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Old 04-26-2011, 11:15 PM   #51 (permalink)
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I was trying to figure this part out in the other thread... This makes it a lot easier to wrap my head around it... Very cool...
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Old 04-27-2011, 10:57 AM   #52 (permalink)
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how about some pictures of this rectangle tube bending log splitter setup.
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Old 04-27-2011, 11:01 AM   #53 (permalink)
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Quote:
Originally Posted by BRORSAM View Post

Why even bother with the u bolt when you allready have the Steel Sleeve bolting together? Add two more tapped holes and capscrews per side if your worried about clamping force.
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Old 04-27-2011, 11:51 AM   #54 (permalink)
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subscribing to read and see the end results of this novel.
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Old 04-27-2011, 08:01 PM   #55 (permalink)
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Quote:
Originally Posted by MNtal View Post
Why even bother with the u bolt when you allready have the Steel Sleeve bolting together? Add two more tapped holes and capscrews per side if your worried about clamping force.
The wall thickness of the housing is about 3/4", which wouldn't leave room for anything much larger than about a 1/2" bolt. It would probably take three 1/2" bolts per side to equal what I'd get with the two 5/8" u-bolts.

Tapping holes in one half, and then creating counterbored pockets for the bolt heads could be done, but would have complicated the machining more than I intended to. Given the machine tools at hand, what I did was the easy
route.

I kinda prefer the u-bolt route. Simplifies fabrication, and I'm not going to end up with bolts sheared off (and difficult to remove) in one half of the housing.

If you go back and look at the pics in post #32, you will notice that there are a couple small allen-headed bolts set into the parting surfaces of the housing halves. They're tiny (5/16") and are really only there to act as alignment dowels.

Your suggestion is good though, and if I'd had reason to go thicker on the housing and had the machinery to cut the bolt bores and pockets, I might go your route. This was easier for me, and we will proceed with it until we have reason to do otherwise.
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Old 04-27-2011, 08:24 PM   #56 (permalink)
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Quote:
Originally Posted by fordnut View Post
how about some pictures of this rectangle tube bending log splitter setup.
Didn't expect that to be a popular request, so I didn't bother to take too many pictures. I do have these though:

Basic setup. I should be able to adapt any of a wide variety of homemade dies to the business end of this thing:



Splitting wedge in place:



Male die with about a 18" radius:



Crude square tube and angle iron female die:



Nothing extravagant, basically just an oversized conduit bender. Good for up to about 15 degrees---that's about the limit before the tube starts to kink (at least for the 3" x 2" x 1/4" tube I was using).


Side note: This goes a long ways towards explaining why the truck has been broken since 2007 and is taking so long to finish. It's bad enough that I need to build all the parts myself---I also have to build the tooling to build all the parts...
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Old 04-27-2011, 09:12 PM   #57 (permalink)
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Now that's ingenuity!
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Old 04-28-2011, 08:55 PM   #58 (permalink)
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Custom Urethane Bushing

At this point, we're making decent progress on the front suspension, but the whole design depends on the urethane or rubber bushing in the radius arm pivot. As previously noted, the nylatron bushing shown in post #26 was about the right shape and size, but the nylatron material wouldn't have been flexible enough. The solution I chose was to cast my own urethane bushing.

That's not as bad as it sounds. After some research, I came across this website (http://www.smooth-on.com/).

Not only do they have a wide array of different rubber and urethane compounds for a wide scope of applications---they have a very helpful database of frequently asked questions and a great deal of video demonstrations of the moldmaking and model casting process. If you're considering a rubber or urehthane casting project of your own, I'd highly recommend checking them out.

Anyway, here's what I figure I'll need to build in order to make the mold and then pour the actual bushing:

Mold box (a simple wooden box that defines the outer edges of the mold)
Part model (in my case, a full scale chunk of aluminum to represent the finished part)
Axle tube "dummy" core (another chunk of aluminum that represents the axle housing itself---needed because the intention is to mold the bushing with the hole already inside, rather than mold a solid chunk of urethane and then bore the I.D.)

Will follow with pictures to try to explain. Don't worry if it all doesn't make sense just yet.
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Old 04-29-2011, 08:21 PM   #59 (permalink)
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Bushing Model

First up, we need to build a full scale model of the part we want to produce (the bushing, in this case). Doesn't really matter what material you use to build the model, as long as it's dimensionally stable, can be formed or machined to the desired shape, and is either non-porous or can be sealed so that the urethane doesn't stick to it. I figured a chunk of aluminum should satisfy all those requirements.

Many hours of work on the lathe later, and we have this:



Notice the two bands of electrical tape? Another minor technical oversight on my part. I'd only just finished the machining and was feeling pretty good about nailing all the dimensions, when it occurred to me that it might be beneficial for the O.D. of the bushing to be ever so slightly larger than the housing bore, to maintain some preload on the bushing material. No good way at this point to build up the O.D. of the aluminum model, and I didn't intend to start over, but it was really easy to wrap a couple rounds of tape to build up the O.D. Once the mold is poured, nobody will ever know the difference.
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Old 04-29-2011, 08:52 PM   #60 (permalink)
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Mold Box

Nothing special here, just a simple wooden box a little bit bigger than the part model. I just made it big enough so that there would be no less than 3/4" of material thickness in the mold itself at the thinnest point.



