Dumb question about threads

[historicalarms]

Battery hold downs! Easy project. A decent HSS die and long handle die wrench would make it go easier. I would be concerned if it was load bearing. Real bolts are carefully roll formed and heat treated for strength. This project though is simple. You could probably just buy 5/16 ready rod at PA and bend to fit. Put a torch on it till red and bend with pliers.

I think I'm right in assuming that this is a heavy transport truck to have 2 batteries in a battery box...if so, the battery hold downs are subjected to considerably more abuse than for a simple 4 wheeler (basically any passenger vehicle) application.

A 4 wheeler travels down our highways on 30-35 psi tire pressure and an 18 wheeler rides on 100-120 psi, (a 4 wheeler will glide across railway crossings or bridge abutments without hardly feeling a bump but an 18'er will feel like your driving across a pit-run gravel pit floor). The transport truck batteries are always mounted outboard of the frames in a bracket attached box, and are subject to a lot of vibration and bouncing that an inside the bonnet solid mount seen on pleasure vehicles. Another factor that enters into it is that a 4 wheeler battery will weigh 20-30 lbs and very good transport battery can easily weigh 80 lbs. creating its own force of movement. Quite frankly, if not secured adequately, the amount of vibration & movement abuse they take will destroy a battery internally, causing shorts & fires in extreme situations (I have seen this).

All that being said I wouldn't recommend using a bent ready rod to make these, ready rod cracks at the thread root most times when a bend is created but readily agree that substitutes can be made from a new rod of similar dia.. If you feel that a bit heavier rod will make it better there usually is enough allowance in the hold down frame and box itself to drill a bit larger holes to accommodate the larger rods.

 

[Chicken lights]

I think I'm right in assuming that this is a heavy transport truck to have 2 batteries in a battery box...if so, the battery hold downs are subjected to considerably more abuse than for a simple 4 wheeler (basically any passenger vehicle) application.

A 4 wheeler travels down our highways on 30-35 psi tire pressure and an 18 wheeler rides on 100-120 psi, (a 4 wheeler will glide across railway crossings or bridge abutments without hardly feeling a bump but an 18'er will feel like your driving across a pit-run gravel pit floor). The transport truck batteries are always mounted outboard of the frames in a bracket attached box, and are subject to a lot of vibration and bouncing that an inside the bonnet solid mount seen on pleasure vehicles. Another factor that enters into it is that a 4 wheeler battery will weigh 20-30 lbs and very good transport battery can easily weigh 80 lbs. creating its own force of movement. Quite frankly, if not secured adequately, the amount of vibration & movement abuse they take will destroy a battery internally, causing shorts & fires in extreme situations (I have seen this).

All that being said I wouldn't recommend using a bent ready rod to make these, ready rod cracks at the thread root most times when a bend is created but readily agree that substitutes can be made from a new rod of similar dia.. If you feel that a bit heavier rod will make it better there usually is enough allowance in the hold down frame and box itself to drill a bit larger holes to accommodate the larger rods.

You’re correct, transport truck. I have four group 31 batteries on my rig.

Everyone I’ve talked to has brought up vibration being battery killers. I think I’m going to add an old mudflap under them and see if that mitigates anything.

A friend of mine told me about batteryuniversity.com, but I haven’t wandered over there yet.

Does heating steel up to help bend it change the properties of the steel at all? Are you better off cold bending?

 

[CalgaryPT]

Yes it does. I have seen guys just cold bend regular round rod, then weld a long coupling nut on. Then just add Allthread and a bolt into the other side for your adjustment. As long as your batteries have a grove in the side to offset the coupling nut a tad, you're good to go.

Lots of solutions here.

 

[Chicken lights]

https://www.practicalmachinist.com/vb/general/how-do-you-pick-correct-rod-dia-threading-175196/

I went looking for die charts to know what size rod to get, then I stumbled on that and spent the last 20 minutes learning about threading with dies.

The other guy asked all the questions I was gonna ask. There’s a lot more that goes into cutting threads than I thought!!

