How should I make this?

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How should I make this? Ian 03-29-2008
Posted by Charles Lamont on March 30, 2008, 9:29 am
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 Dave Baker wrote:

> On a manual lathe with conventional tooling figure on several hours per part
> and lots of burnt out tooling. Stainless is a pig. You'll probably start
> trying to drill the bore with successively bigger HSS drills just to get
> something you can get a boring bar into, shag them all and wish you'd never
> started the job.

That's the most sense I have yet seen on this topic.

--
Charles Lamont

Posted by Mark Rand on March 30, 2008, 12:34 pm
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> Stainless is a pig. You'll probably start
>trying to drill the bore with successively bigger HSS drills just to get
>something you can get a boring bar into, shag them all and wish you'd never
>started the job.


316 Se/ EN58JM/ 326S36

free(er) cutting 316 stainless ;-)



Mark Rand
RTFM

Posted by Emimec on March 30, 2008, 1:08 pm
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>
>
>> Stainless is a pig. You'll probably start
>>trying to drill the bore with successively bigger HSS drills just to get
>>something you can get a boring bar into, shag them all and wish you'd
>>never
>>started the job.
>
>
> 316 Se/ EN58JM/ 326S36
>
> free(er) cutting 316 stainless ;-)
>
>
>
> Mark Rand
> RTFM

303, even easier !!!



Posted by Dave Baker on March 29, 2008, 8:34 pm
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>I need to make several 'Top Hats' out of stainless steel, below is a sort
>of cross section in my first attempt at ascii art.
>
> The part is about 45 diameter and 45 long and will have a wall thickness
> of 1.5mm thick. The flange (brim) is 3mm thick and 48 diameter.
>
> llllllll
> llllllll
> lllllllllllllllllllllllllllllllllllllllllllllllll
> llll
> llll
> llll
> llll
> llll
> lllllllllllllllllllllllllllllllllllllllllllllllll
> llllllll
> llllllll

Starting from sawn blanks 48mm diameter and 45mm long with some machining
allowance on both dimensions.

1) Hold in 3 jaw with a few mm sticking out and drill/bore the hole to 42mm
dia and 43.5mm depth. Check depth of bore and face off the bottom flange.

2) Turn round in chuck and face off the top flange. Part is now at finished
length and i/d.

3) Now make a "pushing button" for use with a running centre - 44mm diameter
bit of aluminium or mild steel about 30mm long. Stick the biggest centre
drill you have into one end to fit over the nose of the running centre.

4) Chuck some scrap with 45 to 50 mm sticking out and turn that to a 41.95mm
diameter plain mandrel. Chamfer the end. You can counterbore the end lightly
to a diameter of 35/36mm if you're concerned that the bottom of the bores in
your top hat bushes aren't perfectly flat or have a pip in them. Then it
will just register around the outside of the end of the mandrel on a rim
about 3mm thick.

5) Fit the bored blanks over the mandrel and press back hard with the
pushing button and running centre in the tailstock. From now on you'll just
be using friction to hold the piece while you turn the o/d and flange.

I use friction to hold more jobs in my lathe than I do chucks. I'm always
surprised that no one else ever thinks of using it or realises just how hard
you can machine into something held this way before it slips. The same
people presumably also won't give a thought to the fact that the only thing
connecting the engine in their car to the gearbox and wheels is the same
principle transmitting 100 plus bhp.
--
Dave Baker
Puma Race Engines



Posted by Richard Edwards on March 30, 2008, 12:34 am
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>I need to make several 'Top Hats' out of stainless steel, below is a sort of
>cross section in my first attempt at ascii art.
>
>The part is about 45 diameter and 45 long and will have a wall thickness of
>1.5mm thick. The flange (brim) is 3mm thick and 48 diameter.
>
>As 50mm barstock will not pass through the headstock of a 5" Boxford I have
>though about buying cut blanks, gripping the OD in the 3 jaw and fully
>machining the bore. Then machining the OD by holding the part on some sort
>of mandrel. (The inner and outer concentricity need to be within 0.2mm or
>so)
>
>My dilemma is trying to decide how to hold the part on the mandrel (which I
>don't want to take out of the chuck until I've made all of the parts.
>
>I have thought of making an expanding mandrel which is somehow activated
>through the headstock spindle but it seems overcomplicated
>
>
>Thanks in advance for any suggestions
>
>Ian Phillips
>
>
>
>

A
llllllll
llllllll B
lllllllllllllllllllllllllllllllllllllllllllllllll
llll
llll
D llll C
llll
llll
lllllllllllllllllllllllllllllllllllllllllllllllll
llllllll
llllllll

Whilst I like Dave Bakers option it seems to ignore bore "C"

I would

Buy cut blanks at 47 long
Chuck in the "A" area as little as you are comfortable with
Rough allparts at "B" and "C" within .5mm of finished OD and ID
Turn around, chuck on "B" and complete roughing of "B". Rough out Bore
"D". Rough diameter "A".
Mark jaw 0 on part to allow putting back up with minimum error.
Do all parts
Finish bore "D" end face and diameter "A".
Main problem now is holding to finish "B" and "C"
Make a mandrel as follows

R S T U

111111111111111111111111 111
1111111111111 1 1 1
11 1 1
1 1 1
Drill 10 1 1 1 Tap 10
1 1 1
11 1 1
111111111111 1 1 1
1111111111111111111111111 111


The "R" diameter and length is to allow chucking. "S" will be a slip
fit in bore "D". A thick "O" ring will sit on diameter "T" and be
compressed with washer "U" clamped up with a piece of 10mm studding
through the spindle.

The parts previously roughed and part finished can now be loaded to
the mandrel with the "A" face on the chuck jaws and finished on "B"
and "C".

Some may say too much picking up and putting down, but the above tends
to differentiate between roughing and finishing and the associated
tool changes.

Thats what I would do, but I have "all the time in the world". <G>

--

Richard

Email address is valid but remove burrs before sending!

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