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Michael Hardwick built a traverser track from 3-D printer parts, an Arduino microcontroller, and other low-cost electronics. See the push-button controlled traverser in action on Michael’s N scale layout in this video.
Upon further review; have you had any problems with the belt drive?
Just scanned this now. I’ve had no problems to date and have never needed to adjust the mechanism. It has been surprisingly stable.
Slicker than all the lines leading to a turntable. I like it a lot!
Fascinating and well done. Great video.
I know Walthers used to sell a transfer table (which is what you have) in HO. Haven’t check lately, but they may have also done one in N.
This is so cool Michael! I would really love to see a step by step wiring video or article. Thanks for the video!
Rod: You can see the breakout board orientations in Figure 8, which matches the pinout diagram when rotated 180 degrees. As you might expect, the Arduino Nano USB port faces the edge of the assembly so it’s easy to attach a cable. The potentiometer for current adjustment on the A4988 is on the side closest to the Arduino.
To get to the code: From the MR home page, under “The Magazine” on the right, click on “Table of Contents.” You’ll find a link to the code under “Online Extras” at the bottom.
Kevin: An aluminum extrusion would be a good choice, one lighter than steel. I’ve had no issues with the mechanism precision. The belt load is low and I haven’t seen any problem in 18 months of use. Though the article isn’t explicit about how I tensioned the belt, I used the motor mounting strap to do so. The top screw applies the tension (there are clearly more elegant ways to do this). If you used a lead screw in a horizontal configuration, you’d have to deal with a small amount of backlash (unless you paid more for ball screws), but the properly tensioned belt and a freely moving table work great. In a vertical configuration, lead screw backlash shouldn’t be a problem since gravity would keep the table abutting the screw thread.
Ron: Counterweights would minimize the load on the motors, but the added complexity of managing the weights, pulleys, and cables might not be worth the benefit of smaller motors.
Thanks Michael! I received my August copy of MR and was glad to see that you had written the article.
Great article!
Two questions about the article. First, diagram #6 shows the wiring and pinout diagrams. The pinout diagram is shown in vertical format and the wiring diagram is shown in horizontal format and doesn’t reference any of the pinout pins. So my question is, which way is the Arduino Nano & the Pololu A4988 that are in the pinout diagram oriented, in the wiring diagram.
The second question you may not be able to answer. At the bottom of the last page of the article on the bottom left of page 41 is a notation from MR that says “Download a copy of the Arduino software used for this project at http://www.ModelRailroader.com“. I tried going to MRs website, but I was unable to find the link to download the copy of the Arduino software used for this project. Do you have any idea where on MR I can find the software?
Thanks for your help.
Thanks Michael for the reply. I’m thinking of an aluminum extrusion for the actual elevator; big boxes have these for screen door fabrication (probably where you got the bars in for the table) and the U-shaped ones are light and stiff.
Did you have repeatability issues with the belts? I’ve had experience in the past with lead screws as the long ones tend to wobble and vibrate, but they would certainly solve any repeatability problems if the belts stretch.
Kevin: Another thought… For an elevator, you need enough motor torque to overcome gravity and lift the weight of the platform and its contents. The average motor current will be a function of how fast the platform elevates and you can limit that current by moving slowly, which you likely want to do anyway. ZYLtech has an 84 oz-in NEMA 17 motor that should lift 10 lbs with a standard belt drive. However, instead of using a belt, I might drive an elevator with two (or more) vertical lead-screws connected directly to the motors. You’d have a simpler, though slower, mechanism and be able to use smaller motors. The choice of belt or lead-screw may come down to transit time. In any case, make sure your power supply is large enough to handle all the motors. I’d love to see what you come up with.
Kevin: The long elevator track is a great idea. If I had enough room for a layout with multiple decks, I’d consider using one in place of a helix. A single Arduino can easily handle multiple stepper motor drivers since it is only sending low current signals. The A4988s manage the higher motor current and are designed to do so. For a larger structure, you’d want rods that are not only longer, but also larger in diameter so they are stiffer. The rods and associated hardware are all available online. The longer platform itself would need to be fairly stiff. When I was thinking about a large traverser for a friend, I considered using low-profile Unistrut (Superstrut at the home Centers) as the basis for a very rigid structure.
On the vertical lift: could you also use smaller motors if you used a counterweight of some sort to make the effective weight of the whole structure less?
Nice work. I like that the article specifies the motor etc; I’ve never explored steppers because I have no idea which ones are powerful enough to do a job.
I want to run two identical stepper motors simultaneously to power both ends of a 6 foot long traversing track. The track raises and lowers like an elevator to feed a staging yard which is basically a bunch of shelves permanently mounted on a wall, each with one track on it, that doubles as a display case. At the bottom level where the feeder track is I would add a runaround track and space to uncouple the loco at the far end. Can a single Arduino can send input to two stepper controllers instead of one? I assume I can find longer chrome rods and associated bearings and bearing blocks for them.
I second Rod’s vote for another article to that provides a “how to step-by-step” on building one of these so us non-electronics guys can build one. I have an HO layout and have been in desperate need for this exact solution. Three cheers to Michael ! This is an awesome invention.
Rod: There is an article in the August MR that includes a materials list with suppliers and part numbers. My suppliers include Adafruit Industries, Oddwites, Pololu Robotics, Sainsmart, and ZYLtech Engineering, though there are many more that provide similar products. The article also describes how I fabricated and assembled the parts. As to the coding, once you get over the initial Arduino set up, which isn’t difficult, a good approach is to copy someone else’s code and make your own mods. A lot of people post code for you to use.
Great!!! Very precise mechanism… Could you post the circuit and the code used? Thanks
Excellent application of technology. Would be curious to see how long of a table could be managed, you could then eliminate the yard ladder at the entrance as well. And I like the vertical idea as well. My hat is off to you for such a cool project.
Excellent idea, Michael, and we got to watch the operations for free with out having to sign up for anything. Would like to see an in depth article in MRR, Thanks!
Great idea! Yard ladders waste so much space.
I like it a lot! Very nice work! Not being familiar with all of the electronics, would it be possible for you to post a listing of parts and where to get them along with maybe doing an article in MR on how you put it all together along with the resources? How easy/difficult is it to program?
Really cool! Now build one for vertical lift. Thanks!
Well done. Always llike seeing N scale projects with Arduinos – two of my hobbies in one combination! Any chance for project details in a MR magazine?
Very cool – can you give any more details about the traverse table (type? Where you got it etc).
Really cool !! Nice work.