Need tap size

[vick]

I will have to admit I have have never done any tapping, but I wanted to try some stuff out. Would anyone out there who user CSU American Rollerball pen kits (snap caps) be able to tell me what size tap and threading I would need to to not use the nib coupler and just tap a hole in a resin blank to screw the nib into, or how I could find out for myself. Hope this makes sense like I said I have not idea what I am talking about.

 

[Paul in OKC]

You will have to measure the diameter of the thread, and count the threads per inch. It is not a standard thread, but a tap could be made.

 

[vick]

Well I must be stupid since I am obviously doing something wrong. I just have a cheapy tap and die set with 4 sizes and a couple of threadng options. I tried to bet the diameter of the pert using a drill bit size card and it came out to something like 5/16 (not sure exactly I am at work). When I tried tapping with that size the tap hole was way to small. Any idea what I am missing.

 

[marjoe]

It could be metric but the only way to tell is measure the dia. like paul said. It will be about .004 undersize. To check the thread,count the number of threads per inch or use a thread gage metric and english. You could also go where they sell nuts and try to find one that fits.

 

[btboone]

It will likely be metric since all the nib threads are, and the fact that they are normally made overseas. If I had to guess, if it's close to 5/16", it is probably 8mm diameter. The question is what the pitch is. It is probably an even 1mm or a fraction like .75mm.

 

[vick]

I am beggining to think my idea is a lot more difficult than I thought.[:I]

 

[Paul in OKC]

The thread measures out at 8.4 mm (.330), which is close to 21/64 (.328). Definately not standard. The pitch did match up to 1.0. The closest special tap I have seen is 11/32-32, which is about .012 too big and the thread is too fine.

 

[Thumbs]

Does resin stick to UHMD? That is reasonably soft. Could you cut the threads into that using the nib coupler as a die? Then pour your resin around the UHMD, in effect, using it as a tap at the end of your pouring receptacle? Sounds kind of wonky, I know, and probably unwieldy and unworkable.

 

[btboone]

I made a nice working tap with my CNC. It could be done by a hand lathe as well. It's not too tough.

 

[Fred in NC]

Bruce, if you still have the program to make that tap, maybe you can offer these taps. They will be cutting mostly plastics anyway, so I don't think they need to be hardened.

 

[Paul in OKC]

Originally posted by btboone
<br />I made a nice working tap with my CNC. It could be done by a hand lathe as well. It's not too tough.

I have made several taps on a manual lathe out of drill rod. They work great for cutting softer material.

 

[vick]

Bruce - I am guessing that not 2 tough is a relative term. What is not tough for you is probably very tough for me ,especially since I do nto have a metal lathe.

Thumbs - I am not sure I am following what you are saying but it does sound like it may be kind of inline with another idea I was thinking about. Basically my idea was to take the nib section and attach to it some kind of rod (or empty rollerball refill) that is the length of a refill plus the extra length for the spring. Use a round vertical mold ( pvc or copper pipe)and dip this in casting resin just past the threads. The threads then should be cast into the resin. That way no drilling or tapping would be required for a once piece pen body.
I have not used polester resin and I am not sure if shrinking or something would cause this idea to be a flop, and obviously you would have to use some kind of release agent on the part to be able to get it out(unscrew it) from the hardened resin. With as fine as the threads are I do not have high hopes.

 

[vick]

Originally posted by Fred in NC
<br />Bruce, if you still have the program to make that tap, maybe you can offer these taps. They will be cutting mostly plastics anyway, so I don't think they need to be hardened.

I would be interested depending on the price.

 

[dubdrvrkev]

Mike you might take the part down to HD or Lowes and see what it'll thread into. If you can find a nut that threads on well enough, it should be fairly easy to figure from there.

 

[btboone]

I don't have the program, but it was very easy to write. I just made some out of a scrap of titanium. I used mine to tap brass, and it worked great for that. I'm still up to my eyeballs in rings, but I could probably cost justify doing taps for around $25. You could send me a part to measure and match. I could test the tap on something like aluminum.

