Threading a long rod and keeping it straight.

[goldstar31]

I wrote earlier about 'steadies and fixed bushing steadies' but doubt that you have read it up or perhaps haven't got them.
Again, I don't quite get my head around 'soft shims'. However I have two sets of soft jaws for my Sieg C4 whereas I have 'umpteen' assorted chucks and collets especially for my Myford. I'm a bit 'iffy' about using a split die in a self centring 3 jaw chuck and slightly happier about a 4 jaw SC. You DO get a lot more grip with a set of soft jaws but my thoughts are that without all this the chances of a broken die are high and if you are prone to holding the end of a rod by hand without any other assistance, you are probably risking severe injury.

I'm not going to join the ebdless discussion on the old masters apart from mentioning my name is Norman Atkinson and there fore the same as the biographer on Joseph Whitworth and an E-mail requesting details of Whitworth's sex life

So cheers from the other Norman who isn't a dead Labour Member of Parliament.

 

[Longboy]

Good job the engineers in the past didn't take the attitude " doing the set task with the tooling one has available most likely will get you there"..................

Personally I'm really glad that people like Henry Maudsley, Brunel, Whitworth and James Watt et. al. were inquisitive, adventurous and ambitious enough to push the envelope and develop new tools and methods - and spend the time and effort to make them. [/URL]

TerryD

OK Terry! They would be glad that you depend on them to lead the way and one can run to the library for their insight..........but I am not familiar with their monopoly on thread cutting procedures. As inquisitive engineers, it would be unlikely they would be disappointed when one finds an alternative to reach the same end. Seems like they would foster that approach looking for ideas and asking questions as justila has.

"Reading a lot of golf magazines and having lots of golf clubs...... doesn't make a good golfer." (author unknown).
Dave.

 

[Tim Wescott]

Yahoo!

You guys are officially the best.

I thought long and hard about all of the advice I got. I decided to try terryd's suggestion first, because it'd be quick, because I have some brass* rod sitting around that's about the right size, and because if it worked it't fit really well with my process.

I also figured out how to turn long thin rod adequately using a center -- it's kind of stupid, but I'd been so hard over on "keep it rigid" that I didn't think about the fact that I can have a couple of inches on the chuck side of things, as long as I'm not turning too great a length on the supported end. So -- yahoo twice. And it's still a crappy lathe.

So I turned the end of a rod down to 0.122 & change (0.1227 is supposed to be the "correct" number; I wanted to be a bit small, if anything). I made up the holder that terryd suggested, turned a thread, and voila! I measure less than 0.001" of runout. So, I'd say it's a success.

* Of unknown alloy. I got it as a joke, because I'm working with some students who handed me a drawing calling out "brass" as the material. Clearly, if you get a drawing that calls out "brass" without an alloy, then you should go get some brass of unknown alloy to do the work -- right? So I happened to be at Clackamas Steel, wandering through their "brass & copper" shed, and this bar of brass called to me.

 

[Charles Lamont]

Well, that looks as though you have it cracked.

Turning small parts with tailstock support is never easy because bits of lathe get in each others way. When I put my indexing QC toolpost on the web, in 2003 if memory serves, I fondly imagined that I had invented the extended toolholder for the purpose:

http://www.charleslamont.me.uk/iqc_toolpost4.htm
I had never seen one before, but now they are available commercially for some QC systems. I have never been able to get on with the 4-tool turret toolholder your lathe has. I even sold mine.

 

[BaronJ]

Hi Guys,

I sold my Dickson QCTP, far too expensive ! I made the Norman patent one and have never looked back. It was good enough for Rolls Royce, and its more than good enough for me.

I no longer have any of the problems that seem to be associated with other tool holders and posts.

I do note that some of the articles and drawings for more recent designs don't actually stick to the original design and use a slit instead of the split collet to secure the tool block. Having said that mine doesn't either, I used a slot to hold the tool bit, Where the original used a broached square hole.

 

[terryd]

OK Terry! They would be glad that you depend on them to lead the way and one can run to the library for their insight..........but I am not familiar with their monopoly on thread cutting procedures. As inquisitive engineers, it would be unlikely they would be disappointed when one finds an alternative to reach the same end. Seems like they would foster that approach looking for ideas and asking questions as justila has.

"Reading a lot of golf magazines and having lots of golf clubs...... doesn't make a good golfer." (author unknown).
Dave.

It wasn't really about thread cutting monopolies or otherwise per se. nor about reading whether magazines or library books.

I'll leave you to reread my posting and work out what I was getting at.

