OT? Seeking conical washer for heatsinking

  • Thread starter Mike Rocket J. Squirrel E
  • Start date
M

Mike Rocket J. Squirrel E

Guest
I'm trying to find a vendor of #4 conical, sometimes called compression
or "Belleville", washers. My hardware supplier could not find them. I
thought to get clever and contact Key Bellevilles directly but they
don't make anything that small.

Does anyone have a lead to a US vendor of such things?

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.

-Chuck Harris

Mike Rocket J. Squirrel Elliott wrote:
I'm trying to find a vendor of #4 conical, sometimes called compression
or "Belleville", washers. My hardware supplier could not find them. I
thought to get clever and contact Key Bellevilles directly but they
don't make anything that small.

Does anyone have a lead to a US vendor of such things?
Click to expand...
 
www.mcmaster.com

Chuck Harris wrote:
Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.

-Chuck Harris

Mike Rocket J. Squirrel Elliott wrote:
I'm trying to find a vendor of #4 conical, sometimes called compression
or "Belleville", washers. My hardware supplier could not find them. I
thought to get clever and contact Key Bellevilles directly but they
don't make anything that small.

Does anyone have a lead to a US vendor of such things?
Click to expand...
 
Chuck Harris wrote:

Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.
Click to expand...
$17.10 each in the .125'' size. Yikes!

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
Sporkman wrote:

www.mcmaster.com
Click to expand...
Duh. Thanks!

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)

Chuck Harris wrote:

Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.

-Chuck Harris

Mike Rocket J. Squirrel Elliott wrote:

I'm trying to find a vendor of #4 conical, sometimes called compression
or "Belleville", washers. My hardware supplier could not find them. I
thought to get clever and contact Key Bellevilles directly but they
don't make anything that small.

Does anyone have a lead to a US vendor of such things?
Click to expand...
 
Mike Rocket J. Squirrel Elliott wrote:
Chuck Harris wrote:

Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.


$17.10 each in the .125'' size. Yikes!
Click to expand...
Nah, that's $17.10 for 10 washers. Just a mere $1.70 each.

Some of the stuff that Small Parts has is very attractively priced,
but... sometimes it isn't.

-Chuck Harris
 
Chuck Harris wrote:
Mike Rocket J. Squirrel Elliott wrote:

Chuck Harris wrote:

Small Parts Inc, http://www.smallparts.com has stainless steel
Bellville spring washers in the following sizes:

3/32",1/8", #6, #8, 3/16" 1/4" 5/16" 3/4"

Kind of pricey, though.



$17.10 each in the .125'' size. Yikes!


Nah, that's $17.10 for 10 washers. Just a mere $1.70 each.
Click to expand...
Oh yeah. That's right.

Anyone have a pointer to how to stack Belleville (conical) washers to
achieve higher clamping force. The best .125 i.d. / .25 o.d. washer I
can find has a force of 49lbs when tightened fully flat. What if I want
three times that?

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
Mike,

Anyone have a pointer to how to stack Belleville (conical) washers to
achieve higher clamping force. The best .125 i.d. / .25 o.d. washer I
can find has a force of 49lbs when tightened fully flat. What if I want
three times that?
Click to expand...
You're supposed to be able to stiffen the spring constant by stacking
them so their conical sides fit together. Stack in an opposing manner
to reduce the spring constant.

--Mike
 
Mike Engelhardt wrote:

Mike,


Anyone have a pointer to how to stack Belleville (conical) washers to
achieve higher clamping force. The best .125 i.d. / .25 o.d. washer I
can find has a force of 49lbs when tightened fully flat. What if I want
three times that?


You're supposed to be able to stiffen the spring constant by stacking
them so their conical sides fit together. Stack in an opposing manner
to reduce the spring constant.
Click to expand...
Thanks, Mike. I've found that stacking them in parallel (all pointing in
the same direction) allows you to sum spring (clamping) force. Stacking
them in opposition keeps the force the same but increases the deflection
range.

My application has some of those itty-bitty Caddock TO220 power
resistors mounted to a big heatsink, and I'll be dissipating up to 50W
from the parts. So I need to clamp these parts are mighty good.

I don't know where I read about these washers. Someone (Motorola?
National?) has on a data sheet somewhere that a good mounting technique
for TO220 devices is to use these washers as part of the hardware. They
specify how much pressure (150lbs, need three .125 i.d.
conical/Belleville washers in parallel to achieve this) and how much
torque to use to tighten the bolt. A torque screwdriver is specified.
Torque screwdrivers are not inexpensive, as I've found. Anyone want to
sell one?

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
Mike,

Anyone have a pointer to how to stack Belleville (conical) washers to
achieve higher clamping force. The best .125 i.d. / .25 o.d. washer I
can find has a force of 49lbs when tightened fully flat. What if I want
three times that?

You're supposed to be able to stiffen the spring constant by stacking
them so their conical sides fit together. Stack in an opposing manner
to reduce the spring constant.

