dougweil

dougweil

Well Known Member
Hi guys:

Just got Van's battery box (steel) and wondered what you have been using to cut the lightening holes. I did cut one 2" inch hole on the with a hole saw backed up with a block of wood, but it was a BIG effort and ruined the hole saw. Plus it left a big lip on the back which I had to file and polish down. I thought about a fly-cutter but not sure just how that might work. I have 7 more to go if I want to cut them all.

Any good ideas???
 
Get a better hole saw....

....lots of lube and go slow. Cheap hole saws at high rpms dont last long.
If you have access to a set of Greenlee punches, they work very well and leave little burr to deal with.

A fly cutter has the same issues with heat and speed. You can ruin a fly cutter tip in a heart beat but they are easy to grind back into shape and heat treat again if you know what you are doing. Once you ruin the temper with heat, you are done.
 
As I have routinely done generating uncounted lightening holes prior to today's advanced kits, with cutting oil bathing the work, I used a fly cutter chucked into a floor mounted drill press, turning at 250 RPM. Some may say even that speed is too fast but I've never experienced the slightest trouble. Because a fly cutter can be dangerous, always make certain the work is clamped down securely and don't force it. In this particular case, I also stuffed a chunk of wood into the steel box so it could not distort as I cut into it. Worked well for me. YMMV.

2iaa1eh.jpg
 
Rick6a said:
As I have routinely done generating uncounted lightening holes prior to today's advanced kits, with cutting oil bathing the work, I used a fly cutter chucked into a floor mounted drill press, turning at 250 RPM.
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I use 170 rpm.
 
I didn't put the holes in mine as I thought the weight to frustration ratio was not worth it. I am curious to find a good solution though. It's not too late to drill em.
 
Ditto!

apkp777 said:
I didn't put the holes in mine as I thought the weight to frustration ratio was not worth it. I am curious to find a good solution though. It's not too late to drill em.
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But why oh why did the factory design the installation with the attachment bolts on the inside of the firewall and inevitably underneath the bonded insulation blanket? And why oh why didn't I change it? :rolleyes:

Jim Sharkey
RV-6 Phase 1
 
AX-O's Idea

Looks sort of like what we use with our Greenlee punch at work. It requires a hydraulic (manual) pump. But, ours works like a charm.
 
apkp777 said:
I didn't put the holes in mine as I thought the weight to frustration ratio was not worth it. I am curious to find a good solution though. It's not too late to drill em.
Click to expand...

This is the best answer posted on this subject so far......:)

I did not cut out the holes..... Just placed the battery sticker on it.
 
dougweil said:
Hi guys:

Just got Van's battery box (steel) and wondered what you have been using to cut the lightening holes. I did cut one 2" inch hole on the with a hole saw backed up with a block of wood, but it was a BIG effort and ruined the hole saw. Plus it left a big lip on the back which I had to file and polish down. I thought about a fly-cutter but not sure just how that might work. I have 7 more to go if I want to cut them all.

Any good ideas???
Click to expand...
Did you use a standard hole saw for wood or the more appropriate bi-metal hole saw? Using the latter, which cost just a couple bucks more, should have made easy work of it. It did for my battery box. Hope this helps.
 
dougweil said:
Hi guys:

Just got Van's battery box (steel) and wondered what you have been using to cut the lightening holes. I did cut one 2" inch hole on the with a hole saw backed up with a block of wood, but it was a BIG effort and ruined the hole saw. Plus it left a big lip on the back which I had to file and polish down. I thought about a fly-cutter but not sure just how that might work. I have 7 more to go if I want to cut them all.

Any good ideas???
Click to expand...

I recommend you look at this thread, particularly post #6.

http://www.vansairforce.com/community/showthread.php?t=49840&highlight=battery+box

Cutting lightening holes in the battery box for an Odyssey 680 saves a tenth of a poofteenth in weight, compromises the powdercoating protection (on a steel product), and in some circumstances can lead to battery failure.
 
