Tap sizes? Baron, Americana snap cap, Ligero

[woodscavenger]

Does anyone with better skills than me know the thread sizes for some of those pens. I am interested in the nib threads as well as the cap threads. I would like to buy a tap and die set but I don't know if any of these are standard sizes.

I would also be interested in any of the pen kit if anyone has measured them out. We could put together a list.

Thanks for your help.

 

[Deere41h]

Shane.....I too have been looking for the same information. I have done some measurements and have determined that all the threads are metric. I think they are standard metric but I'm not ready to go out on a limb with my measurements until I am sure I have them correct. My major interest now is the Baron (Gent Jr. is the same). I will probably buy a metric thread jig to verify my results.

A thread chart for these pens would be great!

 

[btboone]

I don't happen to have those pen kits, but I agree that they likely are metric. I measured the threads from Anthony's small nibs at M6.5 x .75, and I measured one I got from Rich at M6.5 x .5. Both are strange enough that normal taps aren't readily available.

 

[Tangboy5000]

I would also say metric, but that's only because the country of origin on almost all the knibs I've seen is Germany.

 

[Randy_]

Originally posted by btboone
<br />I don't happen to have those pen kits, but I agree that they likely are metric. I measured the threads from Anthony's small nibs at M6.5 x .75, and I measured one I got from Rich at M6.5 x .5. Both are strange enough that normal taps aren't readily available.

Shane: I'm sure Bruce is correct about this. When I get home I will check for the link that I have for a chart that shows all of the "standard" metric threads. Wouldn't surprise me if the pen threads were proprietary standards of the manufacturer and just not available to the public at all.

Since these nibs come from Germany, you might contact someone(hardware dealer) there Germany and see what they have to say?? There is a guy from Holland who posts regularly on Richard's group. You might try to contact him for some information. The guy is highly educated(PhD??) and is really good with technical stuff so he might be a good source of information.

 

[Thumbs]

We have at least one member here from Germany that ought to be able to check on tooling availability right there......

 

[woodscavenger]

Bruce, could I cut those custom threads on one of the smaller HF metal lathes?

 

[btboone]

Hi Shane,
Yes, the little lathe should be able to do it. The gears apparantly get changed out by hand, but .75 and 1 should certainly be pitches it could do.

 

[Fred in NC]

Cutting threads with a lathe can be very tricky, especially inside threads. The outside threads are easier, since you can see what you are doing.

Bruce, please tell me if I am off my rocker, ok ? I think it will make more sense to use a metal lathe to fabricate taps to cut the inside threads. Since plastics are not so hard, a tap made from say O-1 drill rod should work very well.

ADDED: To make it easier, a custom made tap could have a pilot shaft to keep it centered and straight in the blank. This would make it very easy to tap by hand.

 

[btboone]

Yes, the homemade taps can work well plastic and in brass too. That's definitely the way to go for internal threads. The external threads aren't too bad by hand when you know the theory and practice a little. It opens up a whole new set of capabilities for a pen. Another interesting thing I'm trying with my lathe is making contouring mills. Any strange and complex shape can be cut in a metal rod such as a parabolic curve. Sure, it's tricky by hand, but can be filed and sanded to final shape. The part can then be gouged with an abrasive cutoff wheel to make sharp edges, almost like the flutes of an endmill, and Voila! you have a tool for cutting that contour on the inside of a wood pen. Different shapes such as round beads can be done too. I just made a trepanning tool that way and it worked great! I'm going to modify the opposite end of the metal bar to become a contouring mill with a quarter round radius.

The drill rod is great stuff. It's deadly accurate in any size you need for a couple bucks for a 3 foot piece. I use it a lot for fixtures and mandrels. Mandrels! Another great thing to make on the mini lathe. You can make to whatever diameter you need without having to rely on WoodCraft. Need bushings? Make them!

 

[Fred in NC]

Bruce:

Turning a 10" piece of drill rod down to a consistent diameter along its length is a bit tricky, since it really needs a <b>follow rest</b> to keep it from flexing and changing diameters along the length. Just holding a drill rod by the ends does not work, I have tried it. Anyway, they sell drill rod in sizes to match the two types of mandrels in use. The 'A' mandrel just needs the threads. The 'B' mandrel is more complicated, I made one already.

Bushings are easier to turn because they are thicker and shorter.

I had already thought about contouring mills, mostly to cut miniature rosettes.

Thank you very much for your input !

 

[btboone]

Yup. That's exactly what I mean Fred. No need to turn the long shaft since you can buy about any diameter needed, just turn the threaded part. It's really cool to be able to buy such a precision diameter shaft so cheaply. I made some 1/2" mandrels for my new pen that way. If you need something a little undersized for a pin chuck or whatever, MSC is just a call away. My cutoff time is 9:00pm, so even if I'm designing at night and need a strange diameter drill rod, I always can get it the next day.

