"Tom Gardner" wrote in message
...
On 7/12/2014 1:06 PM, Carl Ijames wrote:
"Tom Gardner" wrote in message
...
On 7/12/2014 9:02 AM, Bob Engelhardt wrote:
On 7/12/2014 5:29 AM, Karl Townsend wrote:
...
My *guess* is pre sltting would not be any easier and would slow down
the CNC lathe work.
The trade off is slitting 15 4" pieces vs 1 5' piece.
BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5'
piece. $2.50 material cost for each 4" piece! 'Course when you're
buying 2500', you'll get a better price, I hope.
Bob
Their lab tried that size and it's too small.
[/quote]
So when you say they will supply the Delrin, does that mean they supply
tubing with the correct id and od, or what? If the outside is going to
need
turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide
each piece onto a SS tube mandrel (have to experiment a bit on the size)
and
toss piles of them into an oven at 425F or so for 30-45 minutes. The
Delrin
will anneal and relax and take up the new ID of the mandrel +/- a bit, so
you get your correct od without turning the full length. Two sets of
mandrels so while one batch is baking the other is cooled, finished tubes
removed, new ones loaded on the mandrels and the mandrels loaded into a
crate maybe standing them on pegs or whatever, so the entire oven can be
unloaded and reloaded quickly. Anyway, just a suggestion.
-----
Regards,
Carl Ijames
They will supply tubing 1.040" UD x .500" ID and want it bored to
11/16". I wonder if their original size of 1" OD x .75" id could be
stretched open to provide more holding power? That would eliminate yhe
boring op.
[/quote]
I figured I better check if you are going to try this, and my memory was a
little off. Here's a table I found online for lots of different plastics,
handy as a guide
http://www.boedeker.com/anneal.htm. I was using 1/32"
thick by 1" Delrin strip that was straight, cutting 9" lengths, coiling them
inside a 1-3/4" od stainless steel tube, putting four side by side and four
layers. Any more layers and the id was too small. Put that into a toaster
over that is room temp-ish, set to 325F and turn it on. It was a big oven
that could do a 12" frozen pizza so it had a decent amount of heater power.
I used the convection toast setting so the fan, upper heaters, and lower
heaters were all on. Reached temp in about 20-30 minutes and the timer
turned it off after 45 minutes so 15 minutes at full temp for the soak. Let
cool to under 175F, maybe 45 minutes, so I could grab it barehanded, pop out
the coils and reload. That gave me coiled rings I snapped around 3" iron
pipe as trim rings that would grab tightly enough to stay put but if the
annealed diameter got too small they wouldn't lay flat and look good. I
wasn't going for a perfect anneal, I just needed them to hold the coiled
shape. Anyway, that table recommends a much slower heat and cool, soaking
at 300F, but that is a general recommendation for machined pieces up to 1/4"
thick. Your pieces will be thinner and I don't think need the greatest
precision so you can rush it a good bit. Yes, I'm sure the 1" od would work
fine - you can even make the slit 1/4" since it will grow about 1/8" when
you anneal to the larger dia.
-----
Regards,
Carl Ijames
"Tom Gardner" wrote in message
...
On 7/12/2014 1:06 PM, Carl Ijames wrote:
"Tom Gardner" wrote in message
...
On 7/12/2014 9:02 AM, Bob Engelhardt wrote:
On 7/12/2014 5:29 AM, Karl Townsend wrote:
...
My *guess* is pre sltting would not be any easier and would slow down
the CNC lathe work.
The trade off is slitting 15 4" pieces vs 1 5' piece.
BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5'
piece. $2.50 material cost for each 4" piece! 'Course when you're
buying 2500', you'll get a better price, I hope.
Bob
Their lab tried that size and it's too small.
[/quote]
So when you say they will supply the Delrin, does that mean they supply
tubing with the correct id and od, or what? If the outside is going to
need
turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide
each piece onto a SS tube mandrel (have to experiment a bit on the size)
and
toss piles of them into an oven at 425F or so for 30-45 minutes. The
Delrin
will anneal and relax and take up the new ID of the mandrel +/- a bit, so
you get your correct od without turning the full length. Two sets of
mandrels so while one batch is baking the other is cooled, finished tubes
removed, new ones loaded on the mandrels and the mandrels loaded into a
crate maybe standing them on pegs or whatever, so the entire oven can be
unloaded and reloaded quickly. Anyway, just a suggestion.
-----
Regards,
Carl Ijames
They will supply tubing 1.040" UD x .500" ID and want it bored to
11/16". I wonder if their original size of 1" OD x .75" id could be
stretched open to provide more holding power? That would eliminate yhe
boring op.