A fellow group member and I are both experiencing a little issue with
the 200 series QCTPs fitted to our BH600 lathes. With the post central
bolt tightened to a "normal" level the post sometimes rotates when the
tool holder is unlocked/locked. Being a practical sort my solution has
been to really tighten up the post but I wonder if anyone else has
experienced this and found a more elegant solution. We have checked
the usual things to ensure that the post is flat on the bottom, the
bolt thread is clear, the T nut is below the top slide surface etc but
haven't found anything obvious. Has anyone else had a similar problem
and cured it? Otherwise, just how hard should we expect to tighten the
central bolt holding the post?
I solved a similar problem by inserting a small piece of 'non-slip'
matting - shelf liner type material, looks like an old Aertex vest -
between the underside of the toolpost and the topslide. I also tried fine
emery cloth, which also worked.
Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
I have one of these on my Harrison L5, but as it doesnt have a t
slotted cross slide Ive had to use a long M12 bolt and make some
spacers to fit the bore. I havent had it shift on me, but I do tighten
it up quite a lot. I use about 12" long ring spanner on the bolt.
The answer must lie in two flat- flat surfaces being
together. Frankly, if that was the case, the whole gubbins would not
have moved. The logical deduction must be that one or the other
surface is concave- or becomes distorted upon tightening.
Is there any practical experience of a top becoming concave? My Myford
long top slide on the saddle had been pulled out of shape with
incorrect bolting down by the previous owner. Now George Thomas also
refers to the problem in Model Engineers Workshop Manual. Again,
'Martin Cleeve' made a fabricated block for milling and this kit is or
was sold by Blackgates. When I had a Axminster 9180- near a 918, I
built a steel subtable following the afore mentioned concepts.
Coming back to your own problem requires a possible solution. assuming
that the top is or becomes buckled, it is pretty difficult to surface
grind or scrape it flat- flat and it would thin the lot if done. So, I
would hollow the bottom of the tool holder around the bolt hole to
leave a ring. Again, has this been done? The answer is that Cleeve did
it on one of his fabricated tool holders with great success. I had one
If you follow Cleeve through on a ML7 top slide which he made, his
single bolt at the side- mark you- held despite being only finger
I may be wrong- but it is worth a try
Thanks for all the ideas Guys with help I hope that I have finally
found the problem with mine.
Chris, thanks, I had forgotten about the lesson we were all shown that
a piece of paper wrapped round a MT in a worn socket could stop it
moving. My only excuse is that it was a long time ago!
Dave, my post is fitted with a locking lever (just welded to the nut)
but it is only 4 1/2" long so will not produce anything like the
torque your ring spanner will; when I've fixed what I believe the
problem to be I'll think again about if the handle is long enough. I
have an aversion to bashing handles with my hand as I've seen a few
hands damaged that way.
Charles, I can't really blame the BH600 (do I sense a tinge of "yuck"
in your comment :-) Vbg) However, the mounting system supplied by the
importer is I now believe part of the problem.
Norm, thanks for your pointer and I have previously used the principle
of relieving the centre to allow a firmer "ring" contact with total
success. The BH600 however has a very wide T slot (1 1/4" wide) and so
contact between the tool post and the top slide is actually two strips
5/8" wide by 3" long. Your other comments about possible distortion
was also very useful as checking for it led me to find what I believe
The T nut supplied is some 5/8" thick and as I said very wide so one
of my first checks was to ensure that there was a gap between the
bottom of the post and the top of the T nut so that proper clamping
force was exerted. This checked out fine at the front with a .005"
feeler having no trouble entering the gap. However, on further
checking the back of the post, it doesn't; in fact a .002" feeler is
grabbed by the post as soon as you start to tighten it. Obviously
either the T slot is not parallel with the top surface of the Top
slide or the T nut is tapered. Either way I'll mill the T nut thinner
and that should (fingers crossed) cure the problem. No time today so
it will have to wait until the domestic authority is satisfied with
the progress on the bathroom.
One other question on this toolpost, it has a 3/8" UNC tapped hole in
one of the side faces, any idea what this is for?
Thanks again to all, enjoy Harrogate if you are lucky enough to be
I did try to avoid the apparent teaching you how to suck eggs( which I
can't) and a cry from the heart but it did happen to me.
