On 2010-05-30, Searcher7 wrote:
On May 21, 6:51*pm, "DoN. Nichols" wrote:
On 2010-05-21, Searcher7 wrote:
[ ... ]
* * * * This is why I ask about the locking angle for one of the
supplied holders tried in both stations. *Normally, you should have the
same fit in both stations.
Yes. the supplied holders fit the same in both. In others words the
travel of the locking bar is about the same, regardless of which of
the two sides I use.(About 90 degrees, regardless of the supplied
holder I use).
From the most CCW starting position in both cases?
And when on the side it does fit on the swing distance of the locking
bar between locked and unlocked is only about 10 to 15 degrees.(Though
I don't know how important that is).
* * * * Given the starting angle, I consider it quite important, as the
lever will be over the tailstock -- and perhaps hitting a drill chuck or
live center mounted in it.
Ok. Since I don't have it mounted I can't be sure what will be in the
way.
*I* can -- from the photos alone.
* * * * Ideally, the unlocked position should be something like 3:00
o'clock (parallel to the bed, pointing towards the tailstock end of the
bed), and the locked position should be with the lever pointing out at
the operator.
Ok. With the tool post mounted 45 degrees from square(diagonal),
No! -- No! -- No! -- No! -- No! -- No! -- No!
The sides should be parallel to the chuck face and the bed,
*never* at an angle. You can't do parting with it at an angle, even if
you can sort of make other things work.
that
is the way it would be with one of the supplied tool holders on it.
Without a holder the locking bar will point toward the headstock.
Which means that it is likely to be hit by a swinging chuck jaw
and the knob be shattered. (*Always* wear safety glasses when using the
lathe or mill.)
[ ... ]
* * * * If you have two lengths of round rod of the same diameter (e.g.
drill rod), set the lever in the fully locked position and try measuring
the width of the two dovetails. *Do this using the rods as follows
(view with a fixed pitch font like Courier to avoid distortion):
* * * *______________
* *( ) \ * * * * * */ ( )
________\ * * * * */_______
(the rods should be bigger, but that is the biggest that I can show
using ASCII graphics.
* * * * Anyway -- place the rods into the Vs of the dovetails, and
measure the width across the outside of the rods (using a caliper or a
larger micrometer).
* * * * The measurement across the rods should be close to the same on
the two dovetails. *If it is not so, then one of them is improperly set
on the threads.
I'm not sure what "close" would be but I just measured both sides with
a ruler.
I'm talking about measurements with something which reads out in
0.001" increments or better.
And the measurements are 1-21/32" on the right side, and
1-2/3" on the left.
What kind of ruler do you have which reads in thirds of an inch?
And if that is correct, they are just a bit out. 1.6563" vs 1.6667"
(giving fractional sizes with different denomenators leads to confusion.
Convert to decimal fractions *first*.
And measuring with a ruler, without the rods is no way to
measure it, because the edge of the wedges has been "broken" to avoid
sharp edges, and there is no certainty that the same amount has been
ground off of each.
And I just noticed that the left wedge has some
play when the tool post is in the locked position. But in the un-
locked position it is the right wedge that has a slight amount of
play.
This is with no holder in place, I presume? And which are you
calling left and which right? One should be the front (the side towards
a long workpiece) and one should be the side (on the left, towards the
chuck).
* * * * Now -- just for the fun of it, do the same kind of measurement
*inside* the dovetails on both the supplied holders and the genuine
Aloris. *I suspect that you will find a somewhat wider measurement on
the supplied holders based on your fit experiments.
No doubt. I measured using the ruler and got 1-13/32" for the Aloris
and 1-14/32 for the supplied holders.
Again -- without the rods, you are measuring were the edges of
the dovetail were rounded off, not where the actual clamping forces
occur.
* * * * None of the photos show your post from the needed angle. *Look
at the toolpost diagonally from the corner between the two dovetails, so
you can see both wedges at the same time -- ideally with the viewpoint
at a level about half-way up the toolpost.
I took a another couple of pics, but it is difficult,because my Canon
G2 Powershot porduces washed out pics when flash is used or is too dim
when I don't use flash. The only good shot are outside when it's a
sunny day.
http://s290.photobucket.com/albums/l...slander/Tools/
O.K. A trick is to put a white card in front of the flash to
bounce it up to the ceiling -- or if the flash is in the wrong place of
this -- bounce it to a side.
* * * * If you can easily see that one wedge is higher than the other,
you have one started on the wrong thread -- an assembly problem at the
factory. *You *can* go back to the vendor and see if he can supply you
with a replacement one.
I don't know about it *easily* being seen, but the right wedge is
*slightly* higher.
*I* can see it easily in the photo. And that position may be
forced by the screw.
Take it apart as I described before and see whether you can
re-align the wedges. And see whether the screw can be removed while you
are about it.
* * * * But what *I* personally would do is to disassemble the toolpost
to the point of removing the wedges (I described how to do this in an
earlier article today) and re-installing them so you get both starting
at the same time, and so the lever angle winds up more reasonable.
* * * * Note that if you do this, you will probably void the warranty,
so if this is important to you, try the vendor route first.
I got this tool post years ago, so that is not an option. :-)
O.K. So fixing it is the only reasonable choice.
I seem to have already deleted the model number from the
toolpost, but do I remember it starting with something like "250-"? If
so, that is not an AXA size. The AXA should start with "100-" based on
the Phase-II system of marking. Are the holders starting with "200-" as
well? If so, you have a BXA toolpost, and it will never properly fit
the Aloris AXA holders. And -- it will be too large for your lathe, as
well.
* * * * And if it turns out that the screw is not present in others, it
might be that the screw caused the wedges to be put in with this offset.
The screw mentioned does hit the floor when the post is in the locked
position.
That should not happen Take the post apart and remove the screw.
Or perhaps adjust it to limit the over-travel?
* * * * It might help to know how these work internally:
1) * * *The lever turns a cylinder inside the body of the toolpost
* * * * which has a multi-start thread on its outside diameter.
2) * * *The wedges have partial mating threads on the inside, so
* * * * when the lever turns the cylinder, the wedges move up and down.
3) * * *The wedges move in contact with an angled surface which causes
* * * * them to increase or decrease the width of the dovetail as they
* * * * move down or up.
* * * * Since the thread is multi-start, it is possible to get the two
wedges started out of step, so one remains higher than the other. *And
-- it is also possible to remove the wedges and re-start them so both
move at the same height.
* * * * If the wedges are not at different heights, but the dovetails
measure significantly different widths, the cure would be to use a
proper dovetail mill to narrow the one which is giving the problems.
This problem would *certainly* call for a vendor replacement as the
first approach.
* * * * And if it comes to a choice between a proper fit for the
supplied holders or a proper fit for the Genuine Aloris holders, I would
go for the latter as this would increase the number of holders available
through surplus and eBay channels.
Yes. that is the goal. I just have to get the WD-40 out and wait for a
sunny day so I can take decent pics of everything as I go.
I can see enough to see that you should *try* to take it apart and
re-set the wedges.
Good Luck,
DoN.
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