Getting the pen blank / hardware diameter right

[Scottydont]

I wanted to post this after posting in the discussion about how do you organize your pen kits? I have developed an efficient process to help me more consistently turn my pens to the right diameter to get a perfect fit and finish. Most newbie pen turners get frustrated trying to turn down to the bushings only to find out that the wood hasn't been turned flush with the hardware. You can remedy this with the use of a caliper. I prefer using a digital caliper like you can find at Harbor Freight.

Rather than measure the bushing, I prefer to measure the actual pen components first because they can vary from manufacturer to manufacturer. For those who think that is too much trouble its not. I keep seperate plastic bins for each pen kit style. In it I have the pen kit instructions, extra bushings, hardware diameter measurements. I only take the measurements once on each kit, then I can refer to the diameter measurements when turning and caliper checking each pen.

Happy turning!

 

[wayneis]

Scott you may want to recheck the sizes every once in a while because I have heard that size can change between orders for a Company. Y may be safe in only checking only once if you ordered a bunch of kits at the same time, but size can change in between.

Wayne

 

[goldentouch]

Scott I would second checking all the hardware. I had several pen kits that had mix match hardware in them. It appears the tip and center band were oversize but the top was the correct size. I have now started checking more carefully.

 

[jrc]

I use a CA finish and it leaves a coating on the bushing. When I sand down to the shinney metal bushing I know it's the right size. I look at pen making like an art not a rocket science. Keep it simple, it's OK to make mistakes but learn from them.

 

[dougle40]

I'm with Scott 100% with the exception that ,while I do have digital verniers and dial too , I now prefer to use micrometers just because they're easier to use while the blank is on the lathe .
For me the bushing are only a guide to get me close .

 

[panini]

Every pen I turn I use a micrometer on each component then write it down then store blanks and parts in a ziplock bag... takes up lots of time but worth it...[8D]

 

[btboone]

I go a step further. I measure the parts with a digital caliper and draw everything to scale in CAD. This shows me what's important and what can change on a pen. It also gives me very exact dimensions for pressing in the transmissions, so I don't have to trial and error it.

 

[woodscavenger]

Wow, as with any woodworking group there are always a group of dedicated, high tech engineer types that blow me away. I would get so caught up in the CAD that I would have time to make any sawdust. I do like the digital caliper suggestion with measurement of the pen kits.

 

[Fred in NC]

Bruce, with the CAD file, you could easily turn tips, bands, and finials!

 

[Paul in OKC]

Originally posted by btboone
<br />I go a step further. I measure the parts with a digital caliper and draw everything to scale in CAD. This shows me what's important and what can change on a pen. It also gives me very exact dimensions for pressing in the transmissions, so I don't have to trial and error it.

I here ya there Bruce. I too have made a few cad drawings of pen parts, mostly for future project ideas. As for pushing in transmissions, I made a block for the 7mm kits. I jsut push it in up to the block, right every time[]

 

[RussFairfield]

An interesting exercise for those who are working to within 1/1000 of an inch. It might give some insight as to why chasing the perfect match between pen barrel and fitting is often such an elusive dream.

Remember that a diameter difference of as little as 0.003 can be felt with our fingers, and one of 0.010" will apear as a huge mismatch.

Check the diameter of the finished pen barrel when it is still "hot" on the mandrel from sanding and finishing, and again after it has cooled for assembly. You will find that the "cold" dimension will be less than when it was measured on the lathe. The actual difference will vary with the wood that is used.

Another interesting measurement is the one taken after 2-weeks have passed by. This one is particularly important on natural wood (not stabilized) pens. The moisture content was driven to near 0% bone dry from the heat of turning and sanding. It will stabilize back to the equilibrium moisture content as time passes, and the wood will grow with the change. This growth in diameter can be several tousandths, the exact amount depending on the species of the wood and the diameter of the pen barrel.

In a perfect world the shrinkage from hot to cold, and the expansion from dry to equilibrium moisture would be equal. In the real world, they are not, and its growth from the change in moisture content will be the greater.

It is that diameter of the barrel after the aging that counts, and not its diameter while it is still "hot" on the mandrel. Unimportant?? Check the OD of the pen barrel as suggested the next time you turn a large diameter pen. You might find that getting that perfect fit between wood and fitting will require making an allowance for these dimensional changes.

 

[Fred in NC]

Remember that a diameter difference of as little as 0.003 can be felt with our fingers, and one of 0.010" will apear as a huge mismatch.

True. Especially for us who know what to look for !!! [8D]

 

[elocyar]

So,
What CAD systems do you guys use?

Most are real pricey.

Thanks
Ray

 

[Paul in OKC]

I have AutoCad at the shop where I work.

 

[btboone]

I use Mechanical Desktop, which is AutoCAD based, and can do solid modeling as well. I sweated some swoopy groove details on a pen I'm working on for two entire nights, probably around 16 hours of work. I was up one night until 5am. I was able to see what different combinations of cutter size and depth and helix angles looked like on the pen, all before cutting a part. I totally revised one of the two parts when I realized that I would have a manufacturing issue later down the line, and ended up improving the look considerably in the process. I might try to pull a late night tonight to catch up on rings so I can get back to pens.

 

[Paul in OKC]

Originally posted by btboone
<br />I use Mechanical Desktop, which is AutoCAD based, and can do solid modeling as well. I sweated some swoopy groove details on a pen I'm working on for two entire nights, probably around 16 hours of work. I was up one night until 5am. I was able to see what different combinations of cutter size and depth and helix angles looked like on the pen, all before cutting a part. I totally revised one of the two parts when I realized that I would have a manufacturing issue later down the line, and ended up improving the look considerably in the process. I might try to pull a late night tonight to catch up on rings so I can get back to pens.

