Last night, as I was doing a polar alignment, one of the bolts snapped inside the base of the mount. The remaining length of bolt can't be unscrewed because the thread is damaged, so I need to remove the mount from the base so I can access the inside portion of bolt and cut away the damaged thread.
As I understand it, the two black plastic discs are removed in order to access the bolt which fixes the mount to the base. I've made alignment marks for refitting, but I'm having a bit of trouble getting these off, and was wondering if anyone could offer advice?
I put M10 screws.. Much stronger than original.
The also do not need to be much longer.. if you do not travel much with mount.
Thanks Bojan. That's where I want to end up, I just need to get rid of the damaged bolt. Is your replacement using the original M10 thread in the mount, and the exterior nut is an addition?
Bolt and nut are from bunnings... Original thread in the mount is (was) M8, I drill it out and tapped M10.
It is easy to dismantle the mount, once you remove plastic caps (they are glued with neoprene glue) you will see how proceed...
Just an thought, have you loosened off the other altitude adjusting screw, unless you loosen it the broken screw is still locked in with pressure on it. If and when you do get the broken screw out you could try something like these as an option.
AS Bojan said, you would have to drill and tap a 10mm thread, if you are able to do that, otherwise you can get similar 8mm thread hand knobs from the same or similar suppliers. There are suppliers in this country as well if you want to obtain locally.
Thanks Jeff.
The other adjustment bolt is not engaged, but is in the right position. The bolt in question snapped as I was trying to push the mount against the intact bolt, if you know what I mean. The bolt wasn't strong enough to move the mount with scope etc, even though its only about 10kg payload.
It's something I've expected to have to do anyway, and I'm still really happy with the mount. A few upgrades here and there still make it excellent bang for buck.
If you take most of the weight by lifting the counterweights when raising the altitude, the original alt bolt will last the lifetime of the mount. It is not reasonable to expect a budget quality bolt to raise the mount unaided when
operating adjacent to the mount's pivot point, against the huge leverage of
the counterweights out near or at the end of their shaft. I haven't done any
measurements, but your 10kg load probably equates to a 70-80kg load
on the bolt, plus the not insignificant resistance when the end of the bolt
grinds on the mount as it rotates. I had 13kg on my HEQ5, and when I sold it after 7yrs the bolt was still fine.
raymo
The mount is back up and running. I used a heat gun to soften the glue and managed to get the discs off in one piece. The original bolts are M10, so ther was no need to tap a new thread. If the new high tensile bolts struggle I might go up to M12 fine thread, but it seems pretty solid now.
Thanks to everyone for the help.
Cheers
Stephen
Good to hear that it is up and running again, one other tip I should have mentioned earlier is to round off the ends of the new alt bolts , where the press against the casting inside. The ends of most bolts, screws etc have raised leads to the threads from the thread forming process and they could bite into the cast lever, or whatever its called causing problems with binding and also putting undue pressure on the screw threads and possibly damaging the thread .
Thanks Jeff, yes I noticed the rounded ends on the original bolts, and used my grinder and a file to clean up the new ones. I have to say it's now a LOT easier to make adjustments using a spanner.
