If I were drilling a hole in a chrome moly mast without the benefit of a drill
press, I’d be looking to borrow or rent a mag drill.
Yes it requires 120v but the amount of time and aggravation saved would make it
worth figuring out how to get power up there.
That or replace those clamps with something better.
W2XX/7
> On Jul 28, 2020, at 6:53 PM, john@kk9a.com wrote:
>
> You made a good decision going with a 3" mast. It is stronger and you have
> more surface area to clamp. I just looked at photos of ProSisTel mast clamps
> and basically it looks like two formed plates are bolted together. Either
> these plates are bending or it is just not clamping enough surface area. I
> think K7NV is the only one to figure out that using a round clamp on a round
> mast has a lot of contact area. From the photos it appears that there is a
> center hole for pinning, just like Yaesu recommends. Two options that I see
> are pin the mast or purchase a clamp from K7NV. In my opinion drilling 4130
> is really not that difficult but you have to use quality drills, the right
> speeds etc. If I were doing it I would spot the center on each side with a
> center locating punch and then drill a small hole though first and then
> drill it larger.
>
> GL,
> John KK9A
>
> Les Brown VE3NNT
>
> I have 2 large Yagis attached to a 3 inch OD ¼ inch wall thickness Chromoly
> mast running down the tower to a ProSisTel PST-71D. On a windy day, I hear
> creaking sounds from the tower. The mast is slipping slightly in the rotator
> mast bracket. I’ve already tried to tighten the 6 bolts, but it still slips.
> I don’t want to tighten them to the point where they might snap. I’m
> thinking that what I need to do is to go up the tower, drill a hole through
> the mast (the rotator mast bracket already has holes), and pin the mast and
> bracket. I understand that it’s not easy drilling through Chromoly pipe, so
> before I try this, I thought I would ask if any of you have any other
> suggestions.
>
> 73, Les VE3NNT
>
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