[Moon-Net] metric bolts for RAK ... (etc.)
Edward R Cole
kl7uw at acsalaska.net
Mon Apr 5 18:26:48 CEST 2021
After several replies to my comment that there were no nuts welded on
the RAK, I went to the garage where my 2m-eme RAK lies. It has nuts
welded, so I would guess I am mistaken in that observation, made
below. In fact that jogged my memory why adding a stop nut did not
allow enough bolt thread to tighten on the mast (because there is
already a nut and thickness of the upper pipe housing).
Its just 8am here in AK so too early to call my hardware supplier (AK
Bolt & Chain) if they stock 50mm long M10 bolts and nuts. If not
they can probably order them for me, so thanks to several who offered
to ship them to me.
Also winds are calm this morning and I was able to rotate the array
(enough grip on the mast apparently for that). But expect antennas
will be subject windmilling any time there is wind (so array not
usable on windy days). But this may allow me a few weeks for spring
to arrive in AK before attempting repair (new bolts, nuts, lock-tite,
and new shear bolt).
In meantime, I hope to get a boom truck to pick up the 50-foot 2m-eme
tower and lay it down on the ground. When snow melts, I will be able
to remove bottom 20-foot of the tower and use upper 30-foot. Base in
concrete appears bent so not sure if can be straightened or it will
require pouring a new base for the shorter tower. Plan is to put up
one ten foot section and assemble 4x array temporally clamped to the
tower, then add 20-foot more of tower and raise array to top using a
boom truck. Expectations this will take the month of May to accomplish.
73, Ed - KL7UW
Re-install of my 4.9m dish will likely be done after the 2m-eme
system restored; waiting on welder to build new base tower.
6m Harris kw amp faulted last time I tried loading it; so will look
into that (50v-50A PS shut down at 20A, so might be the PS??).
At 02:25 PM 4/4/2021, you wrote:
>Had several replies so will answer all here:
>Sorry Alfa-Spid RAK nor Alpha-Spid (got it)
>The RAK has just a round housing (call it a pipe). No nuts welded
>to it. Thread is only the depth of the pipe (maybe 1/8 inch or
>Therefore was concerned that over tightening would strip out the thread.
>Mast is what we call black-pipe; mild steel. 1.25inch I.D.
>schedule-80. Used same on my other antennas with no bends or failures.
>I have learned thru experience not to trust pipe bolts from slipping
>so have been using a 5/16-inch bolt thru rotator pipe and mast to
>help hold the pipe but small enough to shear if something binds
>up. Well the rotator was installed in Sept. 2020 (six months ago).
>I did maintenance on antennas and cables last weekend and found at
>least five loose set bolts. Also the head of the 5/16 inch bolt had
>been sheared off and weight of the array caused mast to drop
>slightly (nut end of shear bolt was intact and bolt had bent
>downward making removal impossible). So I re-tightened the set
>bolts figuring that would be OK for a couple months as I had plans
>to do more work in warmer wx (still winter here).
>This was a Sunday and only Home Depot open. The good bolt outlet is
>closed weekends. Rented Man-lift returned on Monday morning. So
>unlikely to find eight longer metric bolts on Sunday.
>Guess I could have used lock-tight (never occurred to me as other
>rotators never had this issue). I use an identical RAK on my 2m-eme
>system and it free-fell 50-feet in a high wind storm yet rotator was
>secure and undamaged; set bolts tight.
>Well I will use lock nuts and longer M10 bolts, plus lock-tight. I
>will replace shear bolt with at least 3/8 inch diameter.
>6m-eme array is very large: 25-foot long cross boom with 32-foot
>long yagi booms. That catches a lot of wind force.
>Rotator may still turn the array in calm wx (??), but will require
>re calibration, frequently. Maybe, I can delay until May wx when
>easier to work without winter coats/gloves. I have to replace my
>elevation actuator and repair my digital encoder (which will require
>dismantling). Actuator arm is 40-inch long and weighs probably
>35-lbs or more; awkward to handle at 45-feet. So I had planned to
>rent the man-lift for this work.
>At 01:15 PM 4/4/2021, Don Hawbaker wrote:
>>My SPID has nuts welded onto the pipe. It's an RAS. Different
>>model. You have to be careful. I have stripped the threads on at
>>least one of the nuts. Someday I will cut it off and weld on a new nut.
>>Sent from <https://go.microsoft.com/fwlink/?LinkId=550986>Mail for Windows 10
>>From: <mailto:moon-net at mailman.pe1itr.com>Edward R Cole via Moon-net
>>Sent: Sunday, April 4, 2021 4:50 PM
>>To: <mailto:sp2fry at gmail.com>Andrzej Hoffmann
>>Cc: <mailto:ak-vhf at mailman.qth.net>ak-vhf at mailman.qth.net;
>><mailto:moon-net at mailman.pe1itr.com>moon-net at mailman.pe1itr.com
>>Subject: Re: [Moon-Net] metric bolts for RAK
>>Well we got as windy day, today. Only been a week since I discovered
>>the Alpha-SPID set screws loose and tightened all eight of them.
>>My 6m-eme array is free-rotating in the wind. Apparently the set
>>bolts loosened up in only a few hours of wind, and the remains of the
>>shear bolt has fully sheared off. And all because the mfr was too
>>cheap to supply stop-nuts (or lock-nuts) to keep the set bolts
>>tight. I actually tried adding a stop nut but that left too little
>>thread to tighten the set bolts (nut needs to be thinner or bolt longer).
>>So either try to find longer metric bolts in America or quit and
>>smash everything to H and take up stamp collecting.
>>Was considering trying eme with the new array pretty soon, but it
>>will cost me another $233 to rent a man-lift just to tighten the
>>Well, I will use a 1/2-inch shear bolt this time (equivalent diam to 10mm).
>>I did test the RAK and its rotating ((evidenced by the change in
>>direction on the indicator) so apparently not a gear failure -just
>>not attached to the antenna.
>>Hopefully array will not over-rotate and destroy coax lines in the process.
>>At 02:37 PM 3/31/2021, Andrzej Hoffmann wrote:
>> >Hi Ed.
>> >If you have a problem with the metric screws I can send you some.
>> >Write down the length of the bolt you need. The original ones are
>> >probably 25 mm. As far as I know, they are M10 threaded screws.
>> >Vy 73
>> >Andrzej SP2FRY
>>73, Ed - KL7UW
>>Dubus-NA Business mail:
>> dubususa at gmail.com
>>Moon-Net posting and subscription instructions are at
>73, Ed - KL7UW
>Dubus-NA Business mail:
> dubususa at gmail.com
>Moon-Net posting and subscription instructions are at
73, Ed - KL7UW
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