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Looking for a vendor for 0.6 - 0.8 mm shafts — Parallax Forums

Looking for a vendor for 0.6 - 0.8 mm shafts

varnonvarnon Posts: 184
edited 2017-10-02 14:43 in General Discussion
Hi all,

I haven't posted or even read much on the forums in a while. I've been very busy finishing my phd, with a propeller-powered dissertation, and applying for jobs. I'm now an assistant professor psychology (animal behavior), and I'm looking to start working on some more animal behavior research equipment. I had to leave most of my old equipment at my previous lab, as it was built on my advisor's budget. As I'm working on new things, I'm rethinking the designs a little.

This time I'm working on a shuttle box that can deliver shock across a small grid. I'll be using this to study learning in insects. It occurs to me, that for the insects I am working with, 0.1" pin header spacing is about what I want for the shock grid. I would like to find rods that can fit into the female pin headers. This would be very useful for me, and it would make my equipment much easier to design, assemble, clean, and modify.

I'm measuring the pins at ~0.64 mm from side to side, or ~0.8 mm diagonal. I think 0.6 or 0.7 mm rods would work. Uncut copper pin header rods would be fine, but stainless steel rods would be even better. I will likely need something 100 - 200 mm long. So far, I have not found rigid rods of this diameter at the vendors I normally check. I mostly only find flexible wire. I have found a few dowel pins that are close, but they are either not the right diameter, or very short

Any suggestions?


  • Heater.Heater. Posts: 21,233
    Not sure there is any material that is 0.07 mm diameter and 200mm long that is noticeably rigid.

    I suspect what you need is something like stainless steel wire and stretch it taut over a frame. Think tennis racket.
  • varnonvarnon Posts: 184
    edited 2017-10-02 14:43
    Thanks, I might have to go that route. The actual pins on the male pin headers are plenty sturdy for my purposes. It's just not long enough.

    Also, brain fart. Added an extra zero to those measurements. I need something around 0.7 mm, not 0.07 mm.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,977
    edited 2017-10-02 15:03
    Music wire is probably the most rigid in that diameter. It comes in straight lengths, but it's not rust-proof.

    And here's some spring-tempered stainless wire:

  • jonesjones Posts: 281
    edited 2017-10-02 16:52
    0.7 mm is about 0.03". McMaster-Carr carries 0.032" hardened 304 stainless steel (spring temper) rods in 305 mm (1') lengths. or just search for music wire to find other sizes.

    If you need something smaller, another option might be to use crimp pins on stainless wire, and stretch the wire across a frame (e.g. G-10 fiberglass) as Heater suggested.
  • You might want to experiment with different diameters first. Header connectors are designed for 0.025" square pins. That's why I selected 0.025" (0.635 mm) wire. But wire is round. So a slightly larger diameter may be called for to fit the socket more tightly. You just don't want to permanently spring the contacts.

  • varnon,

    Is the entire grid electrified or do you need to control each individual point?
    I am thinking that you could investment cast the entire grid from a 3D print.
  • A printed circuit board, sans soldermask, laid out in the desired grid pattern might also work.

  • Congratulations on the degree and the job!

    #7 insect pin will be 0.7mm diameter and 50mm long.
    They are very stiff.

    Round pin header sockets might be an option, various sizes available, clamp from 4 sides instead of two.

  • Thanks for all the suggestions everyone. I ordered a few rods of different diameters to play with. I have at least one rod that will work now, but I'm still waiting on the other alternatives. I'll update the thread once I find the part I like the most.

    To clarify some of the other comments, the entire grid is electrified. The odd rods will be positive, the even rods will be ground (or vice versa). I'll use some sensors to know where the animal is. I can then activate shock when the animal is in a specific position. To them, it can seem as if only certain points are electrified. I could potentially cast a grid, but I think the rods method will be a little easier. I also don't have my new printer yet. A PCB would potentially work, but any liquid, including animal waste or vomit, on the board might short the grid. The purpose of having elevated rods is so that waste falls through the grid and is less likely to cause a short. I haven't seen a PCB service that can do such an odd shape. I haven't looked into it a lot though. I want to get more in to custom PCBs, but for now that is a new skill for me that I don't really have time for.

    You can see a rodent example here:

    If the grid is well constructed I can work with a very mild shock. I would prefer this. I only want my bugs to learn to "dislike" something, I do not want to cause them any actual damage. For bees, if the shock becomes too strong, they will start stinging the shock grid. This either causes the grid to be shorted by the venom, or causes the bees to receive even more shock. Mild shocks are thus better for both ethical and experimental reasons.
  • W9GFOW9GFO Posts: 4,007
    0.025" or 0.032" aviation safety wire should work for you. It is stainless steel and comes in rolls. Put one end of a length of wire in a vice with some locking pliers on the other end and give it a good sharp snap to straighten it out.

  • Aviation safety wire, neat. I'm learning about all sorts of new wires.

    I think, based on the parts I ordered, McMaster's music wire is going to be the best. McMaster was my first stop for wire, but I did not see anything that fit. Sometimes you just have to know the right terms to search.

    I ordered 0.029" Spring-Back 302/304 Stainless Steel Wire. This size seems to fit very nicely in the female pin headers. It is snug, but not too hard to assemble. (Larger diameters are a little more sturdy, but it is more difficult to assemble a grid between to female pin headers.) The wire is also a good rigidity for my purposes. And the finish on the wire is nice and smooth, so the bugs have to work a little harder to grip the surface, which makes it a little easier to shock them. The 1-foot lengths are nice too. They are already straight enough for my use. I think this is something easy enough that I could have a student assemble it. That is always a plus, and was NOT the case with my last shock grid. I think I will be really happy with this. Thanks for your help everyone.
  • @"Tracy Allen" said:
    Congratulations on the degree and the job!

    7 insect pin will be 0.7mm diameter and 50mm long.
    They are very stiff.

    Round pin header sockets might be an option, various sizes available, clamp from 4 sides instead of two.

    Thanks for the link. However, we sold our original domain & old link doesn't redirect correctly. So, here's the new one:

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