Bushings and Shim Stock

[Hartwell85]

The ID on the Classica bushings I was using had too much clearance on my pen mandrel. That caused a slightly out-of-round barrel unless I rotated the blank 180 degrees before final shaping. I fixed the problem by inserting a piece of 0.001" brass shim stock inside the bushing hole. This resulted in a close but not tight fit on the mandrel. No more out of round barrels. The shim stock stays inside the bushing if you carefully place it on the mandrel.

The dimensions of the shim stock equal the length of the bushing and the circumference of the hole.

 

[egnald]

Interesting. Do you know the diameter of your mandrel?

Most mandrels (and most bushings) are made according to the Berea standard "A" mandrel dimension which is 0.247" +0" / -0.0002" , but at one time PSI made and published their own mandrel specification as 0.243". Perhaps you have one of the smaller diameter mandrels? If so, many of your bushings might suffer from the same out-of-round problem.

Dave

 

[Hartwell85]

Interesting. Do you know the diameter of your mandrel?

Most mandrels (and most bushings) are made according to the Berea standard "A" mandrel dimension which is 0.247" +0" / -0.0002" , but at one time PSI made and published their own mandrel specification as 0.243". Perhaps you have one of the smaller diameter mandrels? If so, many of your bushings might suffer from the same out-of-round problem.

Dave

Axminster mandrel, 0.242"/6.13mm diameter. I need to check fit on other bushings. On some pen kits I use TBC bushings.

 

[egnald]

Axminster mandrel, 0.242"/6.13mm diameter. I need to check fit on other bushings. On some pen kits I use TBC bushings.

I don't have a real set of pin gauges (wish list item), but so far nearly all of the bushing I have bought fit over a letter "D" Drill Rod (which is what I use for a mandrel). It is made of Tool Steel and is specified as 0.246" +0.0005" / -0.0005" (0.2455" to 0.2456"), so I know they are at least in that range. The only thing that doesn't fit are the brass tubes on the Slimline kits I have. Then I drop down a size to a letter "C" Drill Rod which is specified at 0.242" +0.0005" / -0.0005" (0.2415" to 0.2425"). - Dave

 

[Hartwell85]

I don't have a real set of pin gauges (wish list item), but so far nearly all of the bushing I have bought fit over a letter "D" Drill Rod (which is what I use for a mandrel). It is made of Tool Steel and is specified as 0.246" +0.0005" / -0.0005" (0.2455" to 0.2456"), so I know they are at least in that range. The only thing that doesn't fit are the brass tubes on the Slimline kits I have. Then I drop down a size to a letter "C" Drill Rod which is specified at 0.242" +0.0005" / -0.0005" (0.2415" to 0.2425"). - Dave

I checked a few other bushings on the Axminster mandrel and they fit better than the Classica bushings did. I took a spare mandrel measuring 0.246" diameter and used it to replace the original Axminster mandrel. Better fit on all bushings although the Classica bushings still use the shim. If I need to replace the mandrel, I can get 0.246" drill rod from McMaster Carr.

 

[egnald]

I checked a few other bushings on the Axminster mandrel and they fit better than the Classica bushings did. I took a spare mandrel measuring 0.246" diameter and used it to replace the original Axminster mandrel. Better fit on all bushings although the Classica bushings still use the shim. If I need to replace the mandrel, I can get 0.246" drill rod from McMaster Carr.

That's where I get my drill rod too. - Dave

 

[ed4copies]

Thank-you Gentlemen!! You have clarified a problem I receive on the phone from time to time!!

Now I will have a documented, measured answer!!