Added friction for Accumate box


George Hofmann
 

Some time ago I posted a self-centering mod for narrow shank Sergents in the Accumate box (sergentcouplermod.blogspot.com). This works but requires an irreversible modification to the shank and some fiddling. The reason for self-centering, for me at least, is that it is far too easy to knock the coupler out of alignment when opening the knuckle with the wand. Getting it back into alignment is frustrating to put it mildly. The spring in the shank is supposed to supply friction but in the Accumates at least, it does not provide nearly enough.

So I thought if lack of friction is the problem why not add more? After some twiddling I devised this method. I take some 3M blue painter's tape (accept no substitutes) and cut some narrow strips whose width is about the same as the height of the pivot post in the box., Then I cut segments from this strip, maybe 3/8 inch in length. I wrap these segments around the post and put the shank in place. The spring is not needed. This technique provides a significant increase in friction. Only the clumsiest operator would now knock the coupler out of alignment. But the friction is not so much that it interferes with normal operation of the coupler assembly. This is a completely reversible modification, unlike the self-centering. Will it last? Time will tell but my experience is that the 3M tape is extremely durable and does not deteriorate. But again, if it did, the mod is reversible.

As for the springs, they can be tossed. Or get a piece of monofilament, string the springs on it and give it to your wife as a necklace.

George
Edgewood, WA


Dale Buxton <dbtuathaddana@...>
 

Nice solution George!


On Sat, Aug 28, 2021 at 10:22 AM George Hofmann <george.hofmann@...> wrote:
Some time ago I posted a self-centering mod for narrow shank Sergents in the Accumate box (sergentcouplermod.blogspot.com). This works but requires an irreversible modification to the shank and some fiddling. The reason for self-centering, for me at least, is that it is far too easy to knock the coupler out of alignment when opening the knuckle with the wand. Getting it back into alignment is frustrating to put it mildly. The spring in the shank is supposed to supply friction but in the Accumates at least, it does not provide nearly enough.

So I thought if lack of friction is the problem why not add more? After some twiddling I devised this method. I take some 3M blue painter's tape (accept no substitutes) and cut some narrow strips whose width is about the same as the height of the pivot post in the box., Then I cut segments from this strip, maybe 3/8 inch in length. I wrap these segments around the post and put the shank in place. The spring is not needed. This technique provides a significant increase in friction. Only the clumsiest operator would now knock the coupler out of alignment. But the friction is not so much that it interferes with normal operation of the coupler assembly. This is a completely reversible modification, unlike the self-centering. Will it last? Time will tell but my experience is that the 3M tape is extremely durable and does not deteriorate. But again, if it did, the mod is reversible.

As for the springs, they can be tossed. Or get a piece of monofilament, string the springs on it and give it to your wife as a necklace.

George
Edgewood, WA


George Hofmann
 

A further experiment I tried was to cut through the end web of the shank such that the two prongs remaining could be squeezed together to create more friction. I expected the prongs to snap off but they did not. I was able to get satisfactory friction this way without using any tape. The resulting motion was a little smoother too. Of course this is an irreversible modification to the shank and may easily result in it's destruction especially if you try to pry the prongs apart again.

The next thing that I want to try is to take a stock coupler in Accumate box and add some springy material on either side of the prongs. This would be to provide self-centering, not added friction and I'm good with that. I'm thinking the material could be a bit of foam rubber or something similar. There's not a lot of space there for a real spring.

George
Edgewood, WA


George Hofmann
 

I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George


Greg Amer
 

Interesting. I gave up on Sergent couplers because they were too easy to uncenter and too hard to see to get them back to center. I’m glad you are finding solutions to make them more modeler friendly.
--
Greg Amer
https://www.gregamer.com
Kent, WA


Mike Conder
 

That's brilliant!  Thanks for all the research ....

Mike C

On Thu, Sep 16, 2021 at 8:56 PM George Hofmann <george.hofmann@...> wrote:
I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George


Bill Keene
 

George…

Pictures? 

This old dog thinks … and learns ... more as a graphic experience. 

Thanks & Cheers,
Bill Keene
Irvine, CA
 

On Sep 16, 2021, at 7:56 PM, George Hofmann <george.hofmann@...> wrote:

I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George


Jonathon Hedtke
 

Great idea George.  I put very short lengths cut as long as the Accumate box is thick and put them so that the open end of the tube is visible.  They are placed like you said on each side of the back end of the coupler.  Seems to work very well.  Thanks for the idea.  

Jon

On Thu, Sep 16, 2021 at 10:56 PM George Hofmann <george.hofmann@...> wrote:
I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George


Donald B. Pirkey
 

How long of a segment of tubing are you using? How big is the "donut"?

