For all you machinists

[44man]

Where can I get a chart showing the depth of threads for each size and TPI? I cut a lot of threads that I can't see if they fit before making the cut off. For instance, if I cut a 9/16 X 14 thread, how deep do I cut so I am sure it will screw into the other part?

[JerryW]

Go into a good tool catalog and buy a set of thread triangles they come with a chart. works gteat. JCW

[KCSO]

I always test with a nut befroe I finish, but the machinists handbook has the actual dimensions. This is just a little 2X5 paperback manual and I should have about 5 of them by now. I'll check for a spare.

[fishhawk]

i have a program here on the computer that i could send but it's in a zip file so think it would have to go via Email dont think it could be done here on the site

[Dragoon]

It's a whole lot better to fit it to your part. If you cut the thread to a standard hardware nut it probably won't go in a tapped hole. If it was something I had a good bit of work in or would be hard to set back up, I would make me a test nut.

The Machinery Handbook tells you the dimension over three wires and that will work too.

[charger 1]

single depth for standard 60 degree
External Thread Depth = .61343 x ( 1 / # of threads per inch)
Internal Thread Depth = .54127 x ( 1 / # of threads per inch)

Creating the same depth for a given pitch irregardless of dia.

So like you mentioned the 9/16 x 14. Well really for standard thread the 14 is the important thing. The dia comes in when you calculate pitch circle, and add dia to get a wire measurement. So for your 14 if it were external we would have a .044" depth for each side.....dougl@nrtco.net
if I've fogged the issue to bad and you'd like to talk

[R.M.]

There's a set of special wires that's used to measure the depth of your threads. They come with a formula to calculate what the measurement over the 3 wires should be.
Most good tool suppliers should list them.

[gzig5]

Pick up a Machinery's Handbook. All that and more in there, blows my mind. Really the machinists Bible. Used ones can be picked up pretty cheaply check ebay and amazon. Even if it is sixty years old, the info is still pertinent.
Greg

[Buckshot]

Pick up a Machinery's Handbook. All that and more in there, blows my mind. Really the machinists Bible. Used ones can be picked up pretty cheaply check ebay and amazon. Even if it is sixty years old, the info is still pertinent.
Greg

...........Yup, Machinery's Handbook. Also as a "Nice to have" item is a thread mike. Rutland Tool currently has one (an import 0-1") on sale for about $36. Comes with 6 or 8 anvils, each covering a spread of pitches.

.............Buckshot

[R.M.]

44man
Go to the linked page. It should give you a better idea of how the 3 wire measurment works.

http://www.auto-met.com/greenfieldlgage/PDF/thrdwires.pdf

[44man]

Great, thanks to all of you. I just looked and seen I pushed the wrong number, it is 9/16 X 18, not 14. I have been making expanders and compression tools to fit in an RCBS die. I make them all at once with one end knurled, then the threads and finally the expander or compression (Black powder.) portion. I can't see if they fit the die until I cut them off and then it is too late to correct too large a screw. I got lucky with the last one and it screwed right in.
I needed an expander that does not expand but just slips in the 45-70 sized case to just put on a flare. It works like a champ.
If I was to use my head, I would make the knurled end real small so I could screw the die on over it but it doesn't feel right trying to turn that small end.
How do you guys avoid the burrs at the point of the threads?

[floodgate]

44man:

I deburr both threads and knurling by running one of those stainless-steel hardware store "toothbrushes" (preferably a half-worn-out one) HARD against the spinning workpiece for a few seconds. That usually smooths them up nicely.

floodgate

[charger 1]

There's a set of special wires that's used to measure the depth of your threads. They come with a formula to calculate what the measurement over the 3 wires should be.
Most good tool suppliers should list them.

And if your always doin the same thread pitch you can use # drill bits and if their not bang on just adjust the calc to suit. The sharp edges you mention are from machining a material of poor quality, not sharp enough tool,poor coolant or a bit of all 3

[Dragoon]

Are you turning your work under the nominal thread size before you start threading? A 9/16 male thread should be well under .5625 over the top of the threads.

I haven't spent enough time on this to really figure out what you are doing but you might reconsider your order of operations and/or how you are holding the work. It makes life a whole lot easier to be able to test the male thread with a nut.

[44man]

Yeah, I cut a 5/8" piece of cold rolled to .562 and that is what made the sharp edges. I didn't have a piece of tool steel to waste on it because it will not do any sizing, it will just put a flare on the case mouth. No need for good stuff or hardening.
I should have turned it to .558". I just touched a fine file to it when done.
I make my compression punches out of brass. I use an old RCBS expander die to hold all of these I make.
Anyway, I am happy, it does a great job and I seated boolits today and gained a lot of neck tension. These are for my BFR revolver.

[uscra112]

It sounds to me like it's the DATA about thread forms and such that you want.

Shell out the money and buy a copy of Machinery's Handbook. In there you will find everything anybody anywhere knows about every thread form under the sun, including how to measure over wires with a micrometer, and al that. You can get it from most mill supply houses, or on-line from J&L Supply, or McMaster-Carr. (www.mcmaster.com)

This tome is such a mainstay of the machinist's art that some Gerstner tool chests have a drawer specifically sized for it.

