SmartWheel and Force Probe Connector Repairs

Hello TEEMSS teachers! *Important cautionary note!

We've had several reports of the jacks on the SmartWheels and Force Probes breaking.  The jacks are small black plastic elements that the cables plug into.

Obviously we will need to redesign this connection to make it more durable.  The SmartWheels and Force Probes are prototypes and we will fix these problems the next time they are manufactured.

In the meantime *please* be as careful and gentle as possible with the cable connections. Tell your students they must insert the cables gently, not push too hard, and avoid bending them or pulling on the cables. When they attach the SmartWheels to meter sticks, it would be good to tape the cables (loosely) to the meter sticks so that they are less likely to be pulled sideways.

We are investigating some quick fixes to strengthen the connection for the existing probes. We hope to get to nearby schools and make these reinforcing changes. We may be able to repair some of the SmartWheels that are already broken.

We also have some reports of the SmartWheel wheels (the plastic CDs) cracking. Again: we will improve in the future, but for now, encourage your students to be gentle!

Thank you for your cooperation. Such is the world of prototypes.

Preliminary Fix

Wednesday April 10, 2002, Stephen Bannasch

I am using a nylon washer with an inner diameter of 0.200" and a thickness of 0.062" as a collar around the nose of the connector and then using general purpose hot melt glue to form a mass around the connector and on the circuit board side of the washer.  I am now also using this on the SmartWheel, Force probe and Light probe probecards.  The probes still work, the internal spring contacts in the connector still work and it is much stronger.

Washer specifications for strengthening

Broken probecard jack.



Strengthened probecard jack, notice the hotmelt glue on either side of the connector but none is in the hole.

Washers for strengthening

The best washer I have found for strengthening the connector jacks is the following:

Type:	Round
Material:	Nylon
Screw-Size-(Inch):	#10
Inside-Diameter-(Inch):	.200"
Outside-Diameter-(Inch):	7/16"
Thickness-(Inch):	1/16"

I bought out the local hardware store.  Their supplier was:

part# NYW10
Serve-A-Lite Products
East Moline ILL  61265

However I can't buy this washer from McMaster-Carr which is the supplier I normally use.  They have the following washer:

Part Number  90295A122     $3.23 per Pack of 100

Type:	Round
Material:	Nylon
Screw-Size-(Inch):	#10
Inside-Diameter-(Inch):	.200"
Outside-Diameter-(Inch):	.450"
Thickness-(Inch):	.031"
Thickness-Tolerance:	±.005"

However the thickness is half of what I would like.  So right now I am using the following shoulder washer from McMaster-Carr:

Part Number  90061A011     $5.65 per Pack of 100

Type:	Shoulder
Material:	Black-Nylon
Barrel:	Short
Screw-Size:	#10
Inside-Diameter (inches)	.201"
Outside-Diameter:	.437"
Length:	.050"
Thickness:	.050"

Other companies make the appropriate washer.

Here is another supplier I found:

http://www.wclco.com/

16730 East Johnson Dr.
P.O. Box 3588
Industry, CA 91744
Tel (626) 968-5523
Fax (626) 369-9805
We are Open
7am - 4:30pm, Pacific

size	ID	OD	thickness	alternate-part#
10	.200	.437	.062	FW437200062

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Questions and comments: stephen@concord.org