Of all the things I've had to build so far for this project, THIS turns out to be one of the things I outsourced. My carpentry skills suck, and for me, it's easier to cheat with steel (can always weld on another piece to fill gaps, wheras wood isn't modified as easily).

A couple points here:
1) Get the wood sanded smooth and get a good coat of polyurethane applied to seal the surface. That will be very helpful when the time comes to remove the mold from the box.
2) Put all the pieces together with screws, so that it's easily disassembled to remove the mold.
3) Test the finished mold box by filling it with water to ensure there are no leaks. if the joints hold water, they'll hold the liquid urethane compound. No sense in finding out at the wrong moment that the liquid urethane is leaking through---that would kill an otherwise perfectly good pour, not to mention the cost of wasting the urethane compound.
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Old 04-29-2011, 09:09 PM   #61 (permalink)
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Pouring one half of the mold



Here we have the part model set into the mold box. It is not sitting directly onto the floor of the mold box, it's actually sitting up about 1" on top of a pair of rubber stoppers (which can't be seen in this photo). Those rubber stoppers (along with the inside surfaces of the box and the entire part model) are all liberally coated with a release compound before pouring the mold. When the mold has cured, those two rubber stoppers will come out, and the cavities left behind will act as the fill port and air release port for molding the bushing itself.

The four large rubber stoppers seen in the picture are strictly there to hold the part model in place, and will be removed before pouring the second half of the mold.

The aluminum angle pieces in the picture have some long bolts sticking through them down into the mold material. There's an acorn nut on the end of each of those bolts. The purpose of that is to produce features in the mold that key one half of the mold to the other. Once the mold half has cured, removing the bolts and acorn nuts leaves four nice acorn nut shaped cavities in the mold.

I chose Smooth-On PMC-744 material to pour the mold itself. This half of the mold consumed about 6 pounds,

Oh---though we're pouring the mold compound into the bottom of the box, what we're actually producing in this process is the top half of the mold.

All that excess material I spilled on top of the model will peel off and won't affect the second half of the mold or the finished part.
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Old 04-29-2011, 09:15 PM   #62 (permalink)
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Pouring the second half of the mold

I can't believe I didn't take a picture of this while I was dong it...

Anyway, from the photo above, we let the whole affar cure for about 3 days. Then we pull out the acorn nuts / bolts / support bars, the four large rubber stoppers, and we trim any loose quantity of the mold material. Then we apply more release compound, mix up another batch of the PMC-744, and pour enough to finish filling the box. As soon as that cures, we'll have a finished mold.
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Old 04-29-2011, 09:25 PM   #63 (permalink)
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Removing the mold halves from the box

After allowing time for everything to cure, it's then just a matter of disassembling the mold box and extracting the mold halves.

The finished mold top half:



The finished bottom half:




A couple notes at this point:

I used the same material for both halves (Smooth-On PMC-744). The amber color is the natural color of the material, wheras the black is the result of adding a black tint to the urethane during the mixing process.

Also, turns out that the mold material does a very nice job of picking up all the detail from the model. All my chatter and tool marks that I left on the model are apparently going to transfer to the finished part as well. Not a problem in my case, but FYI just in case you were wondering what to expect.
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Old 04-30-2011, 07:02 PM   #64 (permalink)
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Pouring the bushing

We start the process with the mold bottom half, and apply release compound liberally:



Here's the axle tube "dummy" core. This piece simulates the axle tube, which enables us to build the bushing with the hole already in the middle (rather than having to machine that hole afterwards):



The dummy core piece gets treated with release agent, and is then placed into the bottom mold half:



The top mold half gets a coating of release agent, then goes atop the bottom half:



Now it's just a matter of mixing up the urethane compound of choice, and pouring it into the mold. I chose Smooth-On PMC-790 urethane (shore 90 durometer). Really didn't have any practical experience to base that decision on, but the product specs looked favorable for the application.
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Old 04-30-2011, 07:11 PM   #65 (permalink)
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Finished Urethane Bushing

So---here's the result of the urethane casting experiment:





Had one little issue here, as can be seen in the second picture. That PMC-790 material started to harden far quicker than I was expecting. I got the mold about 95% filled before the material simply wouldn't flow anymore. The result is that my flanges on the bushing didn't fill out completely.

This finished piece is still very much acceptable for me, at least as a first test piece. I'll run it as is, and once I have some time on it, I should be able to make a determination on whether a different urethane product might be a better choice.
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Old 04-30-2011, 07:24 PM   #66 (permalink)
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Lessons Learned:

Obviously, to fit this over the axle tube, it needs a slit in it somewhere. No problem---one cut with the hacksaw, and it's mission accomplished.

