74weld steering rack coming!

[Tex]

What steel are you using, what are you doing to get even heat through the blade, and what are you quenching with?



I think that line boring it and running a tapered roller bearing on both sides along with a anti-deflection brace along the outside of the housing would likely be a means of significantly strengthening these racks.

I think that you are on the right track with this line of thought.

LOL nah, I usually don't have a problem with it, but sometimes you do everything right and then, banana (or tasty bacon!). I've never made a mistake, but I have made some knives a lot smaller than intended. Bladesmithing is one of the dark arts I've decided, and I simply don't know all of the spells yet. Most of my stuff is 1095, O-1, or 52100, and when I hate myself, I'll throw in a scavenged mystery metal that passes a coupon test. I'd love to have a HT oven, but currently using the forge with a flame diverter that heats evenly as long as you flip occasionally. Using Parks 50 for most cases, water for hamons. I've got a decent setup if you ever want to check it out or make a knife or something.

I'm trying to understand how a tapered roller bearing would function in this case though. Wouldn't something like a silicon bronze or babbitt bushing be better? The ft/min speed of the rack alongside the reciprocating motion in the bushing would put it squarely in boundary lubrication mode, and that's really where silicon bronze excels, and manganese bronze, to a lesser degree. Babbitt would be a much softer metal by comparison but you certainly wouldn't have to worry about premature wear on the rack.

I have considered a bolt on brace for the housing to help strengthen the portions of the rack that seem to have the most stress, notably a set of clamps over the bushing areas on each end to keep the housing from splitting open, and another clamp over the steering yoke preload area to keep it from popping out so easily. I suppose they could all be tied together and made into a single brace that would add some rigidity and strength to the aluminum housings. ideally, if the design allowed, utilizing the existing frame mounting points and not having to remove the rack in order to get the brace on.

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[mpeugeot]

LOL nah, I usually don't have a problem with it, but sometimes you do everything right and then, banana (or tasty bacon!). I've never made a mistake, but I have made some knives a lot smaller than intended. Bladesmithing is one of the dark arts I've decided, and I simply don't know all of the spells yet. Most of my stuff is 1095, O-1, or 52100, and when I hate myself, I'll throw in a scavenged mystery metal that passes a coupon test. I'd love to have a HT oven, but currently using the forge with a flame diverter that heats evenly as long as you flip occasionally. Using Parks 50 for most cases, water for hamons. I've got a decent setup if you ever want to check it out or make a knife or something.

I'm trying to understand how a tapered roller bearing would function in this case though. Wouldn't something like a silicon bronze or babbitt bushing be better? The ft/min speed of the rack alongside the reciprocating motion in the bushing would put it squarely in boundary lubrication mode, and that's really where silicon bronze excels, and manganese bronze, to a lesser degree. Babbitt would be a much softer metal by comparison but you certainly wouldn't have to worry about premature wear on the rack.

I have considered a bolt on brace for the housing to help strengthen the portions of the rack that seem to have the most stress, notably a set of clamps over the bushing areas on each end to keep the housing from splitting open, and another clamp over the steering yoke preload area to keep it from popping out so easily. I suppose they could all be tied together and made into a single brace that would add some rigidity and strength to the aluminum housings. ideally, if the design allowed, utilizing the existing frame mounting points and not having to remove the rack in order to get the brace on.

Taper roller bearings are overkill, BUT pretty much can take loads in any direction, works great for applications like lathes.

Silicon Bronze is an excellent idea, and would be an inexpensive (by comparison) way to support a larger area to reduce point loads.

 

[Snacktime]

I would like to acquire your services so you can tell me why my knife forgings keep warping during quench. I forge something that looks awesome and the oil says "abracadabra, your knife is a banana". I've already tried sacrificing chickens and waiting until a full moon and all that stuff.

You need an oven and to heat the metal slower. Also may need to leave the knife in longer to let the steel de-stress if it's cold rolled steel. Goal is to get the metal structure to de stress before the quench.

 

[bstottlemyer85]

Just got this video in my feed.




"While in California a few weeks back I stopped at a shop that we heard was making some pretty badass parts for Jeep Wrangler and Ford Bronco. Man was I blown away with 74 Weld and the stuff this company is inventing. "

 

[Tex]

You need an oven and to heat the metal slower. Also may need to leave the knife in longer to let the steel de-stress if it's cold rolled steel. Goal is to get the metal structure to de stress before the quench.

