plaster of paris ???

hi all ,i'm hoping for a bit of advice ! ive offered to make an adapto

for a boat steering wheel . the new wheel has a larger taper etc to th origional and needs a counter bore to let the nut tighten on the shaft i can only take the new wheel with me ,can i make a cast with plaster o paris of the origional wheel bore ? will it carry the taper accuratel enough to let me check fit when i copy the bore to the adapter ? sorr to go om lol but im fishing for ideas

-- willowkevi

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What I have used, successfully, in the past when faced with a similar problem was to wipe some oil around the surfaces of the original as a release agent and then cast a plug of Plastic Padding. I used a bit of perforated zinc to strengthen the padding and give me a handle, since the cast I was making was hollow with a thread on the outside. When the Plastic padding was set I unscrewed the cast and could measure the diameter and pitch of the tread to make the puller that I needed.

I assume that the same would work with plaster of Paris but I needed something which would take a fine thread without crumbling.

HTH Mark Rand RTFM

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Mark Rand

In circumstances like this, one would machine a stub that fitted the old wheel to use when machining the adapter. Of course, if the old wheel fitted in the lathe the topslide could be indicated to the bore of the taper, saving some time.

Tom

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Tom

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