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Track alignment problem Walthers DCC 130-ft. turntable

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Track alignment problem Walthers DCC 130-ft. turntable
Posted by Scale Hogger on Sunday, March 17, 2013 9:31 AM

Track is perfectly aligned at both ends when non-cabin end of bridge is at position 1 and cabin end is at position 2. After rotating 180 degrees, open end is at position 2 and tracks are slightly misaligned -- enough to derail engine.

How can this be fixed? We have calibrated several times. Makes no difference. HELP!

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Posted by gandydancer19 on Sunday, March 17, 2013 10:40 AM

Aside from the fact that it appears that the center of the turn table is off, there is not much you can do short of sending it back.

However, you could try this: Put the track down so it is slightly miss-aligned at both ends. Then file the inside of the rails to 'help' the loco align itself withe the tracks as it moves on and off the turn table. You could also add a guard rail or two on the tracks leading to the turn table that would help keep the loco lined up properly.

Elmer.

The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.

(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.

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Posted by richhotrain on Sunday, March 17, 2013 10:50 AM

I have the older non-DCC version of the Walthers 130' turntable.

I have always thought that the indexing feature was unreliable, so I long ago resorted to disabling the indexing feature and aligning the bridge track manually.

Rich

 

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Posted by jrbernier on Sunday, March 17, 2013 1:22 PM

  We just went through a re-alignment of the clubs 130' turntable.  You have to align both ends of the bridge.  In our case, there is a position set for the approach tracks and for each roundhouse track directly across from the approach tracks.

  The big issue is that if any ballast/grit gets in the bridge motor teeth or the rim rail, the turntable may lose alignment and sometimes just goes dead.  Normally doing a 'zero' will fix this, but if the turntable was really 'jumping' due to the fouled gear teeth, it may loose electrical contact and just go 'dumb'.  If this happens a complete power on reset/zero/re-program the positions may need to be done.

  After cleaning out the gear teeth on the rim and bridge, we vacuum the pit and the 'hole' where the bridge fits into.  We then 'formed' the wipers that contact the bridge a little higher so that they may good solid contact even if the bridge jumps due to ballast/grit still in the gear teeth.   A power on reset, zero, & programming about a dozen stall positions was done and tested - All seems to be working now.

  I am looking at some kind of regulated 'wall wart' power supply to replace the old Tyco power pack that is now powering the unit.  Also, some surge filtering or a small UPS should make it 'bullet proof'.

  I have the 90' version of the turntable, but only have 2 approach tracks and 3 stall tracks - I only had to re-program once(after ballasting the engine terminal and I got ballast stuck in the pit gear teeth).  I have a regulated power unit(about $20) for mine, but no surge or UPS.  I see some folks buy those clear plastic cake travel containers and use the top to cover the turntable pit when not operating the layout - But I think finding a 18-19" one for the 130' turntable might be difficult!

Jim

Modeling BNSF  and Milwaukee Road in SW Wisconsin

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Posted by richhotrain on Sunday, March 17, 2013 3:03 PM

jrbernier

The big issue is that if any ballast/grit gets in the bridge motor teeth or the rim rail, the turntable may lose alignment and sometimes just goes dead.  Normally doing a 'zero' will fix this, but if the turntable was really 'jumping' due to the fouled gear teeth, it may loose electrical contact and just go 'dumb'.  If this happens a complete power on reset/zero/re-program the positions may need to be done.

  After cleaning out the gear teeth on the rim and bridge, we vacuum the pit and the 'hole' where the bridge fits into.  We then 'formed' the wipers that contact the bridge a little higher so that they may good solid contact even if the bridge jumps due to ballast/grit still in the gear teeth.   

I don't know if that is the OP's problem with the bridge track, but I readily concur with Jim on the issue of grit in the gear teeth.  I have had a single piece of ballast bring the bridge track assembly to an absolute halt and nothing but disassembly and cleaning will rectify the problem.  Any grit in the gear teeth will lift the bridge track right up and out of the toothed gear circling the rim of the pit.  I can see that problem causing misalignment of the indexed stops.