I agree with Kevin, if you can find a bolt that's like the part thread, you could just get a separating disc on a Dremel to do chip relieving slots, and presto, it's a tap.

 

[arehrlich]

Bruce,

For those of us without the facilities to cut a tap, you would be offering a wonderful service if you could provide them. The $25 pricetag seems reasonable.

Alan

 

[btboone]

I'm willing to try. I don't really know if I can be cost effective or not, but I can't know until I just jump in. I should be able to do double or triple leads as well. Just send a male threaded part for me to measure and copy. Send a check or use the Extra Costs page on my site,(link in the FAQ page) and add a few bucks for Priority Mail shipping.

 

[Paul in OKC]

Originally posted by Paul in OKC
<br />The thread measures out at 8.4 mm (.330), which is close to 21/64 (.328). Definately not standard. The pitch did match up to 1.0. The closest special tap I have seen is 11/32-32, which is about .012 too big and the thread is too fine.

As stated above, it is not standard diameter but standard metric pitch. It is single lead. (we are talking snap cap roller balls, right?) that what mine measured out to.

 

[btboone]

I like to measure the part with my optical comparitor just to really nail the depth of the threads. It shows the thread form magnified 50X. You can see if they actually have theoretical 60 degree threads or a different variation since they are plastic. The ones I looked at for my nib were nowhere close to anything theoretical. Probably a factor of the plastic shrinking.

 

[vick]

I appreciate everyones help on this, but I think I am going to go a different direction on my project. For the record that same part seems to be used on the Jr Gent and probably a few more CSU kits (fountain pen, Rollerball, ect.), so it should not be a single use tap if some one does decide to do this. Bruce I may revisit this in the future, but not right now.

 

[Paul in OKC]

Originally posted by btboone
<br />I like to measure the part with my optical comparitor just to really nail the depth of the threads. It shows the thread form magnified 50X. You can see if they actually have theoretical 60 degree threads or a different variation since they are plastic. The ones I looked at for my nib were nowhere close to anything theoretical. Probably a factor of the plastic shrinking.

Bruce, best I can tell is that the tops are 'pointed' like a normal thread, but the minor diameter is shallow with a wide flat at the base.

 

[btboone]

That sounds like the ones I did on the nib. The included angle was something like 45 degrees rather than the usual 60, and the root of the thread was all filled in to be flat. I guess the pointier threads have less friction and the filled in root adds strength to the thin plastic part. I used a normal 60 degree threading tool to make the tap, and it seemed to work fine. I was actually somewhat surprised that it worked as well as it did.

 

[woodscavenger]

Bruce, I think it would be cool to get a tap for something like the Baron/Jr Gent/Classic pens for a start since they all seem to take the same thread. My second would be the Ligero then Gentlemans/Statesman. $25 definitely seems reasonable. Let us know when you have some time.

 

[btboone]

Shane, I'll just have to squeeze them in anytime. I can't predict the ring traffic day to day. I had something like 28 of them today!

 

[woodscavenger]

Man I wish I would have seen your site before I bought my wife's 10th anniversary ring a year ago.[] Your rings are much cooler!

 

[vick]

Theya re even cooler in person. I needed to replace my weeding ring and I got it from Bruce. Money well spent.

 

[btboone]

Thanks guys! [8D] I looked for a titanium ring years ago when I got married. They weren't out there. I made bike parts and had some 1" diameter titanium bar pieces left over from making bottom brackets. I thought, Hmm... I made myself a ring, and the rest is history. After a while, the wedding rings overtook bike parts. Hopefully, one of these days, I can also take a serious stab at making high end pens. It looks like I'll need some help in the shop before that can happen.

 

[JimGo]

Bruce, if you want to set me up with equipment, I'll lend a hand! []