Ha, thanks for the advice man, I'm just giving him a hard time really. Metallurgy is a practice for most of us rather than a science

If you're curious about my method, I heat soak my steel for about ten minutes before any heat treatment. I generally go through an annealing cycle with a can of pearlite after any forging or shaping, followed by three normalization cycles of reducing temperature from austenizing temps to refine the grain structure and air cool to below 900F, then finally bringing it up about 50F above critical so it hits the oil at the precise temp. Once I get below 500F in the oil I transfer to thick aluminum quench plates in a vise to reduce warpage until it drops below martensite finish (or room temp if I'm cryo treating). Cryo consists of submerging the blade in a tray of alcohol and dry ice for two hours within a cooler. After cryo treatment I'll remove scale to bare metal, and test hardness. If it's to my liking, into the oven it goes...I clamp it into my homemade medieval torture device for knives (basically two c-channel steel bars trued up on the inside, holes have been drilled for grub screws to put opposing tension on warps and alleviate them if present during tempering cycles). Tempering varies (or doesn't happen) depending on design and intention, but usually two cycles of 400-450F for 2hrs each. Bare metal allows me to verify the right colors formed and will hint at any imperfections in the steel or heat treatment. Stainless steel follows a lot of the same steps, but wrapped in foil and fully plate quenched. Oh, and of course, crucible steel too...but that's a fickle beast if there ever was one. Warps and cracks still happen to all of us anyway when least expected, it's not a perfect science and nobody has a perfect process either, sometimes we just get poor steel or get too hammer happy on cooling steel and there's no way to know until you pull it out of the oil.

I'm much better versed in steel metallurgy than aluminum, as most of my experience with aluminum is already treated and aged by the time I get it. I do have some experience with icebox rivets and making sheetmetal brackets with 2024-T0, but I'm certainly not well versed in stress relieving/heat treating/aging for typical alloys of cast aluminum often used in automotive applications. It's probably another big annoying rabbit hole that I'm going to go down sometime in the future to see what I might need to address if I do any reinforcing welds to this housing. Thanks for coming to my ted talk, that was a lot longer than I thought it was going to be

 

[Evolkidbell]

I priced 7075-T651 vs 6061-T6 at online metals yesterday for giggles. 6061 was more expensive than 7075 for 4.5" round stock (they showed that in the video).

Not sure on 7075-T651. It’s included in the do not use list at work. We use -T73 or -7531.

Did a quick google search and you are correct. Seems 6061 has become more per lb than 7075. Quite interesting as when I used to design shocks, I wanted to use 7075 for a few components and the boss man always shot me down due to cost. Might have been a volume thing as we were buying thousands of feet of 6061 bar stock a month.

The steel housing, to me, would make the most sense. Ends machined and welded/brazed into a tube section. Minimal weight increase, but much higher strength.

I'd be really curious if they are up for selling just the finished housings for the handy people out there.

 

[Tex]

The steel housing, to me, would make the most sense. Ends machined and welded/brazed into a tube section. Minimal weight increase, but much higher strength.

I'd be really curious if they are up for selling just the finished housings for the handy people out there.

The way he was tossing that empty housing around compared to how much my rack weighs, I'd say 90-95% of the weight at least is in not-housing parts. Swapping it to steel probably wouldn't add more than 10-20% overall weight, if I were to guess.

 

[BigMeatsBronco]

True, but I would only want to machine it once. I agree that would likely add a little to the cost due to tool wear, but wouldn't you prefer a slightly more expensive rack that was more than 50% stronger?

7075-t6 is not that much harder to machine. 6061-T6 has the advantage of being weldable, but in this application, does that matter? Unless I am missing something, and maybe I am, 7075-T6 is the best choice for a high end housing.

7075 is NOW weldable!!! The professor in CA university designed so.e tig rod with Titanium in it and it passed all the tests and then some. Been available a few yrs now but most welders don't even know. A real game changer in the aviation world.

https://www.repairerdrivennews.com/2019/02/26/ucla-team-develops-new-wire-to-weld-7075-aluminum/

 

[Snacktime]

7075 is NOW weldable!!! The professor in CA university designed so.e tig rod with Titanium in it and it passed all the tests and then some. Been available a few yrs now but most welders don't even know. A real game changer in the aviation world.

https://www.repairerdrivennews.com/2019/02/26/ucla-team-develops-new-wire-to-weld-7075-aluminum/

That sounds expensive lol!

Based on the portal video it looks like they are well set up to just CNC the whole thing. When I worked in the packaging industry we always preferred to machine as much as possible vs fabricate/weld assemblies to cut down on rejects. Soon as you mix in any people in the process you start getting into 10-20% reject rates.

I think you guys like to argue metal to much, my experience I would just machine less off and say it was done to add strength(not save machining costs).

My concerns would be corrosion and electrolysis. After having several aluminum boats I would be concerned with inducted current and coating more than anything. Once you mix the two you get some funky white crud in weird spots.

