Prep for post-Pandemic EAA Airventure 2021

Getting ready for Airventure

Making a Rotisserie for the Fuselage - Part 4

 With new hardware to play with, the next steps were to remove the front wheels of the engine stand, determine the height of some wood to replace the front wheels to keep the mast of the engine mount level with the ground, and start the process of cutting the 1x1 steel angle to size, and drill the first set of holes in one end of each angle.

Here is a pic of the stand with the wheels off. I first used a piece of 2x wood that I cut long ago to use as a form block for bending the mounting plate for the LE mod, and a piece of 2/8 inch thick plywood. That seemed to put the mast back to level when I checked it with my torpedo level.

Then I had the idea to put the mounting bracket on the stand and recheck the level. What I discovered was that the mounting bracket has a lot of play when mounted in the cylinder at the top of the stand, adn when I put the level on the actual mounting bracket that everything would be attached to I found that mast was no longer level and was indicating a bit too high. Then I found a piece of 1/4 inch plywood that was from the top of the crate that my wing kit came in years ago, and this seemed to set everything back to level again with the mounting bracket installed on the stand. Now I just need to cut the wood pieces to size and mount those to the stand using more nuts and bolts.

With that figured out, just prior to removing the front wheels from the stand I was wheeling it around in the garage, and I noticed that only 2 of the 4 wheels were making contact with the floor. A closer inspection revealed that that cross bar that serves as the front axle for the front wheels was at the angle to the rest of the frame. This means that some of the metal and/or the welds of various pieces were not done very well to ensure that the mount points for the wheels would be square to each other. This also means that when the fuselage is mounted to the frame it would not be sitting square but a bit lop sided in the front. I just could not allow that to happen, so my solution was to get out my sledge hammer to see if I could coax the front axle to be a bit more square to the rest of the frame. As I pounded on one side or the other I noticed that the square post was being forced into the corner of the frame. Either way this allowed the front axle to reposition itself so it was a bit more square to the rest of the frame, so I was satisfied with that. 

That exercise just further convinced me that welding is totally an imprecise, unreliable method of joinng metal together. I am also sure that the fact that it came from China has something to do with that as well. You get what you pay for I guess. These next pics attempt to show the angle of the front axel when compared to the rear axel of the stand. it is hard to tell but there is small when you look at the front axel and how it aligns with the axel in the rear of the frame. I just wanted to make certain that the stand would not wobble with the front wheels removed.

The next step was to find the exact center of the firewall at the front of the fuselage. The idea is that the exact center of the firewall is also where the exact center of the mounting bracket should be located. This ensures that the width and height of the front of the fuselage when mounted on the stand will allow the fuselage to be rotated so that it will clear the bottom square metal frame of the stand. I will have to get my figures posted tomorrow, but I used my flexible 2 foot long metal ruler and a tape measure to find the widest and highest points of the firewall, found the half way point and marked it with a Sharpee on the firewall. I believe those measurements for the half way points were 18 and 1/8 inches wide and 15 and 1/16th inches high I ran the tape measure from end to end to find the widest or highest point of the firewall. As shown in the following pics, it ran through the exact centers of some rivets in the firewall. 

Fitting the mounting plate so that it is centered with the center of the firewall ensures even clearance of the fuselage when right side up, upside down, or to either side as needed. 

With that out of the way the next step was to start cutting and drilling the holes in the steel angles that will serve as the extended arms that connect the mounting plate to the spider arms on each corner of the firewall. Since 1/2 inch AN bolts seem to fit rather well in the precut slots and holes in the mounting brackets, I decided to drill 1/2 inch holes on both ends of all 4 of the angles as well. This becomes a bit of a challenge when you consider that the 1x1 inch angles are 1/8 inch thick. This means that you only have 7/8 of an inch to drill a 1/2 inch hole. 

I also had to ultimately decide where along the flange I would drill each hole. I decided to start with one inch inboard of the end of the angle. The next series of pics shows how I marked and set each angle in the drill press clamp. The drill press did allow me to drill very accurately placed holes in the angle. The clamp and the wood allowed me to secure the angle in the vise and line up my 1/2 inch drill bit.

