Faceter Pressure Sensor rather than Woolly depth of cut - experiences anyone ??

[ianRobinson]

Hi Folks
I have a late series polyhedron faceter - very similar to the Polymetric Scintillator. I am currently fitting a super new US Digital encoder for angle measurement based on that in Tom Herbst's book.

I am wondering - whilst I have it in bits, whether to use a pressure sensor rather than  the 'traditional' resistance based Beale/Woolley depth indicator. I.e the hard-stop pad has a pressure sensor between the hard-stop and the faceter body. This would be compressed slightly as the hard-stop is made. There are reasonable priced piezo-electric forces sensors now.

Has anyone experience of doing this and do you have any tips/recommendations. I am reasonably proficient electronically and programming up interfaces


Cheers

ian - in the sunny north of england

[Rusted]

Hi Ian,
A few people here have made the digital readout from the Tom Herbst books, It could be worth having a look at that.
MakkyBrown is a moderator here and has quite a bit of experience with it, also programming arduino, he should be along later.
Other people have been successful using Raspberry Pi.
Really the only tricky part of the operation is fitting the digital encoder to your particular machine.
Here's a thread about fitting the encoder to a Gemmasta faceting machine.
http://aussielapidaryforum.com/forum/index.php?topic=4997.msg55839#msg55839

[MakkyBrown]

Hi Folks
I have a late series polyhedron faceter - very similar to the Polymetric Scintillator. I am currently fitting a super new US Digital encoder for angle measurement based on that in Tom Herbst's book.

I am wondering - whilst I have it in bits, whether to use a pressure sensor rather than  the 'traditional' resistance based Beale/Woolley depth indicator. I.e the hard-stop pad has a pressure sensor between the hard-stop and the faceter body. This would be compressed slightly as the hard-stop is made. There are reasonable priced piezo-electric forces sensors now.

Has anyone experience of doing this and do you have any tips/recommendations. I am reasonably proficient electronically and programming up interfaces


Cheers

ian - in the sunny north of england

Hi Ian, If you haven't got your encoder yet I suggest getting a 5000cpr(20000ppr) unit. I also wouldn't bother with US Digital, but get an an Avago/Broadcom encoder from Digikey.  Digikey ships free to Australia when over a certain amount and I bet they do the same to the UK. If you haven't purchased your arduino bits let me know and I'll suggest a cheap serial screen the same size as the one Tom uses but heaps easier to wire.
I also wouldn't bother with Tom's depth of cut setup and I don't use the hard stop for cutting on my machine anymore, just use it to hold the quill up.  I just cut with the encoder and it's is really good.I was using a 1250cpr encoder and a DOC indicator was slightly useful but after swapping to a 5000cpr encoder there is just not any point having a depth of cut indicator in my opinion.
CheersAndrew

[Orange Pirate]

I am wondering - whilst I have it in bits, whether to use a pressure sensor rather than  the 'traditional' resistance based Beale/Woolley depth indicator. I.e the hard-stop pad has a pressure sensor between the hard-stop and the faceter body. This would be compressed slightly as the hard-stop is made. There are reasonable priced piezo-electric forces sensors now.

I guess you are talking strain gauges to measure quill flex. Something I contemplated but after putting in the in the 5000cpr I feel it was not worth doing for the reasons MB has pointed out.
I don't feel it would improve accuracy.