Looking for images/info on B.C. Ames chase screwcutting mechanism

Hi all,

I recently acquired a chase screwcutting attachment for my 1940s-era B.C. Ames No. 3 lathe. My lathe is slightly more recent than the screwcutting mechanism is (I think the screwcutting mechanism is closer in age to the lathe shown here), and so I'm going to need to adapt the gear that rides on the spindle to match what I have. The adaptation is pretty straightforward (bore out the gear, cut a keyway, figure out some way of locating along the spindle), but I'd like to keep this as close to historically accurate as possible.

If anyone has one of these screwcutting attachments on their lathes - preferably my generation, but older lathes welcome as well - I'd very much appreciate any photos or other documentation you can share! Thanks very much.

All I can offer is a page from Ames Catalog 14 dated 1930 that I own and a list of serial numbers I found somewhere.

Larry

Jlel12 said:

Hi all,

I recently acquired a chase screwcutting attachment for my 1940s-era B.C. Ames No. 3 lathe. My lathe is slightly more recent than the screwcutting mechanism is (I think the screwcutting mechanism is closer in age to the lathe shown here), and so I'm going to need to adapt the gear that rides on the spindle to match what I have. The adaptation is pretty straightforward (bore out the gear, cut a keyway, figure out some way of locating along the spindle), but I'd like to keep this as close to historically accurate as possible.

If anyone has one of these screwcutting attachments on their lathes - preferably my generation, but older lathes welcome as well - I'd very much appreciate any photos or other documentation you can share! Thanks very much.

Click to expand...

Ah, so you're the one who got that. Don't suppose you ended up with the rest of that load did you? There were some widgets in there that I would have liked, but didn't need *another* pair of lathes. (I have 6 already....thankfully they're small.)
You didn't end up with that little wooden box of extra thread masters did you? I'd dearly like decent photos of them.

Anyway, I do have the chase rig, and as far as I know, it never changed. The missing link is the gear that's built into the rear end of the lever closing attachment. *That's* what ties the spindle into the threader. Remember, these machines were never meant to run much with chucks. They were collet machines first and last, so building part of the threader into the collet closer wasn't a problem. If you've got the threader, odds are you have the closer already, was their belief.

There were some extra gears that were floating around loose in that auction. I'm not entirely sure they actually related to the threader. Did you end up with them? (Or, what all of that did you end up with after he split it up?)

I'll attach a picture of the lever closer with the gear on it, from a 1942 vintage machine. ('scuse the condition, that was what it looked like when I received it.)

Unless you ended up with the rest of that load, you're probably missing the little flat skid plate that went on top of the bed. I'm missing the one for mine. I looked at that photo of the pile of misc crud that was in that auction, and didn't see the skid plate, but there were good odds it was in there somewhere. (It's about the size of a paperback book, and about 1/8" thick, but I can't tell you much more than that about it, having never actually seen one.)

I'm the guy who originally posted that serial number list that L Vance attached.
What's your serial number? I'm trying to keep a list of 'last known sightings' by serial, just for my own amusement.

Regards,
Brian

Greetings again,

I was digging through my collection of "Ames in the wild" photos, (mainly from here on PM) and found a late 30's machine with the gear for the threader *not* as part of the collet closer. This particular machine has no serial number, and was last seen on Malta, about 5 years ago. (Construction details say very late '30s or very early 40's.)

FWIW,
Brian

Hardinge provided the spindle gears in several sizes, along with the several sizes of spindles they made. You had a choice of sliding a gear directly onto the left end of the spindle if you did not use the lever collet closer or onto the serrated cap for adjusting the lever collet closer tightness. The spindle and the cap have keyways and the gear just slides on one or the other, with no set screw or clamp needed.

Ames apparently only provided one gear ratio, saying in the catalog that each thread master only cuts one pitch. Hardinge provided four to six gear ratios so each master would cut four, five or six pitches. For instance a 10 pitch "hob" as the thread masters were called, might cut 10, 20, 30, 40, 50 or 60 TPI.

Larry

I may have spoken too soon, at least if this is the threader that was on Ebay a couple of weeks ago.