Greenlee Punch

I have a friend who is a HVAC contractor, I borrowed his Greenlee hydraulic punch kit to do my firewall penitrations. The kit comes with a number of different hole size punch tools and the holes require little of no clean up . I have seen this kit at our local Home Depot tool rental dept.
 
Allen231ah said:
I have a friend who is a HVAC contractor, I borrowed his Greenlee hydraulic punch kit to do my firewall penitrations. The kit comes with a number of different hole size punch tools and the holes require little of no clean up . I have seen this kit at our local Home Depot tool rental dept.
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Yeah, these punches are cool and they work well but you have to be careful if you are trying to punch a precise hole (obviously a lightening hole doesn't need to be exact). Some of these punches are conduit punches. The conduit punches will actually punch a larger hole than is usually desired. For example if the punch says that it is a "1 inch conduit punch" it will punch a hole larger than 1 inch so that a 1 inch piece of conduit will fit through the hole.
 
apkp777 said:
I didn't put the holes in mine as I thought the weight to frustration ratio was not worth it. I am curious to find a good solution though. It's not too late to drill em.
Click to expand...
I took every opportunity to "build lightness in", thus I used a cheap hole saw, a block of wood, and a lot of cutting oil.

It is so much easier to get the battery in and out with those holes. Once th engine is in place, it is difficult to lift it out of the box. With the holes you can work it up with your fingers. (Careful, it might make a nice guillotine.)

jsharkey said:
But why oh why did the factory design the installation with the attachment bolts on the inside of the firewall and inevitably underneath the bonded insulation blanket? And why oh why didn't I change it? :rolleyes:

Jim Sharkey
RV-6 Phase 1
Click to expand...
Jim, that is a good question. If I build another RV, I will put the platenuts on the inside of the firewall. I see no reason why you can't do this.
 
I can't tell from Rick's picture. Is that 2.9 lbs or 2.9 oz? Frankly I need weight in the front. I may have to ballast in the future.

Bill- I hear you. Batteries are NEVER fun to remove. The holes may be worth it for that.
 
Tony,

My -9 with the O-290 was just a touch nose-light (as apposed to tail heavy). I just found out that Saber makes three diffent crush plates, the standard aluminum one and two different steel ones, depending on how much weight you need up there.

It always easier to add weight than try to remove it, in planes and on the belly.
 
apkp777 said:
I can't tell from Rick's picture. Is that 2.9 lbs or 2.9 oz?......
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In my first post, the image of the postal scale readout indicates a slightly lesser amount than the total weight savings enjoyed by generating lightening holes in the battery box which is 3 ounces or a bit more. Now that may not seem like much to those who balk at the effort but you either make a decision to build "light" or you don't. Van's clearly offers the builder the option to cut lightening holes into the battery box. A no-brainer decision for me, I seized (almost) every opportunity however slight to shave weight. In the aggregate, I think the effort paid off. Coming in at 1106 lb. my unpainted constant speed/IO-360 Grove gear equipped -8 is a mere SEVEN pounds heavier than my fixed pitch/O-320 equipped -6A. When it came to battery location in my -8, a perennial topic of debate, I chose to follow Van's own advice and recommendation because if one thing is certain...no matter what the topic happens to be, you can be sure there will always be a wide range of open forum opinion....from agreement to those who will always stake out the polar opposite view. Obviously, Van's did its homework. Note the numbers you can clearly read on this digital scale readout of the empty weight and go ahead and do the math if you so desire. Those numbers demonstrate that with the firewall mounted battery installed per Van's recommendation, the CG in my RV-8 is perfectly acceptable.