Rich

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Posted by rrinker on Sunday, March 17, 2013 4:07 PM

 At issue is the fact that other than the 'zero' position, it simply counts the motor revolutions to determine position. Anything that makes it skip a tooth on the pir rack, or any play in the drive train will result in error. That's why it calibrates in both directions, to account for any sloppiness in the drive system. It's mostly effective but must remain scrupulously clean. The transfer table is the same way. A better option would be if it had some sort of index wheel or encoder disk along the pit wall, although that would apprear unprototypical.

 Neither of the two, a 130' turntable and the transfer table, ever seem to work on the club layout, but the modules are subject to much vibration and dirt from transport and setup in varied venues. The other turntable is I think a Diamond Scale Models one, with a manual drive of the sort with a motor turning a large disk underneath the turntable, manually aligned - but it's right on the edge of the layout where it can easily be seen. It always works. Much as those Walthers turntables are neat and an impressive piece of electronics, I do believe when I implement a turntable it iwll be placed up front for easy visual alignment and I will use a simple drive.

                          --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by farrellaa on Sunday, March 17, 2013 9:08 PM

I have had the 130' non DCC TT for about 5 years now and never had to reprogram it. I had to re-zero it when I remove the bridge to weather it. I program both ends of the bridge for every track and only have issues with one track out of 17.  I believe the railhead is too low, as you can see the locos (steam mostly) drivers lift or drop when crossing the gap from bridge to track. I filed them down a little and it seems OK most of the time, but I think one end of the bridge is slightly higher than the other, or maybe there is something on the pit rail/gear at that location. I haven't looked that close at that area yet. Overall, I love the Walthers TT and would buy it again. Mine is 99% in aligning the tracks.

   -Bob

Life is what happens while you are making other plans!

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Posted by selector on Sunday, March 17, 2013 9:55 PM

I purchased the 90' built-up when it first came out seven years ago.  Apart from the initial programming, I have never had to reprogramme.  I have had some glitches when it seems to want to set itself about 20 degrees off for some reason, but a power down, lift the bridge, set it back in place where I had expected it to stop, and power up seems to always get it to settle down.  Don't know why.

As for the rails, the four ends on the bridge should have been sharply beveled.  I did the same for all the radials and the lead rail ends, and it all works well.

Crandell

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Posted by Scale Hogger on Monday, March 18, 2013 5:38 AM

Thanks, guys! Upon a REALLY close inspection of the cogs in the rim gear/rail -- and a cleaning with a toothbrush -- it works like it ought to. There was no ballast; just dust and maybe some filing particles. We also cleaned the small wheels that roll on the rim rail.

That, plus a very small adjustment of the location of the approach track's lead rails, seems to have done the trick. Case closed -- with THANKS again to all.

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Posted by zstripe on Monday, March 18, 2013 5:49 AM

SCALE HOGGER,

Good FOR YOU, and thanks for letting everyone know that you fixed it, you'll find that is just as important in life as asking the questions..

Cheers,

Frank

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Posted by Modeloldtimer on Monday, March 18, 2013 1:40 PM

You must program both track ends of the bridge track to aline with each track being programed.

Each track will then have a programed number for selection of either end of the bridge.

Good luck!

Modeloldtimer

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Posted by KemacPrr on Monday, March 18, 2013 3:04 PM

A question regarding the programming of the 130'er. I have 4 approach tracks and 14 stall/storage tracks. I avoided the dead area completely. Do you program one end to all tracks first then the other ? I zeroed the table first then started programming track positions in a clockwise direction. After doing one end I then started on the other end. I discovered that after doing one end when I went to do the other end I was getting the red led lit showing the table too close to another position. I've also heard that you need to go back to the zero location every time after you program a track location. I've ended up doing a manual operation using the two direction buttons but would like to use the automatic indexing. ------------------  Thanks,  Ken

