Rod threading question

[WA2TTP Steve]

I'm building a retractable mobile mount for my Icom 7000. I needed to thread some .25 " rod with 1/4-20 threads.
I had a heck of time getting the die started on this rod stock. It seemed the rod was just to big to allow the die to engage it. I finally ground the rod end to cone shape and was able to start the die but only got about 3 good threads on it before it ran up against the full dia. and wouldn't go past that point. It was all the threads I needed but was I off base thinking .25 stock could be threaded to 1/4-20? I tried the die on some .225 stock and it worked fine. I was using cutting oil.

73,
Steve
WA2TTP

[w4bfs]

it depends on the alloy and temper state of the rod stock ... you may have to 'draw it down', thread it and then 'draw it up' ... you can test this by heating a test area with a torch to dull red (1600 F) or so and let it cool slowly and then re-trying the threading process ... I assume you have already used something to verify the actual diameter of the rod stock at 0.25 inch or less ... if not may be up the creek ....73...John

[Ed/KB1HYS]

I thought that the bolt blanks (rod stock) should be slightly smaller than the size inidicated.  As long as you're getting full thread depth (check with a thread gauge or use a commercial bolt in a pinch) you're ok.  
If you try to force the die on oversize stock you can damage the die.

I suppose if you needed to use 0.250 rod stock you could put it in a drill and turn it down a bit with some sandpaper to get a closer fit.  Check the size occasionally with a caliper while turning.

[WA1GFZ]

Some Dies have an allen screw to open it up slightly to cut an initial thread then you can back it out to get the final OD. 

[W3SLK]

Steve said:

I had a heck of time getting the die started on this rod stock.

A few things to consider. Make sure you are using the correct end of the die (I know it but I assume nothing). The open end will begin a taper on the threads. Second, use a good cutting lubricant. Cutting threads generates heat. The oil dissipates the heat and lubricates at the same time. Third, for every half revolution of the die, back off a 1/4 turn to remove the material you just cut. Fourthly, just for good measure, I like to run the die up and down for every inch I cut. Rotsaruck.

[Mike/W8BAC]

For 1/4"-20 thread the major (peak of the thread is 1/4" or .250".  Your stock should be as close as possible to .250 within or just a few thousandths less is best. I hope you have a caliper to measure with.

Not all die nuts are the same. If the die has no lead or taper on one side you might have a finish or chaser die. Not made for cutting new thread.

Usually what happens if the stock is too large the major of the thread will come out jagged and rough. As mentioned, use oil and don't push the process SLK said it best.

Mike

[KM1H]

If the rod is truly .250" and you are using the correct die end to start then Id suspect you have a Chinese die that is probably a mismarked metric size.

Carl
KM1H

[K9ACT]

Are you sure the stock is soft?  Rub it with a file to make sure.  Most of the hardware store stuff is but you did not say what kind of material it is.

Aside from that, threaded rod is readily available for about the same price so if the threads don't get in the way, this is another option I frequently take.

js

[WA2TTP Steve]

Thanks to all of you for your input. Here is my reply to posted comments of everybody.

The rod stock is from Home Depot. I don't know the hardness but it's very hard to bend but can filed or cut with a hack saw without trouble.

I did measure it and it's .252"

The threads I cut on some .225 stock check out fine with a 1/4-20 thread gauge and are clean.

I did use cutting oil.

The die is tapered and that's the end I used to start the thread.

It has no adjustment screw.

The set is store brand of Lowes called Kobalt, made in China. What isn't these days!!

If you run the die onto a 1/4-20 bolt is will cut the threads deeper by a small amount.

I will try heating the rod to see if it helps.

Again thanks for helpful replies.

Steve
WA2TTP

[K9ACT]

The set is store brand of Lowes called Kobalt, made in China. What isn't these days!!

Stuff that works and meets our expectations.

It would not surprise me at all if the dies where just carbon steel.  "Kobalt" is  meaningless Chinese nonsense that tells you nothing about the steel.  If they are not at least "High Speed Steel" they are junk and even if they say they are, they probably are not.

Here is a good example of Chinese junk as it relates to steel.

About six months ago I decided to use my listening half of our reading hour to exercise my forearms using those wooden handled springs that have been around since men started doing exercises.

I have broken 3 sets of these since I started.  That is, 6 Chinese springs just snapped when squose too many times.  It's pretty scary to think that they can not make something as simple as a spring when you consider all the stuff we buy from them.

About two months ago, my wife found a pair made in Taiwan and they will probably last forever.

No matter what the diplomats say, Taiwan is not China.

js

[KM1H]

There is some real China junk and there is some real great quality.

Having outfitted my hot rod shop with several China items Ive weeded thru a lot of junk over the years.

My tap and die sets are a 45 piece "Titanium Coated Tungsten Steel" sold under the Cal-Hawk Professional Tool series. The SAE set is Part # BTD45P. The dies are the adjustable split type.

I bought them off Ebay about 4 years ago and they still work as new and some sizes get a lot of use. A previous no name set I bought at a car show was so called carbon steel and was 100% crap.

Ive continued with the Cal Hawk brand with many other tools and have never been dissapointed.

Carl
KM1H

[K9ACT]

A previous no name set I bought at a car show was so called carbon steel and was 100% crap.

Carbon steel does not even belong in a woodworking shop these days.

In defense of China, I have had a pair of Chicom 811's in one of my rigs for over a year with no problems and I just installed a brand new $45 810 in that same rig to replace the 811's in the RF deck.  So far, so good.

On the other hand, did you ever have Chinese batteries last longer than it took to determine that whatever they came with works?  They are the crappiest batteries on earth, all of them, no exceptions.

It seems that they have two different quality standards and stick to them religiously.  I wonder which they use in their manned space program.

js

[W1ATR]

The chinese (aka cheesco) dies are normally too damn small for true fractional stock. That .252 stock is exactly what you needed and running 1/4" threads on it with a true fractional die would have left the thread peaks at .250 (It almost makes me thing they fall somewhere between a metric and a fractional size.)

The .225 stock you needed to use will not have the same holding power as a correctly sized 1/4" bolt due to the short thread peaks. I can't see it as being a problem making a mounting bracket for a radio in your car, but I certainly wouldn't try it on anything that needs to be strong.

For that small crap, I have and old craftsman tap and die set that hasn't let me down yet and it's going on 20 years old.