Author Topic: Concrete Tie strip for N Scale and Code 40 Rail  (Read 12463 times)

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narrowminded

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #255 on: February 24, 2020, 12:21:33 AM »
+1
Per a request I've just added #14 Frog machining and soldering fixtures to the list.  Easy now with the batch of similar fixtures so may as well have this one, too.  A quick check of the NMRA standards and then Fast Tracks tools show that they both stop at #12's.  It's not likely to be a standard offering but maybe a custom. 

Long switches bring their own set of concerns with long, floppy rails but I don't have the experience yet to really know how bad it will be to work with them.  I may be overly concerned. :|  Also the frog gap keeps getting bigger and may be a concern.  The way I'm making my frog and point rails with the webs fully supported at the ends should allow for the narrowest points therefore the smallest gaps possible but they still continue to get larger as the frog number goes up.  What has crossed my mind is, has anybody ever made movable frog points in N scale?  I'm aware of them in prototype but not up close and personal, like what frog size might be the conventional size to start considering moveable points. :)  Quick search attempts haven't yielded much on this specific info.

Edit add:  I think I'll start a thread in the standard N and Z forum for the movable frog question.
« Last Edit: February 24, 2020, 12:27:19 AM by narrowminded »
Mark G.

narrowminded

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #256 on: March 04, 2020, 06:04:19 AM »
+1
An update with something to show.  No, the fixtures aren't done yet but chip will be flying this Thursday. 8)  To start, there are 32 rail gripping/ positioning fixtures for the range of Code 40 and Code 55 turnouts, 9 each from #4 thru #14, ignoring #11 and #13.  Then 3 Frog soldering fixtures with 3 sizes per fixture, and a precision rail bending brake with adjustments for precise angle and precise position.  There will be others made in my manual machines for assembly, hinge soldering, etc, for all of the little detail stuff and assembly rigs.  I'm getting anxious. :)

Meanwhile, I made a rail grip fixture set to test the design approach for the tiny code 40 rails and also on the Code 55.  This will be used for frog and especially closure rail preps  where the angles get very shallow and a thin point is most desirable but difficult to accomplish with the rail head and foot overhanging the web.  It's one of those things that has huge effect on the rest of the design and if not executed pretty near perfect results in gauging fluctuations, the need to relieve the stock rail head for the fatter point as is common for most commercially produced turnouts, or jockeying the nose with a taper inside and out, trying to get the nose slim enough, but then ending up with a gauge fluctuation by whatever the inside face taper is. 

What I've measured on Atlas turnouts is .015" point at the closure rail point and on some hand builts I have that were made using a point filing tool they are .010" but also had a bit of an inside taper at the very point, showing up as a slight taper at the very end, getting a little fat within the first 1/8" of the stock rail contact point.  Meanwhile, that closure rail from the point all of the way to the heel block (hinge) is supposed to be perfectly straight, holding gauge with the opposing straight stock rail.  Any bends in either one at this point show up in gauge fluctuations.  With some tweeking and work with the gauge this can be adjusted somewhat and kept within a generous NMRA tolerance for this position in the turnout.  But it's still fluctuating wider or narrower.  This is where the wide treads on our models are saving the day, taking up the non-prototype fluctuations.  For all of the turnouts that work well, the real tight tolerances are at the frog and guard rail positions but the more accurate the turnout is throughout its many dimensions, the smoother it will run.   Those who have hand laid and with some practice and care have already experienced this. :)

With that said, my point rails will be/ are all machined, accurately positioned in the machine and maintaining perfectly straight cuts, not filed with all of the inaccuracy that introduces, even if tolerable, and with a full, straight, vertical point with the finest point that can withstand use.  Also, while the stock rail foot will need to be relieved there is no filing of the mating stock rail head to tuck a fat point in to get a functional dimension.  (There's more reason for this too but enough for now.) ;) 

The machined test piece pictured below is for a #4 turnout.  The point is .002", about as fine as it can be while still being strong enough. 8)  The plan is .003"/ .002" as the standard point thickness dimension.  It is aligned perfectly straight and parallel with the opposing stock rail, holding extremely accurate gauge throughout the assembly, and fully supported as the web is not removed.  The rail starts the process by precisely bending the point end of the rail outward to move the face of the thin web outward in the direction of the gauge face of the rail, and then the now bent rail head and foot are precisely machined back to the original straight plane but now with the web fully supporting the head vertically.  With the rail head now back to perfectly straight on the gauge face and with the web fully supporting the rail head, the rail is placed in a second fixture where the angle is precisely machined from the back side at the proper angle and to the extra fine point that the solid web can support.