I went back and looked at the pictures of that auction, and really looked at the threader. It's different than the normal ones.
The normal ones have the same slide bar as that one, but the master holder's different. This one only grabs one end of the master, and has bigger gears than mine. Mine grabs both ends of the master, and the holder is a much lighter rig than this one. Smaller gears too.
I still think it uses the same spindle drive gear, but the details may be different. Interesting. Yet another Ames freak. (they did a *lot* of custom machines.) They also didn't note their design changes particularly well.

You said your machine was an AM-3. 5/8 max collet? You may have trouble with the spindle then. All the threaders I've seen have been for 1" machines. I looked at the picture of all the misc. stuff that was in the original auction, and I still don't see the skid plate, but I did see a gear that I think may have been the spindle drive gear. Sized for a 1" spindle. The 1" spindles also have a cutout for a woodruff key to grab the gear. (It's the one at the absolute bottom right of the 'misc' picture.)

Welcome to the wonderful world of scrounging Ames parts. That's why I have 6 of them. Every time I found a part I wanted, it came with a whole new lathe.... Speaking of which, I do have a spare 1" ball bearing headstock. There are things I might trade it for, if you've only got the 5/8 headstock. One of Ames' big things was that they scraped all their machines to the same standard. So you could swap headstocks and tailstocks around between machines and hold center.

Regards,
Brian

PS--> Both of the machines in that auction were pretty late model. 1944-1945-ish. So it doesn't surprise me that a threader from one of them looks more modern (and beefier) than my '30s vintage threader.

Wow - thank you all for your help! I'll try to respond to all of the questions above:

Larry: thanks! According to your serial list, my lathe is a 1944 model. For Brian's benefit, I bought it from my alma mater, Swarthmore College, who could conceivably have been the original purchasers. Also, I was incorrect previously: I have an AM-1 lathe, with a 1" capacity headstock. If you're interested, there are more photos of the lathe and the parts that came with it (production compound, 3-jaw chuck, collet assortment, face plate, etc.) at my website, here.

Brian: Happy to oblige - photo attached:



There are 4 sets of threading gears: the 3 in the box, plus the set on the threader. They are marked E-24, E-25, E-34 and E-40. By my rough count, they are threaded at 12, 12.5, (didn't measure) and 20 TPI. The thread form is a strange asymmetric thread that I haven't seen before, almost like a saw tooth. I'm guessing it's designed to slip in one direction and engage robustly in the other.

You're correct that I unfortunately didn't wind up with the slider plate (or any of the other stuff in the auction lot). Gotta make one of those, I guess...

The gear in the lower right corner of the photo did come with the purchase, and I think it is the gear that was intended to mount to the spindle - but unfortunately not my spindle. It looks very similar to the gear on the 30's model that you posted - it has a set screw, is ~2.5" dia, etc. - and the bore (which is too small to fit my lathe) is probably just about right for the smaller spindle capacity.

The image of your #1 headstock with the gear is interesting - I think that's actually what I need. I'd like to make something similar, albeit without all of the collet-closer components around it. Asides from the Woodruff key, what other features locate that gear to the spindle assembly? Is there anything locating it axially along the spindle?

HI Julian,

I think I remember seeing your machine come up for sale...it was listed here on PM somewhere if I recall correctly. (Or somebody mentioned that it was available. I remember the table.) Congratulations on scoring a very nice machine.

The thread on the masters is a buttress thread. The idea with the funny shape (in this application) was that if you put normal threads on the master, the 'V' shape would cause the threader handle to want to disengage, so you'd have to force it down. The flat side of the buttress thread doesn't generate any upwards thrust, so it doesn't want to kick out. Speaking of which, if you mount one, orient the flat face of the threads towards the headstock. (Buttress threads were also used in vises, once upon a time. They were thought to better reinforce the thread. Thus the name.)

What's your machine's serial #? Like I said, I'm keeping a list. I also have a limited number of Ames' war years serial number pages. If you're on the pages I've got, I can tell you who it was sold to originally. Very likely it was sold to HL Norden in Long Island, and spent the war making Norden bombsights. Most of Ames' war production was.

As far as the gear goes, I'm glad you got it. Could you give me a tooth count? The way it worked was that the AM-1 headstocks have a groove on the rear of the drawtube sleeve that takes a woodruff key. Put key in groove, slip gear on, and then setscrew the gear into place. It's only held in place longitudinally by the setscrew. There's no longitudinal force on it in use, so there's no reason for anything fancier. I'll attach a photo of one of my headstocks, showing the groove for the key. You've probably got one, every 1" headstock I've seen has. Don't remember about the 5/8's, haven't paid as much attention to those.

