lml@lancaironline.net Mailing List Archive

Bill,

The stock pin size at the time of my testing was 0.085". Some time later I saw a notice on the Carbinge website stating they had switched to .080" as the new standard. I have some of that material as well and it measured out at 0.078", like your sample.

Yes, Nylon increases dimensionally with moisture. There a lot of papers out there that quantify the effect. -also how to mitigate it, such as adding glass fiber etc.

Chris

Chris Zavatson

N91CZ

360std

www.N91CZ.net

From: Bill Wade <super_chipmunk@roadrunner.com>
To: lml@lancaironline.net
Sent: Tuesday, December 6, 2011 5:43 AM
Subject: [LML] Re: [Norton AntiSpam][LML] Re: Legacy vibrations resolved

Hi Chris-

That’s a bit worrisome. Does Nylon swell when it absorbs moisture? Shrinkage could cause a double whammy- loosening not only the pin fit but also the fit of the sleeve in the carbon bore.

Your earlier post mentioned a pin diameter of 0.085”. The stock pins I measured with my Ebay Chinese calipers showed 0.078-79, so the 0.083 diameter I settled on improved the fit. In your case that would result in a looser hinge. It appears that anyone who wanted a tighter fit might have to experiment with a range of sizes as I did initially.

I accidentally got some Superfil in one of the hinge bores. After pushing out the resulting plug it measured 0.090 (for reference only- your results may vary). That might be a way for anyone else to get a starting measurement for pin sizing. -Bill Wade

From: Chris Zavatson

Sent: Monday, December 05, 2011 8:58 AM

To: lml@lancaironline.net

Subject: [Norton AntiSpam][LML] Re: Legacy vibrations resolved

.....

Nylon is hydroscopic. This means Nylon absorbs moisture and changes dimensionally as it does so. In many applications this can be accommodated, but here a change of just one percent would turn a nice close fit into a no-fit. Many papers have been devoted to quantifying the relationship between relative humidity, moisture content and dimensional part growth. Nylon is not well suited for applications where dimensional stability is needed. Extra dimensional tolerance must be allowed in design to accommodate this characteristic.

....