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Posted by ravensworth2674 on September 7, 2008, 3:16 am
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On 7 Sep, 00:57, jontom_...@hotmail.com wrote:
>
>
>
>
>
> > On Sat, 06 Sep 2008 17:59:51 +0100, Charles Ping
>
> > >On Sat, 6 Sep 2008 03:47:17 -0700 (PDT), jontom_...@hotmail.com wrote:
>
>
> > >>Snipped Interesting Stuff
>
> > >>> It's only an HLV and it cost me about =A3250 (plus two years so far=
rebuilding
> > >>> it without seeing it run yet...)
>
> > >>> Mark Rand
> > >>> RTFM
>
> > >>Mark, in reading your comment here I thought it must be at least 4 or
> > >>5 months since our last update on Dovetail grinding etc as related to
> > >>"just an HLV". Have you made progress or indeed finished the bed re-
> > >>build? Apologies if I have missed an update but family diversions mak=
e
> > >>my forum access irregular at the moment. I am always on the lookout
> > >>for such a machine (at a similar price :-)) but even if I fell over
> > >>one at the moment I would lack the confidence that it can be "sorted"
> > >>without spending something a fortune.
>
> > >>Regards
>
> > >>Keith (interested but impoverished of Wales)
>
> > >Keith
>
> > >One of the big benefits of a Hardinge is that the bed ways are
> > >removable and therefore easily taken off for regrinding. The fact that
> > >Mark chose to do it the hard way with an undersize surface grinder
> > >shouldn't put you off!
>
> > >Charles
>
> > It's actually 6 months almost to the day since I started the bed regrin=
d. I
> > did the thickness and needed to take 6 thou off before I got below the =
wear
> > marks. Once I'd done that I could measure the wear on the dovetails. On=
e
> > interesting thing that I discovered in so doing, was that the bed was n=
ot made
> > parallel to the piece of metal it started off as. There are non-wearing
> > vertical edges for the top 1/8" or so of the dovetails. The original pl=
an had
> > been to use these as references when regrinding the dovetails. Unfortun=
ately,
> > Messrs Hardinge put a 12 thou sideways slope on the dovetails with resp=
ect to
> > these verticals :-(.
>
> > I intend to regrind these vertical bits so that they are parallel to wh=
ere the
> > bed should be. I can get this alignment from the unworn parts of the do=
vetails
> > at the very ends of the bed. The reason for correcting this original
> > sloppiness is so that I can use a fence on the sine vice to align the b=
ed.
>
> > To align the bed to grind the verticals, I intend to accurately mount f=
our
> > datum blocks on the bottom of the bed and adjust them on the surface ta=
ble
> > until they're parallel to the correct line. Then I can mount the bed on=
the
> > vertical sine vice on the grinder and adjust the alignment with a dial =
gauge
> > against the datum blocks. Once I've ground one side, the other vertical=
edge
> > side and the dovetails can be referenced from the ground-in-place fence=
of the
> > sine vice.
>
> > It should be noted that AFAICT, Hardinge never intended the beds to be
> > reground. You're supposed to simply buy a new two piece bed and bolt it=
on.
>
> > =A0A minor issue is the fact that I don't actually have a sine vice. I'=
m in the
> > process of making one based on a 6"x12" electromagnetic chuck that I ha=
ve.
>
> > Unfortunately, pressures of work, spending weekends and holidays trying=
to
> > find the garden and stuff meant that I haven't yet finished the sine vi=
ce.
>
> > The recent deluges handily stopped all garden reclamation work for the =
year
> > :-)
>
> > Then to add insult to injury, I got distracted by making an electricall=
y
> > heated salt bath to harden the apron gearbox gears. I spent a weekend
> > hardening them. More time fitting them, toolpost grinding journals, gri=
nding
> > the width of some of them, finding that I hadn't allowed enough clearan=
ce for
> > most of them, trimming some and re-making two (too hard to recut). Then
> > discovering that Hardinge had originally bored some of the holes 3 thou=
too
> > small for the needle roller bearings they were using (explained the und=
ersize,
> > shagged shaft though!) and so on.
>
> > Note to self:- Next time fit dowels in the gearbox bearing holes and
> > accurately measure the centre distances instead of making assumptions. =
Also
> > don't trust that any hole was originally the right size, even if there =
is a
> > bearing pressed into it :-(
>
> > I've got one more gear to finish trimming to get the running clearance =
to a
> > level that I'm happy with. Then after grinding the clutch bearing thrus=
t races
> > to fit and making new brush caps for the motor and cleaning that up, I'=
ll be
> > able to finally put the apron gearbox on the finished pile. Then I'll g=
et back
> > to the bed.
>
> > There is progress, but it's not always in the right direction or speed.=
I
> > really want to get the job finished so that I can get on to rebuilding =
the
> > mill, which I was about to start before the HLV turned up!
>
> > _
> > Mark Rand
> > RTFM- Hide quoted text -
>
> > - Show quoted text -
>
> Mark
>
> Thank you very much for taking the time to provide such a
> comprehensive insight to your rebuild, it has been extremely helpful
> to me. You have also covered some areas where I had concerns caused by
> stories I heard (20+ years ago) from the technicians that looked after
> such machines. Their belief, not just with HLV, was that while
> superbly engineered there was in fact a lot of "individual" fitting
> with each of these toolroom machines. They also had stories of a
> number of well engineered "fixes" that were obviously used to recover
> minor production errors. I have also encountered the undersize bearing
> housing in aerospace components, mainly to overcome the possibility of
> differential expansion but, on one occasion" the rep said that it
> allowed the use of cheaper "standard size" bearings and ground
> shafting. Apparently, if anything shafting would be slightly
> undersize, never oversize, with thin housing bearings the other way
> round; therefore a "small degree" of pre-load would always ensure a
> zero clearance bearing. In that instance it was not a problem as it
> was a very short life component. I can't see yours being for the same
> reason as I wouldn't think the production numbers were high enough.
> This was over 20 years ago and I suspect production tolerances of even
> basic items is much better nowadays.
>
> I must say that my confidence is not improved as your bed problems
> seem only a part of the issue. Perhaps I won't rush at a machine until
> I can have a good look at it, even if cheap. I suspect like you, once
> I owned it I would "have" to put it right no matter how long it took.
> I should really continue to use my present machines until I can out
> perform them rather than, as it is now, the other way round. Anyway
> thanks again Mark, best of luck in your rebuild - it will be all
> worthwhile in the end.
>
> Best regards
>
> Keith- Hide quoted text -
>
> - Show quoted text -
Getting old and somewhat able to stand back a bit, I wondered and
wandered.
I felt that I wasn't the only one here. The big question is just how
much worn out crap is being discussed.
At first glance, it suggests that more than one of you is the proud
possessor of a worn out lathe.
Assuming that the Myford ML7 has nothing worse than a worn bed, it can
be fixed for a perhaps =A335.
If it has a worn spindle( as mine has) then it it is a different
matter altogether. However, replacing a dodgy old Myford
with a dodgier lathe which cannot be re furbished for less than the
price of a tank of fuel is another matter.
I may be rambling somewhat but I am the only one who has put a sort of
price on my comments. Again, I have actually got to the end of a
restoration project.
Maybe there is another 'cost accountant' who will add his two
pennorth.
Meantime, my kind regards
Norman
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