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Posted by Scale Hogger on Tuesday, March 19, 2013 8:31 AM
Hi, Ken --
Must confess that I'm so new to this turntable that I'm still trying to figure out why in the world I'm supposed to program both ends of the bridge rather than just the open (non-cabin) end that has the sensor. The instructions clearly state that this TT can have up to 29 tracks, each with TWO numbers (up to 58). Why in the world would anyone want to have two numbers for the same track and have to keep that in their head?
I'm SURE there is a reason, but so far it has escaped me, along with how to program the cabin end of the bridge. So I'm leaving it to wiser heads than mine to respond to your question.
From the instructions as well as experience, I know that calibrating the TT automatically sets the open end to Track 1 and the cabin end to Track 2. 
Also from experience I know I do NOT have to go back to Track 1 (zero-degrees position) each time after programming a stop.  I have successfully gone (clockwise) from 1 to 3 to 5 to 7, etc., without going back to 1 before programming the next stop.
That's as much as I can help you. The problem I was dealing with was that the open end of the bridge was misaligned when I told it to go to Track 2. That was solved -- thanks to advice received here -- by my cleaning the teeth of the cogs along the rim rail.
JHF
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Posted by farrellaa on Tuesday, March 19, 2013 11:35 PM

You have to program both ends of the bridge to each stall/approack track because the bridge is not perfectly aligned or centered on the pivot shaft and the end you didn't program can't stop at any of the tracks; therefor you have to rotate the bridge almost 180 degrees to line up with a track on the other side of the pit. By programming both ends, you can choose the closest end to the track you want.

 And no you don't have to go back to zero after each programmed track. The bridge alignment is done with a rotary encoder, which counts the number of steps (probably .9 degrees per step) from the home position or '0'. So when you tell it to go to '0', it goes back to home and then knows where all programmed (steps) tracks are located. When you go to align a track with the bridge, you stop pressing the direction button just before it gets to the track you want. If you have a lot of tracks, it can stop at another track 180 degrees from the one you wanted and then you will have to press the direction button a little more for the track you wanted.

I hope this all makes sense as it is going on 1 a.m. and my mind is tired.

    -Bob

Life is what happens while you are making other plans!

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Posted by Scale Hogger on Friday, March 22, 2013 3:05 AM

Thanks, Bob. What you wrote does make sense and it fits with my experience of using the TT with only the open (non-cabin) end programmed. In fact, if I understand, it's a good explanation for why the TT often does not choose the shortest travel distance to the desired stop. Instead, we noticed that it often goes "the long way around."

From reading the instructions that came with the TT -- which I found strangely out of what I would consider a normal sequence for a first-time user -- I have no idea how to program the non-cabin end of the bridge. So  here comes the embarrassing question: how do I go about programming "both ends of the bridge"?

I'll appreciate your step-by-step wisdom, including whether I should begin by doing a RES (reset) to get rid of the stops I've already put in. Hopefully, my willingness to admit my ignorance will be helpful to others, too!

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Posted by farrellaa on Friday, March 22, 2013 8:19 AM

Just follow the same instructions for programming that you did, only line up the other end of the bridge with each track. Remember, the tt encoder is just counting steps, so it doesn't really know what you are lined up with, just that you want it to stop at that position. It doesn't have to be in any order as it will always stop at the nearest programmed position. This is why I mentioned that if you have tracks opposite each other, not exactly 180degrees but close, it will pick the first one it comes to, on either end of the bridge. So in that case you would have to wait until the bridge end you want is almost right at the track you need to stop at. If you over run the stop you just run it the opposite direction; just takes a little practice knowing when to let go of the run button in those close alignment situations, which usually aren't very often.

Just play around with programming tracks and you will see how it really is easy, once you understand how it keeps track of the positions programmed.

Oh, and you don't have to do a reset unless the ones you have programmed don't line up.

     -Bob

Life is what happens while you are making other plans!

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Posted by richhotrain on Friday, March 22, 2013 8:36 AM

Bob, I have to agree with you.  I am not at all sure that I see what the problem is here.  Just program each end of the bridge track in the various positions desired.  

Rich

Alton Junction

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Posted by farrellaa on Friday, March 22, 2013 8:46 AM

That's all you have to do.

   -Bob

Life is what happens while you are making other plans!

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Posted by Curt Webb on Saturday, March 23, 2013 6:53 PM

After losing the index positions twice (my fault) on my 130 ft TT, I decided enough was enough. I now put the TT in program and move the bridge manually using the arrows on the controller and it works great for me. It is definitely the show piece of my layout and it was worth the wait. I have 2 approach tracks and 21 storage tracks.

