Re: [CAD_CAM_EDM_DRO] Re: RepRap

Charles Anderson wrote:

>It can be done, but requires support and a lot of space ;-)
>
>Aw come on tell us :-)
>
>
>Regards Charles
>
>Jon Elson wrote:
>
>
>
>>>Apparently you can make a lathe on a lathe. Possible since you can do
>>>milling on a lathe, but not vice-versa. Whether the one you make is the
>>>same as the one you used to make it is a different matter.
>>>
>>>
>>>
>>>
>>>
>>>
>>I can't possibly imagine how you could make a lathe bed on a lathe.
>>Milling in
>>the lathe is generally for very small parts.
>>
>>Of course, with the proper hand tools, you can make a very good lathe bed
>>using no power tools at all. But, that is a SLOW and laborious process
>>(don't
>>ask me how I know this!)
>>
>>
>>

Well, I repaired deep wear in a 6 foot lathe bed. Normally, you'd use a
scraping tool,
but this was a hardened bed, and a carbide scraper would not even
scratch it! I first
set up a toolpost grinder on the base of the lathe's tailstock and towed
it down the
bed with a small gear motor and fine steel cable. This got things
pretty close, but
duplicated any sag in the bed from one set of ways to the other. I then
used an
air-powered die grinder with small Cratex muslin-bonded abrasive wheels
to finish
the process. I first did broad-scale metal removal until the ways were
flat as indicated
by a level, then used a hand-scraped straightedge to remove high spots
until the bed
was flat and true. Essentially a spotting and hand-scraping job except
on material that
was too hard to scrape.

I tried the well-known Cratex rubberized abrasive first, but this left
an "orange-peel"
surface. I then tried the white Cratex muslin-bonded wheels, and they
left a much
smoother finish. It is a SLOW process! But, amazingly good results can
be had, if you
have the patience, and the measuring tools to be able to keep it straight.

Jon