Simple answer, I need 5/16 rod to cut 5/16-18 NC threads

 

[Chicken lights]

One step forward, two back.

I bought a decent HSS die, not knowing there are different size die handles. I borrowed a buddies die handle, only to find out it’s the wrong size. His die was just a cheapy Canadian Tire special and was just chewing up the stainless and not cutting.

Then digging around to see what else we could find we found a broken die. Jeez louise how the heck do you break a die??

Also, why are we keeping said die instead of tossing it? Can you still use it?

From what I read before, the smallest one in the picture (the new HSS one) must be a better quality because where the split is there’s a tiny screw to adjust how tight it cuts.

 

[PeterT]

If you run the numbers (for example common class 2A) you get an OD range of 0.3113 - 0.3026" so between -0.001 to -0.010 under 5/16" nominal.
http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

OD tolerances on vary quite a bit depending on what kind of stock. If you happen to have bought 5/16 nominal with say +/- 0.005", then you can see how the tolerances can potentially stack against you especially if its on the high side. That can make die threading more difficult & might even explain the one pic LOL. Hopefully you are OK.

Stainless & tool steels can be a bugger with dies in larger threads size so you pretty much have to be within the range. And yes, that's why the set screw adjustment is there. The thing to watch is that the die wrench socket ID allows for this slight diameter variation. A lot of the hardware store products are garbage..

 

[CalgaryPT]

Somewhat related story—when I was 18 I worked at a store called "Hometown" in SW Calgary. One of the depts. I covered was plumbing. We had a big Rigid pipe threader like this. I got pretty good at using it. Some customer came in and wanted an entire 10 foot length of black pipe threaded. I'd been told by the Rigid rep never to do this because the dies weren't designed for continuous threading. But my Stupidvisor (who had missed the training session) said the customer is always right and to do it. I still refused, so he did it himself. The die broke like yours after about 2 feet. So this genius of a mentor put a hose clamp around the die and tried again. The die broke apart, and this time a piece of it shot out into his eye. When this happened he released the handle of the die holder; it flipped around from the torque of the machine and clocked the customer on the chin, cutting into him.

Fortunately he didn't lose his eye, and the customer only had a minor injury, but every time I see a broken die I think of this day.

I remember watching EMS working on his eye in the back of the ambulance, and then patching the customer's chin. It was such a great lesson for me.

 

[Janger]

Peter! OMG!

 

[CalgaryPT]

Peter! OMG!

Yeah...a Darwin Award candidate for sure.

 

[ducdon]

There can be 2 types of dies Threading dies and thread chasing dies. Ones for cutting threads, the other for cleaning or reforming damaged threads. Back in the day the difference was easy to determine. Round dies were meant for cutting. Hex dies for chasing. It appears Asian imports don't always follow that convention. I had a set of Canadian Tire dies. They were round but the card in the box said they were for chasing only. They would not cut, just mangled the crap out of the material. Moral of the story is if you want dies that cut buy or order round split dies through a proper machine shop supply. Also if the rod is close to nominal dimension chuck it in the lathe and reduce the threaded are by about .005 inch. The dies will cut much easier.

 

[Chicken lights]

Somewhat related story—when I was 18 I worked at a store called "Hometown" in SW Calgary. One of the depts. I covered was plumbing. We had a big Rigid pipe threader like this. I got pretty good at using it. Some customer came in and wanted an entire 10 foot length of black pipe threaded. I'd been told by the Rigid rep never to do this because the dies weren't designed for continuous threading. But my Stupidvisor (who had missed the training session) said the customer is always right and to do it. I still refused, so he did it himself. The die broke like yours after about 2 feet. So this genius of a mentor put a hose clamp around the die and tried again. The die broke apart, and this time a piece of it shot out into his eye. When this happened he released the handle of the die holder; it flipped around from the torque of the machine and clocked the customer on the chin, cutting into him.