On Thursday, September 16, 2021, 09:56:44 PM CDT, George Hofmann <george.hofmann@...> wrote:


I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George


Andy Reichert
 

IIRC, Frank deliberately avoided making the couplers self-centering in order to make them as true scale and prototypical as possible.

Andy

On 9/18/2021 10:11 AM, Donald B. Pirkey via groups.io wrote:
How long of a segment of tubing are you using? How big is the "donut"?

On Thursday, September 16, 2021, 09:56:44 PM CDT, George Hofmann <george.hofmann@gmail.com> wrote:


I discovered how to put springy material in the Accumate narrow coupler box to provide self centering. I found that I could use shrink tubing cut into short lengths to create donuts. These are then placed one on either side of the rear end of the shank between it and the box wall. When the coupler moves side to side it squeezes the donut which provides the springiness. The tubing I'm using looks like it is about 1.5 mm in outer diameter. I tried a bigger size but it was too stiff. I also tried using insulation stripped from 24 awg silicone wire and that worked but was also quite stiff. It seems that the tubing used must have a relatively thin wall.

This solution is quick, easy, inexpensive and reversible. It works perfectly for self centering. It will be what I use going forward.

George
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George Hofmann
 

Thanks for all the comments.

Here's the picture for Bill et. al. I believe the shrink tubing that I am using is 1/16" that I probably got from Litchfield Station, although it should be available anywhere. The length of segment (thickness of donut) is about 1/16". It must be slightly less than the height of the coupler box cavity. As Jon described, the donuts are placed so that the donut axis is vertical. In the picture you can see that they are pretty squished even when the coupler is in the centered position. They have to be placed far enough to the left to leave space for the part of the cover that extends down around the pins. Sorry that the picture is a little fuzzy around the edges. Depth of field is thin at this mag.



Regarding Andy's comment, Frank certainly made an absolutely magnificent product. But I and I think many others found them to be so cantankerous to work with that we were ready to give up.  The possibility for them to be set off center does not add to my enjoyment. Self centering helps in most circumstances and for me it's the difference between go and no go. I'll deal with the coupling on a curve issue should I encounter it.

So use this idea if you want to. It does no harm. My next quest will be to find a similar technique for the standard shank version. Others have shown various techniques for SC there but I'm hoping that this simple donut method can be adapted.

George


Dale Buxton <dbtuathaddana@...>
 

I really like your solution George. Very elegant, simple and to the point.

I know a lot of our older eyes find Segent's more than a bit fiddly to operate. I have found that a physician's pen light attached to the uncoupling wand works rather well without any modification to the coupler at all. It puts the right light on the subject so I can see what I am doing.

However, I mostly model in HOn3. So I need the full swing of couplers to negotiate 20" radius or tighter curves. Second, I can not use the Accumate coupler box on HOn3 equipment as the width of the box obstructs the rotation of the HOn3 trucks on those same 20" radius or tighter curves.

Dale Buxton


On Sun, Sep 19, 2021 at 10:12 AM George Hofmann <george.hofmann@...> wrote:
Thanks for all the comments.

Here's the picture for Bill et. al. I believe the shrink tubing that I am using is 1/16" that I probably got from Litchfield Station, although it should be available anywhere. The length of segment (thickness of donut) is about 1/16". It must be slightly less than the height of the coupler box cavity. As Jon described, the donuts are placed so that the donut axis is vertical. In the picture you can see that they are pretty squished even when the coupler is in the centered position. They have to be placed far enough to the left to leave space for the part of the cover that extends down around the pins. Sorry that the picture is a little fuzzy around the edges. Depth of field is thin at this mag.



Regarding Andy's comment, Frank certainly made an absolutely magnificent product. But I and I think many others found them to be so cantankerous to work with that we were ready to give up.  The possibility for them to be set off center does not add to my enjoyment. Self centering helps in most circumstances and for me it's the difference between go and no go. I'll deal with the coupling on a curve issue should I encounter it.

So use this idea if you want to. It does no harm. My next quest will be to find a similar technique for the standard shank version. Others have shown various techniques for SC there but I'm hoping that this simple donut method can be adapted.

George


George Hofmann
 

Here's one more technique. This one is for increasing friction rather than self centering. I found that Kadee 209 fiber washers can be used as friction inducing shims in both the Accumate/narrow shank and the wide box/standard shank versions. They fit right over the pivot post in both cases. For the former I add one washer under the coupler. For the latter I need two on top of the shank as well for a total of three. We just need enough washers to remove all of the slack. When the lid is tightened down the washers squeeze on the shank. The beauty of this scheme is that the amount of friction that results is a function of the torque applied to the screw. Make it as little or as much as you like. The washers are a little too wide for the narrow box but can be easily trimmed to fit with a hobby knife.



George
Edgewood, WA