Re: Help - Counterweight shaft stuck to Mach 1 counterweight adapter.

Joe Zeglinski

Hi Terry,

Same thing happened to me on my brand new AP-900.
It seems that the adapter isn't torqued strongly enough during assembly. Luckily, I didn't screw in the shaft too tightly, and this was in the house, rather than in sunlight.

I suggested to AP that they apply a bit more pressure on the adapter with their wrench, during final assembly. I think mine was barely finger tight - I figured mine was an exception, possibly something missed in QA before shipment.

Second suggestion was to add a Teflon washer to the threaded end of the counterweight bar, so that the bar and adapter don't seize together in a death grip, as has happened in your (and my) case.

In your case, have you tried a fine machine oil, to see if it would unlock the two pars? WD-40 might work, but don't keep it on very long, since it is mildly corrosive - then again, it really shouldn't mar a black anodized part.

If the Mach1 adapter is like the AP-900, you might be able to fashion a "huge spanner wrench". My adapter has two diametrically opposed holes (about 1/4" diameter) for AP's spanner. Take a length of 2x4 (say a couple of feet long). Drive two heavy nails, along the length, into the end to fit into the "spanner holes" of the adapter. Or, a couple of machine screws bolted through the 2x4, and into the adapter (flange) with rubber or plastic washers under the nuts to prevent marring the adapter - this would be a very solid spanner, where the nails might just twist under torque.

With the shaft covered in rubber, cork, or some other protective material, locked in a vice, try to use the 2x4 to twist off the adapter. A 2 foot length of 2x4 should give you plenty of leverage.

That's what I would do to mine, if it ever locked again. I'm still looking for a suitable diameter Teflon washer, but even a margarine tub lid cut to size, will do in the short term. Perhaps AP, on request, could mail their customers a couple of these Teflon washers, to prevent future lock ups.

Good luck,

----- Original Message -----
From: "TerryLO" <>
To: <>
Sent: Sunday, June 08, 2008 11:48 PM
Subject: [ap-gto] Help - Counterweight shaft stuck to Mach 1 counterweight adapter.

I need some assistance. My counterweight shaft (1.875" x 10.7")
is "stuck tight" in the Mach 1 counterweight adapter (the part of the
Dec. Axis portion into which the counterweight shaft is threaded).
The shaft is attached externally (in its normal use position) to the
adapter and not internally (in its optional storage position).

At a public star party Saturday evening, I set up the Mach 1 for use
about an hour before sunset. I hand-screwed the counterweight shaft
into the Mach 1 counterweight adapter and stopped when snug-tight as
usual. (It was in direct sunlight on a warm evening.) When I
dissembled the scope, mount and tripod about 1:00 AM Sunday morning
to go home, I noticed that when I unscrewed the counterweight shaft,
the counterweight adapter unscrewed from the mount attached to the
counterweight shaft.

Not thinking that anything significant was amiss, I wrapped the shaft
and the attached counterweight adapter in large sheet of bubble wrap,
placed in a carrying case and drove home, thinking I would make
everything nice during my usual morning-after clean-up.

But alas, the shaft will not cooperate and separate from the adapter.
I tried several things (using the screw head in the center of the
shaft with an Allen wrench for leverage; soaking the shaft in ice
water while keeping the adapter warm, having two people try to turn
the parts free;.) but nothing has worked. I am cautious about getting
too aggressive with the adapter for fear of damage or disfigurement.

I now have a pretty black machined aluminum adapter firmly apart of
my counterweight shaft and a large opening on the Mach 1. It is
possible to be could used like this (the adapter does have thread
that screw into the body of the Mach 1). But I don't think the
delicate threads of the adapter are meant for frequent use in the
field, it leaves a large opening for dirt on the mount, and it makes
storage of the counterweight shaft awkward.


First, Roland, Wally, other Mach 1 users, what should I do?

Second, have others had this problem with their Mach 1? (I have not
had this problem in 7 years of use of my 600EGTO, but then it is
constructed with different materials and machining than the Mach 1.)

Third, what should be done to prevent this in the future? (E.g. Not
allowing the shaft/adapter to get direct sunlight? Put a washer on
the end of the shaft to allow some play? Get a modified Mach 1
adapter? .)

Thanks for your help

Terry Opdendyk


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