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AstroPro JMI Wheely Bar Stability Modification Project

Posted by Paul Atkinson   06/23/2004 00:00:AM

AstroPro JMI Wheely Bar Stability Modification Project

I have used JMI Wheely Bars for years to haul various scopes and mounts in and out of my garage. Yes, I am one of the poor souls who doesn’t have an observatory of his own. One thing about Wheely Bars that has always bothered me is the fact that the single rubber tipped bolt on the end of each leg, combined with the locking wheels, never seemed quite secure in my opinion. I always felt like it could be better. Considering that I have over 300 pounds on my Wheely bars, and being concerned, I decided to do something about it! I call this my AstroPro Wheely Bar Stability Modification Project.

Now in any project I undertake I always follow my 6 “P’s” for success. Simply put, PROPER PREPARATION PREVENTS PISS POOR PERFORMANCE. In other words, take your time, think things through, and always pause before you do anything permanent. By doing this you will avoid making mistakes and you will end up with something that looks good and functions great!

The modification I am going to detail is simple to do and can be done by just about anyone with even mediocre mechanical skills. What you are going to do is create three additional support points and threaded guides to enhance the stability of the Wheely Bars. I like to use stainless steel parts whenever available although it is considerably more expensive. However, I think they are more durable, look better, and are less prone to rust. Of course zinc coated parts are fine and work the same. In fact, some parts I couldn’t find in stainless so I substituted zinc where needed. Parts for this project will cost between $10 - $40 depending on what you decide to use. You can find these parts at Home Depot, Lowe’s, or Ace Hardware. You might want to buy an extra of each part listed below in case something gets messed up. This will help to avoid having to make a special trip back to the store in that unfortunate event.

You will need the following:

3 - 6” Long x ½” Diameter Carriage Bolts (Stainless)
3 - 1 ¾” Long x ½” Coupling Nut (Zinc)
6 - ½” Wing Nuts (Stainless)
9 - ½” Flat Cut Washers (Stainless)
3 - Rubber Feet (Only found these at Ace Hardware)
1 - Loctite Metal/Concrete Epoxy (2000 psi)
Mixing Sticks (I used wooden Q-tips)
½” Metal Drill Bit
High Speed Drill

Once you aquire you parts you are ready to proceed. From this point forward I will use a point by point format of steps that I followed to complete this project.

1. If your Wheely Bars are together they will need to be disassembled. Before you do this use a pencil to mark exactly where each leg is currently positioned. This will help you find the best location for the addition of the stability supports, and also make it easy to return the wheely bars to your original configuration.

2. Disassemble the Wheely Bars and set the center section set aside.

3. Turn Wheely Bar center support over and determine the best location for the extra stability supports you are going to make to be placed. Carefully mark the center point where you are going place them for drilling later. Use one of the ½” flat cut washers to do this, or as pictured one of your completed stability couplings.

4. At this point you will need your epoxy, mixing sticks, and cardboard. Follow the epoxy directions carefully. Although you don't want to hurry you can't take all day as once you mix the epoxy it will start to harden within 5 minutes.

5. Mix a small amount of the epoxy using your wooden stick. A pile about the size of quarter will be adequate. Once mixed, take a coupling and one of the washers and spread a very small amount of the epoxy very carefully to the bottom of the coupling. There is not a large surface area to work with on the bottom of the coupling nut. If you put to much when you seat the coupling nut against the washer it will squish out and you may get some onto the inside threads. You don't want this. You only want enough to hold the coupling to the washer. DO ONLY ONE AT A TIME AND MIX ONLY ENOUGH EPOXY TO DO ONE AT A TIME.

6. Seat the coupling and washer together using great care. You want the hole in the washer to line up as pefectly as possible with the threaded opening on the coupling.

7. Set the washer and coupling down onto a flat surface. Using your stick take the remaining epoxy in your pile and carefully spread it around the base of the outside of the coupling and onto the washer. This is what will actually provide the strength and bond that will hold them together. You can see from the picture how much I used to accomplish this. You might want to hold straight down on the coupling while doing this so that you don't move the washer or coupling. If you do, simply slide it back in place. The epoxy begins to harden in about 5 minutes and sets pretty good in about 20 minutes.

8. After 20 minutes carefully thread one of the carriage bolts into your setup to make sure that everything is aligned properly and there are no problems.

8. Repeat steps 5 through 7 until you have 3 washer / couplings. Set them aside to dry for at least an hour or two.

9. Now take your drill and the 1/2" drill bit. At your predetermined locations drill out the holes from the bottom of the JMI center brace. You may need to take a drill punch to set exactly where you want the bit to start as some cheaper bits will chatter and might not start and stay exactly where you want.

10. Once the holes are drilled be careful to check for metal push through "shards" that may be present on the top or bottom of the brace. These can be sharp and can cut skin very easily. I took a Dremel tool and simply buffed these off but a small file will work. This is especially important on the bottom so that your washer / coupling sits flat and flush against the brace when you go to secure it with the epoxy.

11. If enough time has passed, take your couplings and using the same procedures as 5 through 7, you are going to seat the coupling to the bottom of the brace and epoxy it in place as shown in the photo. I placed the brace on the edge of a table that allowed me to thread one of the 6" inch carriage bolts into my coupling. I really gooped on the epoxy at this point to make as strong a bond between my parts and the Wheely bar brace. Leaving this in place for an hour allows it to seat properly and the weight of the carriage bolt also pulls down and holds your new stability coupling where you want. After 60 minutes I proceeded with the next one. AGAIN, DO ONLY ONE AT A TIME.

12. Once you have all three set in place I highly recommend letting everything set for 24 hours so that the epoxy cures fully and you get maximum strength from your bond. After 24 hours you can now reassemble the wheely bars and proceed.

13. For each new brace I threaded one wing nut onto each of the 6” carriage bolts followed by a washer. Next thread this into your newly created stability point. When the carriage bolt comes out the bottom put another washer on and then the second wing nut. Place your rubber foot on last. You can see from the picture my orientation of each item.

That’s it. Finished. Wasn’t that easy? Now you have created three additional stability points on the Wheely Bars. Each one should be rated for about 2000 psi based on the epoxy strength rating although I doubt you will ever approach that kind of stress under normal use. I have included a photo showing the setup once complete and in use. You simply screw your new braces down like the original threaded knobs on the end and then lock them in place with the wing nuts. You can see I also replaced the original hardware on the ends with wing nuts as they work much easier then the standard nuts that JMI sends. This modification made a huge difference and holds the wheely bars in place better and with a much higher degree of stability.

Good Luck!