[R-390] Need a MC knob clamp and BFO extension shaft clamp

[Roy Morgan]

On Jun 18, 2009, at 3:35 AM, stoth47 at yahoo.com wrote:

>
>
> I need a replacement bristol screw clamp for the megacycle knob on  
> one of my R390A's - the existing one will not hold firm on the shaft  
> no matter how much it is tightened down and the knob keeps slipping.

Are the faces of the clamp at the middle of the screw meeting?  Maybe  
the clamp has stretched or the shaft is a bit too small.  If so, try  
filing those faces a bit.  That may restore proper operation.

>  Also, where can we get spare bristol screws for the clamps?  I  
> checked McMaster Carr for both bristol and six spline set screws and  
> couldn't find them.  Maybe I'm searching on the wrong description?

You might try the Bristol Wrench Company to locate sources. They make  
the (best) wrenches:

Bristol Wrench Company (the originator of the tools):
http://www.bristolwrench.com/
Their table on spline wrenches (also found at Max-Gain Systems in  
partial form)
http://www.bristolwrench.com/spline.pdf
Bristol Wrench Co.
P.O. Box 4317
Salem, OR 97302

Phone: 503-371-9655
Fax: 503-371-9662

If that fails, there are a number of suppliers of military hardware,  
but  you would rather not pay their prices, I'm sure.

May I suggest that if you wind up using an allen screw, even if only  
temporarily, you paint the head of the thing a bright color to alert  
yourself or another worker that it's not the same as the rest.

Roy

Roy Morgan
k1lky at earthlink.net
529 Cobb St.
Groton NY, 13073
Home: 607-898-3607
Cell: 301-928-7794