 

[Randy_]

Shane: See if there is anything of use to you at this web site.


http://mdmetric.com/thddata.htm

 

[scubaman]

Originally posted by Randy_
Since these nibs come from Germany, you might contact someone(hardware dealer) there Germany and see what they have to say?? There is a guy from Holland who posts regularly on Richard's group. You might try to contact him for some information. The guy is highly educated(PhD??) and is really good with technical stuff so he might be a good source of information.

Don't need a PhD though if that's a requirement I feel maybe I can help. And chemists don't know taps anyway [][}] These taps are generally NOT standard sizes. I did a lot of searching a while ago for some of these. You can get taps made in Poland via www.e-taps.com . Larger cities should also have shops that make these custom. e-taps prices come down with quantity, so if a couple of people get together... unfortunately, there is little standardization. Now if someone should find M8x.7 a useful size, I have some of these. What do they fit? Don't remember...

 

[Fred in NC]

I am very curious ....

 

[Fred in NC]

I am very curious ....

The need to use a tap to match the thread on a nib is very understandable, because the nib is already threaded.

For the body, if we are going to thread both parts, we can use any size tap and die of proper diameter. There is no need to use exactly the same thread that comes with the kits.

Am I confused here ?

 

[btboone]

Very true. I found myself in the mindtrap of only looking at metric threads for the body parts of my pens. I could optimize the wall thickness if I went with a US standard size. Nobody should care whether it's standard or metric as long as they fit together!

 

[scubaman]

Originally posted by Fred in NC
<br />I am very curious ....

The need to use a tap to match the thread on a nib is very understandable, because the nib is already threaded.

For the body, if we are going to thread both parts, we can use any size tap and die of proper diameter. There is no need to use exactly the same thread that comes with the kits.

Am I confused here ?

No, you're not confused. There is no reason to use metric when you make both parts.

But there is another aspect. Many (not all!) of the cap threads are multiple entry. It doesn't matter whether that's metric or imperial - you will not find a matchin tap off the shelf. So don't even bother - you won't find it [] A good reason to use your own matchin parts.

If you want to pursue this, I would suggest staying close to what people use. Just ballpark. You avoid some pitfalls that way. That puts a threads in the 32 TPI or 36 TPI range. If you make it coarser you require more depth and the walls have to get thicker and all that. So that still means custom tools in the diameters of interest. Or single-point cut on a metal lathe which IMO is the better approack

 

[Fred in NC]

Rich, cutting outside threads on a metal lathe is not a problem.

The inside threads are more difficult, because you need a boring bar type of tool, and you cannot see what you are doing.

If you can cut the outside threads with the lathe, the same setup should be able to thread a piece of drill rod. All you need is to cut some flutes on it, and you have a tap.

I will look into it. Maybe I can make these taps.

ADDED: One thing is often overlooked. Taps have a taper that allows the tap to start the cut. If you use this kind of tap, you will have a tapered section at the back of the thread. That will make it possible to screw in the body of the pen until it becomes very tight. I don't think this is a desirable feature in a pen !!

Because of this, taps are usually available in sets of 3:

1. Regular tapered tap.
2. Plug tap, which has a smaller taper.
3. Bottoming tap, with almost no taper.

To cut the thread correctly, I think one would need the bottoming tap also.

Another possibility is to have a shaft to guide the tap into the barrel. That will insure a straight cut into the barrel in such soft materials like plastic.

 

[scubaman]

Originally posted by Fred in NC
<br />Rich, cutting outside threads on a metal lathe is not a problem.

The inside threads are more difficult, because you need a boring bar type of tool, and you cannot see what you are doing.

If you can cut the outside threads with the lathe, the same setup should be able to thread a piece of drill rod. All you need is to cut some flutes on it, and you have a tap.

I will look into it. Maybe I can make these taps.

Quite so [] You can buy a bit that is ground for cutting inside threads. (I have one bought from littlemachineshop.com but can't find it in their current lineup.) Yes, you can make your own tap, to tap soft materials like plastic and wood. I have read of people just grinding 3 flats on a bolt. I have made such taps as you describe - took a Dremel and cut a bunch of flutes into essentially a bolt. Not pretty - but worked for me. The thing is I believe ideally you want a positive rake at the cutting teeth, otherwise you get a bite but not a good thread. I don't think you need to worry about hardening. At least not in something for your own use [] What I think you can do is cut the male thread, then mill or grind flutes. If that leaves a burr in the wrong place (depending on how you cut the flutes) you can clean that up with a chaser die maybe.

The point is to cut a thread for fastening things is easy, and the simple tricks you read about in the metalworking groups are serviceable. But for a pen cap, you need much better than that - getting a grip is not good enough. It has to feel good also

Not to discourage you in the least! I'm just giving you some things to think about from the start to get to the desired results faster, I've gone through the thought process

With a metal lathe, the thread I would think about is a 36 TPI triple-lead thread.