This process will be the same for the frog points which allows them to be very fine points.  With that fine frog point it will allow for less unsupported gap in the rail transition across the gap left where the flanges pass on the opposite route.  That gap is an unavoidable turnout design problem (unless you make a movable frog point) ;)  and it gets worse as the frog angle increases and is further aggravated by a less than sharp frog point.  By prepping the end so that the web is supporting all of the way to the point and then precisely machining the components this gap can be kept to the minimum possible for each size.

Here are the pics of the Code 40 machined test part.  The ones being held were photographed through a magnifier light to get a view of the .002" point.

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« Last Edit: March 04, 2020, 02:30:18 PM by narrowminded »
Mark G.

narrowminded

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #257 on: March 20, 2020, 08:20:46 PM »
+5
Work is progressing on the rail machining fixtures but boy, it's like pulling teeth to get this done. :|  Much is the legitimate scheduling of time in the machines I wanted to run these in, for ease of producing so many pieces.  And then, with this virus business, one of the main customers of that shop has just ordered any and all parts that the shop can produce over the next couple of months.  Unheard of. :| 

So what I've gotten done (a week ago) is all of the clamp bodies are machined for 56 matched sets of rail clamping fixtures, all held to extremely tight tolerance (.0002" in key dimensions and no worse than .0005" anywhere), and now ready for the final clamping groove details.  It is hard to say when I can get access to those machines again, probably some months, so I am now bringing several of those blanks home to complete grooves for a few turnout numbers in my home manual machines.  This isn't the end of the world but it is much more time consuming to set these up at the accuracy desired but in the end, the results are the same, just much more time consuming. 

I have to get a few done so I can prove out their effectiveness to keep the project moving forward.  Trial runs of parts are normal when developing something this involved but (temporarily?) losing the access to a very efficient CNC machine that lends itself perfectly to the fixture features I needed to machine in these blocks has slowed down the process.  It doesn't stop it but it slows it pretty dramatically.  I will keep posting progress. 

Meanwhile, here's the box with just the rail clamp fixture bodies, sitting on the shop floor, with 56 perfectly executed and matched sets of fixture bodies (plus some spares?), ready for the final steps that make them actually useful for the intended purpose. ;)  These are used for accurately machining the assortment of angles and features for all frogs and point rails #4 thru #14 (skipping #11 and #13).  There are more fixtures to be made for other details but not of this type.  This picture evokes a mixed emotional swing between thrilled and frustrated. :D

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« Last Edit: March 21, 2020, 12:48:18 AM by narrowminded »
Mark G.

jagged ben

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #258 on: March 20, 2020, 09:59:18 PM »
+1
Well... wow.

narrowminded

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #259 on: April 04, 2020, 04:55:42 PM »
+1
A quick update.  Because I've not been able to use the CNC machine of my choice due to that shop being buried in work I've resorted to machining them old school on my home machines.  The accuracy doesn't suffer but the schedule sure does. :facepalm:  It's much more time consuming due to the multiple, involved setups per fixture.  And many long passes with a .015" cutter at depths over 2x diameter doesn't make it any easier. ;)  What's helpful to the setups is having those pictured rail machining blanks already run and accurate to the extreme.  It makes what would have been pure torture little more than a pain in the a$$. ;)  But it's all for a good cause! :D
« Last Edit: April 04, 2020, 04:57:17 PM by narrowminded »
Mark G.

71jeep

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #260 on: July 27, 2020, 03:26:11 PM »
0
Anyone know what happened to narrowminded?
He was very active here but his profile says he has not been on since beginning of may?
I watching this thread with excitment hoping to see where all this was going.
But it seems  to have fallen flat and and narrowminded disappearing with it?
I hope he is okay as I always enjoy reading his post as he is allot like me i thinking and technique    .
Hoping he chimes in just to let us know he is okay?


MK

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #261 on: July 27, 2020, 05:08:59 PM »
0
Oh dear, May 16th is a long time ago.   :?

robert3985

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Re: Concrete Tie strip for N Scale and Code 40 Rail
« Reply #262 on: July 28, 2020, 01:46:47 AM »
0
I PM'd him a couple of days ago, but haven't heard back yet.  I hope all is well with him and his family.

Cheerio!
Bob Gilmore