Making my own trailer axle (2 Viewers)

[meatloaf]

I ordered the 1.5" square spindle below to make the axle for my trailer... I have some 2"x2" by either 1/4 or 3/16. I will be using the Dexter 6x5.5 hub with oem steelies. This would be my first attempt at making an axle and no I am not a professional welder but I do weld my own stuff including bumpers for my fj60 which have taken several beatings and are still intact.

I would appreciate any pointers you all can give me. Axle will be used on an off road trailer I am making out of a Ford Courier truck bed.

Spindle 1.5" SQ x 4" STUB (1750 lb)

Thank you all for the help!
ML

 

[cjmoon]

The square you have will have a seam. Take a die grinder to it and the 1.5 should slide right in to the 1/4" wall with a block of wood and hammer to "press" it end to place. I would only use a tight fit 1/4" wall, you want it all tight so the weld doesnt really take much load and it all.stays in place while you weld. I would put the seam on the bottom it it was me.

with the spindle being solid I would hit it with a torch to warm it up first and hit the weld after to help even heat through the piece.

In theory trailer axles will have a little camber and toe. Many people use straight without issues.

 

[ntsqd]

IF the seam is centered in the face I would put it at the front or the back. Reason being that in bending the center is neutral and sees neither tension or compression forces. If it is not centered on the face then I'd put it on the bottom too.

X2 on wanting a tight fit.

Suggest drilling a pair of holes large enough to weld thru in both sets of faces and at each end. Offset them length-wise along the tube so that you don't have a thin spot between the holes.

Might go as far as to put the hubs on the spindles after they're "pressed" into place, but before welding. Set the assembly on the floor and spin the axle while holding the hubs still. Any misalignment will show up as a wobble in the tube and if bad enough in the hub flanges. Do whatever it takes to remove the wobble before welding. After you've removed the wobble clamp the spindles so that you're pushing them both in the same direction inside the tube. Then weld both ends on the same tube face. Spin on the floor and check for wobble again. Once corrected or if none then weld on one of the faces adjacent to the first welds, again at both ends. By now whatever wobble you've got is only curable by bending the axle, so finish welding the plug-welds.

 

[meatloaf]

Thank you cjmoon & ntsqd for all of the tips above, the spindle is not "snug" on the 2" x 2" square tubing I have. I will go get another piece tomorrow and will take the spindle with me to make sure.

ML

 

[cjmoon]

IF the seam is centered in the face I would put it at the front or the back. Reason being that in bending the center is neutral and sees neither tension or compression forces. If it is not centered on the face then I'd put it on the bottom too.

i debate myself all the time on things like this. the "neutral" spot is where tension and compression meet. that means you have shear stress. sheer and tension are the weakest in a brittle weld joint. thats why i choose the bottom.

just get 2" 1/4 wall the spindle will not fit until the weld joint is ground out.

 

[e9999]

may be easier to grind a small groove in the spindle if it is solid than to grind the joint in the tube, especially if you have to go deep in there. Plus that may help with securing the spindle in place some.

 

[ntsqd]

Since the tensile or compressive stress tapers off towards zero as your sample point gets closer to the neutral line, the shear stress will be tiny to almost nonexistent because *just* to either side of the neutral line the tensile and compressive forces will be tiny as well.

Good idea, make a groove in the stubs rather than removing the seam from the inside.

 

[Chris Wilcox]

ntsqd, check your transvers shear diagram for that comment. I think you will see it is fiarly high at the neutral axis. Regardless, in actual structural steel construction the weld location is never specified in my industry. We treat the weld as equal to the parent material. If you perform proper structural calculations you will have a safe design. Personally I'd put it at the bottom as that is primarily in tension and it looks better also.

 

[TRAIL TAILOR]

Any weld (given the welder is capable) should be, by design with proper testing and procedures, stronger than the parent material.........PERIOD.

I hate square spindles. Most I've run across are on the smaller side of the CHINA metric specs and the reason you are getting a "loose" or easy fit in your 2" x .250" HREW square tube.

I run round spindles with A106 seamless pipe for most of my axles (usually 2x the material thickness as ANY trailer axle mfg out there), IF I don't order a spec'd axle from my mfg.

Make sure you are SQUARE (tube and spindle) when you weld the spindle to your tube. As @ntsqd stated and great advise for a newbie builder... roll it to make sure there isn't any visual mis-alignment. You can tell pretty quickly.... You're wallet and tires will thank you later down the road.

