerline of the ballnut. They put their DTI in the groove and setup the lathe to machine a thread that is equal to the screw pitch so the screw would turn and drive the table holding the indicator along with it to better yield a true zero. Is this necessary or have most of you just gone with the outside edge and had good accuracy out of it. What say ye?
I lucked out recently and was able to buy a nice desktop computer with an all black case and monitor that is pretty fast to run the show out in the shop while I do all the design work on my laptop here in the den. Should make for a nice setup as it is an e-machines unit and seems to run very well. I also have a nice box that I am gonna be using to house the electronics for the machine and will be starting that build also soon.
Anyways, I hate to call this my build thread as I sometimes do not get much time to work on my own things so it might be all winter or longer before I get this finished but I will try to post here whatever progress I make and ask whatever questions I may have of you nice cnc gurus!! http://www.cnczone.com/forums/images/icons/icon6.gif
Cool
Peace all....