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Why Kapton tape?

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Why Kapton tape?
Posted by SouthPenn on Sunday, September 18, 2016 4:57 AM

Why not use Scotch 33+ electrical tape? Its rated for 600V, sticks to most anything,comes in a ton of colors, and is rated for use up to 220F. 

I can't justify the cost of Kapton tape for anything in model railroading.

South Penn
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Posted by carl425 on Sunday, September 18, 2016 9:20 AM

SouthPenn
I can't justify the cost of Kapton tape for anything in model railroading.

There are many sizes & sources for it on Amazon for less than $10.  If you can get a lifetime supply of something that is universally recommended as the best choice, why waste time shopping for a better deal?

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by tstage on Sunday, September 18, 2016 9:53 AM

One plus to Kapton tape is that it's thin but holds very well.  And sometimes that thin-ness determines whether a shell is going to seat properly or not onto the chassis.  It's also clear (which allows you to see underneath what's taped) and it won't leave a sticky residue.

I only use Kapton tape for decoder and headlight installs.  Great stuff!

Tom

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Posted by Stevert on Sunday, September 18, 2016 11:40 AM

In addition to what Tom has mentioned (and not leaving sticky residue behind is a BIG advantage, IMHO), Kapton tape is more puncture-resistant than vinyl electrical tape.

That's important when insulating the bottom of a decoder, for example, with all those pointy little solder nubs.

It's also more thermally stable than vinyl tape, so if the decoder or motor heat up, it won't come unglued (and leave more of that sticky residue!)

And it's not that expensive.  Without doing any comparison shopping at all, here's a link to a place selling a half-inch by 36 yard(!) roll of 1-mil Kapton tape for $11.  That's enough to share with your club and still last you a lifetime!

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Posted by richg1998 on Sunday, September 18, 2016 12:12 PM

The black tape oozes as was mention. Too thick for insulating motor from the frame. Can affect gear lash in steamers.

I have been using black electrical since 1954. As a modeler and industrial electrician and mechanic. It can be messy under certain conditions.

Kapton is thin and tough.

I had to insulate a model motor from both frame parts. Kapton and nylon screws. The motor halves were mechanically connected to each brush.

The motor halves fitted right into each frame half. I still had to mill the inside of the frame a little with a Dremel and bit.

In a couple single motor Bachmann 44 tonners I used Kapton to mount the LokSound micro and tie down the wires. The decoder is insulated with clear shrink.

Careful online shopping for prices and cost of shipping.

Search the forums. This has been discussed here before with places to buy it.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by rrinker on Sunday, September 18, 2016 12:26 PM

 Kaptop isn;t really all that expensive - there are may dealers that sell fractions of a roll. You never need all that much. I have 2 rolls of different widths I bought about 8 years ago and both still look like I've barely touched them. The first Kaptop tape I bought, I got I think a 3 meter quantity and after dozens of decoder installs I hadn't even used all that up.

 I think the reasons for it over regular electrical tape have been covered.

Thinner

No icky residue

More puncture resistence (key for locos like Athearn Blue Box where you need to put a layer of tape under the motor to insulate it from the frame)

Higher heat resistence (not really applicable to model railroad use - however if you solder a wire next to something taped down with Kapton tape, it won't melt the tape)

Re-sticky - I've pulled a piece off that was holding a decoder in palce and then was able to re-stick it, the adhesive is somewhat of a PSA (pressure sensitive adhesive) so it was possible to resecure it to the loco chassis instead of using a new piece.

                      --Randy


Modeling the Reading Railroad in the 1950's

 

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Posted by richhotrain on Sunday, September 18, 2016 12:40 PM

Kapton tape is an excellent insulator, and it is ideal to place on a metal frame or chassis to prevent contact with a decoder.

Rich

Alton Junction

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Posted by 7j43k on Sunday, September 18, 2016 12:59 PM

SouthPenn

Why not use Scotch 33+ electrical tape? ...comes in a ton of colors...

 

 

A super minor point:

Scotch 33+ comes only in black.  Scotch 35 DOES come in 9 colors.  But not black.

Here's a 3M chart for comparing their vinyl tapes:

 

http://multimedia.3m.com/mws/media/770753O/3mtm-vinyl-tape-performance-comparison-chart.pdf?&fn=Vinyl%20Electrical%20Tape%20Compare.pd

 

My experience is that 35 is less user-friendly when temperatures get away from "room".

Ed

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Posted by peahrens on Sunday, September 18, 2016 2:39 PM

i need a roll for an upcoming decoder install in a metal steamer.  On Ebay I noted some advertised as Kapton in the title (a Dupont material), price approaching too good to be true, show "Koptan" on the roll in the photo.  While they may be made of the correct material, the adhesive might be questionable, etc.  Looks like a buyer beware issue, and tough to tell what is the real thing and/or quality differences. 

I ordered one from Amazon but think the issue is probably there also; i.e., nearly impossible to tell which ones are quality compromises. 

Paul

Modeling HO with a transition era UP bent

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Posted by tstage on Sunday, September 18, 2016 6:03 PM

I believe I purchased my 1/2" roll of Kapton tape from Litchfield Station.  It's the real stuff and worth every penny...

Tom

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Posted by richg1998 on Sunday, September 18, 2016 6:17 PM

 

One caveat. When I did an isolation, the screw was Metric. I re-tapped for closest size SAE screw. Forgot to file that spot smooth and the tape was punctured. A thin ridge will form when tapping metal. Forgot that. Ohm meter check showed me that before wiring the decoder.

Mating surfaces have to be smooth.

Rich

 

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Posted by Guy Papillon on Monday, September 19, 2016 5:59 PM

South Penn

Very informative thread. Thank you for posting.

Guy

Modeling CNR in the 50's

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Posted by Anonymous on Monday, September 19, 2016 11:41 PM

Not only is it resistant to the heat from a motor or decoder, it can also keep the decoder from overheating because normal electrical tape insulates heat very well...

I've never actually used it myself, but I have seen other people use it and it seems logical

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Posted by hon30critter on Tuesday, September 20, 2016 11:59 PM

Electrical tape, regardless of colour, will leave a messy, sticky residue and the tape will come loose over time. Electrical tape seems to work great when the joint can be wrapped tightly several times and the tape can be pulled tight before the excess is cut off. However, go back to that connection in five or ten years and you will still have a sticky mess.

Heat will quicken the degradation of the electrical tape's ability to stay where it is supposed to, and when it is used to simply hold stuff down the loss of adhesion will set in fairly soon.

Why create a sticky, unreliable mess when it can be avoided?

Dave

I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!

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