Regards,
Brian

PS--> The threaders are rare, but they do float by every few years, and the lever closers are slightly more common, so you may end up with one of those eventually. Grab one if you see it, they're right useful.

PPS--> Don't suppose you'd be open to me borrowing the masters for a few days to measure them? I've toyed with the idea of tooling up my CNC to make a batch of them in various sizes to fit my machine. If I'm going to do that, it's just as simple to make a bunch of them while I'm tooled.

Thanks, Brian! I did post it here ages ago when I first got it (although wasn't for sale at the time). Neat to know re: the buttress threads - makes perfect sense.

I meant to include my serial number previously - sorry about that. My lathe is #3826. Let me know if you have any info on it!

The gear is 48-tooth gear. It measures 2.5" OD, just about on the money. I am *guessing* that it is a 14.5-degree pressure angle gear given the age and the size/tooth count match, but I could be wrong (haven't analyzed closely). It meshes with 2 45-tooth gears in series, and then a 96-tooth gear which drives the thread master.

Thanks for the details on the headstock and gear. That's exactly what my headstock looks like. I'm a little surprised that they only use a setscrew for axial positioning (also, ugh, setscrews), but that makes my job easier. Would you mind sending some photos of the gear on your machine that show the keyway and setscrew?

I'd be happy to loan you the masters - would you be willing to make some for me? I'd love to have metric sizes (1mm and 0.5mm would be awesome), and I could probably design the threads if needed.

The thread on the masters is a buttress thread. The idea with the funny shape (in this application) was that if you put normal threads on the master, the 'V' shape would cause the threader handle to want to disengage, so you'd have to force it down. The flat side of the buttress thread doesn't generate any upwards thrust, so it doesn't want to kick out

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Alberic sort of got it right.
As described, that is one of the corollary benefits of the buttress thread.
However, the reason to use it on a chase threading attachment is so the thread does not vary with depth of engagement.

These were made to thread fast, and I use mine that way for small job-lot "production". Even when in the swing of things, or maybe especially when in the swing of things and only another 50 parts to go, the mind wanders, and maybe the lever is not started with the same alacrity or force each time. A Vee or even acme lead would then reward you by skimming off the face of the developing thread. That may or may not be an issue depending on the thread form being cut in relation to the hob form & how close to done when entering the last infeed increment. Using a straight face on the hob obviates all the little issues. & makes it feed nicer as Alberic mentions.

It looks like Ames intended their hobs to be used with a 2:1 reduction for the stamped pitch?
You are in luck, then, if a sufficient gear train exists to set up 1:1, as then it will cut the actual hob pitch as well.

As Larry notes, the Hardinge hobs with a gear train will cut about any pitch. (Before I had an engine lathe, I cut an oddball 13 pitch actuating screw for a 2 Jaw die filer chuck) In practice, hobs/chase threadin are "convenient" only with integer multiples of the hob pitch. It's too easy to cross thread when doing fractional multiples.

Not intending to high jack, I can probably dig up photos of the Hardinge parts and skid plate if useful.

I made one master hob, years ago. They are/need to be hardened. Though maybe not if you rarely cut or recut the follower.

I'm curious about Ames claim of 3-1/2" of cut. The hobs just don't look that long. Is that with first thread of follower just starting engagement, to where it runs off the hob at the other end? Or are parts bigger than photos seem to indicate?

smt

Greetings all:

Interesting about the buttress thread holding starting location on the chased thread. Makes sense once you think about it.
I've never actually run mine, I've been too tied up with work to play with it.

Julian: I don't have the extra gear. I bought that entire blue 1" machine just to get the lever closer which had the drive gear on it, so that's what I'll use whenever I put it all together. (Remember what I said about all decent Ames parts come complete with entire new machines?? Yeah. That's how I ended up with so many of them.) At this point, I'm keeping them around just in case I ever decide to teach classes on micro machining for jewelers. Ames are really good for that kind of work.

