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Old 10-22-2011, 01:48 AM
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Default Threaded Rod Grade/Strength

At work we use two 7" long pieces of 1/4-20 threaded rod to compress some springs when we rebuild caster wheel assemblies. Sometimes the threaded rod will break before the springs are compressed enough to remove. At that point we throw the caster wheel housing and springs away because the threaded rod can not be removed without cutting the assembly apart.

Several weeks ago I had some rod break, and decided to try and figure out what other types of threaded material could be used. I found a burned up electric motor in the dumpster and remove the 4 long bolts that hold everything together. These were 1/4-20 cap screws that had enough threaded area to be used in place of the threaded rod after they were cut.

These cut down bolts worked a lot better than the zinc plated 1/4-20 rod we had been using, but they eventually start galling from the pressure, and after several uses are no good.

I went to Fastenal and asked if they had some long 1/4-20 bolts or threaded rod that was somewhat hardened. I was told by the fastener guru that they did not have any bolts that were threaded far enough, and that my only option might be trying some stainless 1/4-20 threaded rod.

I bought a 3 foot length, and will give it a try. While there I noticed that their catalog shows a B7 threaded rod, and asked what the difference was. I was told that B7 is un-plated, ant that is the only difference. When I showed Boltmeister a column where it showed the B7 available plated, he said it was referring to the plated threaded rod I did not want. I then showed him where the part number was different than the plated threaded rod part number. He said not to pay any attention to it..................hmmmm.

Now I am wondering if the B7 is as hard a grade or harder than the over priced stainless. I have never had such a hard time finding some good quality threaded bolts, rod, etc. Is there some other option I am over looking.......thanks
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Old 10-22-2011, 02:51 AM
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How about grade 8 threaded rod? readily available thru McMaster-Carr. I know I have purchased some 1" grade 8 threaded rod from my local Fastenal as well.
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Old 10-22-2011, 06:21 AM
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Grade B7 is supposed to be a heat treated alloy like 4140 according to ASTM A193 specs. Strong stuff.

See this: http://www.portlandbolt.com/technica...ASTM_A193.html
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Old 10-22-2011, 09:53 AM
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Methinks the guru is a pretend guru
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Millermatic 200 w/ SKP-35 Spot Pulse Weld Panel, Tweco MIG-GUN #2, running ER70S-6 .035 wire on CO2, Spoolmatic 1 Spool Gun
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Old 10-22-2011, 10:58 AM
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USMCPOP, Chris,

Thank you for the info and link. I went back to Fastenal this morning and chatted with one of their senior employee's. It seems that the B7 rod was in stock but kept in the back room. I returned the stainless and bought 2 six foot lengths of the B7. I was told that the B7 is graded between a grade 5 and 8, and is indeed made from 4140 steel. When I explained what I was using it for, I was told that repeated use will probably deform the threads which could be cleaned up a few times with a chaser before becoming unusable. The regular zinc plated threaded rod is a grade 2 which explains why the threads start galling / smearing after just one use. I think the B7 will work for our purpose since we should get several uses out of it, maybe more if we lube it.

I also picked up another bag of 3/8-16 Heavy Hex nuts. These things work a little better for them times when you need to weld a nut on something. The dozen or so I took to work did not last long once the others discovered that the heavy hex do not deform as easy from the heat.......Fastenal part# 1136548.
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Old 10-22-2011, 11:39 AM
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Pat when the rods break is it at the hidden thread or just inside the assembly ?
When I have used threadewds rod that way I leave it long use an oiled extended nut and hold the end of the threaded rod with a pair of locked nuts to prevent it turning inside the assembly. failures then are recoverable.
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Old 10-22-2011, 11:54 AM
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maybe a little never-seize would help the galling issue---
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Old 10-22-2011, 11:58 AM
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If the 1/4-20 B7 doesn't work out and the diameter is limited, you could try 1/4-28 rod. It's marginally stronger.

Where are the grade 2 rods breaking? Is the face of the nut(s) perfectly perpendicular to the part you are clamping? What kind of torque are you applying?
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Old 10-22-2011, 01:35 PM
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USMCPOP and Terry,

The threaded rod has to pass through a 1/4" thick part of the wheel bracket, then through the center of 2 springs (one inside the other) then it screws into a disc that is approx 1.5" diameter with 1/4-20 threads tapped in the center hole. On the opposite side of where the threaded rod enters, the disc has a cone shape that comes to a point. This point (tit) is forced into a hole from the pressure of the springs against it, and holds the springs in place.

In order to remove the springs, this disc has to be pulled back far enough so that the tits on the disc's will clear the holes they sit in. Quite a few times when the disc's are about 2/3 out of the holes, it feels like the threaded rod is going to twist off before it gets pulled back far enough to remove the disc and springs. If the rod does twist off, there is no way to get to the piece broken off inside the disc because on the one end you have the 1/4" bracket, about 3" of spring length.

On the other side is the disc which is closed because it is a blind hole. At one time I had the big idea of drilling through the disc's and tapping them out to 5/16 thread. After doing that I discovered that the 5/16 bolts were to large of a diameter to pass through the center spring holes. Quite frankly, this forklift manufacturer does not want places repairing their own equipment, and want you to pay their techs to do the job, so many things are designed to make you say "F%*k this". The parts that are very simple to replace are for the most part also very expensive. These pieces of crap are very over engineered. They have 3 computers and are AC drive. The manufacturer claims that AC drive is more economical because of less battery draw down compared to the older DC contact type units. I do not believe this. The older units that had nothing but switches and contacts held up much better. They did not have computers that when they go out can cost $4000.00 each. Yup, I am sure this particular manufacturer makes these trucks with the sole purpose of selling parts down the road. Never had near the problems with the older DC non-computer models.

I also think that no one with any lift truck knowledge makes the decision to buy from a certain company, and that this person also has his hand buried deep in the manufacturer's back pocket. I would not give you scrap price for these trucks when they are new...............there, now I feel better.
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Old 10-22-2011, 09:43 PM
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I used my small bolt cutters to cut several pieces of the B7 to take to work Monday. It takes a lot more force to cut than the regular zinc plated #2. The B7 type actually snaps apart when the cutter is about half way through, and the grade 2 basically cut's/smears off.
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