Do you check the press fit diameter?

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Do you check the press-fit component diameters?

  • Yes, I check the fit!

    Votes: 10 23.3%

  • No, I don't check!

    Votes: 22 51.2%

  • I will now!

    Votes: 11 25.6%
  • Total voters
    43
ChrisN

ChrisN

Member
Joined
Mar 23, 2013
Messages
730
Location
Denver, PA
Today I was happily making my first feather pen using Majestic components. I got the blanks turned and polished without incident. They turn very nicely! Anyway, I went to assemble the lower barrel, and I noticed the finial was tight - normally you can slide the components inside the tube ~1/32" before you need to press them in with something other than your fingers. This one barely went in at all. But I started pressing it in anyway and it cracked the blank!:mad:

I knocked the finial out of the blank, and checked the diameter of the press fit part. Then I measured the tube in the blank (at the other end), and I also measured the tube that came with the kit. The finial press-fit part was ~0.008" larger than both tubes. So I measure the threaded piece for the other end - it was only 0.004" larger than the tubes!:confused: So that would probably explain why the fit was tight and the blank cracked! I measured a finial from another Majestic kit that I happened to have, and it measured the same - 0.008" larger than the tube!

So long story short, do you measure the fit of the components? I didn't this time, but next time I use a high-end blank, I'll definitely check to make sure I don't crack another expensive blank!
 
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I have never checked the dimensions on any components and have never had a blank ruined for that reason. I know a lot of people have an issue with trustone type blanks but I have never used any. Did you get the components from a reputable dealer? Maybe the parts got mixed up somehow? Can't blame you for being upset and if I did have a problem like that I would probably want to make prior measurements too.
Tim.
 
I do not check.... but I think it is a good idea to check everything out. One minute or two of measuring saves a lot of time and money.
 
With special cast blanks, I sand the inside of the brass tubes for a slide-in fit. Feathers, watch parts and any other expensive blanks - I want no pressure to potentially damage them. I then use Locktite to secure the hardware.

Most cracks would appear when we assemble, but temperature changes, or even just the unrelieved initial pressure, may cause cracks down the line.
 
I guess the basic question is `How much interference constitutes a secure assembly while minimizing the risk of blank failure b?` . My best guess - and it is a guess - would be 2-3 thou . I would certainly think 8 thou is excessive for this application .

However , measuring the amount of interference is not quite so easy . It is easy to get the insert OD , but not so easy to get an accurate tube ID .

The other side of the coin is when you can press the component nearly completely in by hand , which means a glue job is required .
 
Particularly as we look at the "sierra-size", or the "Jr. Gent size", it will be wise to measure before forcing the fittings into the tubes.

We (penmakers) "assume" the tubes will be the same from one pen design to the next. This may NOT be a safe assumption. Certainly, "on ounce of measuring is worth a pound of cracking". There are many suppliers of "sierra tubes". I can tell you with certainty that they are not all exactly the same ID and OD. VERY close, but not exact!!

Just a FWIW,
Ed
 
Out of curiosity, I started checking the I.D. of the tubes with small hole gages or ball gages and micrometers. Then I would check the O.D. of the mating parts with micrometers. I was surprised how variation there was in both actually.

Maybe I need to keep track of the dimensions in a spreadsheet just for kicks and grins.
 
I do not check the sizes. I only buy tubes from the where I buy my kits and don't belie that I've ever had a problem in this area.
 
panamag8or said:
You sure the blank wasn't for a Jr. Majestic? I don't know, just throwing that out there.
Click to expand...

Well, there is a slight difference between the blank sizes for a Jr. Majestic and a fullsized Majestic, isn't there?:biggrin::biggrin: The upper & lower barrels happened to be connected together when I got them, and the upper barrel made a quite nice Majestic cap, so I am quite sure the lower barrel was also for a Majestic.:biggrin:
 
thewishman said:
With special cast blanks, I sand the inside of the brass tubes for a slide-in fit. Feathers, watch parts and any other expensive blanks - I want no pressure to potentially damage them. I then use Locktite to secure the hardware.

Most cracks would appear when we assemble, but temperature changes, or even just the unrelieved initial pressure, may cause cracks down the line.
Click to expand...


Thanks for the tip. I was going to ask how you would prevent cracks with tube-in pens. I don't want to ruin another feather blank! I'l have to remember this tip for the other tube-in blanks I have.
 
jscola said:
this is a dumb question. Would you sand the inside dia of the tube to get the part to fit ?
Click to expand...
I've used a file to remove a little of the fitting. In most cases I've used my collet chuck to hold the piece & file of enough for a slip fit. Then I use blue locktite to secure the fitting.

I voted that I don't measure. But if I'm making a segmented pen with segments near the part that's pressed in, I file the fitting to get a slip fit.

Here's why:
 
I have had this happen to me a couple of times as well.
Most recently with the cap of my Retro "She-Oak cast" Pen , it is very annoying when it happens.
 
Just about any industrial supply house sells ball gages. Either flat bottom or ball end will work. Flat bottom are for blind holes but also work on thru holes.

Adjust them in the hole to the point that you are just dragging on the I.D. Not tight. Slide them out and measure them with a set of micrometers while rotating them. They are made out of round so there is a high spot to measure with. They are more accurate that way. BTW, use micrometers to measure them, not calipers.

I have a set of flat and ball that I use. Both are Starrett brand. They will measure from about 1/8 to 1/2 diameters.
 
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