Tail Stock Spider

[hemmjo]

One of my current projects involves working with 4”
schedule 40 steel pipe. Specifically truing up the ends
after band sawing to length, chamfering the ends for welding,
and cleaning up the outside from welds in its previous life.

Like many others, in the past a I have used a wooden cone
shaped plug. The wood plug is typically only good for one
use. It is not adjustable for good centering. It gets in the way
of machining the ends. It is time to make a more permanent tool.

The spider idea evolved while centering a pipe with the chuck
jaws on the inside. Putting the initial thoughts on paper
I get something like this

01

To get started, Layout out and rough cut a thick disk



Turn to size



Finish turn




Scribe for holes using the cross slide and cutting tool.



Transfer scribed lines to the edge, Drill and Tap



The original design needed modification. There was not
enough room between the body and the inside of the pipe
to work the wrench when centering the part. In retrospect
the body could have just been square. The bolt and sleeve
were held in the tailstock chuck to hold the part in alignment
while the chuck is tightened. Steel bars provide more
support for the part.



Since the part was already threaded, insert a set screw.
Remove after machining to clean up any damaged threads.



Note nuts added and jammed against the head of
the bolts. This provides a better surface for the wrench.



A length of PVC pipe was pressed between the spider
and the chuck which held the spider in position while
adjusting. NOT an ideal solution.



Ready to face end



After the first use, the bolt heads needed to tapered.
The flat head and hex shape made centering awkward.
The jam nuts become even more important with
the head trimmed.



Removable tabs were added to replace the PVC.



Dial in the center. Although the surface of the pipe is
rusty, pitted and the pipe is not perfectly round you can
still get it pretty close.



Remove tabs after spider is centered securely in the pipe.



Face the end. Replace the tabs after facing and slide
the spider in to be sure there is pressure holding things
together in case the spider works loose while turning the outside.



The parts






The goal. Eventually this pipe will be an extension, welded
to the crucible for my electric furnace. I have to stop at this
point until I get my furnace back in service. The welds are
just too hard to effectively machine. Hoping I will be able
to anneal the whole pipe then finish machining the welds and
bevel the ends for welding


Will keep you posted as things progress