Somehow, it does suggest that we go off at a tangent and think of
blueing in and scraping everything in that imaginary circle to mate.
Don't fire rude remarks as it ain't according to proper workshop
practice- you experts!
I did mention a sub table which can be bolted down so as not to slip
but you can bugger about with it- and not lose precious metal.in the
Has it been done? Well, 'Cleeve' did it and so did Prof Chaddock.
Meanwhile, Keith, I am also up to the curly bits in work and I am
trying to get to Harrogate- with John's bottle.
Have domestic bliss
Norm, guilty as charged :-). Missing the obvious is a major tendency
with me, despite being told about it many times. I'm much more
interested in "that" obtuse and complex piece of emerging engineering
that "really" causes all the problems. I expect you have seen this but
I think it is typical of me (and not only me?):
"The Lone Ranger and Tonto are camping in the desert, set up their
tent, and are asleep. Some hours later, The Lone Ranger wakes his
"Tonto, look up and tell me what you see."
Tonto replies, "Me see millions of stars."
"What does that tell you?" asks The Lone Ranger.
Tonto ponders for a minute.
"Astronomically speaking, it tells me that there are millions of
galaxies and potentially billions of planets.
Astrologically, it tells me that Saturn is in Leo.
Time wise, it appears to be approximately a quarter past three.
Theologically, it's evident the Lord is all powerful and we are small
Meteorologically, it seems we will have a beautiful day tomorrow.
What it tell you, Kemo Sabi?"
The Lone Ranger is silent for a moment, then speaks.
"Tonto, you Dumb Hoss, someone has stolen our tent."
The BH600 has a relatively high topslide and even though it is a 6"
lathe, with the 200 series post you can only use tools less than about
15mm high. There is just no room for a sub table. As you will know
from your 9180 Norm, the mounting on those is in effect a sub table,
one of my most successful improvements was changing mine to a four
bolt sub table.
Norm, hope you enjoy a good ride over to Harrogate in that new mini.
Take care with that bottle you know how "cranky" John can get when he
is thirsty! I'm sure that a long day serving all those "nice"
customers and explaining the CNC at least a thousand times will make
his throat very dry. He'll be "right pleased" to see you.
Thanks again Norm, take care.
Eh? You have a bar welded to the nut? Doesnt that get in
the way? (QCTP not 4 way TP?) or are you using the 4wtp locking lever?
I have a locking lever in the top conical piece(silver on mine) and
then a nut on the bolt that goes through. I had to make some end
spacers for the tube which sits in the hole to reduce that to
12mm(ish). I did notice that if this tube jams slightly then locking/
unlocking the slides becomes quite hard, which might be part of your
problem? With no toolholders on the post the tool locking lever is
spinnably free when its all clamped up correctly.
Mine is the set from arc euro if a picture helps to see if its
I have what looks the same QCTP but mine came from Warco and is about
5 years old, it is marked "250-200" China. The "bar" is welded at a 30
deg (upwards) angle to the nut on the through bolt, it's all black and
obviously done at manufacture. At that angle it clears the toolholder
slide locking lever. I therefore have two levers and don't require a
spanner at all. I find it a nusance as I'm always unlocking the wrong
lever and may well revert to a normal nut and spanner to avoid my lack
of attention. My central tube is about .040" higher than the silver
conical piece and does not seem to have any interaction between the
silver conical piece and the central tube, I can see however that this
could well happen if the tube was a little too short or rather a tight
fit going through the conical piece or even if the two pieces were not
concentric. Dave, hope that explains a little more clearly what I
Apologies Charles, no slight intended. It's just my sense of humour or
what's left of it after battling with a few feet of copper pipe all
morning. Lunch didn't taste much of other than cardboard either so
must be just a bad day.
Yes I follow that. Mine is marked the same, but came with a nut, a
post and iirc a large square theaded bit to make your own t nut from.
Would you like a new post etc? I cant ever see me using mine, so its
surplus if its of use. drop me a mail off list to small dot planes at
ntlworld dot com
The spacers I had to make were because the tube in the post is much
bigger than m12, which is all that would fit through the harrison
topslide (metric bolts free issue where I used to work, imperial
didnt) and without them the post wouldnt sit nice and turn/tighten up