I'd definitely like to see what Hardinge's skid plate looked like. I've got a sense of what Ames' had to have been, given what it did, and where it fit, but other than an old engraving of a machine with a threader, with the skid plate half hidden behind the headstock, I don't *know* what it looked like.

Julian: I checked, your machine is higher in the list than any of the pages I have. Sorry.

Are we sure the masters *must* be hardened? The followers are bronze. I've got a rockwell tester. I'll try to dig up the master off of mine this weekend and punch it to see how hard it is.
I'd be willing to do some metric ones, but keep in mind this is a *very* back-burner issue for me, on a machine that we use for daily production, so it'll be quite some time probably.

Julian: Could you take a few pictures of your threader? Especially the master holder. It's different than any of the ones I've seen, and it'd be nice to get some pictures of it.

Regards,
Brian

This is the Cataract/Hardinge plate for chase threading. Parts being made are a run of modified square thread lever cap adjusters, for woodworking planes. These are brass & I did not want to divot the nose for a center, due to how they are used. For harder materials or to speed the work with heavier cuts, the TS is better used to prevent deflection.



In the next photo, it can be seen that the hardened steel wear strip is dovetailed into a cast iron plate, which is keyed to the lathe bed. The support screw that rides on the hardened wear strip is also hardened, ball nose. Set the screw so the tool edge is on center, and then make infeed cuts with the carriage leadscrew referring to the mic dial. Tool holder shown is shop-made. The original tool holder came with the lathe, but I did not have the cutting tool. Also, again, these were modified (5°) sq. threads. I have since made an original style round 60° V threading tool, out of a HSS blank.



Back side of Hardinge, simple gear train (outside gear on the intermediate double gear is merely a spacer on a double stud). The Hardinge sets can be compounded. But without a threading dial, it is impractical to use them for chase threading "oddball" threads.



Hardinge hobs include, well, the hobbing (cutting) section. For making new followers, and aligning them exactly where they will run.
After the follower is cut, stops can be set to avoid that area.

BTW, Hardinge offered a direct-only (no gear train) manual chase threading system right up until the end of the line in the late 1990's/early 2000's on the HC lathes; and further developed an optional electro pneumatic system for automatic cycles to chase finished threads without further operator input.

Do you know what the Ames gear pitch is?
OP, how many gears are you missing for 2:1 &/or for 1:1?

smt

HI guys,

Since this seems to be turning into a depository of information on chase threaders, I took a few photos of my older Ames thread rig. This is the one you see in all the catalogs. It's 20's-30's at a guess. In 'original' condition. Translation: I haven't had time to clean it up yet, so please excuse the dust and grime. The paint looks a little blueish in the pictures, but it's black in person. Most Ames machines prior to the late 30s were Japanned black.
I was planning on taking a Rockwell punch to the thread master, but it seems like it's welded on there, and I don't have a whole lot of time to fuss with it at the moment, so pictures are it for now. I note two things: this one is set up so that the flat face of the thread is pointed towards the tailstock, and that there is a fair bit of impact damage to the peaks of the threads, which argues against their being very hard. The Hardinge masters have to be, since they hobb their own followers. The Ames masters don't.
Now that I've seen one of the Hardinge threaders, I think I like theirs better. Micrometer adjustable DOC, and the ability to hob followers in place. I like that.
If I CNC more thread masters, the hardest part of it is going to be doing the blinking followers. Being able to do them with the rig itself is so much easier.

So here's the first batch of pictures.

Regards,
Brian

More pix.

Regards,
Brian

this one is set up so that the flat face of the thread is pointed towards the tailstock....

Click to expand...

It's operator choice whether to thread RH threads toward the headstock (tool "upside down", lathe turning forward/conventional). Or to cut away from the chuck, lathe tool "rightside up", lathe running "backwards". I've never used a chuck when threading (collets or step collets and closer for large work). However, the last user of your lathe may either have never used chase threading and assumed "always cut toward the chuck" as on an engine lathe. Or they may have been cutting large diameter work, and feared the chuck unscrewing.

My understanding of, and very convenient practice, is to cut threads with lathe running in reverse, tool rightside up, and tool/slide progressing out, away from the nose toward the TS. I have cut LH threads, and done either with either method. Tool moving away from headstock promotes the faster, easier work for most things.