Curt Webb

The Late Great Pennsylvania Railroad

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Posted by richhotrain on Saturday, March 23, 2013 9:22 PM

Curt Webb

After losing the index positions twice (my fault) on my 130 ft TT, I decided enough was enough. I now put the TT in program and move the bridge manually using the arrows on the controller and it works great for me. It is definitely the show piece of my layout and it was worth the wait. I have 2 approach tracks and 21 storage tracks.

Curt, I do the same thing with my older non-DCC 130' turntable, just turn it manually with the buttons on the control box.

For those who don't do it that way, choosing instead to use the indexing feature, they don't realize just how cool the manual operation can be.

Manual is a misnomer, since you still need to operate the buttons to bring the bridge track into position,

It is a lot closer to prototypical than using the indexing feature which is more hands off.

Rich

Alton Junction

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Posted by rrinker on Sunday, March 24, 2013 11:54 AM

 I'm going to guess that the reason they keep loosing programming is using a marginal power supply, subject to dips when the motor kicks on, or excessive ripple (not filtered well enough, if it takes a DC power source for the mechanism).

 That said, I prefer the ideaof manually lining things up, even more so after watching a demonstration of the turntable at the Railroad Museum of PA (since it's a former Reading turntable, they operate it for people during the Reading Railroad Days show in July). it operates more like our other turntable on the club layout that is driven by the motor rolling on a disk under the table type of drive and a simple DC throttle. I think to make it ideal there would need to be another switch for fast traverse/fine jog plus the direction switch, which is what this particualr real turntable has.

 Although not everyone has their turntable right up front where you can easily see the tracks to line things up. If your turntable is obscured, there's not much you can do but use an indexing system so the tracks line up properly and you aren't constantly putting locos on their side in the pit.

            --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by farrellaa on Sunday, March 24, 2013 6:12 PM

Randy,

You may be right about using a good power supply. I have a instrument grade (Condor Mfg I think?) power supply I got on Ebay that is regulated and quite heavy with the transformer and heavy aluminum chassis and heat sinks. I have had my 130' tt for about 4 years now and never lost programming/positions. You do have to keep the pit area clean though as dust will mess with the gears.

   -Bob

Just found a pic of the power supply!

Life is what happens while you are making other plans!

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Posted by RVFLYER on Monday, October 10, 2016 10:18 PM

I had the same problem. I spent an entire Sunday afternoon documenting move accuracy. I found most moves varied about .015 inch mismatch at the rail head; occasionally twice that. I could also document about .005-.010 inch eccentricity. If you are DC my solution is not appropriate. I finally took the entire Walther's control system out and replaced it with a DCC Decoder (Digitrax DH126D). I used the existing Walther's contact wipers to bring power up to the bridge track. I actually doubled up on contacts since there are four rings and now I only need two coonduction paths (you have to connect the two halves of the outer ring). I then used a Digitrax automatic reversing unit (AR-1) to take care of the phase reversing when the bridge reverses. The motor drive is a double worm drive so on speed step one or two, the bridge creeps extremely slow so it is possible to get perfect track alignment. In my case, speed step 30 exactly duplicates the normal Walthers speed. The other advantage I now have, is that I don't get that sound and light shutdown as the bridge rotates through the dead zone as was necessary in the Walthers arrangement. Of course you have to be close enough to see when rails are aligned.

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Posted by rrinker on Wednesday, October 12, 2016 7:54 PM

 If you enable the switching speed - you then have the perfect setting, since switch mode (F6 by default on Digitrax decoders) exactly halves the speed - so if 30 is the normal speed, hitting F6 will put you at the "jog" speed for the final alignment.

                                  --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by bagal on Thursday, October 13, 2016 2:06 AM

Scale Hogger

Track is perfectly aligned at both ends when non-cabin end of bridge is at position 1 and cabin end is at position 2. After rotating 180 degrees, open end is at position 2 and tracks are slightly misaligned -- enough to derail engine.

How can this be fixed? We have calibrated several times. Makes no difference. HELP!

