I'm now up to vol.3 of David Gingery's metal shop series, the one on
how to make your own metal shaper. He has a few comments in two places
about how to make your own arbors. The ones he's describing are about 6
inches long and his comments are not very detailed. For example, on p.13,
he writes: "It is impossible to drill a precise center in each end of a
shaft, so you must begin with over-size stock to make your arbors. The
diameter will then be concentric with the centers, and you can do accurate
work on anything that you mount on the arbors."

I think what he means is this:
(1) You can't to take a cylindrical rod the size you want and expect to
drill a dimple at each end accurately enough that when the rod is
mounted on a lathe using the two dimples, the axis of rotation will
coincide with the axis of the cylinder.
(2) Therefore, you have to take a rod which is too big, do your best to
drill the holes you want, and then use the holes you drilled to mount
the rod on a lathe and turn the rod until you have it down to the
desired diameter.

Is that what he means?

Ignorantly,
Allan Adler


************************************************** **************************
* *
* Disclaimer: I am a guest and *not* a member of the MIT Artificial *
* Intelligence Lab. My actions and comments do not reflect *
* in any way on MIT. Moreover, I am nowhere near the Boston *
* metropolitan area. *
* *
************************************************** **************************

Yes. That's exactly what he means.
Paul K. Dickman

Allan Adler wrote in message ...

I'm now up to vol.3 of David Gingery's metal shop series, the one on
how to make your own metal shaper. He has a few comments in two places
about how to make your own arbors. The ones he's describing are about 6
inches long and his comments are not very detailed. For example, on p.13,
he writes: "It is impossible to drill a precise center in each end of a
shaft, so you must begin with over-size stock to make your arbors. The
diameter will then be concentric with the centers, and you can do accurate
work on anything that you mount on the arbors."

I think what he means is this:
(1) You can't to take a cylindrical rod the size you want and expect to
drill a dimple at each end accurately enough that when the rod is
mounted on a lathe using the two dimples, the axis of rotation will
coincide with the axis of the cylinder.
(2) Therefore, you have to take a rod which is too big, do your best to
drill the holes you want, and then use the holes you drilled to mount
the rod on a lathe and turn the rod until you have it down to the
desired diameter.

Is that what he means?

Ignorantly,
Allan Adler


************************************************* **************************
*
*
*
* Disclaimer: I am a guest and *not* a member of the MIT Artificial
*
* Intelligence Lab. My actions and comments do not reflect
*
* in any way on MIT. Moreover, I am nowhere near the Boston
*
* metropolitan area.
*
*
*
************************************************* **************************
*

"Allan Adler" wrote in message
...

I'm now up to vol.3 of David Gingery's metal shop series, the one on
how to make your own metal shaper. He has a few comments in two places
about how to make your own arbors. The ones he's describing are about 6
inches long and his comments are not very detailed. For example, on p.13,
he writes: "It is impossible to drill a precise center in each end of a
shaft, so you must begin with over-size stock to make your arbors. The
diameter will then be concentric with the centers, and you can do accurate
work on anything that you mount on the arbors."

I think what he means is this:
(1) You can't to take a cylindrical rod the size you want and expect to
drill a dimple at each end accurately enough that when the rod is
mounted on a lathe using the two dimples, the axis of rotation will
coincide with the axis of the cylinder.
(2) Therefore, you have to take a rod which is too big, do your best to
drill the holes you want, and then use the holes you drilled to mount
the rod on a lathe and turn the rod until you have it down to the
desired diameter.

Is that what he means?

Ignorantly,
Allan Adler

Yes, that's what he meant. You can actually do it without using oversized
stock, but it requires a little knowledge and equipment. By dialing in the
material and carefully drilling the center holes, you achieve the same
results. Centers are best drilled concentric with one another, although
reasonable results can be expected when drilling randomly. In all cases,
it's important to have the faces parallel and the centers as near concentric
as possible to guarantee you end up with cylindrical turns. Many argue
it is not important. I know it is.

Harold

"Harold & Susan Vordos" wrote in message
...
In all cases, it's important to have the faces parallel and the
centers as near concentric as possible to guarantee you end up
with cylindrical turns. Many argue it is not important.
I know it is.

Now now Harold, let's not forget that the best tolerance the average HSM'er
cares about is maybe half a thou, and especially that we're talking Gingery
here. BG

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting
and Games: http://webpages.charter.net/dawill/tmoranwms

On Wed, 14 Apr 2004 17:43:47 -0500, "Tim Williams"
wrote:

==="Harold & Susan Vordos" wrote in message
...
=== In all cases, it's important to have the faces parallel and the
=== centers as near concentric as possible to guarantee you end up
=== with cylindrical turns. Many argue it is not important.
=== I know it is.
===
===Now now Harold, let's not forget that the best tolerance the average HSM'er
===cares about is maybe half a thou, and especially that we're talking Gingery
===here. BG
===
===Tim


Well since its a Gingery item, I would think plus or minus a 1/32"
would be close enough!


Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

"Roy" wrote in message
...
On Wed, 14 Apr 2004 17:43:47 -0500, "Tim Williams"
wrote:

==="Harold & Susan Vordos" wrote in message
...
=== In all cases, it's important to have the faces parallel and the
=== centers as near concentric as possible to guarantee you end up
=== with cylindrical turns. Many argue it is not important.
=== I know it is.
===
===Now now Harold, let's not forget that the best tolerance the average
HSM'er
===cares about is maybe half a thou, and especially that we're talking
Gingery
===here. BG
===
===Tim


Well since its a Gingery item, I would think plus or minus a 1/32"
would be close enough!


I try to never work that closely. Wears out my Lufkin tape! g

Harold

If your rod is of the correct diameter, or is oversized, but turned
truly round, you can center drill and get it almost correct. Then you
put the end of the rod in a center rest, and turn the taper part of
the center drilled hole concentric. Accuracy obtained, with patience,
approaches turning between centers.

Brownnsharp

Yes.

And to make a 'true' arbor, or remove and replace the arbor and have it
STILL running true, it also assumes the lathe is trammed properly and
both lathe centers are themselves true to the lathe's axis.

Dan Mitchell
==========

Allan Adler wrote:

I'm now up to vol.3 of David Gingery's metal shop series, the one on
how to make your own metal shaper. He has a few comments in two places
about how to make your own arbors. The ones he's describing are about 6
inches long and his comments are not very detailed. For example, on p.13,
he writes: "It is impossible to drill a precise center in each end of a
shaft, so you must begin with over-size stock to make your arbors. The
diameter will then be concentric with the centers, and you can do accurate
work on anything that you mount on the arbors."

I think what he means is this:
(1) You can't to take a cylindrical rod the size you want and expect to
drill a dimple at each end accurately enough that when the rod is
mounted on a lathe using the two dimples, the axis of rotation will
coincide with the axis of the cylinder.
(2) Therefore, you have to take a rod which is too big, do your best to
drill the holes you want, and then use the holes you drilled to mount
the rod on a lathe and turn the rod until you have it down to the
desired diameter.

Is that what he means?

Ignorantly,
Allan Adler


************************************************** **************************
* *
* Disclaimer: I am a guest and *not* a member of the MIT Artificial *
* Intelligence Lab. My actions and comments do not reflect *
* in any way on MIT. Moreover, I am nowhere near the Boston *
* metropolitan area. *
* *
************************************************** **************************