A TS is very useful, it does not take much projection to get deflection on small diameters. Though on bench lathes, it becomes imperative to be sure the TS is still in alignment, since few have any provision for set over. (to avoid inducing tapered work)

...and that there is a fair bit of impact damage to the peaks of the threads, which argues against their being very hard. The Hardinge masters have to be, since they hobb their own followers. The Ames masters don't.

Click to expand...

I realized after thinking about it, you are correct that "soft" masters are fine as leadscrews (without the cutting hob function). No different from the non-hardened leadscrews on millions of engine lathes. It does beg the question, though, how the heck to you ever make the followers accurately, and such that they are guaranteed to align centrally with the hob?

I thought another PM'r had an Ames and photos of his chase threading, and that they had an adjustable tool slide, albeit smaller than the Hardinge? Maybe yours is missing something, and the non-moving holder was shop added as a make do? It's hard to imagine chase threading accurately without - if the cut depth is arranged only by the height of the screw on the skid-plate (I don't know what that piece is actually called) the tool will either have to start above center and drop there to finish; or on center and drop below, or somewhere in between. It would be difficult to cut multiple pieces without gaging every one, as well.

Have your figured out the gear pitch?

smt

HI Steve,

I'll have to unbury the blue Ames headstock to get a tooth count on the drive gear. May take a couple of days.

As far as worrying about the chuck unscrewing, no. Ames chucks mount via a modified collet, so they've got a drive pin. No way to unscrew in either direction.

As far as the micrometer DOC adjustment on the Hardinge chase threader, I don't think any of the Ames versions had anything like that. None that I've ever seen has, at any rate. My understanding was that you started the cut high and came in to CL on the final pass.
I think that's why there are two depth setting screws on the bottom that ride against the skid plate: one for rough, and one locked down for 'finish'. You tweak the 'rough' one for each pass, and leave the other locked to generate final OD.
Remember, these things are overgrown watchmaker's lathes.
They grew 'up' from there, rather than down from Engine lathes, so they think about things differently.

Regards,
Brian

I neglected to register the significance of 2 thumbscrews in the follower's height registration feature.
Your explanation makes perfect sense. The necessary ever more acute extra clearance to grind on the tool for larger pitch threads might become problematic. Though as you mention, these were evolved to make watch (scale) parts. Hardinge seems to have evolved theirs partly for the optical industry - all the mounts and retaining rings for lenses, and adjuster screws for the mechanical parts. Though IBM was a big customer, when those machines ran on clockwork.

When using my Hardinge, it is usually for short threaded parts that are expected to be a close, smooth fit. I infeed on the mic dial to a pre-tested "snug" condition and set -0-. Then i run each part down to -0-, stone off any burrs, and test a nut. If it goes on smoothly, the part is done. If too snug, I run another spring pass or 2, or infeed a "fraction" of .001" on the dial. With a newly sharpened tool, the infeed will need set a "fraction" deeper over the first dozen or so parts, then it will tend to settle down and run reliably to a number. i continue to check every few parts, though.



These are 1144 collet bodies for a woodworking mortiser. The nuts are 12L14. So not exactly difficult materials.



If the set up is not time consuming (I only have a half dozen hobs, but can often find a pitch that works to an integer ratio with a gear train) I even prefer cutting close fitting one-off parts with this method, as opposed to on my small engine lathe (SB 10K)

Nut for a shop made wood shaper spindle:



My question about the gear pitch relates to the OP's interest in metric threads. If he has enough gears, perhaps a small metric lead might allow him to use that for multiple metric pitches, hence requiring fewer hobs. If he and you settle on the necessary "first" hob, he could conceivably cut the rest himself, given appropriate gearing. Did Ames anticipate compounding in their gear train? (with double width studs,etc?)

smt

HI Stephen,

I don't *think* Ames ever intended to use multiple gearing on their threaders. Certainly mine shows no sign of ever having been capable of it, and it doesn't look like the OP's later version could either. (no extra length on the gear studs, for example, and no real banjo.)
It's a pretty bare bones rig. That's not what these machines did, mostly. They did a lot of tapping, and stuff with geometric die heads, but seldom did full on single pointing.

