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 Post Posted: Thu Oct 14, 2010 11:16 am 
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Von Weise Linear Actuator Acme Nut Repair For Satellite Dish Mover Model V76-5

If you've come here then you likely found this article via Google search and are looking for Acme nut repair info for your Von Weise linear actuator, aka, Satellite Dish Arm or Dish Mover.

I've got two of these part number V76-5, which are 24” stroke. I' not familiar with any other Von Weise Equipment so this article will be specifically about the V76-5 model. On one of mine the Acme nut is completely worn out and on the other (still in use) has a considerable amount of slack in it. With “quality” satellite dish actuators disappearing from the market due to the demise of Cband programming initiated by Echostar/Dish Network/National Programming Service (NPS), I figured it would be a good idea to see if I could actually repair one so I could have a spare for my 10 foot Winegard mesh dish which I use for FTA programming via an AZBox Ultra HD and Openbox S9 FTA receivers controlling the dish mover via a PowerMax Vbox X controller.

In order to see what I actually needed, I first had to figure out how to get the old Acme nut out. I used an 1/8 inch end mill on my Bridgeport Mill to cut the retainer tabs on ONE END ONLY but I do think it would be better to cut the tabs loose with a Dremel tool and cut off wheel instead of milling the way I did. Once the bend down tabs were cut I then used a 3/8 wide chisel and hammer to bend the tabs out to unlock the plastic nut from the tube. Here are a couple of pictures of how I did mine.

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I decided to go with bronze nuts on my two Von Weise actuators rather than the plastic ones that Von Weise sells. Reason for this is that I figured that the bronze ones would last longer than I'll probably live, ie, I'm 65 now so go figure! That and the cost of the plastic nut is $18.95 plus about $20 shipping and handling so you're looking at near $40 for ONE PLASTIC nut from Von Weise. I bought 3 bronze Acme sleeve nuts from Roton for $87.93 SHIPPED to my door. I've sold one of those at zero profit so my actual cost for two bronze nuts will be 2/3 of the total amount or $58.62. For those of you who don't have access to a milling machine, the Von Weise replacement nuts are about your only choice as having a machine shop do this machine work would probably cost another $50.

Here is the machining operation on the bronze nuts I received from ROTON. These are known as 3/4-6 RH Acme Sleeve Nuts and a Google search will carry you right to the webpage that they are on. The locking tab in the tube turned out to be 10mm wide (.393) and 3mm thick (.115) and luckily I had an end mill that size. I machined those flats .125 deep on both sides and yes, they need to be “close” to 180 degrees to each other. Here is a picture of that machining operation.

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Next photo is of the nut in place with the welding dogs holding the tabs in for welding.

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This next picture shows the completed repair with the tube and nut assembly mounted on the acme screw. I welded the tabs back with a buzz box, aka, stick welder, which was OK for the bronze nuts but I do think that a MIG welder should be used for the plastic ones.

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I did drill some holes in the inner tube, which I plan to have align with a larger hole in the bottom of the outer tube so I can put some grease in around the screw with a grease needle a couple of times a year. A hose clamp with a piece of rubber will provide a weather seal for that hole.

So I'm really looking forward to seeing how this rebuild job will work. In the mean time, if you want to order the factory part and try to install that, here is the parts breakdown on this particular actuator and you can order that part (and most others listed on the diagram) from Von Weise direct. Contact Alan Signer there for more info.

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Gear Box Output Shaft End Play

This part is for the real “gear heads” out there!

I noticed that the output shaft in the gearbox, ie, the one that the Acme screw is pinned to had a fair amount of end play in it. So I took that gearbox apart to see if there was something worn causing that but found nothing wrong? So, I made a .030 shim and put it under one of the thrust washers to take up some of that end play. Turns out that now that shaft only has .002 end play which will make it easier to lock on to Ku birds and, I'll have less problems with dish flop with satellites that are at or near due south. Not quite as good as a ball screw but much cheaper.

Should you require additional info on this or other Satellite TV equipment, then I suggest that you visit http://www.satelliteguys.us/index.php


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 Post Posted: Thu Jun 30, 2011 12:45 pm 
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UPDATE: Well, this actuator with the brass nut has been on that Winegard dish now for a while and it's still working fine.

I had made some magnet wheels up with 10 magnets on them so that the count was increased per degree. I put one of those on this actuator when I installed the Vbox X in that system a few months back and right now that actuator gives me 965 counts from 139W to 37.5W so on average that's 9.5 counts per degree end to end. My SAMI dish with the SuperJack mover gets 518 counts for the same travel which is an average of 5.1 counts per degree.

Do I see an advantage? Well, at this point not really? The SAMI will hit the mark as well as the VonWeise with either magnet wheel installed, which really surprised me.

It's been said, and I do agree in principle, that more counts = more accurate dish mover. It just hasn't shown me that it's better than it was with 8 magnets.

Here's a picture of that wheel I made up and installed.

Oh, and keep in mind here that the pols on those magnets have to alternate north and south when you install them so there has to be an even number for this to work.

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 Post Posted: Sun Jan 13, 2013 4:58 pm 
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Well, it's now January 13, 2013 and this "rebuilt" Von Weise dish mover is still working fine. I checked it today and the end play on it is around .010, which is just over the thickness of 3 sheets of notebook paper so it's not showing very much wear.

One thing to note here is that since there is NO sub on this dish it gets moved satellite to satellite way more now via FTA than it ever did when I had a sub with NPS. The original plastic nut lasted a long time but with what I'm seeing now this brass nut will last longer than the nylon one did. Since I'm 67 years old now, I doubt that I'll ever have to replace it again.

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