Fortunately he didn't lose his eye, and the customer only had a minor injury, but every time I see a broken die I think of this day.

I remember watching EMS working on his eye in the back of the ambulance, and then patching the customer's chin. It was such a great lesson for me.

Wow!

That’s a great mentor to have

Did he not understand pipe thread is tapered?

I’m obviously guessing but I would think that’s what happened to the one I have. Someone forced it just a little too far

 

[Chicken lights]

If you run the numbers (for example common class 2A) you get an OD range of 0.3113 - 0.3026" so between -0.001 to -0.010 under 5/16" nominal.
http://theoreticalmachinist.com/Threads_UnifiedImperial.aspx

OD tolerances on vary quite a bit depending on what kind of stock. If you happen to have bought 5/16 nominal with say +/- 0.005", then you can see how the tolerances can potentially stack against you especially if its on the high side. That can make die threading more difficult & might even explain the one pic LOL. Hopefully you are OK.

Stainless & tool steels can be a bugger with dies in larger threads size so you pretty much have to be within the range. And yes, that's why the set screw adjustment is there. The thing to watch is that the die wrench socket ID allows for this slight diameter variation. A lot of the hardware store products are garbage..

There can be 2 types of dies Threading dies and thread chasing dies. Ones for cutting threads, the other for cleaning or reforming damaged threads. Back in the day the difference was easy to determine. Round dies were meant for cutting. Hex dies for chasing. It appears Asian imports don't always follow that convention. I had a set of Canadian Tire dies. They were round but the card in the box said they were for chasing only. They would not cut, just mangled the crap out of the material. Moral of the story is if you want dies that cut buy or order round split dies through a proper machine shop supply. Also if the rod is close to nominal dimension chuck it in the lathe and reduce the threaded are by about .005 inch. The dies will cut much easier.

I couldn’t even get the cheapy die to start cutting. I used the belt sander to taper the end of it and still the cheapy die wouldn’t cut clean

I’m going out on a limb here that “whittling on the belt sander” is a little different than “chucking it in a lathe” to reduce the shank size....

 

[trlvn]

I have a few 5/16-18 dies and several die handles. Glad to help if you can find an excuse to be down this way. I've never threaded stainless steel and have heard that it can be 'gummy' and a pain to work with. Nonetheless, we could certainly have a go at it.

I haven't even had a chance to try out the tailstock die holder I got for the lathe a few weeks ago!

Craig
Oakville, ON

 

[Chicken lights]

I have a few 5/16-18 dies and several die handles. Glad to help if you can find an excuse to be down this way. I've never threaded stainless steel and have heard that it can be 'gummy' and a pain to work with. Nonetheless, we could certainly have a go at it.

I haven't even had a chance to try out the tailstock die holder I got for the lathe a few weeks ago!

Craig
Oakville, ON

I’m guessing on a holiday long weekend is not a good time?
That’s a kind offer, I know you’re a busy man. Thanks!

 

[trlvn]

I’m guessing on a holiday long weekend is not a good time?
That’s a kind offer, I know you’re a busy man. Thanks!

Today is not good but tomorrow could work.

Craig

 

[Chicken lights]

Today is not good but tomorrow could work.

Craig

Alright, I’ll throw them in the truck then. I’ll be going through Toronto around mid-day tomorrow

 

[trlvn]

Sending pm...

 

[Chicken lights]

@Brent H was kind enough to give me a hand threading these.
Thanks again!

 

[PeterT]

So how did you end up doing it? Inquiring minds need to know!

 

[Chicken lights]

So how did you end up doing it? Inquiring minds need to know!

Brent did agree that tapering the shaft helped get it started cutting

But, he used a fairly new Canadian Tire die to cut the threads. No chucking in the lathe or anything fancy. He consulted his Starrett tap and die chart, checked the diameter with a micrometer, and simply cut the threads

He did say chucking them in the lathe would provide a better result, but this way worked too!

We did discuss the difference between cutting with a sharp tap/die versus a dull one, I learned a great bit in a short time