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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 while 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.