Kwm bushing System.

POWERSTROKE

Registered User
Jan 11, 2011
1,116
74
48
The od is 2.7 on the kwm bushings. Have you folks had problems that use kwm bushings with the od being to large for certain places on regula or Hubert Herr movements? For example at the pallet pivot? If so, what is the solution.
 

R. Croswell

Registered User
Apr 4, 2006
10,912
1,075
113
Trappe, Md.
www.greenfieldclockshop.com
Country
Region
The od is 2.7 on the kwm bushings. Have you folks had problems that use kwm bushings with the od being to large for certain places on regula or Hubert Herr movements? For example at the pallet pivot? If so, what is the solution.
Not specifically on that clock movement, but yes, sometimes there is limited space for a bushing. One solution is to use a smaller bushing and broach out the ID to fit the pivot. There is obviously a limit to how far this solution can be pushed.

RC
 
  • Like
Reactions: Karl Thies

Bruce Alexander

Sponsor
NAWCC Brass Member
Feb 22, 2010
7,326
774
113
Country
Region
A custom turned bushing, or a solid bushing blank drilled to size off-center (at the appropriate location for gear mesh).
 

Joe Somebody

Registered User
Jan 29, 2020
14
2
3
59
Country
Would a standard 1.9 od kwm bushing work? This may get you in a better range.
There is a chart of kwm bushing sizes at several sites as a pdf document.
 

Bruce Alexander

Sponsor
NAWCC Brass Member
Feb 22, 2010
7,326
774
113
Country
Region
Much depends on the pivot diameter of course. If you have a pivot much larger than 1 mm in diameter, a bushing with a 1.9mm OD won't give you much brass to work with. That's the obvious limit that RC was referring to.

If you have a relatively wide diameter pivot located close to the edge of a plate, you might have to go the custom route. Reamers place a lot of lateral pressure on the hole that they are reaming. Even if there appears to be just enough room for a bushing, a Reamer may displace towards the thin, weak wall of the bushing prep.
 

Jerry Kieffer

NAWCC Fellow
NAWCC Member
May 31, 2005
2,925
544
113
wisconsin
Country
The od is 2.7 on the kwm bushings. Have you folks had problems that use kwm bushings with the od being to large for certain places on regula or Hubert Herr movements? For example at the pallet pivot? If so, what is the solution.
Powerstroke

The answer to your question is very simple. Select a Bushing system that offers solutions rather than issues.

Often filing and hand bushing requires more space than is available. In other cases, where space is limited, bushing reamers apply outward pressure while reaming that will rupture remaining structures creating a real mess.

Personally use a small Milling machine for bushing that allows me to use Endmills in tight areas. A center cutting Endmill can be centered on an original pivot location and is not effected by hole shape, or location. In addition, the cutting action applies no outward pressure on the structure being machined. With the wide variety of available endmill sizes, proper/ideal size selection is not an issue. A matching bushing can be machined or easily constructed from bushing wire.

In some cases a bushing will be close to an edge as mentioned by Bruce. The following is a response given to another person with that question
_______________________________________________________________________________________________________________________________________________________________________________

You are correct in that the stress of using a bushing reamer next to the edge of a plate can easily push the side of the out and damage it. My most common method of dealing with this is as follows.


(1) I first mount the movement plates in the movement holder (Designed for the job) mounted in the Mill. I then locate the original pivot hole location utilizing a pivot size gage pin mounted in the Mill spindle. "X" and "Y" hand wheel settings are then recorded for relocation to this position when needed.


(2) Next, a desired size center cutting endmill is selected and positioned per the attached sketch, and the hole is machined in the plate for installation of a bushing plug.

When utilizing a Endmill for this operation, there is no outward stress on the edge of the plate or risk of damage when the "X" and "Y" axis are locked in place. Unless of course you are using a movement plate mounting system that is not rigid or designed to be used in a Mill.


(3) From this point, the "X" and "Y" axis slides are returned to the original location recorded in step one and the pivot hole is spot drilled/drilled also per the attached sketch.

Jerry Kieffer

fullsizeoutput_383.jpeg
 
  • Like
Reactions: Old Rivers

Forum statistics

Threads
164,706
Messages
1,432,937
Members
85,756
Latest member
jtvx
Encyclopedia Pages
1,101
Total wiki contributions
2,863
Last edit
Rockford's early high grade movements by Greg Frauenhoff