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Are your bushings compatible with my mandrels?
Are your mandrels compatible with my bushings?
Why are there two sizes of mandrels?
What is the difference between the precision and high precision systems?
How do I prevent out of round problems?
An explanation from Berea Hardwoods on their mandrels and bushings.

Are your bushings compatible with my mandrels?
The “A” series of bushings are designed to work with the standard “7mm” mandrel systems. However, they are only guaranteed to work with the mandrels sold by Bear Tooth Woods. They likely will work with mandrels from other suppliers, but no guarantee is given. The “B” series of bushings are designed to work with the larger “B” mandrel system that is only made by Berea Hardwoods, they will not work on any other mandrel system. This larger system has some significant benefits and is well worth the added cost.

Are your mandrels compatible with my bushings?
The “A” sized mandrel system is roughly compatible with the mandrel systems sold by other manufacturers, however it has not been tested with any bushings other than those sold by Bear Tooth Woods so the compatibility is not guaranteed.

Why are there two sizes of mandrels?
Berea Hardwoods and Bear Tooth Woods support two different sized mandrel systems. The “A” sized system is mainly used for the pens based on the 7mm tube (with two notable additions, the cigar pen and the sierra pen), while the “B” sized system is used with all other kits.

The “B” sized system has the benefit of being thicker than the “A” system. This added thickness provides a much more stable platform for making pens. This stability reduces the out of round problems that can occur when making pens.

What is the difference between the precision and high precision systems?
The high precision system uses drill drivers developed for the metal working industry. These drill drivers hold the mandrel with increased precision and greatly reduce out of round problems. I do not understand why they are better, but all of my experience and the experience of everyone I have sold them to supports the fact that the high precision system provides a better turning system. All of my customers who have purchased the high precision system have felt it was a valuable addition to their pen turning.

How do I prevent out of round problems?
Out of round is perhaps the biggest problem facing many turners. The size of our work and the fact that the turned wood must be mated with metal pieces makes any out of roundness readily apparent on the end product.

I use the round shaft of a screw driver lightly rested on the bushings to see if the system is in or out of round.

Out of round can come from many different areas. Each of them may need to be checked:

• Ensure alignment between the headstock and the tailstock.
• Clean the headstock and tailstock.
• Clean the morse taper.
• Make sure the shaft is straight. (Too much pressure could warp the shaft).
• Do not overtighten the tailstock.
• Do not overtighten the nut.
• Make sure bushings are clean.
• Make sure your tools are sharp. (Dull tools require added pressure that can warp the shaft).

The high precision mandrel system will also greatly aid in reducing out of round problems.

An explanation from Berea Hardwoods on their mandrels and bushings.
From the Berea Hardwoods catalog No. 10. Used by permission. Copyright, Berea Hardwoods 2005.

In order to make pen kits and other kits you must hold the wood blanks on your lathe to turn them to the correct size. In order to properly accomplish this you will need a mandrel, a way to mount the mandrel on your lathe, bushings to help turn the blank to the correct size and the proper drill for the kit. All these things are together called "tooling" . . . All our tooling is industrial grade and precision made.

MANDRELS:
A mandrel is a round steel rod that you slide the wood blank with the brass tube inserted onto. Unlike most other companies who offer only one size mandrel we sell two sizes. The A mandrel (sometimes called a "7mm" mandrel) which is 0.247 +0-0.0002 inches in diameter and another mandrel which has a larger diameter, the B mandrel. This is 0.291 +0-0.0002 inches in diameter. We use the B mandrel on some kits because the thicker diameter helps prevent whip while turning and allows for a much better result.

BUSHINGS
These are round pieces of steel that slide on the mandrel between the mounted pen blanks. You turn the wood down to the top of these bushings to achieve the correct wood size. Each kits [sic] has specific bushings. The letter after the bushing number indicates which mandrel to use the bushings on e.g. A or B.