BTW I'm with you - there is a certain amount of angst even thinking about interior threads, not seeing what you're doing. I think that will be overcome with a little practice. (Anyway I hope so!!!)

 

[scubaman]

Originally posted by Fred in NC
ADDED: One thing is often overlooked. Taps have a taper that allows the tap to start the cut. If you use this kind of tap, you will have a tapered section at the back of the thread. That will make it possible to screw in the body of the pen until it becomes very tight. I don't think this is a desirable feature in a pen !!

Because of this, taps are usually available in sets of 3:

1. Regular tapered tap.
2. Plug tap, which has a smaller taper.
3. Bottoming tap, with almost no taper.

To cut the thread correctly, I think one would need the bottoming tap also.

Another possibility is to have a shaft to guide the tap into the barrel. That will insure a straight cut into the barrel in such soft materials like plastic.

Right, I'm aware of this. But I don't know why you're saying cutting a deep thread is not desirable. It all depends on the overall design. First, I think we should exclude wood from the discussion - you don't want to do this on unstabilized wood. I think wood movement would kill that idea. (Just my thinking, not actual experience.) But also fine threads in wood (incl. I imagine most stabilized) are just not a great idea. So let's say resin. I've seen pens that had a very deep thread cut into the cap. Often, the cap stops on a ledge exterior to the main barrel. not interior to the cap, so depending on how you design it, you can use a bottoming tap which has 3 partial threads.

 

[Fred in NC]

Rich, the flutes can be cut by holding the threaded rod in a rotary table or indexer, and using a milling bit. A positive rake might be a little more work, but a negative rake would be fatal. This is why I think grinding is not the way to go.

Now you are talking about multiple starts .... that is advanced machining, my friend, especially for internal threads. I would attempt to make a tap for that, but cutting inside the pen barrel could cause a lot of waste.

 

[scubaman]

Originally posted by Fred in NC
<br />Rich, the flutes can be cut by holding the threaded rod in a rotary table or indexer, and using a milling bit. A positive rake might be a little more work, but a negative rake would be fatal. This is why I think grinding is not the way to go

Well, grinding can work, for home use. I took a Dremel and used a cutoff wheel. The wheel cuts across the grooves. So the Dremel is at right angle to the bolt. You can angle it a little to get a positive rage. But of course you can also use an end mill. Actually, maybe better use a ... wish I could think of the name... a cutter that looks like a gear... hope you know what I'm talking about. Much stronger than a small end mill.

Now you are talking about multiple starts .... that is advanced machining, my friend, especially for internal threads. I would attempt to make a tap for that, but cutting inside the pen barrel could cause a lot of waste.

Are you sure? Have you trie it or thought about it a lot? I used to be of your opinion and change dmy mind. If you can do 1 lead you can do multiple also. [] (This is theory for me, I need to find the time to do it []) Say you choose 32 TPI 4-lead. You would set your lathe for 8 TPI. Your bit needs enough rake to have sufficient clearance on the leading edge for the steep 8 TPI. You have to go by depth. You do need to understand the use of the threading dial. Say you cut that fist cut on the 2 setting of the dial. You simply repeat the cuts on the 4, 6 and 8 setting to ge tthe 4 flutes. For 36 TPI (less deep thread) you set the lathe for 9 TPI and do the same thing: 2, 4, 6 and 8 on the threading dial.

What perplexed me was how to cut triple leads using a 16 TPI (typical) leadscrew and threading dial, because 16 is not divisible by 3. Finally got the illumination after reading a little booklet on cutting threads: Let's say 36 TPI, triple. Set the gears for 12 TPI. Set the compound to 90 deg (parallel to the bed). Cut 1st thread to depth. Then you simply advance the compound the right amount and cut the 2nd. Repeat for the 3rd. The 'right amount' to advance would be 1/36" or .0278". No magic. [8D] (in theory)

 

[btboone]

[]I like my method better. The machine asks How Many Starts? Type in 3. []

I used a grinder (cutoff wheel actually) for my taps also. I was afraid that an endmill wouldn't get them sharp enough. I didn't worry about getting the slots spaced correctly or at any exact angle and the taps still seemed to work fine. The biggest thing is having enough room for chips to fall into.

I think most taps don't have the thread part change diameter, just the outside shape of the tap. I think on my taps I did change the thread tool diameter a little at the end, but looking at other taps I have, they don't look to do that.

Another thing to remember is that taps are a few thousandths of an inch over theoretical. If perfectly pointy, the threads on the male threaded part would exactly equal the OD, so a 1/4-20 would be .250" to the tips of the points. Of course, the points are knocked off for clearance sake. The 1/4"-20 tap might have the theoretical point to point diameter of something like .254". It depends on what's being tapped and how tight you want the fit though.