I think we are missing the hot Rodders rule here! “ If a little is good, mores better and a huge amount is just right! “ This works most of the time! Lol As for engineers, their job is to design something that will work, not fail , for the cheapest amount of dollars! Hot Rodders do the same for the first two, but since we are building a one off thing usually, the dollars are not quite important! Now I know money is important, but like in this seat problem , I’m sure $25 one way or the other is not going to break the bank! What I have always done is figure , with common sense, what should hold it and then build it a little( or a lot) bigger for strength. Then possibly add braces and extra support. I have always been known as the King of overkill! Lol Oh, I got me a couple of them degrees , too, but not enough to drive a train! Bones
When you drill holes in aluminum, you need to break the sharp edges of the holes. That will go a long way toward keeping cracks from occurring. Paint all your seat frame parts, making sure you get the inside of the holes, with zinc chromate primer to avoid corrosion due to the use of dissimilar metals, aluminum frame and steel bolts.
Somehow I missed this. My apologies for generalizing everyone on here, and I had no intentions of offending anyone. You are without a doubt highly educated with hands on skills, which is truly a very rare combination. My point being was that when dynamic forces are involved, and as I mentioned in my subsequent post, that type of ****ysis is very complicated, even now and many ***umptions are made. I’ll provide an anecdotal story I personnally witnessed. While working for General Motors Diesel Division (now General Dynamics Land System) on the Light Armoured Vehicle (LAV/Stryker), they decided to build a prototype ch***is with a 105 mm gun. The older structural engineer wasn’t comfortable with the challenge, as we had never done anything like that before, so they hire a recent engineering graduate that had finite modelling ****ysis experience. Using ProEng at the time, they modelled a new turret ring, built the prototype, and subsequently tested it. I wasn’t there for the test but it was a total fail, and the entire front section of the vehicle hull collapsed from the blast shock wave, and the modelled turret ring and surrounding hull failed. Needless to say, they gave up on tbat concept at the time. I have several other similar stories of failures from dynamic loading situations. I’m building my speedster from complete scratch, and it never even entered my mind, even as a Mech Eng, to perform any type of structural ****ysis on any part. As I said, I’ll mimic what has worked before.
@sunvalley54 posted a thread back in 2010 about Metalworking 101. It's a very good read and may answer a lot of your questions.
As V.P./manufacturing for a large job shop in Socal in the 80's, one of my duties was liaison between our plant and the engineering departments of customers like Ford Aerospace, Hughes SVS, etc. I'll just say I have a much different thought on that than Boneyard51 and leave it at that, but it's probably spot-on in the retail/consumer manufacturing world. For a super strong seat mounting bracket, check out Unistrut (one brand name)at the big box hardware stores. Also, take note of the hd mounting components sold for it. You'll find it in the electrical section usually. It's what they use to mount heavy heat and air equipment to rafters. The channel will give you much more adjustment and has features like teeth on the t-nut mating surfaces that grip the teeth inside the channel that you can't see unless you look for it. I think it comes in 2 different heights.
It might be that an engineer's job is to design something that will meet all the requirements, including failure rate and cost. Each thing that's designed has different requirements to meet. But even so, Unistrut is about the last thing I would consider using to mount a seat in a car.
To the question of weight savings by using aluminum, I bought a 24 ft. enclosed car trailer and during the process I asked the dealer how much weight difference between the all aluminum trailer and a comparable unit in steel. His answer was about 335 lbs. I didn't feel it was significant, but I got a good price on the aluminum one so I bought it.
Please enlighten me. It worked great for me. Your opinion is always respected. Maybe because we're talking different seat designs....racing vs late model buckets?
The plastic seats aren’t allowed in a lot of racing cl***es. Would be worth checking before you get too carried away. Andy
Unistrut is designed for installing electrical equipment, and the requirements include being a versatile mounting system, being relatively inexpensive, easy to install in the field, etc. They don't include light weight, good looking, strong only in the required directions, etc. I guess you can build anything out of Legos or an Erector Set, but it's not the same as designing a part to do a specific task. If it works for you, great. I can figure out something better.
