[TowerTalk] Rotator Bolt Patterns

[Grant Saviers]

One alternative is a new hole pattern rotated enough to miss the 
existing holes.  The pattern can be drawn on grid paper, taped to the 
rotator plate, prick punch and then center punch the hole position. 
Then use a pilot drill, 1/16" to spot the new holes.  Starting with the 
bolt size drill will likely wander off enough to be a problem.

Mostly I use the DeWalt Pilot Point drills for holes thin metal.  They 
rarely wander, and make round holes with tight tolerances, and are made 
from excellent quality steel. If used at the right rpm's and with some 
coolant they will make a lot of holes, even in difficult steels.

https://www.homedepot.com/p/DEWALT-Titanium-Pilot-Point-Drill-Bit-Set-29-Piece-DW1369/202279644

Generally, Chinese drills are junk steel.  Don't be seduced by the gold 
color TiN coatings (Titanium Nitride, not titanium), it is worthless on 
poor steel drills and is really only useful for volume production.  It 
looks nice though for marketing purposes.

A die grinder (big Dremel) with a double cut carbide burr is one way to 
enlarge holes.  Buy the burr from a tool supplier - Travers, MSC, 
McMaster, Shars, KBC, Western Tool, or your local tool distributor.

https://www.mscdirect.com/browse/tnpla/05293212?cid=ppc-google-Returning+%E2%80%93+Zero+Traffic+%E2%80%93+PLA_sabV7MYAC___291135572310_c_S&mkwid=sabV7MYAC|dc&pcrid=291135572310&rd=k&product_id=05293212&gclid=Cj0KCQiAoo7gBRDuARIsANeJKUaXyOQ3PzKjBX_oIjB4D0N8UEHBZJaLvHGbkj2RekPz37XbhdvSzp0aAhS5EALw_wcB

SGS is a premium USA carbide tool maker, one of several.

A stone grinding point will take forever.  The burr should be a straight 
pattern and smaller in diameter than the existing hole.  It will likely 
bounce around a bit as you learn to control the motion, so having a 
spare burr or two is a good idea.  Considering the amount of usage for 
the grinder, saving $ with the Harbor Fright one may be a good decision. 
  Even though the old adage is never buy something HF with a power cord, 
their stuff is getting much better.

While gouging out holes with the side of a drill works a bit in wood, 
drill bits aren't designed for it. Consider in wood the strength ratio 
of the drill is about 20:1, and in mild steel the difference is ~ 2:1.

In a milling machine a new hole can be placed anywhere with a center 
cutting end mill.

Grant KZ1W

On 12/1/2018 17:35 PM, terry burge wrote:
> I've never found it very easy to match up bolt patterns. Rotors with a flat bottom it would seem like you could copy it to a piece of cardboard or paper to make a pattern you could use easy enough. But the idea of elongating a bolt hole I never figured out how to do without some special equipment. Don't think I ever even seen one. Otherwise I would have one in my shop cause I've always found matching hole in thing much easier with slotted holes on frames or whatever. Best I could do was run the risk of breaking a drill bit by 'trying' to tilt it. And of course that is a risky thing that could just break the drill bit. Done that too many times with light weight drill bits. The last time it was 1/8' on and thanks to Harbor Freight I now have a whole package of just that size which I know will come in very handy.
> 
> Always admired true mechinist and the things the knew how to do.
> 
> Terry
> KI7M
>   
>> On December 1, 2018 at 4:50 PM Raymond Benny <rayn6vr at gmail.com> wrote:
>>
>>
>> The Ham M and Ham 1 - 4 series rotators use (4) 1/4 " bolts.
>>
>> The T2X uses (6) 1/4" bolts. The two additional bolts are in the same
>> radius as the 4 other bolts, but just centered between two of bolts on
>> opposite sides.
>>
>> Ray,
>> N6VR
>>
>> On Dec 1, 2018 5:23 PM, <john at kk9a.com> wrote:
>>
>> I would not let bolt pattern limit your rotator choices. I have not owned a
>> Hy-Gain rotator in decades. Drilling holes or elongating the existing ones
>> is very easy. Your rotator shelf may already have elongated holes, I do not
>> recall doing anything to install a Yaesu G-2800 in my P40A Rohn 55G tower.
>>
>> John KK9A
>>
>>
>> Kim Elmore N5OP Wrote:
>>
>> I'm investigating rotor that will fit the same bolt pattern as a T2X but
>> that are a bit beefier. Mine works well, but in windy conditions, I
>> can't turn may antennas  due to wind imbalance. What beefire rotators
>> will accommodate the same bolt pattern?
>>
>> Kim N5OP
>>
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