|michael bird||27/09/2011 09:39:59|
|22 forum posts|
The article by David Haythornthwaite regarding BW Electronics systems in the October issue No 181 of MEW I found to be very interesting and encouraging for a newbie, re the ease of fitting and the price. However, before I buy I would welcome the views of the experts and anyone who has fitted and is using the system.
|John Kirby||19/11/2011 19:37:44|
|1 forum posts|
|John Stevenson||19/11/2011 19:55:22|
5068 forum posts
I fitted one to the cross slide of a CVA lathe some years ago, actually it's still fitted but I don't use it.
Repeatability is quite good but accuracy leaves a lot to be desired on a lathe due to everything being doubled because of removing material of both sides of the job.
BW say they are good to 0.002" but that, on a lathe, is 0.004" on diameter.
Whilst it helps to keep an eye on things it's best to measure and go the final position using the dials.
I fitted a DRO to my TOS lathe later on and went the glass scale route for about the same money and have never regretted it as this can be used without dials very accurately.
However glass scales may not fit easily on a smaller machine as well.
Personally for the day I think they were very good value but the BW units have increased in price just as the glass scale units have decreased in price and it's now a very hard choice of price versus features versus size.
|1008 forum posts|
Allendale have now brought out magnetic scales which are very neat and very small. They come in 2 ranges I think. One reads to some fantastically small amount, the other to the normal .0002" (.0004" doubled) Which is what many of the glass scales read to, and theye come in a range of sizes.With the magnetic strips,housings and heads I beleive they really have solved the problem of fitting a quality DRO onto something Myford sized, and probably on 3 axes. What I want to find out is whether you can put one of the super ones on the x slide, and ordinaries on the others, because the super ones are a tad pricey. My economy DRO box may not take too kindly to varying ranges on different axes - so I need to ask.
If I am not teaching my granny - one does have to calibrate the scales, (or the output to the box to be precise) but once one has that offset sorted, one can take one mike reading an inch away form the finished diameter, and provided things are rigid, it will be spot on at the far end - to the point that I have got a bit casual about micrometer readings. Which will bite me one day, but so far it hasn't.
Edited By mgj on 19/11/2011 22:46:36
|Clive Foster||19/11/2011 23:08:47|
|2533 forum posts|
On a lathe cross-slide its probably best to run the pull wire round a pulley for a double run giving direct cut on diameter read-out and retaining the nominal sensor accuracy. Of course this assuming the pulley is round and runs true.
I have one of the MPS self contained single axis units on the quill of my Bridgeport. Tucks in nicely above the micrometer scale making a neat, effective and doesn't get in the way of the depth stop like the "display on a stick" based solutions. Being an untrusting type I use it to set the stop rather than cutting to a dimension on a live display.
Edited By Clive Foster on 19/11/2011 23:09:11
|461 forum posts|
Mgj, from the remark about being 'a bit casual' I suppose you use such a magnetic system?
Can you - or anybody - tell me if that system is (electrically and connector-wise) compatible with glass scales? I once bought a display unit for Easson glass scales (mainly because I got it for a good price), but never managed to find a good way to mount such scales on my mill. This problem would be much more manageable with these magnetic scales.
I have a BW unit on the cross-slide, but never had a problem with reading movement instead of diameter.
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