Layout Electrical

 3/1/2021

I would like to share with you something I have had a lot of success with on my current as well as previous layout and a tool I found that has been a big help in doing it right the first time so let's get into it.

A 3M 905 IDC or Integrated Displacement Connector
showing the run through and stub end as well
as the steel tab portion of the IDC that
makes connection with the actual wires

The steel tab you see in the middle of this IDC

when crimped down into the wires, pierces 

the wire's insulation making connection with the actual copper wires. 

The tab you see folds over and

snaps onto the connector preventing the steel tab

from coming out.

I'm sure you have heard of what Model Railroader's call suitcase connectors or the technical term "Integrated Displacement Connectors" or "IDC" for short. These connectors replace the need to solder your track buss and feeder wires that reside under the layout. Soldering these is a very reliable way of ensuring a good, reliable connection but not all of us are good at soldering especially while under a layout while laying in a precarious position trying to keep from getting burned by the soldering iron or dripping solder. 

Yes, I know there are those who say to stay away from IDC's and say they are not very reliable. What I have found is those who say this don't know how to use these which leads me to the second part of all of this. Soldering is a good method if you don't mind getting burned from a dripping solder or a hot soldering iron while working in a precarious position under your layout. Soldering is a good way but not the only way as some would have you believe. Take it from someone who has used IDC's for many years with zero failures or defects.

Micro Mark use to sell a crimping tool specifically for crimping IDC connectors but I haven't been able to find this tool on the Micro Mark website or their catalog of late so I did some searching on the internet and found Amazon sell's a tool made by Klein Tools. Now if you've heard of and have used any of Klein's tools, you know Klein is the maker of some very good tools like Linesmen Pliers, Diagonal Cutters and Linemen bags.

Purchase this tool from Amazon HERE

I use to use a pair of wire stripping pliers but the handles on these were just too thin, hurting my hands and making them fatigue to the point I almost had to stop what I was doing and rest my hands before continuing on. This tool eliminates these issues as the handles are much thicker making them much more comfortable to use and they keep my hands from tiring out. These pliers also come with wire snippers to cut wire eliminating having to have a pair of diagonal cutters with me as well. 

The trick to using these is simple. Make sure the pliers grab the IDC head on. In other words, don't come from an angle to crimp an IDC as this will cause the steel tab to bend over rather than go into the wires as intended. You want a clean, non-angled approach when crimping an IDC as this will give you a clean crimp, one that has pierced the wire insulation and make good contact with the actual wire giving you a good clean connection.

Klein IDC Crimping Pliers

Photo showing how the Klein IDC pliers crimp an IDC

Note the stops on the Klein IDC crimping pliers

I purchase from Micro Mark the 3M 905 IDC connectors. These will accept a 22 awg to 18 awg stub end wire and an 18 awg to 14 awg buss wire. What this means and what probably trips a lot of People up when using these, making them think they don't work is that the stub end wire portion of the 905 will only accept a 22 awg to 18 awg wire inserted only one way into the 905 whereas the run through portion of the 905 will straddle an 18 awg to 14 awg wire. Some People will try to get the 905 to accept a larger wire than what it was designed to accept, causing problems and misconceptions.

An 18 to 14 stranded gauge wire easily slips into the run through
portion of the 3M 905 IDC

On the left is the stub end portion of the 905 IDC.
This is the side the wire is inserted as the steel
tab is on this side of the stop

Photo showing the stop in the stub end portion of
the 905 IDC. Do not insert a wire from this end
as the steel tab will not pierce the wire

 Also, my experience in using solid wire hasn't been all that good. I've had better results using stranded wire as stranded wire tends to get up into the slots on the steel tab and seat better that solid wire. Your results may vary but I wouldn't recommend using solid wire with the 3M 905 IDC Connector.

The only drawback to these pliers is I wish the surface area that comes in contact with the IDC was knarled giving these a better grip of the IDC, especially when your in an awkward position as the IDC has a tendency to slide out of the jaws of the pliers rather easily.

As a recap, the 3M 905 IDC Connector is a very good alternative to soldering. These are designed to limit hand fatigue and make using IDC much easier. Remember to use only stranded wire and crimp head on, not from an angle or side to side as this will cause the steel tab to not go in correctly. Be aware of which side you insert the stub end wire on the 905 IDC to ensure the steel tab will  properly pierce the wire.

Once you get use to using the Klein IDC pliers and know the limits of the IDC you are using, I doubt you will go back to soldering.

The brake stool I use to work under the layout
making Life so much better!