delrin issues

For discussion of fitting and shaping stems, doing inlays, and any other stem-related topic.
caskwith
Posts: 2196
Joined: Sat Dec 08, 2007 6:00 am

Re: delrin issues

Post by caskwith »

Charl is right, the actual size unimportant as long as your stock is consistent and you have a suitable drill bit. My post was just to illustrate my own cicumstances.
Albert.A
Posts: 173
Joined: Wed Mar 05, 2014 3:29 pm
Location: Stockholm, Sweden

Re: delrin issues

Post by Albert.A »

Very true gents, very true. :)
Perfection is key, but damn near impossible to achieve!

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oklahoma red
Posts: 1084
Joined: Tue Apr 12, 2011 6:14 pm

Re: delrin issues

Post by oklahoma red »

Albert,
Don't sweat the minor stuff. Two approaches to consider:
1. if you're going to make a stem with an integral tenon, cut the mortise in the shank first. Then carefully sand and polish the tenon to get the proper fit to the mortise, period the end.
2. if you are going to make a stem with a Delrin tenon don't worry one iota about the rod being over or under its nominal size. Sorry, but I'm gonna have to continue on with the inch system as I don't know the step sizes in metric. Make and install the tenon into the stem first THEN do the mortise. I'll use a 5/16 (.3125) tenon as an example (closest equate to your 8mm). All of the 5/16 Delrin I buy will vary .001 to .003 in diameter (usually more to the minus side than to the plus). I first drill the mortise with a 19/64 bit (.2969). I then carefully measure the diameter of the Delrin tenon with a micrometer or a good pair of calipers. I then ream the mortise with a chucking reamer. These are available on this side of the pond in both one and one-half thousandth increments. I'll first ream the hole .001 under WHATEVER the Delrin measures and test the fit. If it is too tight I'll ream again with a reamer that is .0015 under the Delrin measurement.
If it is still too tight (rarely!) then I'll revert to fine sand paper wrapped on a pin and CAREFULLY sand the mortise to get the fit right. Leave the Delrin alone! You cannot un-ring a bell nor put back briar that you've cut away so think first then proceed.
The fit of the joint will make or break the pipe. You can carve the pipe with whatever means are at your disposal but don't try to cut corners on the joint. I'm sure similar incremented metric reamers are available in the EU. Don't worry about the diameter nor the issue of the rods not being real straight (unless it's bent up like a pretzel) since you're using such short pieces. One thing that helps is to buy the rod in the shortest lengths available.
Delrin is one of those things that you either swear by or swear at but it is a good option for those that are "lathe-less" if one follows the steps that have been outlined elsewhere on this forum.
The steps I've outlined for utilizing Delrin work for me but they are by no means gospel. Others may have different methods.
Good luck!
Chas.
Albert.A
Posts: 173
Joined: Wed Mar 05, 2014 3:29 pm
Location: Stockholm, Sweden

Re: delrin issues

Post by Albert.A »

Thank's Chas. 1. is what I'm currently using and feeling pretty safe with (in terms of flush and good fit) so I think I´ll just stick with that one. Now that I think of it I don't really know why I wanted to try delrin when I already have the means to make integral tenons.

Maybe I'll just make toothpicks or something out of the delrin I now have. :lol:

Thanks!

/Albert
Perfection is key, but damn near impossible to achieve!

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DMI
Posts: 421
Joined: Mon Nov 02, 2009 8:48 pm
Location: Northern Ireland

Re: delrin issues

Post by DMI »

I now order 20 metres at a time and then find a drill bit to fit the rod, when I phone in the order I specify that all the rod must be from one casting batch.

I've had mixed batches of 8mm rod that mic up at 7.5 through to 8.5 mm which is next to useless if you are trying for smooth production.
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