Why Do I Want A Backing Plate And Chuck On A Rotary Table?

countryguy

countryguy

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Hello good People of HM . So I'm into ENCO maddness today. They have the Phase II 8" very well priced and w/the holiday 20% off run. The Tailstock is 50% off regular plus 20% (like 90$) and the backing plate is $50).
Everyone has these threads about baking plates and 3 jaw chucks. . . . I've needed a Rotary table a few times now... but what do I do w/ the chuck on the backing plate?

Any help appreciated on the great work I could do with this nifty trio of additions to the shop ;-)
 
Just anything you can put in a chuck easier than using a faceplate to hold.
 
The back plate is for mounting the chuck on the rotary table.
 
My Tormach RT is actually a Phase II. It came with a 6" chuck mounted on a backing plate. The back plate extends past the chuck body and has four holes for bolts to mount to Tee nut in the table slots.

IMO, the primary reason for the mounted chuck is to easily center small parts on the table. For example, if you wanted to make a custom hex head screw with a hex head, you can chuck a screw with a turned head and cut trial faces. Measure the distance between the faces, and adjust your position to cut the final hex faces.
 
I thought that the rotary table had mounting hardware.... Hmmm so this means that if I really want to Mill a part and need a nice circle I need to mount the chuck side up??? Sorry guys. This one is from Mars for me. If I put the RT on the Mill table... Does the plate go ontop and then chuck go onto the top of backing plate ? so It's RT on table. Bplate on, chuck on. Mill away. ???

what I needed it for was basically an arc and something oblong to mount on the RT. then just turn the handle.... that's what an RT would do also I assume.

I search the archives here and a few sites with no real good outcomes on how to use an RT, plate and Chuck. :)
Thanks all JJ
 
The chuck is normally used to mount round or hex pieces in a simple way, e.g. if you want to cut a gear from a round bar. Bur as long as you can clamp parts directly on the table and the part is cleared to be milled where you intend, you don't need a chuck. You can also use a wise on the table to secure parts or use a clamping kit. A clamping kit may or may not be included with a RT:
 
The chuck backing plate is just an adapter to get the chuck attached to the RT. Any way that you could mount the chuck would work, but the backing plate provides a convenient adapter to provide that mount. You could drill & tap the RT for the chuck mount bolt pattern, but that is generally not good practice unless you are making a permanent fixture for a dedicated manufacturing operation.

Anytime you need to create an arc, or cut angles in a part, the RT is the way to do it unless you are using a CNC machine. The RT allows you to rotate the part relative to the machine axis so you can take a cut that is not in line with the X-Y axis.
 
The following thread/posting was on a lathe/chuck rotary adaptor that I made. http://www.hobby-machinist.com/threads/lathe-chuck-rotary-table-adaptor.13873/
The main benefit I see is that you can remove your chuck from the lathe with the part you have turned remaining in the chuck, and then mount that directly on the rotary table on the mill. If the adaptor you have made for the chuck has a centered shaft that fits into the opening in the center of the rotary table, then the part in your chuck that was lathe turned will be automatically centered if you have centered the rotary table. In other words, center the rotary table on the mill, take the chuck and adaptor and insert its shaft into the rotary table opening, and the part in your chuck is automatically aligned with the center of the rotary table and you are then ready to machine further on the mill, either with the part centered or after you have made whatever x/y table adjustments you need.
 
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