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Author Topic: CNC CONVERSION - 6" ATLAS LATHE  (Read 71442 times)

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Offline budman68

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #10 on: August 31, 2009, 10:36:25 AM »
Great looking project, Rich, should be fun to watch -  :)

Dave
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Just because I'm a Global Moderator, don't assume that I know anything !

Dave->    ;)

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #11 on: September 02, 2009, 10:12:27 PM »
Well the conversion continues.

     SADDLE WORK
 
            New bottom guide plates will need to be made due to the nut location. The contact surfaces and the spare saddle that touched the bed required re-machining to remove wear. The surfaces were made parallel and shiming would be the same for both sides. You really take your time on the machining along with stoning, grinding, or scraping of the surfaces will be required. You can’t screw this up or the x axis will no longer be run perpendicular to the z axis. The finished saddle resurfacing is shown in figure 12 along with the bottom guide plates which are made from tool steel.

Figure 13 shows the  new holes being drilled into the carriage for the guide plates. There is were a knee mill really comes in handy as I have al lot of room on my small mill. That tap extension ( you know the stuff you buy but never use ) just did the trick.

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #12 on: September 02, 2009, 10:13:40 PM »
       CHECKING THE SADDLE TO BED FIT

With the screw adjusted to the bed as before, the tail end will be worked on next.
Note the small clearance of the nut along the bed axis ( I said it was tight! ) in figure14.


The fit of the carriage is again checked and all is well, parallel, perpendicular, and size shims can be used an even shim can be used. The back of bed was cleaned up and the surface checked for square before making a back mounting block. Fortunately no machining or scraping was required.
See figure 15.

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #13 on: September 02, 2009, 10:15:04 PM »
Dimensions are taken and a drawing is made so the mounting of the ball screw bearing and stepper motor can be figured out. This is shown in figure 16.
RICH

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #14 on: September 02, 2009, 10:16:29 PM »
TAIL END BEARING INSTALLATION
A bearing will be provided for on the tail end of the Z axis. The bearing is mounted inside the mounting block and then the motor mounting plate is attached to it. Figure 17 just shows some rough work done on the plates before drilling and machining. All the plates are precision 6061 AL stock. Figure 18 shows the bearing just lightly tapped into the mounting block. A boring head was used to bore the hole into the mounting block.

Figure 19 shows the tail assembly mounted to the lathe. The block was temporarily attached to the lathe bed similar as was done at the spindle end. The saddle is mounted, shimmed and the ball screw turned by hand to set the location of the tail and spindle bearings. There should be no binding of the carriage over the full travel along the bed. That done, the tail and spindle bearing holders received alignment pins.
RICH

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #15 on: September 02, 2009, 10:17:58 PM »
         X AXIS BALL SCREW INSTALLATION
The x axis will receive a different ball screw as the carriage is rather limited in what it can provide for as shown in Figure 20. The carriage requires machining to open up the cavity such that the ball nut can travel inside the carriage. Sometimes post machining of a casting you remove internal stresses and the thing warps some. Hopefully this will not happen as the other surfaces of the carriage were already fine tuned for fit to the bed. Carbide end mills take care of cuttin thru the sand, stone and other crap in the casting.

Figure 21 show the carriage cavity ready to be machined. Set up is very important as there is not that much surplus material. You want the screw to travel parallel to the dovetailed ways in the carriage. You take you time. By the way before this is done details were drawn to see just what would be removed and how the trust and axial bearings would be mounted.

Figure 22 shows the completed machining with the ball screw laying in the cavity.
RICH

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #16 on: September 03, 2009, 07:48:09 AM »
CARRIAGE TOP SLIDE
In order to mount the ball nut to the slide a new one will be made. It’s more robust than the original slide and will also allow for customizing it for tool holders and mounting of other stuff onto the carriage. A chunk of fine grained cast iron will be machined to create it. Figure 23 shows the dovetails being cut and the holes being added. Take your time on the dovetails as you don’t get a second chance if you screw it up! Carbide cutters are the way to go as HS or even cobalt will dull very rapidly.

Figure 24 shows the qib being machined. The gib is made from precision ground steel ( will still need to regrind one side of it ). The jig makes easy for what would be an otherwise PITA job. The jig is something I made some time ago and is actually meant for the surface grinder. The gib needs to beveled on both sides  and also flats put one side at  an angle for the set screws. See figure 24.

Figure 25 shows the semi finished slide with gib installed. A bearing support will be added onto the carriage for the ball screw bearing that you can see in the picture. Note that the slide is machined flat and square on all sides. Figure 26 shows the back side of the slide and you can see the ball nut laying in the carriage. A split attachment will screw onto the nut and also attach to the underside of the slide. That piece will be held via countersunk screws from the top of the slide as adjustment will be required when aligning the ball screw. Yep, you need to lay it all out!

RICH
Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #17 on: September 03, 2009, 08:03:18 AM »
Looking good RICH !
Sure to be a nice addition to your collection.
How are you planning to cover/shield the Z screw ?
Russ

Offline RICH

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Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #18 on: September 03, 2009, 08:31:28 AM »
Russ,
I am not sure, yet. Will add wipers to the ball screw but that dosn't cut it. Maybe bellows or hard covers  or a combination of both. Design yet to be done! At this point still have plenty of time to think of it.  ;)
Collection, ha....ha.... i need to get rid of stuff, as the shop is full.  ;D
 What did you do?
RICH
Re: CNC CONVERSION - 6" ATLAS LATHE
« Reply #19 on: September 03, 2009, 08:56:31 AM »
Bring some of it to York, quality stuff goes for top dollar.
I'll come down and help you load up. :)
I put the Z screw behind the bed and covered its entire length with a sheet metal channel.
It was about a 20" lathe but I only CNC'd about 6" of the Z so the traveling guard never extends beyond the footprint of the machine.
Crude but CLEAN !
NO airguns allowed so it is impervious to debris.
Russ  8)