J

 

[ntsqd]

The weld in question is a resistance weld made by a machine. It's only as good as the guy who set it up, but its exactly like that forever barring normal wear. Those welds almost never on center, but as far as my education took me down that path I stand by what I've said. Neutral is neutral, not almost neutral. The stress concentration is a gradient based on the cross section & section disruptions like holes. The stresses in the metal immediately adjacent to the neutral line can not be anything but very low. Therefore any shear stress in the metal just outside of the neutral line must also be very low.

Welds are no better (and no worse) than an "on-site casting". With all of the usual properties of a casting. Though it can be, the weld usually isn't the problem, it's the HAZ.

 

[Chris Wilcox]

The weld in question is a resistance weld made by a machine. It's only as good as the guy who set it up, but its exactly like that forever barring normal wear. Those welds almost never on center, but as far as my education took me down that path I stand by what I've said. Neutral is neutral, not almost neutral. The stress concentration is a gradient based on the cross section & section disruptions like holes. The stresses in the metal immediately adjacent to the neutral line can not be anything but very low. Therefore any shear stress in the metal just outside of the neutral line must also be very low.

Welds are no better (and no worse) than an "on-site casting". With all of the usual properties of a casting. Though it can be, the weld usually isn't the problem, it's the HAZ.

You are right for tensile/compressive stress but are mistaken in regards to transverse shear. The only point I'm trying to make is that if the weld was so weak, then it would fail in transverse shear if near the neutral axis. It is pointless though because the weld, being ERW, is equal to the base material for all purposes of calculation.

 

[TRAIL TAILOR]

The weld in question is a resistance weld made by a machine. It's only as good as the guy who set it up, but its exactly like that forever barring normal wear. Those welds almost never on center, but as far as my education took me down that path I stand by what I've said. Neutral is neutral, not almost neutral. The stress concentration is a gradient based on the cross section & section disruptions like holes. The stresses in the metal immediately adjacent to the neutral line can not be anything but very low. Therefore any shear stress in the metal just outside of the neutral line must also be very low.

Welds are no better (and no worse) than an "on-site casting". With all of the usual properties of a casting. Though it can be, the weld usually isn't the problem, it's the HAZ.

While this may be your experience on resistance welds (ERW) or any welding for that matter. BUT, if the mfg is following AISC and ASTM standards (including post mfg welding codes AWS D1.1, API, ASME, etc..) the welder and weldments are required to be tested on a periodic basis (through progressive sampling and random inspection, not to mention each engineering firm/owner/contractor has their own specifications that follow or surpass the above stated organizations per their standards and engineer of record(s) requirements whether its when a new welder is reassigned to the machine, new WPS/PQR is implemented or any essential variable of the WPS/PQR is changed outside the % allowed by these governing bodies.) Therefore creating a weldment that is within the WPS/PQR parameters for the accepted code design standards for it's purpose.

J

 

[e9999]

I would have thought a lot of the steel tubing etc is coming from China now. For those, one may be forgiven for wondering about their implementation of US standards.

 

[TRAIL TAILOR]

I would have thought a lot of the steel tubing etc is coming from China now. For those, one may be forgiven for wondering about their implementation of US standards.

For the cheap bastards out there it is.. I only order DOMESTIC/NAFTA materials. ONLY true way to know what you are actually receiving is to request a MTR (mill test report) with your order and compare it to the HT# (heat number) printed on the material. I won't accept ANY material that has a hand written HT# on it. If your supplier won't give you or doesn't have access to MTRs... tell him to pound sand! I pay $2.50 extra for each item ordered that I request a MTR on.

J

 

[ntsqd]

You are right for tensile/compressive stress but are mistaken in regards to transverse shear. The only point I'm trying to make is that if the weld was so weak, then it would fail in transverse shear if near the neutral axis. It is pointless though because the weld, being ERW, is equal to the base material for all purposes of calculation.

If it's not exactly at the neutral line then all bets are off and it will have some form of stress in it.

I didn't say anything about singling out a weld, any weld made in a production environment. I said that they are "on-site castings". All welds are, the good ones and the bad ones both. While the right techniques & processes can reduce the grain size, it takes post-weld processing to achieve grain sizes near that of the base metal (assuming it isn't a casting itself).
But I've unintentionally diverged this topic too far.