Subject: index or rotary table first

From: william tietz <[email-masked]>
Date: 8 Jun 1996 18:31:36 GMT

what would be the best to buy first, a index table or a rotary table? i'm 
building my first hit and miss engine and can't aford to buy both at this 
time, but plan to buy both in the future.

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From: kuhncw <[email-masked]>
Date: 8 Jun 1996 20:30:03 GMT

I am also building my first hit & miss engine.  I have used my index head 
to cut the gears but have not used the rotary table.  They are both 
handy tools, but I don't anticipate using the rotary table on this 
engine.

Guess, I'd vote for the indexing head.  Mine is an import from MSC and it 
seems to work just fine.

Which engine are you building?

Best regards,

Chuck

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From: PPIERCE <[email-masked]>
Date: Sat, 08 Jun 1996 14:22:48 -0700

kuhncw wrote:
> 
> I am also building my first hit & miss engine.  

Which engine are you building Chuck?

>I have used my index head
> to cut the gears

Did you buy gear cutters or grind your own???

>but have not used the rotary table.  They are both

Aren"t you rounding any rod ends, etc.?  I tho't that was real neat.  Guess that could 
be done w/the dividing head though.
> Guess, I'd vote for the indexing head.  Mine is an import from MSC and it

I must have gotten the same one.  It came Wednesday-faxed the order on Monday.  That 
MSC is really something.  The did the samething when I ordered the catalog.
They have a web page  http://www.industry.net/mrop/msd  (Sorry I don't know how to
highlight that and get you right there)

> Which engine are you building?

Paul in AJ AZ

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From: Steve Wellcome <[email-masked]>
Date: 10 Jun 1996 12:44:46 GMT

I'd go for the rotary table.  See if you can get a horizontal/vertical
model.  Also get the largest size you can reasonably handle.  When you
start needing space for clamps, etc., the table fills up pretty fast.

An indexing/dividing head is pretty specialized.  You may want one
someday, but a rotary table will be more generally useful to you.

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From: Mike Rehmus <[email-masked]>
Date: 11 Jun 1996 16:31:43 GMT

By index table I assume you mean an indexing fixture.

Why not purchase a rotary table with the indexing add-ons?
They are not too much more than just the table alone.  The
only fault with them is that all of the indexing heads
are set up for a 40:1 gear ratio and most of the
rotary tables are 90:1. This means that the published tables
for indexing are not of much use.

If I could only have one, it would be the rotary table
so I could cut arcs in the mill.

Much of your indexing can probably be done with either
the square/hex blocks that hold C-5 collets or a 'spin-index'
fixture which holds C-5 collets and can be indexed as fine as
one degree.  Both are much less expensive than an indexing head

Best regards,

Mike Rehmus

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From: "Kay R. Fisher" <[email-masked]>
Date: Tue, 11 Jun 1996 13:59:14 -0400

> time, but plan to buy both in the future.

I just faced the same problem.  I purchased a rotary table with index plates.
ENCO had one for just under $200 (8 inch).  

But - warning...  I picked mine up in person and had to pass on one because 
it was damaged in shipment.  Even at that I had the better part of one evening
cleaning it up and getting it ready to work.

If I had to do it over again I would get the 6 inch Grizzly with dividing
plates.  Price is about the same.

Bye
Kay R. Fisher

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From: [email-masked](Wm. Congreve (Sr.) )
Date: 12 Jun 1996 20:41:09 GMT

In <[email-masked]> Steve Wellcome
<[email-masked]> writes: 
>
>Since we're computer literate (maybe!), I'd like to point out that
>it's no big deal to write a program in BASIC to calculate the 
>degree settings required to get any number of divisions.  Then you
>don't need index plates for the rotary table.
>
I really have to disagree at least from the perspective of a
clockmaker.  It would be totally impractical to read off degrees
directly from the rim of a rotary table with sufficient accuracy, and
certainly impossible to interpolate the arcminutes.  In clockmaking,
and gearmaking generally, there has to be accuracy to a few arcminutes
or better.  In the old days it wasn't done with worm gear 40:1 or 60:1
ratios but was done with large index plates with rows and rows of holes
(e.g. a circular row with 120 holes, a circular row with 150 holes,
etc), and the making of these plates was rather excruciating work. 
Today such plates (mostly about 6" diameter) can be bought from
specialist clockmaker tool suppliers, rather expensively, and some
people do index directly with them.  Personally I can't imagine getting
by without my worm gear table, with its own (smaller) index circle
plates coupled to the worm gear. 

                --Alan Heldman

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From: Steve Wellcome <[email-masked]>
Date: 12 Jun 1996 12:14:35 GMT

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From: [email-masked] (darylb)
Date: 12 Jun 1996 21:02:04 GMT

In article <[email-masked]>, Steve Wellcome
<[email-masked]> wrote:

> Since we're computer literate (maybe!), I'd like to point out > that
it's no big deal to write a program in BASIC to calculate > the degree
settings required to get any number of divisions.  > Then you don't need
index plates for the rotary table.