2zfoped.jpg
 
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apkp777 said:
Batteries are NEVER fun to remove. The holes may be worth it for that.
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As an alternative or additional option to the holes, cut the front side of the box out and then re-attached it using piano hinge. Not only does this make battery removal so easy a caveman could do it (frontal exit - just pull the hinge pins), it also allows you to use the firewall space above the battery for penetrations or whatever - you no longer have to keep it clear to allow for battery removal.

erich
 
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RE:BATTERY BOX LIGHTING HOLES

I cut mine with a wood hole saw and spent a considerable amount of time deburring the resultant hole. The weight savings is probably negligible but the lighting holes do make it easier to hike the battery out of the tray. If I was going to do it again I would use a Hougen Holcutter (they also mfg the Rotabroach Annular hole cutter.)

The Hougen sheet metal hole cutter comes in pretty much any size up to 3 inches and requires the arbor/pilot drill that is made for them but they do a good job. Probably not the cheapest solution but the are designed for holes in sheet metal and won't burr up the hole like a regular wood hole saw.

http://www.hougen.com/cutters/sheetmetal/Holcutters.html

Supplies for Racing and Industry carries them, and I got really good service from them recently.

http://www.sri-supplies.com/products.cfm/category_id/4263

McMaster Carr also stocks them also but they are not Hougen brand.

http://www.mcmaster.com/#3789a33/=5k4w8f
 
I just went throught this task. I tried the 2" hole saw made for metal and some BoeLube. I quit when it started smoking and I was only scratching the black paint. Then I tried the fly cutter and it dulled the cutter tip after a few seconds. So, I finally found a Greenlee 1 1/2" conduit hole punch - comes out to just under 2". Works like a charm, but leaves a burr to deal with like someone else said before in this thread. Whether it is worth the hassle or not is subjective. It takes off about 3 ounces, or about 19% of the battery box weight. Now there ain't too many places on this airplane where you can take that big of a percentage of weight off of something.
 
Okay, so 2.9 oz's from the battery box. Let's see, combine that with the 2 oz that you can cut off the canopy latch, battery top bar 2 oz, control column mount brackets, 3 oz from holes in the rudder pedal bracket, did I miss anything? I am thinking there's a lot of work for 10 ounces. We'll call it a pound.

I am sorry, but I can't see that the holes in the battery box are worth the effort. Besides the box is supposed to be a heat sink. I am not sure that you want to give up 20% of the heat radiating function. Don't use the box if you really want to save weight. There are other ways to attach the battery.

Don't take my wrong on this, I am not criticizing the concept or effort of saving weight. And certainly not the decision to put holes in it. I started to cut mine but barely made a dent with my fly cutter and can't justify the $50 for a descent hole cutter.

I just don't buy the idea that someone is "building in lightness". These are not LSA's. I look at some of the panels with 10 lbs of standby flight instruments and backup radios, mostly entirely unnecessary. Interior sound proofing, primer, paint, stick controls, steps, nose wheels, breakers, etc.

I really think this is a case of "straining the gnat, but swallowing a camel"

I really think there is a "form and function" to be considered with the desire to save weight. You can shave a ton of weight from every part in the aircraft. Most are way over engineered. However, do you sacrifice the "function" by adjusting the "form"?
 
apkp777 said:
Okay, so 2.9 oz's from the battery box. Let's see, combine that with the 2 oz that you can cut off the canopy latch, battery top bar 2 oz, control column mount brackets, 3 oz from holes in the rudder pedal bracket, did I miss anything? I am thinking there's a lot of work for 10 ounces. We'll call it a pound.
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I'm all for building light...and I agree with the reasoning behind it. But, that didn't stop me from not cutting any lightening holes in anything. Actually, if I could go back and do some things over, I would put lightening holes in the VS doubler plate and the seat back positioning tabs. I'd leave everything forward as it is. I think most RV's could use a little more weight up front...mine certainly can!

I just don't think the effort is worth much if it moves my CG forward by .1 of an inch. I was guesstimating the addition of a 15 lb crush plate in front of my prop (using the handy W&B spreadsheet that someone on VAF provided) and my CG moved back only .6". :eek:
 
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