Pen accuracy question

[terry mccammon]

Hi

I am a newer turner still figuring out most everything and I have a question about fit and accuracy on pens. An example is what happened last night. I made a pen using a blank of good, stable cherry. When I was turning and finishing, I was very careful to ensure that I was dead nuts accurate where the bushings and blank touched. I could close my eyes and feel no difference in size at the junctions. But, when the pen was assembled, the writing tip was proud of the lower barrel enough to see and feel. Likewise the pen cap was larger than the upper barrel, enough so that to me it just looks wrong. The band was too small on the upper barrel which is less apparent as that particular band has a rounded edge. The various parts were concentric, just off size. The bushings were new and mic'ed to the dimensions given on the instruction sheet that came with the kit. The kit was from Craft Supplies.

At our club meeting I have seen several where the fit was perfect to the eye and finger. Looking at close-ups posted on line and in Dick Sing's book the fit looks accurate as well.

Am I being a a typical engineer jerk, is this the way it is, am I buying cheap kits? This has happened on every pen I have made (not all that many) but yesterday I was very careful and am sure about the fit to the bushing.

Advice and assistance much appreciated.

Terry

[Lee Koepke]

Depending on the kit that you used, the tolerances arent 'engineer' perfect. Its typical to verify your final diameter with calipers to the particular component you are using, the bushings 'get you close' but never perfect.

Also I have had some issues when I put on too many coats of CA, it will stand proud of the tip / cap slightly because I didnt allow for that extra thickness. MOSTLY, I dont concern myself with these variances, but it irritates me to no end when what you describe happens to me. I have a drawer full of pens that I feel arent suitable for sale, and yet people still buy the ones from my drawer.

[James Combs]

I can't say that I check kit parts against my bushings 100% of the time:rolleyes: but I do check(as Lee says w/calipers) them frequently especially if it is a pen style I haven't made in a while and DAMHIKT. I have also used the wrong bushings a time or two,:o as in using Woodcraft click pen bushings for Slimline Pro pens. Not a good fit, take my word for it:eek:. Those two sets of bushings look very similar but there is a noticeable difference in size if you are looking for it:D.

[Robert McGowen]

Since all of the joints appear to be off, my guess, without knowing which pen kit it was, is that you assembled the pen incorrectly. It is easy enough with some kits to switch the top blank and bottom blank during assembly. The pen would "look" right if the blanks were similar length, but the ends would be a different diameter than the pen kit parts, which is how you describe the finished pen.

[James Combs]

Since all of the joints appear to be off, my guess, without knowing which pen kit it was, is that you assembled the pen incorrectly. It is easy enough with some kits to switch the top blank and bottom blank during assembly. The pen would "look" right if the blanks were similar length, but the ends would be a different diameter than the pen kit parts, which is how you describe the finished pen.

Robert makes a great point. If it was a cigar style pen, each of the four bushings is a different size. If you put them in the wrong locations that could be part of the problem.

[David E Keller]

In my world, that would likely be he result of me screwing up something, but I'm told that kit parts can vary. If you really want to know, check the size of the part in question relative to the sizes listed in the instructions. I've made a number of pens wih the bushings in the wrong position... Very frustrating!

[Jim Burr]

I'll bet you're using a pen mandrel. Stop and order some bushings from Johnny C&C. No pen will ever be perfectly round...just can't happen. The one I sent to our Pastor this morning, he's in Hong Kong (long story) had a run-out of 1/800" I'll take that any day of the week!
CSUSA makes a fine kit, I don't care for the Apprentice line...just MHO, but the regular stuff is fine quality and I use it on a daily basis. Good point on the Cigar bushings...pain in the butt!

[Bernie Weishapl]

+1 for Johnny C&C.

[Kyle Iwamoto]

I found out that when you sand the blanks, and sand the bushings, to make absolutely sure that you are spot on accurate to the bushings, that you can slowly sand the bushing down, and your pen is toast. It may seem elemental to stay off the bushings when sanding. Took me a long time to figure it out. Sometimes the most basic of steps escape us engineer types.

By the way, you can buy a pen disassembly kit, and save your parts......

[terry mccammon]

Thanks for all the suggestions. As one would expect, it never dawned on me to check bushings against the parts to see if they were accurate. Will do so in future. Normally I would suspect me as the cause as in my world it is always my fault. But in this case, I was so careful to keep everything straight. Plus in the case of this particular kit, not so easy to confuse upper and lower.

Let's also be clear. I am new at this stuff and nearly everything I have ever made looked like the back of my lap. So when this pen was going so well (even managed to shape with skew without screwup) I was pretty excited to have something that I did not either throw in the drawer or the trash. Then to have it not fit to my idea of perfect, I was really annoyed. The reality is that we are talking a few thousands, enough to feel and see but not really noticable unless you are a PIA like me.

Will benefit from suggestions as I do from following the discussions on this board. I am amazed by the things I see that you ladies and gentlemen post. Thank you.