Sunday, February 7, 2021

Making a Rotisserie for the Fuselage - Part 3

As part of my effort to re-engage in building my wings, I needed to order some new Primer. My old AKZO Nobel 2 part epoxy primer, although proven by me to work well enough enough at 7 years plus older than the shelf life date on the cans, is now so old and unused that I have decided not to continue to try to work with it. So I ordered a new can of catalyst and primer - expensive stuff. Picked up a tip from a fellow builder to get 8 empty quart sized paint cans from HD airplane supply and pour the contents into each of these smaller cans to make it easier to pour, store, and prepare. Having had real experience with this in the past by spilling it on the floor while trying to pour in in the small mixing cups,  and knowing precisely how bad smelling and toxic the catalyst is, I think this is a very good idea.

In addition to the primer, I decided I also needed some additional AN bolt hardware to finish the  rotisserie. Each spider leg has two holes in either end of it, and each of those are between 7/16 to 1/2 inch wide on average. With the hole on one end being addressed by the AN3 hardware and wood spacers, etc., I needed to figure out how to attach the other end to the angle. This other hole would normally contain the metric bolts that came with the engine stand. I need to use this other predrilled hole and drill an additional hole somewhere near the middle of each spider to provide the necessary holes to attach the angle iron to the spider.  You need to drill the extra hole in the middle to ensure that the angle is secured in at least two places on the spider arm, so that it cannot rotate out of position.

The next problem is figuring out what length bolts I should use for the remaining holes, to ensure they are short enough so that they do not come into contact with the firewall after attaching each angle to the spider on one end and the center mounting plate on the other. Each of the lugs on the spiders allows for about 1 and 1/2 inches clearance from the firewall. Unfortunately, the metric bolts that come with the engine stand are about 1 1/4 inches long after being inserted into the hole in the spider, so that leaves a very uncomfortable 1/4 inch of free space between the firewall and the angle iron adn spider bar - This is NOT good enough for me. 

SO I need to get shorter length bolts and corresponding hardware. That means I needed to go back to the suppliers and the conversion/identification charts to figure out which AN hardware I should get. My decision, based on measuring hole diameters and lengths and grip requirements and such, was the following:

For the other big hole in the spider and the 1/8 inch thick angle iron that will be attached to it, I decided on either AN7-11A or AN8-11A, since the holes sizes seem to hover somewhere in the vicinity of either one. I order both, and I will see which one gives the better. tighter fit. After I figure that out, I will know what size hole I have to drill in the angle iron.

For the second hole in the middle of each spider to lock the angle iron in place like others seem to have done, I decided to use AN3-7A bolts. Both of these bolt choices should leave at least a half inch or more of clearance from the firewall after being bolted together. That I think I can live with. I also ordered the required nuts and washers for all bolts. The AN7 and AN8 bolts get AN960-716, 726L, 816, and 816L washers, and AN365-720A and AN365-820A, or MS21044N8 lock nuts. The AN3 bolts use the same nuts I already received from Straight Flight, so I think I already have enough of those to use on the shorter AN3 bolts as well.  

I also ordered some hardware that I mentioned long ago in my blog when working on the fuel tanks. I ordered about 50 NAS1352-08-8P cad-plated socket head cap screws to replace the fuel tank access plate screws provided by Vans - AN515-8R8. I have seen too many posts from builders stating how difficult it is to remove Phillips head screws from the access plates of the fuel tanks when you need to service or replace the fuel senders or the fuel line or return attachment hardware or connections. There are 17 of these screws for each fuel tank, so you only need 34, but I always need extras, so I ordered a few extras. Somebody on VAF also asked if a washer would be needed for these cap screws, since their grip width of the head is not as wide as the AN515 screw heads. I am glad he asked that question, as I would never even thought about that. The washer for the cap screw is AN960-8 or AN960-8L for the thin version. I ordered 50 of each of those as well.

My order was shipped from Spruce's Georgia location, and at first I found this to be strange, since most western-based orders are processed by the Southern California location. But on second thought, with southern California's horrible pandemic situation, I am actually relieved that my order came from somewhere else. It also wised me up a bit about hardware orders or any orders for that matter that I will be needing for supplies, parts etc., as I re-engage. I need to be careful about where these are coming from, and develop a process to clean them carefully when I receive them - just to be safe. It is supposed to be here in a couple of days, and then I will resume the work on the rotisserie.

Coming - up - I need to degrease/remove the oil coating from my QB fuse, which now has a layer of fine abrasive forest fire ash particles on it from all the fires in the state this past summer and fall. I have stupidly left this unattended ever since it was delivered to me in 2018. This stuff even penetrated inside the house, so everything is covered with it, inside and out. So this is long overdue, and needs some serious attention. Also coming soon is the upgraded electrical service and heat into my garage. Enough is enough, and I really need to address my hostile building environment this year if I ever want to finish this project. I will also need to order more Proseal and some special formulated sealant for the fuel tank access plates. More on that later.


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