[Moon-Net] metric bolts for RAK

Rune SM5CUI sm5cui at telia.com
Mon Apr 5 14:06:06 CEST 2021

Hi All,
My Spid RAK mounted January 2007 looks like this, attached some small (150 kB each) images.

I have drilled a hole in each 2 "steel pipe for a screw to be tightened to a stop, appears in one picture.
Have once during these years discovered that the other screws have been slightly loosened.
This rotator carries 4x15 plus 4x10 elements 144MHz antennas.

73 de Rune/ SM5CUI

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Från: Mitch VE6OH CIW308 via Moon-net
Skickat: den 5 april 2021 09:44
Till: Don Moman VE6JY; moon-net at mailman.pe1itr.com; Alfa Radio Ltd.
Ämne: Re: [Moon-Net] metric bolts for RAK

All the units we have have nuts in them so it does not make sense.  Humm


J. T. (Mitch)  Mitchell
Amateur Radio Call VE6OH / CFARS Call CIW308 / CIW930
780 446 8958  Cell
Past Director for RAC - AB, NU, NWT  RAC.CA
Celebrating 100 years of amateur radio in Alberta
Summer 2021   --   www.ar100.ca

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On 2021-04-04 17:00, Don Moman VE6JY wrote:
That's surprising that the RAK (now) doesn't have nuts welded to the pipe.  All mine have welded nuts, but they are older.  The threads in the pipe itself would not be strong enough. I will make an inquiry.....

On Sun, Apr 4, 2021 at 4:27 PM Edward R Cole via Moon-net <moon-net at mailman.pe1itr.com> 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 metric equivalent).

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.

73, Ed

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.


73  WA3RGQ


Sent from Mail for Windows 10


From: Edward R Cole via Moon-net
Sent: Sunday, April 4, 2021 4:50 PM
To: Andrzej Hoffmann
Cc: ak-vhf at mailman.qth.net; 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 bolts (again).
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.

73, Ed

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 

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73, Ed - KL7UW
Dubus-NA Business mail:
  dubususa at gmail.com
Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html

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