Shaft Coupler Machining

As you might know, many parts claimed to be made here in the US, are kind of pushing the definition a bit.  For example, these 6mm couplers that we sell were machined in Germany and then bought by us for resale. They were not to our liking, so we do a bit more work on them.  They come with only two set screws, and those are a flat slot, screw driver type of set screw.  So we drill two new holes at 90 degrees to the first ones, and use socket head set screws for all 4. 

Now since we are doing a “machining” operation, and then, “assembly”, by all the norms of what is accepted as “standard business practice”, we could claim that we make them.  Well, we didn’t really make them, but we do work on them a little bit.

Here’s a picture of our mill.  It’s a Briddgeport copy, made in China, bought new to make Audience Reaction Pedals.  That’s a pro-audio product, see here.

Yep, that’s an old pinball machine over on the left.  This mill is not CNC, but does have an X-Y digital readout for the table.  It allows us to make parts to a 0.001″ accuracy.  We have a lathe also, but we’ll save that for another page.

So we drill two little holes in the brass coupler, and then hand tap them.  I actually have a very expensive automatic tapping head (a Tapmatic) for the mill, but to do just 80 pieces, which is how big this first batch is, it is hardly worth it.  It takes 1-2 hours just to set up the tapping head to operate correctly.  We did the whole batch in an hour.  You can also see that I made a “down and dirty” jig to hold the coupler, out of plywood.  If I was doing 100’s of these, I would machine a jig  out of 6061 T6, and the work would go faster.

My son wanted to learn some machining skills, so here he is drilling the two additional holes in each coupler, which is not as simple as it sounds, as each piece must be clamped correctly in the vice/jig, and the table moved to the exact position required on the digital readout, or the drill bit will just walk off the round coupler, breaking the bit, or ruining the hole.

So, this is how we “make” the 6mm coupler.  It’s small enough, 12mm OD, to replace the problematic bandswitch coupler on the 530S/830S without taking the final cage apart. 

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