I was wondering about the size of the holes in the rotor mast clamp. I
didn't measure them to see if there was any slop. I know that 3/8 inch is a
little larger than M8. I was worried though that a 5/16 grade 8 might not be
much stronger than the M8 SS bolt. I may be wrong. Maybe you guys know the
tensile strength differences. I was prepared to ream out the holes to fit
3/8 inch if necessary. Do you think 5/16 inch would still be a good choice?
73, Les VE3NNT
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
john@kk9a.com
Sent: Friday, July 31, 2020 7:18 PM
To: 'Jon Pearl - W4ABC' <jonpearl@tampabay.rr.com>; towertalk@contesting.com
Subject: Re: [TowerTalk] Mast slippage
The bracket's hole size was never mentioned in the VE3NNT's post. I thought
it was odd that he was going up a size so I questioned if 3/8 will fit.
John KK9A
-----Original Message-----
From: Jon Pearl - W4ABC [mailto:jonpearl@tampabay.rr.com]
Sent: Friday, July 31, 2020 5:21 PM
To: john@kk9a.com; towertalk@contesting.com
Subject: Re: [TowerTalk] Mast slippage
Hi John,
3/8" is a tad fat for the M8 hole.
5/16" = .3125" and will drop in a M8/.3149" hole
3/8" = .3750" and will drop in a M10/.3937" hole
73,
Jon Pearl - W4ABC
On 7/31/2020 12:36 PM, john@kk9a.com wrote:
> Will 3/8 bolts fit into a plate designed for M8? I believe that
> stainless steel bolts are typically not much stronger than grade 2.
> Grade 8 bolts are available with Armor Coat which has great corrosion
> protection.
>
> John KK9A
>
>
> Les Brown VE3NNT wrote:
>
> Thanks for all the advice guys. I think I'll start with replacing the
> SS M8 bolts with 3/8 inch grade 8 bolts (or grade 9 or 10?) to see if
> that solves the problem. If it doesn't, I'll have to try the K7NV
> clamp, but that will require me to remove the rotor to slip the clamp
> on to the bottom of the mast, which won't be so easy. Given that half
> the mast is sticking out of the top of the tower, I'll have to rig up
> some pipes to hold the bottom of the mast in place for the operation.
> It sounds like drilling and pinning isn't a good solution, and not
> so easy to do.
> 73, Les VE3NNT
>
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