I should also mention that before all this drilling I cut the angles in half as a starting point. So each angle is currently 24 inches long. I used my sawzall with a metal cutting blade. It made quick work of that. I then used my grinder to remove any sharp burrs on the cut edge. Then, before you start drilling holes, you also have to decide how you wan tot position the angles - with the perpendicular flanges faced outward or inward. from the mounting surfaces. In the pics you can see I chose to have them placed inboard - no real reason, but you have to decide how you want to position them so you know which side to drill the mounting holes for the bolts.

After the first 4 holes were drilled I mounted each angle to the mounting flange of the engine stand for a trial fit. 

After this trial fitting, I discovered that the AN8-11A bolts I ordered were just a little short for the 3/8 inch thick mounting flange and the 1/8 inch thick angle. SO I ordered some An8-12A and 13A bolts that arrived today that should fit the assembly a bit better. The issue with the hardware is the length. It cannot be longer the thickness of the spider lugs and the angles. I was concerned about this when mounting the bolt so that bolt threads are facing the firewall and threatening to get a little to close to it after they are tightened down. After reviewing a few posts from other builders I saw that this is much less of an issue if you mount the bolt so that the head is on the side closest to the firewall, and the threads and  bolt shank are on the opposite side and never at risk for puncturing the firewall. 

The last pic is the 3/4 inch wrenches I used to mount the bolts. When the weather improves again I will replace the AN8-11A bolts with the longer ones, and begin the process of reducing the size of each angle to its final size when I fit the other end of them to the  spiders.

Rotisserie Hardware Finally Arrives

 I finally got my hardware that I ordered about a month ago. COVID sucks. Bad weather - the worst snow storm of the year that the news media said would only amount to 5 inches that turned into 15 - also sucks. Then there is UPS, but I digress. I guess I should just be thankful that I got anything at all.

The list is as follows:

50  NAS1352-08-8P 1/2 inch socket head cap screws - to replace the Vans pan head screws used to attach the access plate to the inboard fuel tank rib to make it easier to service/remove/replace with the tank mounted on the plane. 

50 AN960-8 thick washers for the above screws

50 AN960-8L thin washers in case a thin washer is required for proper screw depth

4 AN7-11A 7/16th inch thick bolts to potentially replace the metric bolts that came with the engine stand

4 AN8-11a 1/2 inch thick bolts that should fit the hole in each spider arm a bit better than the AN7s will. I bought both so I could choose which one I would like to use.

4 AN 960-716 thick washers for the 7/16th inch bolts

4 AN 960-716L thin washers in case those are needed for proper fit.

4 AN 960-816 thick washers for the 1/2 inch bolts

4 AN 960-816L thin washers

4 AN3-7A 3/16th inch bolts to firmly attach the angle to each spider arm I already have enough washers and bolts from my previous order for these bolts so I did not need to order any more of those.

4 AN365-720A Nylon Lock nuts for the 7/16th inch bolts

4 AN365-820A Nylon Lock nuts for the 1/2 inch bolts

The primer had to be back ordered - apparently until April sometime. Oh well. The plus side to that is that I will be reasonably assured that the 2 year shelf life will still be in tact, instead of already being expired or close to it as usually happens. Here is a pic of the hardware:

The steel angle will be attached to each spider arm, and while the big 1/2 inch sized hole allows for a large heavy bolt to be torqued down against both parts, there is still a possibility that the parts could shift while rotating the fuselage, and that could spell disaster. TO ensure that this does not happen, one more hole needs to be drilled into the spider arm in between the lug on one end and large bolt hole on the other, so that one more bolt can be added to secure the angle to the arm and prevent it from turning. Most have used a small AN3 bolt for this, and at 122,000 psi tensile strength (AN hardware specs) I am not concerned about shearing any of the smaller AN3 bolts used in this assembly.  

The next step was to set up the drill press to drill the additional hole in each spider arm, and then I can use that hole as a guide to match drill the hole in the angles once I cut those to size. I used a 3/16th inch metal drill bit, and set the belts on my drill press to 990 rpm per the recommended setting for drilling mild steel. this is much slower than the 3100 rpm commonly used for wood. Drilling metal builds up heat very fast, so keeping the drill bit and the work piece as cool as possible is important. 

I measured the distance between the edge of the lug and the edge of the bolt hole and more or less split the difference, so that the new hole would be about half way between the edges of both holes. This turned out to be  about 1 11/16th inches or so.

The white powder in the following pics is Boe-lube that I sprinkled on the drill bit and in the hole of the spider arm. It is a Boeing product that is very much like candle wax but probably has some other stuff in it. It acts as a coolant and lubricant and is highly recommended when drilling into metal.