Great! I have a universal indexing head and can't figure out how to divide
383 (without making a 20T gear).

I can just see the screw-up following a table that long. And you wonder
why the sector was invented. 8^)

Daryl

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From: [email-masked] (Paul Amaranth)
Date: 13 Jun 1996 13:51:52 GMT

In article <[email-masked]> [email-masked](Wm. Congreve (Sr.) ) writes:
>or better. 

I've seen a couple of articles on making index plates for dividing
heads.  You can use a rotary table or spin index fixture to place 
the holes on the plate.  If I've done the math correct (no guarantees 
this morning), if you can get the holes to within 1/2 degree of where 
they're supposed to be, the worm reduction will reduct the error to 
.015 degree (that's close to 1 arc minute, isn't it?) on the dividing 
head which is something like .0015 inch on a 6 inch radius.

I'd get the rotary table and build the dividing head (or buy one of
the MSC sale ones) when I really needed it.  Unless you have a really
big angle plate (well, even if you do), get a rotary table that can be 
mounted either horizontally or vertically as other folks have pointed
out.  It will make life easier.

--
Paul Amaranth  Manager User Services - office: (810) 370 4541 (also voicemail)
               (e-mail)     [email-masked]         
               URL http://www.acs.oakland.edu/~amaranth

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From: [email-masked] (Russ Kepler)
Date: Wed, 12 Jun 1996 21:14:20 GMT

In article <[email-masked]>,
>don't need index plates for the rotary table.

In general, though, the precision for that would be less than that
available from a 40 turn dividing head (comparing dividing heads with
rotary tables not using index plates).  The difference might not
matter for bolt hole patters or low speed gears, but above that I
believe that it might well matter.

I prefer a DH for the reason that mine takes a 5C collet and has 3 and
4 jaw chucks.  A table is better for large radius stuff and rounding
the ends of material, but I can fake the last using a pin in my table
vise.  It's hard to use a rotary table for gear making.

-- 
Russ Kepler posting from home  [email-masked]

                      Please don't feed the Engineers

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From: "John R. Johnson" <[email-masked]>
Date: Thu, 13 Jun 1996 11:52:56 -0500

On 13 Jun 1996, Paul Amaranth wrote:
<snip>
> out.  It will make life easier.
Right Paul.  And if you still need more accuracy from your dividing plates,
use the first set to make a second set.  Then your accuracy will start to
be a function of the clearances in the dividing head and the quality of
your tools.

John

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From: Mike Rehmus <[email-masked]>
Date: 13 Jun 1996 22:31:16 GMT

You are correct in that the Basic program can
certainly calculate the settings.

However, about the tenth time around the circle,
I can be depended upon to forget some little element
of the process.

Index plates with their adjustable arms remove much
of the short-term memory requirements from the
index process.

Now, how about a stepper motor drive on the table or
dividing head, driven by the same Basic program.  
Then we won't have to worry about any short-term memory problems.

Anyone out there want to step up to that one?  I'd think
a 6"-8" rotary table would not take too much torque so
maybe an inexpensive set of electronics would do the
necessary?  Maybe even drive the power-end with a standard
lead-acid car battery?

Oh, don't forget a solenoid for the table lock.  Guess that's
just one flip-flop?

Best regards,

Mike Rehmus.

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From: [email-masked] (Ron Ginger)
Date: Thu, 13 Jun 1996 19:24:26 LOCAL

In article <[email-masked]> [email-masked] (Russ Kepler) writes:
>From: [email-masked] (Russ Kepler)
>Subject: Re: index or rotary table first
>Date: Wed, 12 Jun 1996 21:14:20 GMT

>believe that it might well matter.

But, rotary tables also have 40:1 ratio drives, and mine has a dial calibrated 
with min and sec, so all I have to do is stop the crank at positions 
equivalent to the hole pattern of a division plate. tedious but hardly 
impossible.

and surely as accurate as a dividing head.

Ron Ginger
my signature is http://www.ultranet.com/~ginger

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From: [email-masked] (Greg Dermer)
Date: 12 Jun 96 23:31:12 GMT

[email-masked](Wm. Congreve (Sr.) ) writes:

>...

>                --Alan Heldman

I think what he meant was to calculate the degree settings of the *worm*
not the rim of the table.  If one could set the worm with an resolution of
2 degrees, and with a 90:1 reduction the resolution at the work would be 
2/90 degree = 1.3 minutes.  One would might have to have a vernier on the
worm to get this close.Frankly, I have enough trouble keeping my act
sufficiently togther to count the holes in my dividing plate 
(even with the sector fingers) so I wouldn't want to try doing without.
But it doesn't seem to be "totally impractical".

Greg
[email-masked]

Not speaking for Intel.