Making screw jacks - Lesson in taps and dies

[WobblyHand]

I have not threaded on the lathe yet. I did not have an Imperial tap suitable for the jack body, and didn’t want to figure out change gears. Need to dip my toe into that water…

You need to try this. It's a valuable skill to learn. Try it on some cheap PVC pipe to start. You can buy some 1/2" pipe for very little cash. It's not hard to figure out the gears. Pick a thread to try, and see if you actually get it. If you have a thread gauge, great. If not, choose a thread that you have a screw, that way you can use the screw as a thread gauge. Try to pick a finer pitch and a very slow RPM to start. It's easier to learn the basic timing that way.

 

[Christianstark]

You need to try this. It's a valuable skill to learn. Try it on some cheap PVC pipe to start. You can buy some 1/2" pipe for very little cash. It's not hard to figure out the gears. Pick a thread to try, and see if you actually get it. If you have a thread gauge, great. If not, choose a thread that you have a screw, that way you can use the screw as a thread gauge. Try to pick a finer pitch and a very slow RPM to start. It's easier to learn the basic timing that way.

Totally in my plans for the next month or so. I just had some items come up first, and wanted to knock those out in order to get to the next. Machining is interesting. Sometimes you need to make a part, to make a part, to make another part…etc.

fun stuff.

 

[wildcatter]

Just a note on hex dies. My research ( after having a hex die shatter while threading a rod ) tells me that hex dies are intended for cleaning up existing threads only, not cutting new threads.

 

[jwmay]

Hex dies are great! So long as you are using them on some old fasteners that need cleaned up.
Anywho...yep me too. I bought a cheap set, which I thought was expensive. I guess it's not my fault. I was following the advice. Don't buy cheap taps and dies. I went to the local farm store and plunked down my $90.00 for the best set they had. Garbage, for what I planned.
Funny enough, very soon after that I bought 4 die handles at a junk shop for two bucks a piece, that are quite possibly the best dies ever made. I have gotten a lot of use out of those hex dies though. But it's all repair work. They flat will not start a thread.
And 90 bucks is better spent on 3 hss dies.

 

[mikey]

You cannot make a blanket assumption that all hex dies are only suitable for thread chasing. I have a 35 year old set of HSS Irwin Hanson hex dies that have cut many, many threads onto solid rod and they're still going strong.

Yeah, I know that thread chasing thing is common knowledge and fits the party line, except for it not always being true.

 

[jwmay]

You cannot make a blanket assumption that all hex dies are only suitable for thread chasing.

Yes, I can. Lol. But I can also accept that it may not be universally true. In the future, I'll try to ensure I include the requisite YMMV, if offering an opinion. Just speaking from my own. None of it is a scientifically backed fact. But your 35 year old set isn't enough to convince me to buy any more hex dies for threading. Haha

 

[Christianstark]

You cannot make a blanket assumption that all hex dies are only suitable for thread chasing. I have a 35 year old set of HSS Irwin Hanson hex dies that have cut many, many threads onto solid rod and they're still going strong.

Yeah, I know that thread chasing thing is common knowledge and fits the party line, except for it not always being true.

Isn’t it funny on how the older stuff is orders of magnitude better than what you find now a days in the big box stores? They don’t make ‘em like they used to! The dies I have are Irwin, which from what I read are a far cry from Irwin Hanson

 

[mikey]

A big part of the problem when some guys have trouble with dies isn't the die; its the guy. I kid you not.

Guy: I can't get this brand XYZ die to cut this 1/2-13 thread. The thread comes out crooked and mangled, and this is the second die I bought to thread this rod.

Me: Hmm, how big is the rod?

Guy: Dunno, it's 1/2" rod, right? I measured it with my tape rule.

Me: So, 1/2" rod + zinc coating = way bigger OD than needed for a class 2 external thread. Now you go forcing it on and ruin the die ... and its the die's fault?

EDIT: This guy has kids, which is unfortunate because it proves he is able to reproduce.

 

[jwmay]

A big part of the problem when some guys have trouble with dies isn't the die; its the guy. I kid you not.

Looks like somebody's been reading about me. Lol
It's my opinion, that all things being equal, the purchase and use of high speed steel, name brand, round dies removes all possibility that the tool is to blame. Removing that variable goes a long way towards progress when your mentors are a bunch of strangers on the internet who won't be in the shop with you when you get in trouble. Ymmv

 

[mikey]

Looks like somebody's been reading about me. Lol
It's my opinion, that all things being equal, the purchase and use of high speed steel, name brand, round dies removes all possibility that the tool is to blame. Removing that variable goes a long way towards progress when your mentors are a bunch of strangers on the internet who won't be in the shop with you when you get in trouble. Ymmv

Round dies are okay. More is made of them than is probably warranted. Yes, you can dial in a fit but how many of us really actually do that? You have to turn the work to a specific diameter to close tolerances, then you have to make multiple passes as you sneak up on the thread pitch so it falls within specs. Come on, how many of us do that?

Don't get me wrong. I have round dies and I know exactly how to use them but truth be told, I don't use dies unless I have to. It is faster and more accurate for me to just screwcut the thread on the lathe and be done with it.

Bottom line: Learn to cut threads on the lathe. Leave the dies for field work and then be very careful of the work OD before you take a die out of its case.