[leftiye]

I've for some reason never yet had it work for me to try to move the compond in a calculated amount to make a thread. It's just never came out right. You can calculate the side depth of a thread with some simple trig (if I can do it anybody can). But as I said it doesn't work for me. I watch the thinness of the tops of the threads on a piece turned to the nominal major diameter of the thread, and as I approach finished size I test with a nut. Dies when used for the last final cut would allow better consistency, and adjustable ones will allow any grade of fit you want. Plus they give a better finish. Don't take too much with the die or it will not track straight.

[longbow]

This may help:

http://www.efunda.com/designstandards/screws/screws_intro.cfm

[Buckshot]

"............How do you guys avoid the burrs at the point of the threads?"

"Yeah, I cut a 5/8" piece of cold rolled................."

That's probably most of the problem right there. :-) Even good high quality low carbon 1018 is tough to get a nice finish on, and good really clean threads. But if your stock comes from one of the Big Box stores, then it REALLY sucks channel water. Most of that is import crap. I was making some 22RF swingers and wanted some 5/16" rod to make hangers out of.

I went to Lowes to get a 6' stick and every single one they had in the rack had 2 opposing flanges like it had made one pass between rollers that were too far apart. While it was okay for what I was going to use it for, it was terrible for anything that had to be round in cross section. Guys had bought plate and some sections had identifiable partially melted odds and ends in it, like bits of woven steel cable and such. Their flat stock (at least the thinner stuff) is also sheared off sheets instead of being finish rolled individually.

Didn't waste much juice melting all the stuff down. Just got it mostly liguid and then poured it out into a pig to go to the rolling mill!

After cutting threads I just lay a 10" lathe file on the beginning of the threads and let it wind it's way to the end while the piece turns. No pressure on the file, just it's own weight.

As was mentioned, use a sharp tool with the correct geometry, and a good quality cutting oil. Turning the work faster can also help in the finish of the thread. At least on the flanks. You'll still need to hit the crests.

................Buckshot

[44man]

The steel was a cut off from work before I retired, that is, and was good USA stuff. That crap from China is just that. Funny that some of the cutting tools and tool steel I buy that comes from China is real nice stuff. Depends on the importer and their specs I guess. I get a lot of stuff from Enco and it has all been good.
Reminds me of the time I needed sandpaper real fast and went to the discount store, only place open on Sunday. I started to sand and all of the grit fell off the paper. I looked on the back and seen it was made in Poland. My friend was Polish and I never let up on him about it.

[KCSO]

The finest steel I have yet to cut is old Swede barrels. I had a few take offs in my scrap pile and they made the nicest sizing dies. Cut like butter and finished like they were polished and lapped.

[Buckshot]

The steel was a cut off from work before I retired, that is, and was good USA stuff. That crap from China is just that. Funny that some of the cutting tools and tool steel I buy that comes from China is real nice stuff. Depends on the importer and their specs I guess. I get a lot of stuff from Enco and it has all been good.
Reminds me of the time I needed sandpaper real fast and went to the discount store, only place open on Sunday. I started to sand and all of the grit fell off the paper. I looked on the back and seen it was made in Poland. My friend was Polish and I never let up on him about it.

............I've had some (and still have) 3/8" tool bits I bought to use as some cheap parallels. IIRC they were like $.98 each. They were bright, shiney, well ground with sharp edges and looked very nice (except for that "China" acid etched on the side). I'd bought a dozen to ge the cheaper box price and did in the course of time grind one to use as a cutter. Did as good a job as some Rex Crucible or Cleveland Twist.

I REALLY hate when that happens as I'd sure like to support American workers. When you look at a Chinee 3/8" tool @ .98 a pop vs a US made one for $2.90 you wonder. I was thinking of getting a couple long centerdrills and in the JTL catalog I had at work, the 'Import' ones were $3 to 4 bucks each vs $12.50 for a Keo.

However, obvious quality DOES tell. I've mentioned before about a 10 pack of Guhring 1/4" TiN coated parabolic bits I got on E-Bay for like nothing. The flutes are screw machine length and the shank is 3/8" OD. Looking in various catalogs the closest I can come to them is Titex and one of those 1/4" bits lists at $27!!!!!!!!!!!!!!!!!!!!!! Can you imagine paying $27 for a 1/4" bit?

To date I have used and am STILL using the first bit I took out of that package. I still find it hard to believe how long this thing has survived. I don't use it in a hand drill motor, but the lathe only. Yet that one bit has been stuck through every Lyman, Lee or Star lube die I've made, or anything else that needed a 1/4" hole or a starter hole. I'll bet that one bit has traveled through maybe 30' of steel. Under magnification you can see that the edge is beginning to degrade, but you really can't tell it when using it.

I REALLY don't know at this point if I could bring myself to pay $27 for a 1/4" bit like that. Even knowing what it would do :-)

...................Buckshot

[Dye]

buckshot
How about 103.00 for a 21/32 bit with a 1/2 shank and to top it all off Genuine
Mac Tools 23.00 for 10 1/8 double shank bits. Used one and it was not drilling right,turned it around same thing. Took a glass to it and stamped in it was
1/8 China. The tool companies are making us go to Chinese products

Be carefull Dye