Author Topic: 3d indicator design  (Read 34422 times)

Offline PekkaNF

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Re: 3d indicator design
« Reply #75 on: August 31, 2012, 04:04:23 AM »
..
While it appears reasonably consistent in any one direction ( i.e. once zeroed in a direction it will return to zero within 10um - even if removed from the lathe),  it will not accurately measure between faces because of the play in the bottom taper slide (I had to re-ream this after I threaded it, so I guess it's now too big :()

Maybe it's time to throw in the towel ? (I've lost faith in the design)

Bill
The toublemaker...is it part "lower taper"on picture at your Reply #53 on this page? Would making a new one rectify this problem? Or are you this feeling of uncertainty, when one thing gets fixed and then another chalenge manifestes itself?

To me more changing part looks  "upper taper" . Is it guided on the double tapper end (I mean the narow end that has a taper on both sides) or at far end? You are working on acuuracies and geometries that are pretty chalencing. To me it looks like you wanted to make this probe as short as possible and that will produce fairly narow land on this double taper end which looks to me like very important guide.

I think that the basic design is sound, it just needs some tweaking to get it Goldilocs right.

What is that professional looking probe on upper picture?

Pekka

Offline BillTodd

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Re: 3d indicator design
« Reply #76 on: August 31, 2012, 03:46:14 PM »
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The toublemaker...is it part "lower taper"on picture at your Reply #53 on this page?

No, the problem is the vertical slide part of the ball-slide., when I threaded the part is shrunk slightly.  I had to re-ream it , (which I made a hash of) and now it doesn't fit as well.

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To me more changing part looks  "upper taper" . Is it guided on the double tapper end
Yes, I know what you mean. My hope was that the DTI spring would force it to one side thus reducing the error caused by the slack.

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I think that the basic design is sound,
sound maybe, but not good - it is too reliant on near-perfect sliding joints -  Like the case of the 'upper-taper' above, it started off a very good fit, but as the device was polished and used  the fit became worst - to the point of not being accurate enough.

I'll have another look at it over the weekend, but I have a lot of work coming up, so the 3d probe will have to go on the back burner if it isn't abandoned.


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What is that professional looking probe on upper picture?

It's a Sony TS1 touch probe - It plugs into the back of the Magnascale DRO allowing it to locate to a couple of microns (it says in the manual!)  - It really just a 10mm ball (on a spring) . When it makes contact with ground (machine/earth) it completes a circuit that tells the DRO to bleep (in an annoyingly loud way)

Bill
Bill

Offline BillTodd

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Re: 3d indicator design
« Reply #77 on: February 28, 2015, 03:28:32 PM »
Time to revive a 2 1/2 year old thread....

Dug the old prototype out again the other day and began wondering if the design could be rescued  - having set it up in the mill , it didn't seem as bad as I had led myself to believe, so started thinking again .

The main problem with the design is its (over?) reliance on sliding joints , so improving these seems like a place to start

The upper taper can be made self-adjusting by adding a  floating taper part which expand a new springy upper taper (or at least that's the theory)

more later...
Bill

Offline BillTodd

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Re: 3d indicator design
« Reply #78 on: March 01, 2015, 01:30:25 PM »
Well made the floating taper part. Turned the taper in the existing upper taper to fit the new part then try to cut the slots in it... all the time i'm thinking - make a fixture ,  make a fixture then bang -  end of part one :Doh:


2 hours later I have another upper taper made and, this time a fixture to hold the taper while slotting.

Troble now is the new part is tight and needs to be 'run in' ... Sometime this week I'll pop it in to one of the bridgeports at work and see if it has improved any.
Bill

Offline Manxmodder

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Re: 3d indicator design
« Reply #79 on: March 02, 2015, 01:05:27 AM »
Bill,I hadn't seen this thread before now,that's a really fine piece of prototyping work and I'll be watching with interest......OZ.
Helixes aren't always downward spirals,sometimes they're screwed up