Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

On Mon, 08 Sep 2008 10:37:12 -0700, JR North
wrote:

Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?

A set screw is the only reasonable option if you want to use the flat,
but I don't blame you for looking for something better. The $30
solution is a Trantorque coupling -- see McMaster 5926K11. A much
cheaper option (about $2) is a 3/16" clamp collar screwed to the face
of your gear and tightened on the shaft. McMaster 6435K51

--
Ned Simmons

JR North wrote:
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar

If it's a big cut for the "D", how about milling the hole with a 1/16"
mill. You'll have to go wide on the ends of the flat. It'll be slow,
it'll be hard to do without an NC machine, and it'll look funky, but
it'll put a flat where the flat's supposed to be and put support behind
the shaft where that's supposed to be.

If it's a shallow flat on the shaft, then Mr. Simmons suggestion of a
set screw is a good one. Use the right type -- I only recently learned
that set screws suitable for going against soft round shafts (cup type)
are exactly wrong for going against flats (you want one with a flat
end). The things you learn by hanging with mechanical engineers...

Or make your own broach from O-2 drill rod :-).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Mon, 08 Sep 2008 10:37:12 -0700, JR North
wrote:

Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar
============
The single flat D appears to be a driving method that was
developed early in the industrial revolution and is in the
process of being replaced with the double D as this allows for
balanced machining/less drift.

Much will depend on the material and set-up [and required
accuracy] but many years ago in producing an automotive part I
found out that the single D shape was hard to hold to an exact
location. The solution at that time was to form an oversized
blank, broach the hole, and then use the d-hole to locate from
for the required concentricity/axial runout.

If you have a small volume, no tooling, no press, etc. you may
want to consider OP [outside processing] by a broaching house
such as
http://www.centerbroach.com/4.html
http://www.minibroach.com/Tooling_neu.htm
http://www.buckeyebroach.com/rfq.htm


Rotary broaches are available for the double D.
http://www.slatertools.com/adjustmen...toolholder.htm
http://www.rotarybroaching.net/swissbroaching.htm
and several others
Thus you should be able to produce the blank in one operation at
the cost of slightly longer cycle time. Be reminded that there
will be a *SLIGHT* twist or helix in the formed hole which could
be a problem, or could make a nice snug press fit depending how
you look at it.

The standard D type broach tools are available from
http://www.dumont.com/prod7c.html
http://mdmetric.com/dumont/prod7a.html
be setting down when you check prices.

Another low volume alternative could be a bushing with the D hole
that you press fit /loctite in the blank.

also see
http://www.cnczone.com/forums/showthread.php?t=18170
http://www.janellestudio.com/metal/drilling_tips.txt {about 1/4
down page}

Good luck and let the group know how you make out.

On Sep 8, 1:37*pm, JR North wrote:
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
* * * * Home Page:http://www.seanet.com/~jasonrnorth
* * * *If you're not the lead dog, the view never changes
* * *Doubt yourself, and the real world will eat you alive
* The world doesn't revolve around you, it revolves around me
* * *No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

You could broach a key slot and press the key against the D with the
setscrew. Make the key a light / medium press fit in its slot and the
gear shouldn't shift. A key this small can be adjusted to fit with a
small hammer.

Jim Wilkins

JR,

You have an "old" gear with the correct hole/hub?

If so.. turn the old gear to a size that you can bolt or braze or weld (or
fastening method of choice) to your blank before ya cut it.

--.- Dave




"JR North" wrote in message
.. .
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems there
would be a bazillion different ones, depending on the width of the flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

Good suggestions so far. Grassyass. The original gear is nylon. I
replaced the Nema17 stepper in the application with a much more
powerful N17 double stack motor. I ground the flat onto the new
motor's shaft, to match the original, then determined the nylon hub
will not take the torque. Thus, new gear.
JR
Dweller in the cellar

On Mon, 08 Sep 2008 10:37:12 -0700, JR North
wrote:

Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

"JR North" wrote in message
.. .
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems there
would be a bazillion different ones, depending on the width of the flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."
HVAC motors commonly use fairly wide flats, some 1 and some 2 at 90 degrees,
with round fan hub bores and setscrews. Some of the single flats seem to be
nearly to the center of the shaft. So I would try a round bore with one or
more setscrews.

Don Young

On Mon, 8 Sep 2008 21:33:23 -0500, Don Young wrote:

"JR North" wrote in message
.. .
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems there
would be a bazillion different ones, depending on the width of the flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."
HVAC motors commonly use fairly wide flats, some 1 and some 2 at 90 degrees,
with round fan hub bores and setscrews. Some of the single flats seem to be
nearly to the center of the shaft. So I would try a round bore with one or
more setscrews.


If the flat is that deep, perhaps round hole with a D-shaped insert pinned
to the gear would work (much easier if the gear has a boss).

On Mon, 08 Sep 2008 18:36:04 -0700, JR North
wrote:

Good suggestions so far. Grassyass. The original gear is nylon. I
replaced the Nema17 stepper in the application with a much more
powerful N17 double stack motor. I ground the flat onto the new
motor's shaft, to match the original, then determined the nylon hub
will not take the torque.

Just out of curiosity, did the determination involve a finite element
analysis on the nylon molding or did you just slap it on and watch it
merrily split apart?

Thus, new gear.
JR
Dweller in the cellar

On Mon, 08 Sep 2008 10:37:12 -0700, JR North
wrote:

Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

Sure. Cray computer and all. Actually, I just used my onboard
engineering prescience to 'see' the hub failing. The project isn't to
the point where I can actually run the drive under load.
JR
Dweller in the cellar


Spehro Pefhany wrote:
On Mon, 08 Sep 2008 18:36:04 -0700, JR North
wrote:


Good suggestions so far. Grassyass. The original gear is nylon. I
replaced the Nema17 stepper in the application with a much more
powerful N17 double stack motor. I ground the flat onto the new
motor's shaft, to match the original, then determined the nylon hub
will not take the torque.


Just out of curiosity, did the determination involve a finite element
analysis on the nylon molding or did you just slap it on and watch it
merrily split apart?

Thus, new gear.

JR
Dweller in the cellar

On Mon, 08 Sep 2008 10:37:12 -0700, JR North
wrote:


Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems
there would be a bazillion different ones, depending on the width of the
flat.
Else, how to?
JR
Dweller in the cellar

--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."

Best regards,
Spehro Pefhany

-

Ok JR,

Now that we have a bit more info...

Round hole, then silver brase in the "flat"... make flat from round stock
the proper diamter flattened with method of choice, mill,file,grind...

--.- Dave


"JR North" wrote in message
.. .
Have a project, need a gear for a stepper with .187" Dia D shaft. I can
make the gear; are there broaches for forming the pilot bore? Seems there
would be a bazillion different ones, depending on the width of the flat.
Else, how to?
JR
Dweller in the cellar
--
--------------------------------------------------------------
Home Page: http://www.seanet.com/~jasonrnorth
If you're not the lead dog, the view never changes
Doubt yourself, and the real world will eat you alive
The world doesn't revolve around you, it revolves around me
No skeletons in the closet; just decomposing corpses
--------------------------------------------------------------
Dependence is Vulnerability:
--------------------------------------------------------------
"Open the Pod Bay Doors please, Hal"
"I'm sorry, Dave, I'm afraid I can't do that.."