I figured I would get a response from an engineer, so let me say that there are as many different engineers as there are cars! Kinda what I was talking about is the engineer hired by big companies that build products in quan***y. If you can save a dollar on a product and it still holds it’s integrity and the company makes a million a year, more profit! I have walked in buildings designed by engineers that you can feel other people walking! I have driven on bridges designed by engineers that feel like roller coasters, due to an arch designed into the bridge that didn’t flatten out, several times. But on the other hand, I redid the floor in an old house, no engineers degree, but you could hold a barn dance in it and never feel a thing. My point is most of the time an engineer designs stuff that is “ supposed “ to work/function. Us country boys build stuff at about 2/300 % over what “will work” just to make sure it does! We have that privilege, just building one item, usually! I can’t remember the times I’ve heard someone say “ you think you built that strong enough? “ in jest. Bones
Glen Levitt if I recall correctly. It was gooooood and smoooooooooth and just on the rocks, no water.
When in doubt, build it stout. You can always take material out. Diet Coke is the relaxing drink for me.
That's actually a hell of a good idea... Sorry Jim... It comes in many more sizes than two. You can get single strut from 7/8" deep all the way to 3.25", if you get into welded ***emblies the sky's the limit. It's also available formed from different gauges of metal from 19 to 12. Use the 12 gauge and each attachment point is rated for well over a ton; it's incredibly strong. All the skilled trades use it, not just electrical; I installed thousands of feet of it during my work career, plumbers, pipefitters and HVAC use it extensively also. Now, this isn't something I'd normally use in an automotive application but for a fixed seat track it's nearly perfect. Four 2' pieces for two seats would weigh about 6.5 lbs, a small weight penalty. And infinitely adjustable with just a wrench. If you know someone in one of the above trades who works commercial/industrial jobs, ask them about it. On many jobs a 2' piece could be considered s****, you might get it free...
If calculations always worked there would be no need for testing........... Those of us that don't have the edumacation just have to rely on our natural feel and enginuity for what works best. Just pokin a little fun in here........
oh, I'm pretty familiar with the stuff, we used it a lot on the SATCOM terminal installations I worked on for the Army in the 1980s. I would never put it in any of my cars.
The Company I used to work for was trying to be cheap and having Drilling rigs built in China then having them shipped to the U.S the metal was cracking right away and they were having to replace all of the metal with U.S. Metal so in the long run they were actually spending more money then having the Drilling Rigs built here in the U.S. so going cheap on metal is never a good thing. That’s my opinion at least on any thing load bearing holding weight. Sent from my iPhone using The H.A.M.B. mobile app
S/O = soft, T3= Hard but bendable, T6 = hard , will break or crack if bent. There's more but that's the basics.
I tried to my some s**** from a few of the recyclers in my area, none would sell. One said a liability issue. Others just said no. The steel suppliers will cut a break on stuff they have cut to some customers spec that is left over. But always seems what I need is an inch short.
Great story.....I am quite familiar with that outfit.....I wouldn't allow them tie my shoes!! They also designed a vehicle for the Marine Corps in which they had both water jets rotating the same direction......and the pilot for the prototype had to put the rudder hard over to get it running in a straight line. There were lots of engineering blunders on that project/ Total incompetents.....
Check to see if you have a salvage yard in your area. These guys buy up leftovers, odd lots, overstocks and salvaged metal wherever they find it, that's always the first place I check. You'll pay a premium over s**** price but less than 'new'.
I think I'm a hoarder........But what I do is go to the local metal sales place and buy "off fall".........the stuff left over from other buyers orders. If you go looking for one particular size, or one thing, they charge a lot more for it because it takes "time" for them to deal with you. They often add a charge somehow in the cost of that piece. I take about $300 with me and start loading stuff on a cart. Various lengths and sizes of things I find. Sometimes they want to measure and calc every length, other times they just weigh it. Usually if you are spending a decent amount of money and don't need a receipt.......you can just load a bunch and then offer them $200-$300 and they say OK. Then I eventually have lots of stuff in my shop so I can make things. Couple of trips a year to the metal shop, lots of convenience and cheaper in the long run. Wanted some aluminum sheets one time. Guy had some that had some discoloration and surface corrosion in some areas. Great for patterns and lots of good areas. Started to buy a few sheets at a good price, and because I had been there multiple times,........he gave me the rest of them. That was ten years ago and I still have a bunch of them. There is a lot to be said for getting to know the guy at the metal supply shop.
Years ago, design was done by engineers and other who had an inherent knowledge of their materials because they had physically worked with them. Today, it seems that everything is designed with computer aid and designers have lots of data and super-powerful computations but not a real idea of what the material can do. Or can't.
I have Raco seats with the factory mount. T he ****ers are heavy but I don't fear they will fail if I do something stupid. I drive with my son or wife in my cars an I don't want a seat mount to fail because it is made of ****py metal a few ounces is not worth a life. Sorry if that pisses off someone
The Jalopy Journal
