Stud Alignment Concerns

[Woody]

The majority of the studs look really good with the bus bar and nut. The nut is flat to the bus bar. I have one stud that isn’t the best with a bit of a gap more than I like. There are two others that have a little gap. I have photos below illustrating this. The largest gap one, I’ll try cutting a slight crescent shim for under the nut. The others will just get tighten down as is. As for torquing them down, not going there. Will snug them all firmly by hand. Monitor for poor electribal connection and will recheck firmness over time but tightening them to a rigid spec, I fear, might cause more problems than help.

Need to run to the hardware store for more SS M6-1 x 20 hex head bolts to finish the last set of battery bus bars. So still in the mock up stage. None of the bus bars have been firmly attached (hand tighten only) so I still don’t know how this will turn out. After I get the last set of bolts on, then it’s clean/prep terminals and bus bars. Apply Ox-Guard and tighten everything down. Lastly, my confidence level is high that this approach is going to work just fine.

 

[Hedges]

Bare copper on aluminum is one thing that seems less than ideal.
Maybe tin the contact area?

Tinned copper sheets do exist, don't know if small amounts available locally. Idea would be to insert between the surfaces.

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[jwmark]

For those interested, I successfully re-drilled and tapped my angled terminal threads to M6+helicoil. I did a test on a piece of aluminum at an exaggerated angle - 6 degrees - worse than any of my terminals. I then drilled a 1/4" hole that is standard for an M6 helicoil tap. The hole was clean with no visible threads from the existing M6 hole.

2 of 4 cells now successfully helicoiled to M6 using the method that @ArthurEld wrote up. Will do the remaining two tomorrow.

 

[fafrd]

For those interested, I successfully re-drilled and tapped my angled terminal threads to M6+helicoil. I did a test on a piece of aluminum at an exaggerated angle - 6 degrees - worse than any of my terminals. I then drilled a 1/4" hole that is standard for an M6 helicoil tap. The hole was clean with no visible threads from the existing M6 hole.

2 of 4 cells now successfully helicoiled to M6 using the method that @ArthurEld wrote up. Will do the remaining two tomorrow.

Does that mean you also used a grinder to create a flat-bottomed 1/4” drill bit and also ground a bottoming tap down to near-flat (only 2 tapered threads at the bottom)?

Also, can you please explain what technique you used to drill your new 1/4” hole ‘straight’ (90-degrees to the surface of the terminal)?

Thanks.

 

[jwmark]

@fafrd yes to flattening out the drill bit and tap. Was pretty simple with a grinder.

I used a drill press to drill the hole to ensure it was straight, then a drill guide like this to keep the bottoming tap straight. I ended up purchasing two M6 helicoil kits for the second tap and extra helicoils. I cut two rings off the helicoils for a 7mm hole.

 

[ArthurEld]

Nice job jwmark. Looks like you got 5.5 threads in there.

 

[fafrd]

@fafrd yes to flattening out the drill bit and tap. Was pretty simple with a grinder.

I used a drill press to drill the hole to ensure it was straight, then a drill guide like this to keep the bottoming tap straight. I ended up purchasing two M6 helicoil kits for the second tap and extra helicoils. I cut two rings off the helicoils for a 7mm hole.

Thanks. If I ever have to try again, I’ll grind bit and tap like you and ArthurEld did.

Not sure what to do about my non-straight drill press... either measure & shim or try to drill the hole using the same tap/drill guide...

How many threads of grubscrew have successfully screwed into the Helicoil?

 

[jwmark]

Nice job jwmark. Looks like you got 5.5 threads in there.

Just about. I appreciate your insight on the helicoils. Great write-up.

 

[ArthurEld]

No problem. A lot of people help me around here. I have to do something besides cause trouble once in a while.

 

[jwmark]

How many threads of grubscrew have successfully screwed into the Helicoil?

I'm getting 6 threads on each screw.

 

[fafrd]

I'm getting 6 threads on each screw.

Nice.

Have you tested them with a torque wrench yet?

 

[jwmark]

@fafrd not yet. I plan to seat them with red loctite next week and will give that a try after.