"Gerry" wrote in message news
On Mon, 20 May 2019 18:41:15 -0700, Bob La Londe
wrote:

On 5/20/2019 4:54 PM, DoN. Nichols wrote: On 2019-05-20, Bob La Londe
wrote:
I've decided to go ahead and make a replacement screw with a sliding
handle (like a vise handle), but also with a hex on top "just in case."
This is a 14x40 lathe and there is plenty of clearance. Its not a
giant, but its decent size and there is room to work on it.

I have on 1144 stressproof, 4140QT, and cold rolled on hand. I have no
issue using the 1144 or the cold rolled, but I can't pick up 4140(QT
TGP) at a reasonable price locally. I hate to "burn it up" so to speak
on personal projects. Given the ease with which 1144 machines I am
concerned about shearing off threads on an 1144 bolt, but I have no
issue using it because I can just go get some more if I need it. The
cold rolled is really to soft IMO for making bolts.

I know the 4140 is tough as heck, and would make the most durable bolt,
but I hate to use it up if I don't have to.

I've made bolts using 12L14 -- free machining steel -- and they
have been strong enough for my needs. The 1144 sounds stronger, and the
4150QT may be more difficult to machine, depending. "QT" indicates some
particular temper?

(This isn't all I am doing, and its not "critical.")

So play with what you have and see how it machines.

Good Luck,
DoN.


4140QT - QT means quenched and tempered. Its about the same hardness as
4140HT. TGP is "precision" ground. Actually from what I have been
reading in between feeding the machines is that 1144 Stressproof(tm) is
not ideal for cyclical loads like a bolt that is tightened and loosened
repeatedly. For that they recommend a product called Fatigueproof(tm).
1144 Stressproof(tm) is great for a static load though.

4140QT is tough machining. Maybe a little more so than 304-316
stainless, but its machinable. I get the best finish with modestly
large depth and width of cut on the lathe and a fresh insert. It will
work harden faster than stainless if you screw around. This lathe has
just enough power (3hp spindle motor) to do the job. The 4140QT is left
over from jobs. Not something I bought just to have some. I bought
"extra" just to have some. LOL. The 1144 I bought to just have some
because its so darned easy to cut.

I guess I'll be either using some of my stock of 4140QT or I'll do like
Jim suggested and chase down a big bolt to machine down to the
application.

I've made tools out of all of the above.

I find Tractor Supply a good source for one or five grade five or
grade eight bolts when I want to "invent" something!

**********

Sorry, what I should have said was:

Thank you. They are a good option if one of the closers stores doesn't have
what I need. Thanks for mentioning them.