To finish up on the threader, and the two different depth setting studs, I have a memory of someone (somewhere) mentioning that another production trick was to use strips of shimstock between the depth studs and the skidplate. Set the stud (if you only have one) and then put a couple of shims between it and the skidplate. Take a cut, remove a shim, take another cut. Rinse, repeat until final. Worked pretty well apparently. (mostly these things were used for very fine threads. Not that deep. So probably only one or two shims at most.)

Regards,
Brian

Yabbut...Sounds like the OP might want to use his lathe "seriously" and no reason not to. The other bench lathe makers had complete systems for convenient, light production work. That was the whole promise of the chase threading principle - "simple, fast, reliable"- see Ames own ad copy.
If he only wanted to use it as a watch lathe, then hand chasers could/(would?) be used. My lathe came with a batch of hand chasers, but I've never used them. I have used the old acorn dies at times.

I found pictures of one of the other lathes that has been posted on PM in the past. I had mis-remembered it as another Ames. It is in fact a Stark. Since these are _NOT_ my photos & i don't personally know the owner, here is the best one of 3 from the drop box. Maybe the owner will chime in here; per your note about hi-jacking the OP's thread to include other bench lathes and expanding it to include chase threadind as a wider subject.



Per earlier notes about Hardinge, the tool slide and cutting tool as seen in the Stark photo above, were correct for Cataract/Hardinge lathes as well. It can be seen that my lathe has the holder which i use with small 90° boring bars for internal threading, and have made a smaller version of the circular form 60° vee threading tool seen above. Not shown, the Stark has a hob with cutting section that looks interchangeable with Hardinge, and a similar gear train and banjo(s).

It will be apparent that with chase threading, for internal work, the tool needs to cut on the operator side of the bore (else it can't be retracted). So upside down, in front, lathe in reverse, cutting out from the spindle nose. Or right side up, in front, lathe turning forward, cutting "in".

smt

stephen thomas said:

Yabbut...Sounds like the OP might want to use his lathe "seriously" and no reason not to. The other bench lathe makers had complete systems for convenient, light production work. That was the whole promise of the chase threading principle - "simple, fast, reliable"- see Ames own ad copy.
If he only wanted to use it as a watch lathe, then hand chasers could/(would?) be used. My lathe came with a batch of hand chasers, but I've never used them. I have used the old acorn dies at times.

I found pictures of one of the other lathes that has been posted on PM in the past. I had mis-remembered it as another Ames. It is in fact a Stark. Since these are _NOT_ my photos & i don't personally know the owner, here is the best one of 3 from the drop box. Maybe the owner will chime in here; per your note about hi-jacking the OP's thread to include other bench lathes and expanding it to include chase threadind as a wider subject.



smt

Click to expand...

HI Stephen,
I think we're both outrunning the OP, but I don't see it as a problem: chase threading is obscure enough that somebody may get some use out of all this at some point.

I hadn't thought about internal threading, but now that you mention it, clearly there's a toolholder missing from my rig, because the setup I have won't handle a bar crosswise. I've never seen any photos of the Ames rig set up for internal threading either, so I don't know exactly what their solution was. I'll have to guess when I get to that point.
It'll be all sorts of fun trying to manually engage and disengage with a boring bar stuffed down some of the teeny little holes these machines like to make.

What I meant about watchmaker's lathes wasn't that these machines were intended *for* watchmaking, although they were used for precision gear work a lot, but rather that they grew 'up' from watchmaker's lathes, instead of being a downsized toolroom lathe like a SB9 or whatever. The designers started out with their heads in a different place, doing a different kind of job, so they built a tool that goes about things a little differently.
These machines are happiest with stock under 1" OD. They can handle up to about 6 if they have to, but beyond about 2", it becomes pretty clear that you're outside the envelope of what they were intended to do most of the time.
(For reference, they're about 4x the size of a real watchmaker's lathe, but they have many of the same design features.)

As far as the OP wanting to thread 'for real' on his.....yeah, he could, but frankly by the time he gets done frankensteining up some sort of computer synched electronic system, he'd be money ahead to just get a small-to-midsized machine that already threads. He's got the chase system, there's not much need for anything fancier. (Or if there is, this isn't the machine to do it.) I say that as someone who learned on an Ames, and loves them dearly, but sometimes wisdom is recognizing that not every tool is the right hammer for any particular nail.

Regards,
Brian