On Jun 1, 9:33*pm, "DoN. Nichols" wrote:
On 2010-06-01, Searcher7 wrote:
On Jun 1, 1:23*am, "DoN. Nichols" wrote:
On 2010-05-31, Searcher7 wrote:
* * * * [ ... ]
* * * * O.K. *You don't have a caliper? *Dial, digital, or even vernier?
Any of those would give you *much* more accurate measurements.
*** Yes. i have a vernier, some place. :-) And I do have a Shars
micrometer set (.0001).
* * * * O.K. *For this the caliper is both easier to use (especially
for measuring inside spacings) and certainly accurate enough for the
task.
BTW * * Do you *really* have a vernier? *(One with two scales, one
* * * * the full length and one shorter which is used to interpolate
* * * * between the markings on the full-length scale), or a dial
* * * * caliper, or perhaps a digital one? *Vernier properly applies
* * * * only to the first type -- but some mis-use the old term for
* * * * all calipers of the same basic shape.
*** A dial caliper is on my shopping list, but I have to find my
vernier. It's been a while and I can't remember details in regard to
the scales.
* * * * Go to a hardware store and buy some steel rod about the same
diameter as the depth of the dovetails. *Saw it in two -- or at least
saw off two pieces a little longer than the dovetails so the burred ends
will be clear (since I believe that your lathe is not yet set up to
use).
*** I'll be going away in a couple days and may have to do that next
week.
* * * * O.K.
* * * * [ ... ]
* * * * * * * * * * 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?
Correct.
* * * * With the lever in the fully locked position the screw is
probably hitting the T-nut blank (unless you have either removed it or
turned it to clear) so that would limit the motion of the left-side
wedge (sides as normally mounted, not from your corner view). *The front
side wedge may be hitting the top of travel in the unlocked position.
Ok. I'll have to read that a few more times. :-)
* * * * It will probably make more sense once you have taken the
toolpost apart.
* * * * [ ... ]
P.S. * *I'm likely to skip answering your postings tomorrow, simply
* * * * because by the time I'm through typing to you, there is not
* * * * sufficient time to read the rest of the newsgroup. *It is
* * * * already 1:21 -- though the date information in the headers is
* * * * likely to tell when I started typing on this one. *Hmm ... maybe
* * * * not. *I don't see the date in the header yet.
No problem. I'll have to slow up myself because I'm getting ready to
leave for New Hampshire. on Thursday and won't return until Sunday or
Monday.
* * * * As it turns out, there was not much real traffic in the
newsgroup, so I was able to finish it and go back to your message
threads.
Ok. I took apart the toolpost, but not completely because I didn't
have whatever tool is required to unscrew the ring situated under the
hex nut.
* * * * That's O.K. *You don't *need* to remove that for what we are
doing. *(The tool, BTW, is called a "pin spanner".
*** Ok. This is already on my shopping list.
http://littlemachineshop.com/product...ProductID=1416
First I want to say that three starts in the thread don't represent
much in the way of resolution,
* * * * The three starts are equally distributed around the screw, each
120 degrees from the other two.
*** Yes. Every 1/3 turn of the locking bar cause the wedges to snap
back up to the next thread if I'm pushing up.
* * * * * * * * * * * * * * * *for lack of a better way of putting it.
In all I took it apart several times and it is basically a crap shoot
as to where the wedges will catch when they are re-inserted. There are
three thread starts as you said. But the wedges can only catch the
same threads that are the same relative distance from each other.
Anything else would result in a great big difference in wedge high
between the two. So basically there are only three option for change.
* * * * I figured that one of yours was on the wrong start. *That is how
it was behaving.
*** The wrong start would manifest itself as an *obvious* difference
in height between the two wedges.
Very small change. (I hope I explained that clearly).
* * * * Not if you get one on the wrong start, which is what I believe
was the case. *Shifting the start on one relative to the other would
move one wedge up the distance of one tooth (visible on the back of the
wedge) relative to the other. *Shifting the start on both will move the
lever 120 degrees from the current lock positions.
*** Yes. The distance of one tooth would actually be more than twice
the tooth width due to the loose tolerance.
It's easy to tell when the wedges pass a thread entry point when I'm
pushing them up at the same time I'm rotating the locking bar
clockwise(toward the locking position).
* * * * Yes -- that is how you tell that both are on the start at the
same time -- make sure that both snap up a bit before you start screwing
them back up.
