What's a Spider?
This is a Spider. Or maybe spelled Spyder depending on your part of the country or world. When facing multiple parts to length in the lathe it is helpful to be able to have them all the same depth into the jaws. That way, using a carriage stop, you can easily make multiple parts the same length quickly and accurately.
This one is made of 1/2" thick aluminum and was milled on the BOSS 8 Bridgeport mill. It is certainly possible to make there on conventional machinery and they don't have to be all that accurate. A careful layout and band saw to the line will do just as well for most needs.
I chose to use the CNC mill and made this an exercise in MasterCam drawing and machine setup for one of my students.
This is a spider.
This photo shows the fixture and spider together on the mill. As you can see the holes are for clamping bolts to hold the part on the fixture. I counter bored the holes to get the heads flush with the top of the part.
Here is the spider in the lathe chuck.
The spider and a part in the chuck. You can see how the spider provides a positive stop so that many part could easily be faced to a specific length.
Finally, if you don't have a spider and have to use parallels of one sort or another using a spring (thanks Brian Lawson) to hold things in place when tightening the chuck.
Don't forget to remove the parallels before starting the lathe!!!
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