I used the straight edges of pieces of masking tape and a sharpee to mark the center point of each each hole, then marked it with my center punch so that the drill bit would seat properly. Then ot was just a matter of playing the drill table and vise to get it all lined up properly.

The holes in all 4 arms came out pretty well, and the drill bit plowed through the steel with ease as I slowly lowered the quill. You drill a little and then back it off, then add some more boelube if necessary, and do it again until the hole is drilled completely. The above pic was the first hole that I did not line up quite right, so it is a little off center. The other 3 are much better. If I need to drill another hole in this one later on I will do that.

And finally a trial fit with an AN3 bolt just to check the fit in the new hole.

This is not the same bolt I will use to attach the angle to each arm - it was just handy so I used the super long one just to check the fit.

Finally, after I was done drilling the 4 new holes in each arm, I noted something strange on my drill press. IT has a laser unit, and on the side as shown in the next pic I noticed that the locking ring screw post that is mounted to the edge of the laser unit was slanted to one side. as I moved the quill I could see it change from being off center to moving back to straight vertical. As I repeated this several times I noticed that it was the entire laser unit that was moving. There is a set screw in the back of the unit that secures it to the drill assembly. Sure enough, as I put my hand on either side of it I discovered I could move it from side to side. Not good. 

So I grabbed an allan wrench and tightened it down a bit and verified it no longer moved from side to side. I had been wondering why my laser lines always seemed to be off target during my latest drilling sessions, and now I know why. If you look just below the silver part of the press where the center of the laser unit is positioned, at the small black flange just above it, you will see that it is at an angle. The laser unit should be sitting in this flange so that it is completely level, and obviously this is not the case. A couple turns of the clamping screw took care of that problem. I guess it had come loose after many years of vibration and use. Glad I solved that problem.

Next steps are to cut the angles to size and drill the required holes on both sides. then I will finally be able to position the center plate, mount each of the arms, and try this thing out.

KPR

Effects of COVID on Building an Airplane - Waiting for Shipments to arrive

In an attempt to put together a rottiserie for the fuselage I needed to order some additional hardware as mentioned in my previous post. I decided to order the hardware and also some new Akzo Nobel Epoxy primer, so I placed the order for all of it with Aircraft Spruce. They shipped it UPS, and I watched the progress of the shipment as it left their Peachtree, GA location and made its way here. It was supposed to be out for delivery on the 9th, but never showed up, nor did it how up on the 10th.

There was no update from UPS so I called Spruce and they in turn called UPS. Then UPS started sending me notices regarding a rescheduled delivery and something about a package intercept. Then I got one that said that the sender had inidicated that the package required "special handling." Then I got another one saying they had "lost my package." Then I thought we had finally setup a new delivery date for the 12th, which also came and went, with no delivery.

So apparently just about everything under the sun has happened to my package, presumably AFTER it arrived at my local distribution center. I called Spruce a second time last Friday to find out if they knew anything more, but never heard back. Then, on the 13th, I get another UPS update, and this time it says that the package was damaged adn that were notifying the Sender (Spruce).

I called Spruce this morning and they apparently had not heard anything from UPS yet, so I informed them  that they have indicated that the package was damaged, and they said they were going to immediately begin pulling and shipping a new order, and would file the claim with UPS.

The only thing I am left wondering at this point is when the shipment actually became damaged. To say that I think UPS is giving me the run around is an understatement. I also realize that in many cases, when this primer is shipped, it ends up being damaged because they drop it, put some heavy crate on the top of it and crush it, or run a forklift through it. The last time I ordered this stuff many years ago I remember feeling pretty lucky that it had arrived in tact. This time I guess I am not so lucky.

SO here I sit - hurry up and wait.... To make matters worse, I also have a pending order for some new wing parts for Vans, but they just sent out a notice saying that they will be closed until the 18th for a number of reasons. So I can't even set that order in motion at the moment.

Between the COVID impacts, extreme cold weather over 2/3 of the country, severe lack of communication, and lack of accurate, understandable status information from the shippers, I am all but worn out. The real sad thing about all this is that all I really want to receive was the hardware. I only ordered the primer as an after thought to save some shipping and go ahead and order it with everything else. I am certain that the primer leaked, and is therefore reponsible for all the delays. If only I would have just ordered the hardware. Oh well, another round of hurry up and wait. What else can you do when the temps outside are -15 degrees F.