Best regards

Terry

 

[terryd]

Duplicate

 

[Bentwings]

I'm trying to make needle valves per the drawing below, and I keep screwing up the spraybar.

Basically, I get a nice machined straight brass rod, but as soon as I thread it I end up with a nice, threaded, gracefully bent, brass rod.

How do people do this? I'm currently using a die in a holder, held in my hand -- if I made up a die holder to be held in a chuck in my tailstock would it work? I've considered trying to single-point machine it, my lathe isn't well set up to make such a cut in such confined quarters (but I'll figure it out, if it's the only way to make it work).

(Edit: I'm trying to tap it at 5-44 -- is that just too coarse a thread?)

Thanks.

View attachment 116075

I was tasked with making an almost identical parent out of stainless steel when I started a new job as tool maker. Basically it was a 5-56 thread in the middle or a long shaft. we had a brand ne Hardinge tool room lathe with every option. So tooling was available. Aft several failures I made a fixture that mounted on a tool holder that had a hole tha the first few threads rode on. Well lubricated. Also used a modified steady rest. I did try a die but it failed miserably. I even resharpened it going so far as helping the jug grinder make tooling and dresser for his jig grinder to grind or finish grind these threads. There was a totally rediculous and unnecessary tolerance on the threads. Something I changed when I was promoted to the engineering dept.
id have to sit on a stool at the lathe to re do this stuff as it’s been 30 years in the past.
the bottom line is to support the work however possible. It’s hard to thread a small rod with a die even if it is precision made. Purchased dies today have a hard time cutting straight on much larger rods. I’m not sure of the dynamics as I never ran any analysis of this nightmare. I just remade the device so it didn’t need this piece at all. Saved the co. A huge bundle and got a beautiful custom made pocket knife as a reward.

 

[roncohudd]

Hi Tim,

Depending on how you make your tailstock die holder the die should be self centering on the work in a 3 jaw chuck (hint don't make the die holder too precise a fit on it's slider - allows for self centering). There is no need for a super precise 4 jaw set up. That's just faffing about for the sake of it. Some folk like to spend large amounts of time on super precision even when it's not needed and that's ok if it's your bag. Me, I just like making stuff that does a job and does it well. I don't have enough years left to waste them on uneccessaries

If I'm threading most round stocks I use collects rather than chuck. I machined a 1 inch die holder many years ago. Don't know any more than every one else but sometimes I get lucky.

 

[Bentwings]

I agree unknown time left so I make and use what works for me as long as it’s safe to use. If I threaded a foot long shaft I’d have to visit my neurologist to see if I still had a mind left . It’s bad enough tapping a 2mm hole in soft aluminum by hand I imagine at one point I would have power tapped with the small tapping head or even cut the thread with cnc but today just getting it done is more important if the screw fits great I’m happy .
this steamer has bags full of screws 2an 3mm I YHINK there is one or two m4 screws . Those m 3 grub screws really inhale . I’ve come up with a work around so I don’t even have to use them . All of the eccentrics and flywheels will have much stronger and secure mounting. I’ll take pictures as I get these parts ready for installation I finally got the correct beam coupler ordered. It should be her Fri. It a bit longer so I’ll not re locate second engine yetis it’s a bit longer than I expected but I couldn’t get the very short one . Don’t need it anyway.
byron

 

[isince1939]

Hi Peter,

I would agree with you generally but I make my long threads for Meccano users. The thread is 5/32" BSW and I believe that the stuff now made in Calais is now metric M4. Many users, collectors and builders of traditional Meccano need these threaded parts and it is almost impossible to buy the stuff apart from us specialist makers. Meccano threaded rods were made in varying lengths up to 11 1/2" hence my manufacturing technique and of couse with my tailstock dies I can die cut any thread up to 8mm (5/16) up to that length and they are very straight and take a couple of minutes to set up and make. No sorting out gear ratios, wrestling with setting them up, perhaps finding an interposing conversion gear for another system, grinding tools or finding a stockist, driving around to collect or waiting on some courier to deliver. I simply make what I need, when I need it.

By the way my tailstock die holder has never produced a non concentric thread in years of use and there is a reason for that but I will keep that reason to myself.


Best regards and keep safe,

TerryD

Terry what RPM do you thread using 25mm round dies. I am trying to thread 1/4-28UNF threaded tubes with a 0.120" ID hole(0.065" wall). I have been running at 50RPM but the tubes are 27" long and that takes a lot of time.

 

[xander janssen]

I use this technique by Joe Pie.

YouTube by Joe Pie