Walthers 90' Turntable

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S

Steamfreak

CEO of the LCP
Well... In anticipation of scratchbuilding a new roundhouse, I spent all day Sunday laying down 6 engine tracks, wiring, and putting on/off switches to each one so's I can turn them off while the locos await their tour of duty. Then I go to try each one out. Turns out the bridge on the turntable has about 1/8" of "slop", it can move (in the "direction" it came from), so, even a minor move of the engine as it crosses from the bridge to the storage track will cause the bridge to move and derail the engine.... Also, power to the bridge is intermittent, so driving on or off requires a little "help" to move the engine....
Does anyone here have one of these, and how does it work for you..?? Any hints or tips to make the @%@$* thing work right..?? :mad:
 
I finally gave up on that horrible kit, and so have dozens of others. Good luck to you.

If you can still disassemble the drive under the pit, you need to install two plastic shims, styrene or neoprene, that will snug up the large steel washer provided. You glue the shims of appropriate thickness and size so that they are stuck on either side of the pivot coming down through the pit. Glue them to the pit's nether surface. Lube the surfaces showing on the shims, and lube the upper face of the large washer. Then reassemble. If you do it properly, you should take a great deal of the slop out of the bridge's wobble.

There are other necessary fixes, such as placing washers below each of the brass rings because you may have the copper wipers getting lose and slipping under gravity...in which case they won't wipe any more.

Also, the pit is likely to be out of round...or so many of us complain when we go to rotate the bridge 180 degrees.

I finally bought one of the excellent built-up indexed models and haven't looked back.

-Crandell
 
Gus this is a video of the one I reworked. This turn table has many problems but they all can be fixed. One of the main problems is that it’s not perfectly round that’s why it gets stuck. If you sand down the bridge at its ends it clears.

http://www.youtube.com/watch?v=rRctWSm9hJI

I tried to locate the thread I did on the subject but I guess there’s a limit on how many threads they save. It had to be 3 or 4 years ago.

I do have a few photos from the project.

NYC_George
 


Thanks for the replies guys....Crandell..How thick should those shims be..? Also, there is a small plastic washer between the brass sleeves to keep the from shorting out. Where would the additional washers go..? When I first tested the table after construction, I did notice it was out of round, so that was the first fix, but I didn't run across these other problems 'till the engines had a place to go....:D

That reworked turntable seems to work real nicely....although the drive noise still seems to be there. Is there any way to muffle it some..??

Thanks again....:)
 
I found these 4 photos Gus. Photo 1 - You can see the shims I installed to stop the table from tilting. Photo – 2 Wheels I installed to replace the little plastic wheels that don’t turn very well. Photo – 3 I also got rid of all the hard to solder spring contacts & hardware and ran the power wires straight through. This works fine as long as you don’t continue turning the table in the same direction time after time. Photo 4 A double pole, double throw switch to reverse the polarity.

NYC_George
 
This is not an easy project Gus. I did it becuase I didn't want to spend the $300.00 on a turntable that I wasn't going to use that offen. You may be better off buying one of those $125.00 brands that at least have a solid bridge and proper wheels to move on.

NYC_George
 
Steamfreak said:
Thanks for the replies guys....Crandell..How thick should those shims be..? Also, there is a small plastic washer between the brass sleeves to keep the from shorting out. Where would the additional washers go..? When I first tested the table after construction, I did notice it was out of round, so that was the first fix, but I didn't run across these other problems 'till the engines had a place to go....:D

That reworked turntable seems to work real nicely....although the drive noise still seems to be there. Is there any way to muffle it some..??

Thanks again....:)
Click to expand...

The shim thickness depends on the degree of slop you need to 'soak up.' I would guess that something near 3/32" on either side would do, but you may need less or more. The ones I used were rectangular, maybe 1/2" X 1", and about 3/32" thick.

I created a styrene spacer of my own to keep the two brass rings separated...I didn't trust the screw to hold the wipers securely. So, I cut out something that would provide a 360 degree 'shelf' maybe 1/8" wide outboard of the bottom edge of the top brass ring, and I think I had something else below the bottom one to keep it from slipping down and off the wiped metal....can't recall, it has been a while. Anyway, I carved out wider spacers maybe 1/16" thick of styrene and drilled the appropriate hole side so that it could slide into place.

My drive noise was quiet...the motor is to be hooked to DC current, not AC, so you can dial up the voltage on an unused DC power supply and get the bridge to rotate slowly and quitely...more prototypically IMO.

About the gear meshing....I did say that there were other problems. I found the meshing of the motor drive gear with the large black ring gear to be problematic. So, before I cinched down the mounting screws for the motor, I wedged some folded cardstock between the motor and the housing wall to force the drive's smaller spur gear closer to the ring gear. Also, the ring gear should not move in oscillation as it swings the bridge and engine above it, and that merely affirms the need to get the right snugging thickness of shimstock between the bottom surface of the pit and that large metal washer. I hope that makes sense.