One solution was that I started using my Youtube app on my TV and discovered that Vans and other builders have some videos posted. One was just recently posted. It is about a 2 hour and 39 minute long how-to video on how to assemble and seal an RV-8 Fuel tank. This answered a lot of questions for me and also allowed me to re-visit where I had left off in the preparation phase of my left fuel tank, before the leading edge mod took over.

Unfortuntely, one of things I am planning to order from Vans is more Proseal, since my last order has long since passed its shelflife date. This stuff is also very nasty, caustic material that reqires special handling during shipping. To do the fuel tanks I must have this stuff. SO I don't have much choice but to hope that the shipping of that stuff will go much better than this latest episode. At least I now feel much better about sealing my fuel tanks after watching that video. All for now.

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.

Making a Rotisserie for the Fuselage - Part 2

 With the majority of the Spider Lug concerns addressed, it is time to start working on the remaining components. The hardware I acquired thus far was focused almost entirely on the attachment of the spider arms/lugs to the predrilled holes for the engine mount in the 4 corners of the firewall. The hardware I purchased for this part of project was an assortment of bolts, nuts, and, and washers. Here is a pic of this batch of AN hardware that I ordered. I could not decide if the length of the bolts that I needed was AN3-26A or AN3-27A, so I ordered about 10 of each so I could check the fit and decide which one to use. The difficulty with this was determining the actual length of the threads for each bolt. AN or MS bolts length (total length) is defined pretty clearly in numerous charts that are found on line, but the length of the bolt shank and the length of the screw threads was not so clearly defined.

To make matters worse, there is yet another hardware identification in use called NAS. So to figure this stuff out you need to be able to cross reference AN, MS, and NAS hardware specifications. I checked various books that I have acquired, including AN43.13, and found them seriously lacking in details about the hardware, so I had to resort to other on line sources. There is good info in Aircraft Spruce and Specialty website (search for AN Bolt Selector)< and also on various website via google search, as well as Aircraft Genuine Hardware's website, and even from links and info found on VAF. 

From that research I was able to find out that most AN bolt hardware contains threads that are approximately 1/2 inch in length. but in reality the spec is to create threads to allow for at least one or more washers to be applied, then apply an appropriate nut,  and still have at least 2 threads showing after the nut is properly torqued. 

What I found was that, although the AN3-26A seemed to allow threads to appear where the bolt exists the hole in the firewall/engine mount steel support bracket assembly, the slightly longer AN3-27A bolt shows a small amount of shank that a washer will cover nicely before the nut is applied, so I think I am going to go with that. 

The hardware in the above pic was obtained from a local source - an maintenance facility at Centennial airport (KAPA) called Straight Flight. They offer certain hardware and other items for sell to folks like me. I was first made aware of them from a post I stumbled into a few years ago regarding some problems with Nut slippage and bolt thread issues with the Bolt/Nut combination that Vans provides for their RV-8 Landing Gear. Apparently the Nuts would lose their grip, causing the bolts to become loose - not a good thing. So a discussion ensued and someone ended up recommending a different NUT that seems to work much better and resolves this slippage problem.

Somebody local ended up posting that they found the new hardware from Straight Flight and were able to pick it up without having to have it shipped from somewhere else. that supplier was Straight Flight. So that is where I purchased the hardware you see in the pic, except for the 3/16 x 1 inch stainless flat washers in the noticeably orange packets that came from HD. Very nice to have a local aircraft hardware vendor located not very far away from me.

I purchased AN360-10 and AN360-10L washers (thick and thin versions) and standard and lock nuts so I could decide which of those I anted to use in the final assembly. Then next thing I had to purchase is the steel angle for the arm extensions between the bracket and the Spider arms. I purchased it from HD and got 2 48 inch long 1x1 inch pieces of steel angle:

These will be cut to size once I determine the lengths that I will need for all 4 arms. I also ordered some other hardware that I am waiting on from Aircraft Spruce for this part of the assembly. Straight Flight did not seem to have the sizes I was looking for, so I had to order them from Spruce. More on that in the next post.

