Tube length/accuracy

[dw]

I have a question that's really a comment. I ordered a euro twist pen from one of the major kit manufacturers. Having had some previous problems with accurate sizing on bushings, etc., I have decided to measure everything with a caliper.

The instructions on this particular kit say to cut the wood for the upper barrel inch and seven-eighths. That's good information. But this kit requires that a part of the tube be left uncovered by the wood.

I wondered if anyone knew exactly how much brass should be exposed?

The tube appears at first glance to be 2 inches long but measured with a caliper it specs out at 2.012 inches. Who knows if that's a miscut on the tube or if it's even critical?

It would also be helpful if manufactures would label all parts with their specs and tolerances. If a tube is supposed to be 2 inches long but is cut 2.012, at least you would know that there is a bit of surplus that can be trimmed. And more importantly you'd know how much brass must be exposed on this particular kit.

Having said all that, I would add that I understand completely that at its most basic a person ought to be able to figure out how to put together a pen kit without any instructions---but in my opinion that concept depends entirely on parts being accurate and to spec. If they are not...and already I've experience several kits that were not...then all bets are out the window.

Thoughts? I'd appreciate any input on this.

 

[Scott]

Hi DW,

I think the critical measurement is how much wood is left after cutting the tenon, not the size of the tenon, as long as it's enough to hold on to the center band. Don't quote me. When it comes to tenons, I usually cut the tenon after turning, by using a parting tool. Your tube is probably that much over 2" so that you can lose a little in trimming. I hope this helps!

Scott.

 

[Tom Stephens]

DW
I would not cut the blank short even if I knew how much brass
needs to be exposed. How would you square the end of the blank
with the exposed brass?
I always turn the wood down to the brass (as required) when
turning the blank. If the instructions do not tell you how
much brass to expose, then call the supplier.
I believe that most pen turners do not try to cut the blanks
to the exact length. Usually - cut long, drill short (NOT ALL
THE WAY THROUGH!), cut again closer to final lenght, glue tubes
and then square the ends.
Tom

 

[dw]

Thanks guys. I've never been too good with a saw. I tend to want to see the length be *exact* and it never is. What I've been doing is setting my calipers for the right length...1 7/8" for example...then wrapping the end of the tube with masking tape. Then I hold the tube against one "wing" of the caliper and, with a razor blade, trim the tape against the edge of the other "wing." Then I peel off the surplus tape. That leaves me with exactly 1 7/8" of exposed brass. I slide the tube into the blank and use the barrel trimmer to square up both ends. Then I apply my epoxy and insert the tube into the barrle all the way to the masking tape. When the epoxy hardens I barrel trim the end opposite the tape right down to the brass. Voila! The wood is exactly 1 7/8" long and my brass tube is exposed.

Of course I wipe all excess epoxy off the tape and the wood ...I believe a little renaissance wax on the tape and the tape end of the wood would make final clean up a cinch. That thought just came to me today. But I've been simply scraping the slight amount of excess off when it hardened enough to scrape. No problem doing that and the trimmed barrel remains unfazed.

It seems to work, for someone who is saw challenged...maybe there's a flaw in my reasoning?

DWFII