What Steve K7LXC omitted from his question regarding the M2 mast clamp and mast friction situation is
the mast size, but Grant KZ1W made a great recommendation below to increase the contact area for
variations in mast size. My prop pitch M2 mast clamp was previously modified by K7NV as he had
resurfaced the clamp teeth of the M2 mast clamp included with his rebuilt small prop pitch for handling
my 2-7/8" outside diameter galvanized chrome-moly 22ft mast, but still recommended pinning the
mast. As the newer K7NV designed mast clamp and the DX Engineering modification of the K7NV clamp both
are specified for either 2" or 3", how well would either 3" version capture and secure my
2-7/8" mast? How much tolerance for using a smaller mast diameter is built into the design? The DX
Engineering modification of the K7NV clamp design by adding one or two clamp spreading bolt(s) to assist
spreading the clamp seems like a great idea.
73,
Gary N0GS
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Tim Duffy
Sent: Tuesday, November 08, 2022 8:02 PM
To: 'Steve Dyer W1SRD' <w1srd@yahoo.com>; reflector -tower
<towertalk@contesting.com>
Subject: Re: [TowerTalk] More friction needed
I have 5 tower tops using the K7NV clamp. Large antennas, one Yagi stack (big
40 and 10 meter beams) has 35 square feet of wind load at 260 feet! The K7NV
clamps here have not slipped yet.
73
Tim K3LR
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Steve
Dyer W1SRD via TowerTalk
Sent: Tuesday, November 8, 2022 8:42 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] More friction needed
What would a competent machine shop charge to do this? Most of us don't have a
fully outfitted machine shop :-).
73,
Steve
W1SRD
Bolt the two clamp sections to a lathe faceplate and bore them to the
mast diameter. Remove enough material to enlarge the contact area and
insure the bore is true to the bases. Use grade 8 bolts and use a
torque wrench to max spec torque for the size bolt. Repeat this
tightening 3 times.
The clamp bore as cast wasn't straight to the machined base and only a
few "points" would have made contact in the 2800 I have turning a 375#
100ft tip to tip 2L 80m beam. Now it doesn't slip.
Grant KZ1W
On 11/8/2022 10:00, k7lxc--- via TowerTalk wrote:
Howdy, TowerTalkians -
I need more friction between an M2 mast clamp and the mast. How
could I do that? What materials would work? Tnx. Cheers,Steve
K7LXCCell: 206-890-4188
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