Making a Rotisserie for the Fuselage - Part 1

 While I continue to review my parts situation for the wings to prepare to place a new order with Vans and other vendors, I caught an ad from Harbor Freight a couple of weeks ago for a 1,000 pound capacity Engine Stand that many builders have used as a rotating rotisserie for the RV-8 fuselage. The rotisserie is mainly used as a back-saving tool while assembling many of the parts and components of the cockpit interior and floor panels. It may also come in very handy if I decide to paint my own airplane, which I am once again heavily considering. I have a new idea for a paint job for this airplane that so far seems to be pretty unique. That's all that I am willing to share about that for now, in the interest of keeping it as unique as possible. :)

 I have reviewed numerous other build logs from other builders, but I still rely most heavily on the log from Steve Riffe, who has been flying his airplane now for about 3.5 years or so. He used the same engine stand for his fuselage, and he also learned about this from other builders. While looking at pics of his engine stand, I noticed that the frame design is different, because I think they change designs every so often for the same product. Changes are mainly with how the wheels are attached to the base, and how the support bracket that attaches to the vertical bar and the horizontal bar to add support to that critical area is constructed. I purchased the stand brand new from HF for under $70.00. It requires minor assembly, but the parts are heavy, so be prepared.

Since the QB fuse as delivered by VANs only weights between 150-200 pounds max (if that), this 1,000 lb. stand is more than sufficient for the job. the main issue is the length of the fuse, which creates a long moment (Remember your weight and balance training - WxA=M). This means that if the tail is unsupported while the front is suspended by the engine stand, all of that weight along the entire length of the fuselage has to be supported by the stand and its attach points to the firewall. The idea is to use the stand in the front, and lay the tail down on a small saw horse, milk carton, or custom-built wood stand as needed, so the weight that must be supported by the stand itself is minimized as much as possible. I also wanted this particular stand instead of other available models because it has the additional lateral wheel bracket in the front, which helps provide some additional lateral stability to the fuselage when mounted on the stand. 

The main problem I encountered when considering this, is a lack of  a detailed information about the hardware used. So I will attempt to solve that problem. As always, keep in mind that I make no claim of suitability or guarantee that your results will match mine, so you are responsible for determining if thi will work for you or not. YMMV. 

Here is a pic of the assembled HF Engine stand, ready to be converted to a fuselage stand:

I used my yellow angle finder tool to determine the angle of the vertical post and the base support leg, since the angle is not 90 degrees. Most folks remove the front wheels of the stand to bring the vertical post closer to 90 degrees, so that it aligns vertically with the firewall when mounted to the stand. This needs to be done so that it does not put any undo stress on the firewall when mounted to the stand, which would be very bad. 

Since the wheel brackets on mine seem to be a little higher than others, I may need to compensate for that a little by raising the front up a little more with wood shims, but time will tell on that. The angle I measured is almost exactly 5 degrees, although in the above pic it  appears to be much greater than that. 

The rotating bracket that comes with the stand that the firewall will be mounted to comes with 4 "spider leg" attachments that are normally used for running heavy bolts through the spacers or lugs at one end of each arm that then screw into the back of a car engine. 2 of the arms are shown in the pic below.

The mounting plate has slotted holes to allow the location of the spiders to be positioned so that they match the mounting holes on the engine. Unfortunately we have to change this up a bit to modify this assembly for use with the fuselage, but it is not too difficult to do. I will still use the spider arms, but they will be attached to the ends of some angle iron that is cut to the correct length to act as an extension, so that the mounting plate remains near the center of the firewall, while the spiders will be bolted to the 4 holes in each corner of the engine mount holes and brackets behind the firewall, AND to the angle iron extensions. 

Similar to Steve, I decided to use AN hardware for most of the attach points for the spiders to the firewall/engine mount brackets, which have a minimum 125,000 lbs. of tensile strength, to ensure that the bracket has enough strength to stay attached to the firewall the entire time. The immediate problem that has to be overcome is that the stand comes with very large metric bolts. 

Unfortunately, when Vans builds the QB fuselage, all the engine mount holes are only pre-drilled to 3/16ths of  an inch, which is the smallest AN bolt diameter you can obtain before having to revert to screws. Furthermore, if you read ahead in the VAF forums and the Vans instructions for the Fuselage assembly, you will find that they say NOT to drill out those engine mount holes until you have the actual engine mount in your possession, so you can use it as a drill guide. 

