On Nov 15, 12:24*am, "DoN. Nichols" wrote:
On 2011-11-15, Searcher7 wrote:
* * * * [ ... ]
Thanks everyone.
To answer the questions, the grooves I have to make don't need to have
near perfect tolerances. I'm creating the grooves to place 3/16" wide
phosphor-Bronze strips in them for new contact blocks I'm making.
* * * * O.K.
* * * * If you were working with high frequency RF, Teflon makes a
wonderful insulator, but is probably overkill for the machines you are
working-with/modifying/making.
I'll be running minor voltages (+3.3, +5, +12, +24 -5, -12) through
the contacts.
Making the grooves over-sized wouldn't be a problem because the 1/8"
distance between them is flexible. (In fact I may just go with 1/16"
between each groove).
* * * * You probably want the grooves slightly oversized to give the
fingers room to spring.
Yes. I may lay a 1/16" Nitrile or Styrene Butadiene/Natural Rubber
blend pad in between the block and contacts to keep the contact
consistent between all of contacts of two opposing blocks during heavy
vibration.
The grooves, are just to make sure the strips don't shift. The
finished nylon pieces will be 4-1/2" long, 3/4" wide, and 1/4" thick,
and the grooves will be on the opposite 1/4" sides. Each strip will
wrap around into it's own groove.(Which will probably be the toughest
part of this project).
* * * * O.K. *Just two contacts per, then. *Sort of like this as an end
view?
* +---------------+
* | * * * * * * * |
* *| * * * * * * |
* *| * * * * * * |
* *| * * * * * * |
* | * * * * * * * |
* +---------------+
I'm not sure I get the ASCII above, but here a drawing of the flat
surface of a contact block and a contact block with the strips laid
across and bent down into it's grooves:
http://i290.photobucket.com/albums/l...ntactBlock.jpg
I was hoping that cooling would not be an issue because I'll basically
be making a 4-1/2" long grooves, moving over about 1/8", and then
repeating for a total of 16 of these grooves. I can then cut off 1/4"
thick slices with my band saw. (The other alternative is to cut off
the 1/4" thick slices first and make the grooves in each piece). :-)
* * * * I would suggest that would be preferred, since that will let you
go a little too thick and make a nicer finish with the mill before you
turn it to mill the grooves.
I figure I can use a hand file to clean up if needed.
I guess my mini mill(with sharp 3/8" end mills) is the best machine
for the grooving job, out of the what I have. (I just have to get it
fixed first).
* * * * Yes -- that makes a difference.
* * * * You might, if you clamp the plastic to the mill's table with the
two sides to be grooved on front and back edges, try a 1/4" woodruff key
cutter (if you can find one that big) which would be closer to the
horizontal mill cutter which I said I would use by preference.
I can't seem to picture what you're saying, but I assume a woodruff
key cutter would create a flat bottom groove. (Since these blocks will
only be 4-1/2" long, it looks as though I will definitely go with the
1/16" spacing between grooves in order to fit all 16 on each block.
(The blocks will be clamped by the grooved sides anyway).
I have a lot of Delrin, which is also my favorite, but I like to save
it for the critical stuff, since it is not cheap. :-)
* * * * Understood. *Compare it to Teflon. :-)
I had some opportunities to pick some up relatively cheap, but didn't
foresee any use for it at the time. :-)
Thanks.
Darren Harris
Staten Island, New York.