-Crandell
 
I'm not sure yet which way to go....Initially I had thought of chucking the whole thing out, but I'm going to give it a try, and if it doesn't work...well, I'll fall back on my first reaction....
Which t'table is that you're refering to..?? (The $129.00 one...). I do have the table hooked up to an old p'pack to regulate the speed.
 
Selector said:
About the gear meshing....I did say that there were other problems. I found the meshing of the motor drive gear with the large black ring gear to be problematic.

My drive noise was quiet...the motor is to be hooked to DC current, not AC, so you can dial up the voltage on an unused DC power supply and get the bridge to rotate slowly and quitely...more prototypically IMO.
-Crandell
Click to expand...
Rather than using 'gears' that require very close tolerance, I used a small dia rubber wheel mounted on the shaft of a 'gearhead' motor (large reduction gearhead on an electric motor, and available from surplus electronic stores/sources). This 'drive wheel' was spring loaded against the rim of an old-time stereo turntable that rotated down under the pit of the RR turntable. The friction of the load between the small rubber drive wheel and the much larger rim of the stereo table made it fairly stable against any additional movement once the stopped selection was made. The bottom of the pit was just flat plywood, and the pit walls were to be styrene plastic sheet trimed into long strips.

OR, my alternative for the pit were these alum baking pans I found that fit these Atlas bridge sections.
http://www.modelrailroadforums.com/forum/showthread.php?t=13170
 


I had a lot of trouble and finally, I reworked the connection to the track but bending the brass fingers around each brass collar. I then, effectively, tied them back to the outer edge of the box with tinned copper wire and tightened this up. So far I have good contact.

I could not get the rails to stay on the turntable itself, so I reworked it with a bit of flexi track - not realistic but it works. I had to do a lot of work on getting the turntable to turn all the way round. It is still not perfect so it needs a nudge occasionally but I can live with that.

I haven't cured the rocking but that;s the next job.

I run the turntable through a 2amp DCC decoder and have set the maximum speed to very slow. I now have great control over it's stopping point.

If I can fix the rocking, I will be quite 'happy' but it was a lot of work considering I bought this with a Walthers label on it.

You can see my trials and tribulations on my blog.

Start here

http://gentlemr.blogspot.com/2009/09/turntable-first-steps.html

and follow on.
David
 
Thanks for all the info & alternatives....I think I'll dig into it this weekend and see what comes up. Hopefully I can get it to work, even if it's only marginally....
I'll get back to you all with the fruits of my efforts....
 
Gearhead Motor

beiland said:
Rather than using 'gears' that require very close tolerance, I used a small dia rubber wheel mounted on the shaft of a 'gearhead' motor (large reduction gearhead on an electric motor, and available from surplus electronic stores/sources). This 'drive wheel' was spring loaded against the rim of an old-time stereo turntable that rotated down under the pit of the RR turntable.
Click to expand...
I found my source for that big reduction drive motor I mentioned:
http://www.allelectronics.com/make-a-store/item/DCM-245/6-RPM-GEARHEAD-MOTOR/-/1.html

They have lots of small motors of various configurations
http://www.allelectronics.com/make-a-store/category/400/Motors/1.html
 
I just ordered the Walthers 90" turntable. Anyone have any suggestions on the best way to cut a perfectly round hole in the subroadbed? After drawing the correct size circle using a pencil and string, I was thinking of just drilling some starter holes, cutting a rough circle with a saber saw, and then sanding/filing until it is perfectly round. Any suggestions or comments would be appreciated.
 
You just want 'good enough', no pristine edges!

Yes, do mark it out, keeping in mind you need it correctly sized so that the flange on the outer rim of the pit can rest on it. You don't need anything else but that flange to hold up the entire affair, even with a good heavy engine on the bridge. It doesn't even need to be glued into place. You would want to use an adhesive to fix your lead rails onto the lip, and also all the bay and radial tracks. They will provide lots of anchoring in azimuth.

I began with a single hole, maybe 3/8", and then fed the blade of a jigsaw through the hole, powered up the jigsaw, and let 'er rip. Slow and steady, patience, lots of noise and vibration, some sawdust....and five minutes later at you have your hole. If it is out of round for some reason, use a wood rasp file to eat away at any spots that need grinding down. If you have done it all correctly, you shouldn't need a file at all.

-Crandell
 
BEFORE you start cutting out that hole, make sure you draw out your approach track and storage lines from your TT's center. Without a reference point you're gonna have a hard time getting everything to line up...
 


Thanks very much for the suggestions--they are all helpful. I just ordered the TT kit online today but using that template I may be able to have the hole cut, or at least the approach & storage tracks drawn in, by the time it arrives. I'm glad to hear I can do it with a drill & a jigsaw--I was afraid I might have to buy some new tools. Once it's in I am planning to just operate it manually, so I should be able to avoid some of the problems people have had in motorizing this kit. Anyway, thanks again for the advice.
 
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