I decide to convert the milldrill to have zero backlash in at least the X and Y axes. Again, at the lowest possible cost. I accomplished this with ball screws and preloaded ball nuts. This was my first experience building anything with ball screws so I did a good bit of research before I started.
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For the ball screw, I decided to use the nominal 588243 size for both fit and cost 1.09 per inch. The screws and nuts a readily available from MSC, McMaster Carr, and the local bearing outlet. Pricing was about the same from all sources when you use my employers discounts.
I wanted to do my conversion without the hassle of picking up the milldrill. To disassemble the table from the top down, I first ground away a small area on the under side of the table casting. This allows the table clear the X axis nut and to be slid entirely off the ways. With the table removed, you have access to the socket head screw holding the Y axis nut in place. Detaching the Y axis nut allows you to slide the Y axis slide off the machine base. You must thread the Y axis screw out of the nut in order to remove the entire assembly from the base.
I thought I was going to have an interference with the new Y axis ball nut and the base so I extended the cut out in the base where the Y axis nut travels. I turns out I did not have an interference with the nut, but the extended cut out allowed me to install my new ball screw and nut assembly as one piece. This eliminates having to thread the ball nut onto the screw while the nut is installed under the slide. Whenever threading a ball nut onto a ball screw, there is a chance of all the balls falling out. See my tool below that helps prevent this time consuming event.
My design of the ball screws and ball nut mounts is fairly straightforward. I reused the existing thrust bearings and bearing mounts. The screws have a nut and jamb nut arrangement for taking up play in the thrust bearings a feature lacking in the original screws. Some new hubs were made to fit my original timing belt pulleys, and the motor mounts were re used.
I order to machine the ends of the ball screws, it was necessary to soften them a bit. I wrapped a damp rag around the screw to protect the usable threads, and heated the end to be machined to a dull red and allowed it to air cool. The screw could then be easily cut with carbide tooling.
I decided to make put a ball bearing in the shaft support of the X axis screw on the drive end. The original design has no bearing in this support.
I have had a lot of fun with the whole CNC and ball screw conversion project and would highly recommend doing it if you have any interest. As you can see from my project, you don8217t have to be an expert at anything, and you don8217t have to spend thousands of dollars.
The end result is a CNC milldrill that can mill out a 8221 diameter circular pocket with accuracy of about 0.0018243. This is fine for my tinkering.
I have owned a Grizzly G1005 milldrill since 1991. Interesting to note I paid about 1200 back then and the same model is now listed in the Grizzly catalog for 895.
Since 1996 I had been gathering information and considering converting it to some kind of CNC operation. My plans were put on hold for a while when I had to move and put the mill in storage. During that time I was fortunate to have a CNC knee mill at my employers shop that I had full use of.
In 2001 I decided I was going to convert the milldrill at the lowest possible cost. I was not immediately concerned with accuracy, and just wanted to play with it. I had three Slo-Syn stepper motors with IBM part numbers I picked up for almost nothing at a junk store that was closing. I had also recently torn apart a couple old copy machines so I had a bunch of timing belts and pulleys. Software and stepper motor drivers were still needed.
After realizing I could not find any free drivers, I decided to buy the 5 Amp driver kits sold by Dan Mauch. They were the lowest cost 5 Amp drivers I could find. I enjoyed assembling them and testing them but the documentation was somewhat lacking. As a contribution to the home CNC hobby, I rewrote the documentation and sent it to Dan. I dont know if he ever used it. The three drivers were assembled and mounted along with my homegrown power supply in an old mid tower PC case. My first usable milled product is the airflow slots in the front and back cover plates.
SEIG SX4 GRIZZLY G720R. More details PM-25MV CNC Mill Conversion with Dual Ballscrew Nut. 789 00. More details Sale G0704 Mill CNC Conversion Kit with Ballnut Mounts, Ballscrews with DUF Ballscrew 949 00. More details PM-30MV Mounting Kit With DOUBLE BALL NUT. 949 95. More details PRECISION MATTHEWS PM833T Mounting Kit. 989 00.
I decided to mount the stepper motors on the milldrill in such a way as to not cause any irreversible damage, in case I decided to scrap the project. The X-axis motor and pulleys are mounted to the feed screw on the 8220free8221 end of the screw. This is the end without the thrust bearings. I removed the hand wheel mount, machined off the end closest to the table, and mounted a plastic timing pulley to it. The motor is mounted to a 8221 x 48243 piece of aluminum flat bar. The flat bar is then bolted to the face of the screw support.
The PM-25MV CNC Mill is one of the most popular hobby mills out there. So we decided that it needed a conversion kit that would out perform the kits that are available today, By adding Double Ballnuts to our ball screws we have doubled the accuracy to the kits that are now available today. Because the Double Nut ball screw is more efficient.
Nov 01, 2018nbsp018332I used Vectric Aspire to convert the DXF drawings to gcode. Then on the Z axis ballscrew mount I added some curved surfaces to match the shape of the Ball nut. The ballscrew mounts replace the leadscrew mounts on the Grizzly G0704 milling machine. They are designed to slip over the edge of the Ballscrew nut and bolt onto the flange with 14-20.
My first attempts at running the mill were a bit frustrating. I was running Master5CNC on a Celeron 433 in an ABIT BE6 motherboard and could not get a smooth pulse train to the stepper drivers. This caused the motors to freeze up or miss a bunch of pulses. I switched to an old Pentium 233 in a cheap motherboard, and everything seemed to smooth out.
I knew I would not be satisfied with anything made on the mill until it had zero backlash. At this point I used the mill quite a lot in 8220push button8221 mode. Basically using the jog keys instead of turning hand wheels. I like this so much, the hand wheels were never reinstalled on the mill.
Grizzly mill ball screw conversion G0704 CNC COnversion T5 I relied heavily on Automation Technologies for the lead screw kit, motors, and electronics. Some folks seem to make a hobby of the mill conversion process. in shipping Tooling from combination of Grizzly and Little Machine.
The G0704 CNC Mill is one of the most popular hobby mills out there. So we decided that it needed a conversion kit that would out perform the kits that are available today, By adding Double Ballnuts to our ball screws we have doubled the accuracy to the kits that are now available today. Because the Double Nut ball screw is more efficient.
The X3 and SX3 also include the Grizzly G0619,G0463, and the Shop Fox M1111. Our standard ball screws are C7. They are 16mm X 5mm pitch with a tolerance of.004quot over 12quot Our premium ball screws are C6. They are 16mm X 5mm pitch with a tolerance of 30 microns over 300mm. Anything not listed, please ask.
Jan 14, 2017nbsp018332The 1605 screw makes about 5 turns per inch so the way you have it the motor would only turn about 2.5 revolutions for 1quot of movement. If they were swapped the motor would then make 10 revolutions per inch and have 4 times the power it has now. Your rapids speed would still be close to 100quot per minute which is more than enough.
Ball mill is also known as ball grinding mill. Ball mill is the key equipment for recrushing after the crushing of the materials. It is widely used in cement,.
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