 

[mpeugeot]

7075 is NOW weldable!!! The professor in CA university designed so.e tig rod with Titanium in it and it passed all the tests and then some. Been available a few yrs now but most welders don't even know. A real game changer in the aviation world.

https://www.repairerdrivennews.com/2019/02/26/ucla-team-develops-new-wire-to-weld-7075-aluminum/

That's cool. I have successfully welded 7075 in the past, but it was never something that I would rely on in an aerospace application - so cool that this is now possible!

 

[Tex]

I think you guys like to argue metal to much, my experience I would just machine less off and say it was done to add strength(not save machining costs).

My concerns would be corrosion and electrolysis. After having several aluminum boats I would be concerned with inducted current and coating more than anything. Once you mix the two you get some funky white crud in weird spots.

Nope, not going to stop arguing until we all agree on Maraging 400 or TRIP 780 after a thorough computational stress analysis to engineer the ideal design. Then we can talk about more exotic alloys for upgrading the internals

Might get some surface pitting on the housing after a long while, but nothing that some scotch brite or steel wool wouldn't knock out...the important bits would (ideally) stay protected with grease and the housing would certainly be thick enough to handle a lot of unchecked corrosion even without a coating. Might be a different story if you're doing a lot of beach running, live near the coast, or have lots of road salt, but there's always type III hard anodizing and nickel plating options too.

Anecdotally, the reduced corrosion resistance from 7075 probably isn't enough to warrant concern unless it's sheetmetal thickness. I had a huge 7075-T6 plate used as a gate in ag equipment running paraquat, sodium chlorate, acids, some kind of weird caustic stuff that bleaches your skin if touched, sulfur, fertilizers, and all sorts of other pesticides, you name it. The paraquat was interesting because it was green when mixed but as soon as it contacted aluminum it turned purple...you just know you're losing some aluminum any time you see purple. The rest of the plumbing equipment was a mixture of stainless steel, carbon steel, brass, and other types of aluminum, some of it was carrying current, so plenty of chances for dissimilar metal/galvanic/electrolytic corrosion to happen, and it was usually holding 2400lbs of mix so there was probably a chance of stress corrosion too. This thing had been in service since the early 70's, was always stored with a few gallons of water to keep the gasket in good condition, and it finally developed enough tiny pitting on the surface to cause a drip around the gasket a few years back. I sandblasted it clean, used a SS wire brush to smooth it out, filled the pitting back in with HTS2000 rod, and sanded flat. It's still in service today after 50 years of treating 7075 in possibly the worst way imaginable.

 

[Snacktime]

@Tex
You should throw a lead acid battery in the tank/hopper (spreader?) and we will have the perfect test? I know this out in the weeds but I have noticed issues with billet aluminum accessories in the past. Aluminum can be used as an anode and when mixed with the right metals usually zinc like galvanizing and the gold zinc metalcloak hanging under my bronco.

My experience,
I know that a/c motor cough alternator cough caused a noticeable issue with 5083 aluminum boat. Literally had a spot on the hull next to the alternator look like a salt crystal with very pitted surface. This was after 3 months of being docked at the marina in salt water. Every year it came right back as soon as we left it too long sitting at the the dock. It was one of those things that we never resolved in 7-8 years we had that boat. Dealer put a copper cathode on but that didn't help.

Here I am convincing myself that I am making a Bronco Battery between the aluminum hood and my skid plates..

 

[Tex]

@Tex
You should throw a lead acid battery in the tank/hopper (spreader?) and we will have the perfect test?

It's a fiberglass hopper. Just for fun once because I'm a dork, I decided to see if I could make a battery out of the acid by holding a lead plate in the mix. The multimeter read 1.2V but I didn't want to test current out partially for fear of my life and partially not to weaken the acid solution.

I wonder if a bonded magnesium cathode going to ground would be enough to reduce or eliminate any galvanic corrosion on the housing. Technically it's the most active type of cathode so it should protect aluminum quite well for intermittent electrolyte exposure.

 

[Snacktime]

It's a fiberglass hopper. Just for fun once because I'm a dork, I decided to see if I could make a battery out of the acid by holding a lead plate in the mix. The multimeter read 1.2V but I didn't want to test current out partially for fear of my life and partially not to weaken the acid solution.

I wonder if a bonded magnesium cathode going to ground would be enough to reduce or eliminate any galvanic corrosion on the housing. Technically it's the most active type of cathode so it should protect aluminum quite well for intermittent electrolyte exposure.

This is super tempting, almost worth it for the trail joke next time I see another person with metalcloak.

https://www.amazon.com/TonGass-Zinc...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1

 

[BAUS67]

Info dump on IG.

they will have one at the hammers. Anyone there check it out and send pics.......please.

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