This is necessary because the weldments for every engine mount vary a bit from one to the other, so you are not supposed to up-size the bolt holes without the engine mount to ensure the holes are drilled out correctly. The engine mount bolts are 3/8 inches thick, or AN-6 I  think, so they are substantially larger than 3/16 inches. Since I do not have my engine mount yet, I did not want to upsize the holes, but I was also concerned that this would mean that only AN3 sized-hardware would be attached to each existing hole. 

Steve informed me that he did exactly that - used the AN3 bolts in each corner, and he had no issues with anything while using the rotisserie. I also contacted Vans about this, and they said it would probably be OK to upsize the holes about half way in between the current size and the final size, since most engine mount holes may only vary by a max of 1/8 of an inch or less from each other. They also thought that AN 3 bolts would be "a little light. 

Other builders decided to drill up to AN 4 bolt holes, and I think I saw others yet again that drilled them out the final AN 6 size. At the end of the day, I decided to stay with the AN3 bolts to avoid upsizing the bolt holes without the engine mount. Steve said he had no issues, and the reality is that all the other bolts used in the assembly are the same beefy ones provided with the engine mount. So I think his will be fine.

With that decided, there is another  problem that I felt I needed to solve. While the AN 3 bolts will precisely fit in the predrilled holes in the firewall, the predrilled holes in each spider leg are extremely large, I was concerned about running such a small sized bolt through the large hole in the spacer lug in the spider leg, without having some kind of additional support for the bolt shank. So, similar to another builder (I am sorry I did not capture his build log) I decided to cut a wood dowel to the correct length to fit inside the lug or extension, and insert it into the larger hole in each spider. It turns out that a 5/8 inch dowel from HD aircraft supply works very nicely here, at least as far as the fit into the spider lug is concerned. I measured and then cut the 5/8 inch dowel into 4 separate 1 1/2 inch long inserts using my bandsaw, as shown below.

After you have cut the spacers, the next step is to take a rubber mallet and tap them into "submission" into each lug hole:

IT turns out to be a very nice "press" fit. Each dowel is only long enough to reach the base of the lug where it is welded to the spider arm. The dowel will not fit all the way to the bottom of the arm because the holes from the lug that they welded to the top of the bar are not the same size. The holes in the bar are a little smaller, so they will stop at that point.

Now for the hard part. The next step was to drill out  a 3/16 inch hole in the center of each dowel.  I won't lie, for me this turned out to be a bit of a nightmare, because I found out that dowels do not like to allow a drill bit to follow a straight path from one end to the other. All of initial holes I drilled ended up being misaligned, and I ended up having to continue "custom" drilling each hole in the dowels to "force" them to run more or less from center to center. Basically that means I had to enlarge the hole a bit by using a drill bit to gouge out the holes. 

I also needed to create a few replacement dowels, because the hole drilling went so badly that I could not salvage the insert. I tried using my massive large drill press first. It vibrates badly, and I cannot figure out how to secure things very well to the stupid drill table. After a few attempts with the drill press, I gave up and decided to try it free hand.

First I tried to put it in my table vise vertically - same result. the drill bit would meet the wood and instantly take its own undesirable path to the other end of the dowel.

 Then I tried putting them flat on a drill board and clamping then down with bar clamps:

I originally started with a #40 drill bit, then followed with a #30, followed by a 3/16th inch drill bit for final drilling. This also did not work very well for me. The hole on one end starts out centered, and the hole in the opposite end is completely uncentered and off to one side. I even used my center punch to try to start the hole in the exact center of each dowel, and this did not help much either.

Here are the results of several attempts. This side looks OK:

But not this side:

Example of extra gouging:

About as badly aligned as it can get:

At the end of it all I decided to put my 3/16 inch drill bit into my cordless drill, and after drilling the initial hole, I manually "corrected" any offset in each hole by gouging it out with the drill as best I could.  Then I ran each bolt through the holes to check for centering. it does not need to be absolutely perfect, but I wanted it as close as possible to avoid and excess stress on any of the bolts, or the points where they are attached.  Here are the end results:

Here is an example, taken before I made and drilled the dowel inserts, of the upper left corner of the firewall/engine mount hole, and how the spiders are attached to it. The lower end will be attached to the angle iron:

And here is pic that l also do not see in anyone's build log - how the bolt attachment appears on the inside of the engine mount hole, taken from the rear of the firewall, where the bolt protrudes through the predrilled hole from the factory:

More on the remaining assembly in the next post..