Thanks, Mike. I've found that stacking them in parallel (all pointing in
the same direction) allows you to sum spring (clamping) force. Stacking
them in opposition keeps the force the same but increases the deflection
range.
Click to expand...
Humm, opposing stacking will lower the spring constant, but I guess the
bottom out point is the same because it travelled twice as far.

... A torque screwdriver is specified...
Click to expand...
I'd just tighten until it feels like it's bottomed out and then enough
of an extra twist so that it just feels like something is just about to
cold-flow. I hope this isn't for anything life critical like a pacemaker.

--Mike
 
Mike Engelhardt wrote:

Mike,


Anyone have a pointer to how to stack Belleville (conical) washers to
achieve higher clamping force. The best .125 i.d. / .25 o.d. washer I
can find has a force of 49lbs when tightened fully flat. What if I want
three times that?

You're supposed to be able to stiffen the spring constant by stacking
them so their conical sides fit together. Stack in an opposing manner
to reduce the spring constant.

Thanks, Mike. I've found that stacking them in parallel (all pointing in
the same direction) allows you to sum spring (clamping) force. Stacking
them in opposition keeps the force the same but increases the deflection
range.


Humm, opposing stacking will lower the spring constant, but I guess the
bottom out point is the same because it travelled twice as far.


... A torque screwdriver is specified...


I'd just tighten until it feels like it's bottomed out and then enough
of an extra twist so that it just feels like something is just about to
cold-flow. I hope this isn't for anything life critical like a pacemaker.
Click to expand...
Turns out that the mounting spec comes from Caddock's data sheet for
their MP850 TO-220 power resistors. It's a full-body plastic package,
not just a metal tab and they write, "Mounting torque to avoid package
damage is 8 in-lbs (0.90 N-m)."

Perhaps you have calibrated fingers -- I don't. Hate to crack the
package. I'll get the torque driver.

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
On Fri, 05 Mar 2004 12:31:42 -0800 "Mike Rocket J. Squirrel Elliott"
<j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote:

Turns out that the mounting spec comes from Caddock's data sheet for
their MP850 TO-220 power resistors. It's a full-body plastic package,
not just a metal tab and they write, "Mounting torque to avoid package
damage is 8 in-lbs (0.90 N-m)."

Perhaps you have calibrated fingers -- I don't. Hate to crack the
package. I'll get the torque driver.
Click to expand...
I think at this size you'll find that the limiting thing will be the
strength of the screw that you can put thru that hole. If you want
stronger Belleville washers try the SP series from Rolex. They are not
as precise as some, but they are perfect for stuff like this.

For the all-plastic package, put a steel washer UNDER the Belleville
to help spread the force out over a larger plastic surface area.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
 
Jim Adney wrote:
On Fri, 05 Mar 2004 12:31:42 -0800 "Mike Rocket J. Squirrel Elliott"
j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote:


Turns out that the mounting spec comes from Caddock's data sheet for
their MP850 TO-220 power resistors. It's a full-body plastic package,
not just a metal tab and they write, "Mounting torque to avoid package
damage is 8 in-lbs (0.90 N-m)."

Perhaps you have calibrated fingers -- I don't. Hate to crack the
package. I'll get the torque driver.


I think at this size you'll find that the limiting thing will be the
strength of the screw that you can put thru that hole. If you want
stronger Belleville washers try the SP series from Rolex. They are not
as precise as some, but they are perfect for stuff like this.

For the all-plastic package, put a steel washer UNDER the Belleville
to help spread the force out over a larger plastic surface area.
Click to expand...
Good suggestion on the flat washer to spread the force.

Regaring Rolex washers: I'm a pretty good Google jockey but have struck
out on this one. A Flash animation of a seedy-looking guy did pop up and
he offered me some Rolex washers, but I'm pretty sure they were only
counterfeit. Can you point me to a vendor for these parts?

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
On Sat, 06 Mar 2004 09:21:44 -0800 "Mike Rocket J. Squirrel Elliott"
<j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote:

Regaring Rolex washers: I'm a pretty good Google jockey but have struck
out on this one. A Flash animation of a seedy-looking guy did pop up and
he offered me some Rolex washers, but I'm pretty sure they were only
counterfeit. Can you point me to a vendor for these parts?
Click to expand...
I'll check my catalog on monday.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
 
Jim Adney wrote:
On Sat, 06 Mar 2004 09:21:44 -0800 "Mike Rocket J. Squirrel Elliott"
j.michael.elliottAT@REMOVETHEOBVIOUSadelphiaDOT.net> wrote:


Regaring Rolex washers: I'm a pretty good Google jockey but have struck
out on this one. A Flash animation of a seedy-looking guy did pop up and
he offered me some Rolex washers, but I'm pretty sure they were only
counterfeit. Can you point me to a vendor for these parts?


I'll check my catalog on monday.
Click to expand...
Much appreciated!

--
Mike "Rocket J Squirrel" Elliott
71 VW Type 2 -- the Wonderbus (AKA the Saunabus in summer)
 
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