On Sun, 11 Dec 2011 23:21:37 +0000, David Billington
wrote:
Ed Huntress wrote:
On Sun, 11 Dec 2011 20:58:20 +0000, David Billington
wrote:
Joseph Gwinn wrote:
In article ,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:
" fired this volley in news:7080e05e-
:
Since you do not have to end up with a hole of an exact size, I would
suggest line boring. But you have had a end cap welded on. So I am
kind of too late.
That would require building more tooling than the job is worth. Getting
that tube squared up on the tool rest, at the right height, and true end-
to-end would be a terrible amount of work.
(considered it, though! G)
I assume you are going to use a steady rest...............
Would, but mine won't open to 6.5".
It's fairly easy to cob one up from aluminum plate for a known diameter.
You might also see if you can get some aluminum hollow bar.
??? They're not precision-bored, either. This will end up being a
cylinder for a pasta extruder. (no... commercial air cylinders aren't
cost-effective, either ! G)
For honing I would look at flexible hones.
Just how good does this need to be, to extrude pasta?
One classic dodge I read about in old machining books was to attach the
workpiece to the carriage and mount a long boring bar between centers of
the lathe. The bit is in the center of the bar, perpendicular to the
bar axis. One moves the carriage to machine the bore.
I used that technique last year when I wanted to make some backing bars
for a pipe bender and had no other practical way of machining a
semi-circular channel about 10" (250mm) long to suit 1.5" nominal bore
pipe . The between centres boring bar was trivial as no great accuracy
was required so I just used a grub screw to clamp the cutter in a cross
drilled hole and set its position with the DRO. The larger part of the
project was making a T slotted table to go on top of the cross slide of
my Harrison M300. The M300 has a cross slide with a top like a dovetail
cutter for clamping tooling to, this seems to be a feature of more
recent 600 group products and seems to be used on some
Clausing/Colchester lathes as well. I worked very well and I can see the
T slot table being used for other things in the future. I can also see
that in Lloyd's case he would end up spending some time making suitable
brackets to hold the tubing to the cross slide.
T-slotted cross-slides, FWIW, are a British thing and go 'way back.
During WWII, when South Bends were made under license in the UK, they
made them with T-slotted cross slides. There was a company, either
here or in the UK, who made them available a couple of decades ago;
they were cast and had to be machined and scraped-in. I always wanted
one for my SB.
I didn't realise they were a British thing but my Kerry 1140
http://www.lathes.co.uk/kerry/page2.html has 2 slots as standard.
That looks like a very nice lathe.
A mate
has a WWII era Southbend so the next time I'm over there I have a look
and see if it has a T slot cross slide . IIRC his father has shown him
how to do milling on the lathe so it's possible it has the T slots.
Yeah. I don't know if they made all of them that way, but I know that
was the source of some of them that wound up in the US in the early
'50s. I've seen a couple of old ones here.
Dan in the other response posted a source of the T slot Southbend cross
slide castings, do you still have the inclination to make one and if so
do you have the time?
Aha. Well, the issue now for me is getting the milling done, and the
total cost. I scrapped my milling machine this past summer (a 1917
Taylor & Fenn knee mill that was in need of scraping and lead screws,
or a new mill), and I haven't replaced it yet.
It's not something I'd use all the time but I used to make model steam
engines and it's really nice for line-boring and for some milling
jobs. If I get time, I'd like to make some IC engines. It might be
worth it if it looks like I'll have that much time to get back to
hobby machining. Right now, I don't.
--
Ed Huntress