 

Surprised no one has commented on the OP's original statement. Positions 1 and 2 can't be programmed so alignment depends on TT installation. No amount of caligration will fix the problem. Our turntable does the same but no problem as we don't use  1 or 2 as aligned to tracks.

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Posted by richhotrain on Thursday, October 13, 2016 6:32 AM

What I wondered back in 2013 when this thread began, and what I wonder now, is why this misalignment occurs in the first place?  Does anyone know why?

Rich

 

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Posted by rrinker on Thursday, October 13, 2016 7:07 AM

 As far as I can tell, outside of the one known position in the dead zone, where the little hole is (I assume that's some sort of optical home sensor, IR probably), the whole thing operates as a stepper motor, counting rotations. Once it homes, you move it to position 1 and mark that setting, then position 2, etc. It remembers how many motor rotations that is from the home. It also remembers how many motor rotations (counting up in one direction, down in the other) since it last was at home, which seems to get lost at times, causing the bridge to first go to home then be able to find the set positions - it still has the count of each position from home saved, but it has lost count of how many turns there have been (I wonder if it's something as simple as an overflow - like it happens more often if you always rotate clockwise and rarely ever move counterclockwise or something). At any rate, it is counting motor rotations, so ANY slack in the gear train from the motor down to that drive gear means the table can be off position by that much without another full motor rotation. That shows up in it not being perfectly aligned when coing out a set point counterclockwise but it's perfectly fine clockwise, or vice versa. And of course as noted the internal track must be scrupulously clean, having even just 1 motor rotation not count because the drive gear skipped on a piece of dirt will throw the alignment off by whatever the overall total gear ratio is.

 It's sort of like the new low cost CNC machines you can build - they use steppers, 1 turn is say .0001" of travel, so 100 rotations is .01", vs the big expensive machines which have a servo motor to move the axis with a scale that is read by a sensor for absolute position feedback. It's what enables Walthers to sell the turntable (and the transfer table) for the price they do, when a really accurate positioning system alone, like the one from NYRS, costs more than the entire turntable AND electronics from Walthers.

 It generally works well enough, if kept clean and never forced by hand, but as previously noted the microcontroller seems sensitive to electrical noise in the power supply so a well filtered clean power source (and this is what makes the DCC one worse, if track power is used to run the whole thing, track power is ANYTHING but clean) is critical to keep it from losing its mind and fogetting all the set points. It's reasonably well manufactured so the gear lash should be within the ability of most HO locos to cross the joint between table and bridge, but it is also mass produced so it certainly is possibly to get a lemon with a bad gear in it or something.

 There are really only 2 other options, a different table controlled by a more expensive controller, like the NYRS one, which has an absolute sensor at each stop so there's no guessing where the table is, or a different table with a purely manual control like the real thing, no indexing.  If the table is close to the operator and they can clearly see the tracks to line it up, I see nothing wrong with foregoing the expensive electronics and just use a simple DC speed control.

 I don't have access to the Walther circuit, so my theory on how it operates is based on observation and the description given in the instructions. I may be way off, but I'm fairly confident I'm close.

                        --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 richhotrain on Thursday, October 13, 2016 7:12 AM

Thanks, Randy, for that quick reply.

The misalignment issue was the key reason that I stopped using the indexing on my 130' non-DCC turntable.

The other reason was the slowness of the indexing operation.  It stopped at every indexed position until it got to where you wanted the bridge track to be.

Rich

Alton Junction

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Posted by rrinker on Thursday, October 13, 2016 3:53 PM

Oh interesting - you mean it just won't go from say position 1 to position 5, it stops at 2, 3, and 4 along the way? I thought that was the whole point of an electronic index vs the mechanical Geneva drive like the Atlas turntable. Now I really don't want one.

                        --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 richhotrain on Thursday, October 13, 2016 4:50 PM

I cannot speak for the DCC version, but on my non-DCC version, the turntable will stop at each programmed position. So, if you program positions 2,4,6,8,10,12 and then want to rotate the turntable from position 2 to position 12, the turntable will stop at positions 4, 6, 8, and 10 before finally reaching position 12.

On the non-DCC version, the control box is pretty simple. There is no provision for specifically selecting a numbered position. Press a button and the turntable rotates to the next programmed position.

Rich

Alton Junction

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