Dang Bruce, I'm still jealous of your toys[]

 

[btboone]

I've used SolidWorks, Inventor, Rhino, Pro-E and a few other solid modelers and I keep coming back to plain old AutoCAD. All the new stuff does away with XY coordinates and relies on parametric sketches. Instead of drawing a line 2" long, you need to define how it's constrained. Sometimes simpler is better. I get my coordinates for the lathe and machining center and write my G-code by hand. It's a lot more efficient for production, and I always know where the coordinates came from.

 

[Paul in OKC]

True, sometimes too fancy of software is just that, too fancy. I went to a Solid Works class the other day, neat stuff, then I rembered that the AutoCad will do the same thing, and things are oriented where I understand them[]
The software I have at the shop only writes three axis, any fourth axis things I do get hand written.

 

[btboone]

The biggest thing for me to do in 2D CAD is get a "look." I'll draw something as a series of small lines and go back and stretch them to better looking positions. It's very hard to do that with a higher end CAD package, which want you to define relationships. Sometimes you have those relationships and sometimes you don't know yet. I'll usually start off with a pencil drawing of a shape like I'm looking for. Then I'll draw it with those short lines and fiddle with them until it "looks right." I'll then go back and redefine those short lines with arcs and lines that more correctly define them and give me the coordinates used to machine them. I did my bike parts that way, and am doing new pen designs by that technique. For me, the parametrics are much tougher to get a "look" you are trying to achieve. That's 90% of the sale right there.

It could be argued that making a pen by hand does exactly that in solid form right there on the lathe. Instead of moving lines, more material is carved out or smoothed over a curve. My designs are tweaked on the computer screen before the machine is directed to make exactly that. Different forms of artistic expression, but the same goal.

 

[RussFairfield]

Bruce,
The arguement over Craft vs. Art vs. CNC Production has been simmering for for several years among woodturners. It always remained an academic exercise because nobody was using CNC technology to make bowls. You just brought this arguement into the real world. Be ready for the "resistance" when the "artists" find out about it.

 

[Randy_]

Originally posted by RussFairfield
<br />.....Remember that a diameter difference of as little as 0.003 can be felt with our fingers, and one of 0.010" will apear as a huge mismatch.

Just to put that into a "real world" comparison, 0.003" is about the thickness of a sheet of your average daily newspaper!!

 

[jwoodwright]

Wow! Russ, what an interesting point. We do get some friction going. [:I]

 

[btboone]

Art is definitely in the eye of the beholder. Although I could run fast production and sell good pens cheap, that certainly is not my goal with CNC. I want to be able to produce pens like OMAS or Tighe. To me, the pen kits aren't that much challenge for a CNC. The real challenge is pushing the envelope a bit and working out new designs and the techniques to be able to produce them. As an example, I like the idea of a retractable fountain pen. It would certainly take some custom parts to be able to do something like that. The CNC allows the freedom to be able to produce stuff like that. It takes some inventiveness to design both the pens and the fixtures to be able to make them. The ol' #2 morse taper pen mandrel won't do it.

 

[Fred in NC]

CNC? That is just another hysterical debate!

It happened when color photography came around. Acrylic paints. Airbrushes. New casting methods for sculptures. Etc etc.

There are woodworkers that will not use power tools! There are turners using human powered lathes. Yes, even today in 2005! I respect them for the talent and ability, and preservation of old methods. Ironically, these old school woodworkers have internet groups !!!

One debate going on today is about using lasers for internal measurement when turning hollow forms.

Most buyers are only interested in the final results. They can't care less if the finished product was taken to the art gallery on horseback.

<b>Art has to do with beauty and uniqueness. The method employed is irrelevant.</b>

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Legal disclaimer: The opinions expressed above are mine. I could not care less if your opinion is different from mine. I am entitled to rant just like anyone else.

 

[Gregory Huey]

I have been using micrometers to build pens for a few years now. I do measure every pen kit as I have seen as much as .003 change in center bands in the same style kit.

 

[woodscavenger]

If you get a kit for a retractable fountain pen then sign me up. I was always too cheap to buy the one made by Pilot. It is a great pen mbut only came in a fine nib which writes like crap for most lefties so I didn't do it. They actually made two versions that I am aware of. The older version is my favorite.

 

[btboone]

Woodscavanger, does the Pilot pen have a click type mechanism or a twist type mechanism? I was thinking about a twist one, something like a tube of lipstick with a high helix lead. Maybe an outer sheath is clear so you could still see the nib? It would be a high end pen, that's for sure.

 

[RussFairfield]

Your competition is the retracting point Namiki (by Pilot) that is available in fine, medium, and broad for $90. It has a solid gold nib that in my opinion is one of the best writing points available, regardless of price. (My opinion)

http://www.worldlux.com/cgi-bin/navigate.cgi?brand=NAMI&dept=PENS

 

[woodscavenger]

Here are photos of the two most recent models. The one with multiple pens is the older style. I actually prefer that style to the old one. What you'll notice is the clip is at the same end as the nib so if there is a retraction failyre you don't get a pocket full of ink. I also included a link to a sight that details their history by a fanatic collector.

<br />
http://www.riverapens.com/vanishing_point.htm

 

[btboone]

Nice pen. I see that one has a click mechanism. I don't think I've ever seen one that twists out. Something to ponder in my "spare time." []