I can tell you that the PMC-790 material is plenty tough. It's basically all I can do to pull it open at the split to force it over the axletube. Any stiffer, and I'd need some mechanical means of opening it up.

Thinking more about it, there's probably no good reason why the bushing has to be all one piece. I could probably mold it as two pieces---pour the mold half full, wait for that to cure, then pour the second half. That would eliminate the effort of having to cut it, as the two pieces would have a natural parting line at the seam. Also, it would fix the pouring time issue, as I'd only be pouring half the previous volume of material at a time.

I suppose I'll try those tips soon enough---I might as well mold another one of these just as a spare part.
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Old 04-30-2011, 09:29 PM   #67 (permalink)
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This is great work !! Thanks for sharing the tech.
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Old 04-30-2011, 09:38 PM   #68 (permalink)
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Quote:
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This is great work !! Thanks for sharing the tech.
X2. Been wanting to try making my own bushings for a while.
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Old 05-01-2011, 07:22 AM   #69 (permalink)
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Nice work with the Smooth-On product


Great build as well

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Old 05-02-2011, 08:58 PM   #70 (permalink)
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Back to the rear suspension for awhile

Here's where we left off:



As promised, we can't leave the mounts looking like this. The plan always was to box this area of the chassis. A little work with the plasma cutter and some 3/16" plate, plus some welding, and we end up with this:



Can't leave it in primer, so a couple cans of Kry-oleum later, and we have this:



And this should take care of the frame boxing exercise.

Almost....
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Old 05-02-2011, 09:19 PM   #71 (permalink)
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About the "almost"...

I know TwinTurbo496 won't let me get away with this if I pretend this is all there is to this story, so I'd better come clean:

Apparently my brain went on vacation and left my body home to do the welding. That's never a good combination. In this case, with the brain elsewhere, the body decided that there was no reason that we couldn't just go ahead and weld up the boxing plate---without any bracing to hold the framerails in place.

The end result? Predictable---the framerails bowed inward---badly---(about 2 inches per side). And they were so nice and straight before the welding. Obviously, the brain wasn't too thrilled with this turn of events when it got back from vacation...


Okay, what's done is done. How to fix? Simple...cut it all back apart and start over.

I ended up building a fixture from some large "I" beams to pull the framerails back straight, and to hold the framerails in place as I rewelded the boxing plates. No bowing this time, so we were able to salvage a reasonable result out of all this.

After discovering how badly I'd messed up the framerails with the initial welding, I was far too disgusted with myself to take any pictures, so sorry---no photographs of the entire frame straightening ordeal.
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Old 05-03-2011, 11:42 AM   #72 (permalink)
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Wow, I can't wait to see the rest of this truck. I really like your methods. Also nice to see another guy from Louisiana.
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Old 05-03-2011, 08:52 PM   #73 (permalink)
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Let's get away from the suspension for awhile

I hadn't really mentioned much previously about the engine and transmission, pretty much because I figured those would just carry over from the previous revision. Just for reference, here's some specs on the package:

502 crate motor, with reasonably fresh bore to 509 inches
Crane hydraulic roller camshaft (214/220 duration @.050 lift)
Edelbrock Performer TBI aluminum heads ("roval" intake ports, 100cc chambers)
SRP forged flat top pistons (approx. 10.2:1 compression ratio)
AS&M tuned port EFI intake with Accel DFI Gen7 controller
Comp Cams Magnum roller-tipped rocker arms
Edelbrock tubular exhaust (1 3/4" "shorty" style headers)

TCI TH400 with standard valve body
13" torque converter, rebuilt locally to pretty much stock specs

Klune-V "Goliath" planetary underdrive unit, with output housing for divorced transfer case application.
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Old 05-03-2011, 09:11 PM   #74 (permalink)
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TwinTurbo496 hates my camshaft

Yes, I admit....that's a very mild cam for a motor of that size. TwinTurbo496 does his best to make sure I don't forget that by reminding me of that fact every chance he sees fit (which is quite often). He's the drag race guy, and rpm is his friend, so I can appreciate where he's coming from.

My goal here was to have a motor with a broad torque output, great reliability, and still enough power to pull this 6000 pound mess over anything I point it at. And in the past, it's done that job quire admirably. However, I do want a bit more power (and I have a plan to get it).

So, basically we have a big, dumb sewing machine of a motor, which gets the truck from point "A" to point "B" fairly rapidly, yet is still civilized enough for trailriding. Almost perfect.

Almost?

I mentioned Mike Niebuhr's "Quagmyr" in an earlier post. His front suspension setup isn't the only part of the truck that favorably impressed me. Mike is a big fan of nitrous setups, and has used copious quantities of nitrous very effectively to his advantage. I figure if I ever find myself just a little short on output, I could go with a mild nitrous shot and still not give up on the civilized nature of the overall setup.
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Old 05-04-2011, 11:26 AM   #75 (permalink)
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Your camshaft is gay.
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