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Need plastic screws

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JRP
  • Member since
    November 2006
  • From: Upland, CA
  • 251 posts
Need plastic screws
Posted by JRP on Saturday, October 17, 2020 5:48 PM

Hi all, I need to replace the small metal screw (that holds the motor to an Atlas Alco S2 locomotive) with a plastic screw in order to isolate the motor from the frame so I can add a decoder for DCC.  Anyone know where I can locate small plastic screws?  I've tried EBay and Amazon, but can't find them anywhere.  I think the screw may be metric as the Atlas engine was made in Austria, but I can't be sure. The threaded shaft is 5mm in length and with the flat head, add another 1mm for a total of 6mm.    

 

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Posted by Lastspikemike on Saturday, October 17, 2020 5:53 PM

Can you install an insulating washer under the screw head instead?

What you are looking for is a nylon machine screw.

These are sized by diameter and thread number per inch, two numbers.

I'm not sure about metric numbering.

Kadee supplies nylon machine screws in #2 size with 56 tpi which is very close to 2mm in diameter. Length isn't an issue because you just cut to length you need.  It helps if you have a tap and die set to clean up cut end of  threads but an exacto knife and a hobby file will also work. I just use a steel nut of the correct size as an el cheapo die to clean up cut threads. 

6-32 is also a common size but much bigger at 3.5mm in diameter and 32 tpi.

There are also some pretty tiny screws out there. What diameter are you trying to replace? 

Alyth Yard

Canada

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Posted by wvg_ca on Saturday, October 17, 2020 5:55 PM

both ebay and amazon have plastic screws, both inch and metric

  • Member since
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Posted by Boiler-man on Saturday, October 17, 2020 6:16 PM
You might give McMaster Carr a try.
Boilerman
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Posted by gmpullman on Saturday, October 17, 2020 6:25 PM

Does this look like your Atlas S-2?

https://tcsdcc.com/installation/ho-scale/1900

This only shows three pieces of kapton tape to "isolate" the motor pickups from the frame, no mention of using a nylon screw.

Maybe yours is older?

As long as each brush holder does not touch the frame or if it has a can motor you don't have to isolate any further.

Good Luck, Ed

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Posted by rrinker on Saturday, October 17, 2020 6:37 PM

 The motor in the P2K Alco switchers looks exactly the same, and when I did one of those, the metal frame of the motor did not touch either brush holder, so the metal screw holding it in place did not violate any isolation. However, multiple sources have said the motor used int he Atlas model does short the metal case throught he brush. I have an older Atlas (made by Roco) S2 that I have yet to take apart and look into to see if this is the case or not.

 Easy enough to test - meter on continuity, touch the probes - should beep. Touch one probe to the metal frame part of the motor where the screw goes in (in the screw hole migth be best - that way there's an area cleared of paint) and touch the other probe to each brush cap one at a time. If no beeps - then there is no reason to use a nylon screw, a metal screw holding the motor in place won't connect the chassis to the brush. If it does beep (and only one side would beep - if both sides beep, thent he motor is always shorted, in which case it never would ahve run), then a layer of kapton tape plus a nylon screw will be required to keep the brush isolated from the chassis.

                                        --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by jjdamnit on Saturday, October 17, 2020 6:41 PM

Hello All,

Check out Micro Fasteners.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by RR_Mel on Saturday, October 17, 2020 6:45 PM

You might try using some Kapton tape to insolate the motor from the frame then use some glue like Amazing Goop to hold the motor using the metal screw to keep everything in place until the glue dries then remove the screw.  I’ve been using Amazing Goop to mount motors for years and it not only holds very good but it also absorbs motor noise and vibration.



This motor is attached to the frame using Amazing Goop.


Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.

JRP
  • Member since
    November 2006
  • From: Upland, CA
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Posted by JRP on Sunday, October 18, 2020 1:42 PM

Using standard measurements, I show 10 tpi (5/16 in length) by 1.5mm (diameter). The hole size is 2mm.  Yes, a very small screw.  I already have Kapton tape covering the frame where the motor will sit, but the screw was meant to secure the motor.  I guess I can use glue to do that as one other modeler suggested.  Because I'm installing a new LokSound decoder, I do not want to risk frying $85.   

Thank you.

JRP

JRP
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Posted by JRP on Sunday, October 18, 2020 1:43 PM

Sounds easier.  Thanks Mell.

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Posted by rrinker on Sunday, October 18, 2020 2:28 PM

 Do test it with a meter, that way you will be sure.

                              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

JRP
  • Member since
    November 2006
  • From: Upland, CA
  • 251 posts
Posted by JRP on Sunday, October 18, 2020 3:24 PM

Agree.  Thanks Randy.

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Posted by RR_Mel on Sunday, October 18, 2020 3:48 PM

The Amazing Goop can be really messy to work with, sticky and stringy, but it’s my go glue for mounting motors.  Great glue and has terrific holding power.  If you error or for some reason want to remove the motor a firm grip with a twisting motion the motor will come off.



Both the Canon EN22 motors in my Mel Rivarossi Cab Forward brass frame are mounted with Goop.





Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.

JRP
  • Member since
    November 2006
  • From: Upland, CA
  • 251 posts
Posted by JRP on Monday, October 19, 2020 12:03 PM

I did the meter test and did not get a beep sound when I touched the probes to the screw in the frame and the brush cover.  I do have Kapton tape covering the frame base and narrow sides where the motor sits, so I think I'm good.  

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Posted by snjroy on Monday, October 19, 2020 1:53 PM

To isolate or set the motor in place, I glue two strips of plastic on the frame using CA, leaving space bewteen them, and I used silicone caulk to glue the motor. The space betwen the plastic strips allows the silicone to reach the frame directly for a good firm grip. The strips are really there to prevent the motor from touching the frame despite the use of caulk. I like caulk because it is very easy to remove in case I need to disassemble it for some reason. It happens...

Simon

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Posted by jjdamnit on Monday, October 19, 2020 2:20 PM

Hello All,

JRP
I do have Kapton tape covering the frame base and narrow sides where the motor sits, so I think I'm good.

Keep in mind Kapton tape is a relativly thin material and subject to wear through repetative movements. It also doesn't have a high-tack strength like other tapes.

I use Kapton tape too but when I need to be absolutly sure of electrical insulation and longevity I use 3M doubble sided foam tape- -if there is room. Air is one of the best insulators- -the air bubbles in the foam, along with the foam it's self, acts as an insulator.

The resilency of the foam also provides a cushion between the parts being insulated during repetative motion.

When there is not enogh room for doubble sided foam tape I use Liquid Electrical Tape. This is available at most hardware & home improvement stores.

Be aware that this product is spirit based and should be used in a well-ventilated area while applying and curing with no open flames.

Silicone caulk is also another good insulator with less volitile fumes. The fumes that silicone caulk emits during curing can be a deal breaker for some.

Keep in mind electricity is the lazyist force in the universe- -second only to water.

It will always seek the path of least resistance, no matter how small.

Any breach in the insulating material will allow the electrons to flow and release the "magic blue smoke" that make the component(s) work.

Even just doubbling-up on the Kapton tape will provide a little more insurance against the electronic gremlins.

Hope this helps.

Post Script: This is why I use Digitrax decoders. They have a "no questions asked" return policy. Even if the malfunction is your fault they will replace the blown decoders. H.T.H.
J.J.D.I.

 

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by richg1998 on Monday, October 19, 2020 2:36 PM

Last thing I learned to do is use the program track, FIRST.

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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