*** I'll have to play with it some more when I come back.
In the end I kept the locked and unlocked position of the locking bar
the same(for now), since it is only a problem with the Aloris
toolholder, which cannot be put on or taken off that side because of
the bar positon.(Not that I could put it on anyway).
So here we go. I attempted to swap the wedges, but of course that
didn't work. The surpise was when I took them all the way out. There
was another screw on the other wedge. But on top!
* * * * Intersting. *Those are apparently setting the limits of the
swing of the lever.
http://s290.photobucket.com/albums/l...slander/Tools/
* * * * Note from the photos that the actual threads on the wedges which
engage the multi-start cylinder thread are actually about 120 degrees
apart. *(Your photo IMG_0144.jpg). *It looks as though they are a bit
beyond that 120 degrees, but close enough if they designed the threads
to start at the right places.
When I put the toolpost back together I left the screws out. My
assumption is that the wedges were over-ground at the top and/or
bottom, and someone came up with the bright idea to tap and thread the
top of one and the bottom of the other to act as stoppers.
* * * * What I *think* happened is that they did not drill and tap the
hole for the lever in the right place (maybe each one is off a bit
differently) , and the screws allow them to move the max open and closed
positions somewhat -- but perhaps to have the wedges too tight.
But the only change that I can tell now with the screws out is that
the Aloris will still only slide down on one side, with effort. But
this time the left side. ??? (And I'm not sure that this has anything
to do with the screws anyway).
* * * * That suggests that you got the front dovetail one started one
thread before the left side one, so it is lower (and thus tighter) than
the other. *Or that this design should have the left one started one
thread before the front one.
* * * * I think that the screws do belong in this one -- if only to tune
things so the lever can't hit the chuck jaws.
* * * * The screw in the top of the front one adjusts the position of
the maximum open lever, and the one at the bottom of the left side one
adjusts the position of the lever in the maximum locked position -- the
one where you are worried about hitting the lever with the rotating
chuck jaws -- especially if there is no tool holder on either station.
*** The swing increased to about 225 degrees without the screws or a
toolholder mounted.
So it seems that I couldn't even sell this toolpost(as an AXA) since
it seems to be slightly off original Aloris manufacturing specs. (Now
I wonder if this is common with these knock-offs).
* * * * I've not heard other reports about this, so maybe just this
brand -- and maybe they have gotten better over time, since the other
person who had recently bought one of these (in BXA size IIRC) did not
find the screws in his.
The bottom line is that I'll have to find someone more experienced
than I to take a look at this and there may be some needed machining
involved in bringing it to spec. (ie: Slight milling of the wedges).
* * * * Hmm ... not sure about that being a good idea. *Perhaps the best
thing is to re-make the wedges so the threads all start in the right
place.
* * * * But *perhaps* simply filing off the side of the wedge which
locks up first -- or perhaps using a milling machine and a dovetail mill
of the right angle (60 degree I think) to cut a little off the non-wedge
side of the dovetail (very little -- only a few thousandths -- should
make it possible for the genuine Aloris holder to fit on both.
*** Yes. The non-wedge side is the corner between both wedges that
form 60 degrees for both sides.
* * * * But you might want to first play with them with only one wedge
in place at a time to see whether you can find good positions for each.
And there is still the issue of play. It's like the threads between
the wedges and the threaded cylinder inside have a loose tolerance.
* * * * That is so they don't get jammed by chips working into the
threads and the travel slides of the wedges. *Too much precision makes
things sensitive to dirt.
*** Yes. I was wondering how loose the tolerance should be.
I've been playing around with it and there are only three possible
swing ranges for the locking bar. And even if I can get the Aloris on
one of the wedges it would be with difficulty.
I agree that the screws were to limit the swing, but I don't think it
is a big deal. Especially with a tool post on. (But I'll put them back
anyway).
So It seems that milling the center of the post between the wedges is
the best option.
But first I still need to find out what the respective measurements of
AXA and BXA toolholders are supposed to be, so I can determine not
only which one I have, but also if they use the same size post body
with different wedges, or different sized posts. (which may complicate
things as for as mounting on the mini lathe compound slide).
My tool post is 2-1/8" x 2-1/8" x 2-3/16", without the base, which is
15/32" thick.
I'll also have to re-grease everything when I finish playing around
with it.
Thanks.
Darren Harris
Staten Island, New York.