The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
Today's Task: Turn a test billet in EN8 to replicate the A2-5 blank adaptor nose so that I can test my program before unleashing it on the actual adaptor to turn the taper.
So I re-fitted the manual 3 jaw chuck to the CNC lathe, and mounted the 100 mm bar end of EN8 in the manual lathe to reduce 14.31 mm of it to 86 mm.
Oh -what's happened to my nice Newall DRO - none of the value setting buttons would work although the axis values displayed and were updated with movement :bugeye:
I've had this Newall Topaz two axis DRO on my Colchester for about 20 years - they had a deal whereby the price was greatly reduced AND a man came to fit it, so I parted with quite a wad of cash but it has been excellent apart from one problem that started just after warranty expired: The 'Set Zero' buttons for X & Z didn't work but I could still set zero by entering '0' on the appropriate axis - just an extra key push. Well now I couldn't even do that :bang:
I do have a spare 3 axis head but would rather not use it - time to pull the 2 axis one apart taking great care not to tear ribbon cables. Well as expected there's not much that you can do inside. There is a receiver board for the transducers, a power supply, a main logic board, and sandwiched below the membrane keyboard with a ribbon cable connection. Very easy to inflict fatal damage in these things if you are not very careful.
Now I was strongly suspicious of the membrane keyboard itself, but it was bonded to the front panel and removing it wasn't feasible. OK what CAN you do - well the keyboard connector is a ribbon plug in - clean it, put a bit of switch contact cleaner on it and pray to Mecca.
To my HUGE surprise not only was the fault that developed today cleared, but the one I've been putting up with for decades - it WORKS :ddb:
OK great excitement but get on with some machining . . . the 100 mm bar end was quickly reduced to 86 mm for 14.31 mm of it's length producing some impressive purple swarf (3 mm DOC at 770 RPM) - don't try and handle this sort of swarf - it will rapidly cut you to the bone. I use long snipe nose pliers.
Bar end now mounted in the CNC lathe and I have an embryo program written to cut the taper but it needs a bit more tweaking when there are less distractions around.
BillTodd:
I've had to replace the front panel of a couple of topaz Newall dros, although yours looks in better shape than the ones i replaced
Newall dont sell the membrane separately (may not even sell those any more!) .
Bill
awemawson:
I noticed that the keyboard unit, which seems to be bonded to the front panel, was made by a firm in Eastliegh so obviously outsourced.
awemawson:
I played with the taper cutting program this morning, not working on the final part, and not even on the dummy I made yesterday, but the other end of the EN8 bar end that I had done a trial taper cut using the CNC mill.
This was just to try out feeds and speeds and check for vibration on the rather over long boring bar. As I feared it is excessive. I ramped up and down the feed rates and RPM but cannot get a 'sweet spot'
i fear that I will have to revert to more conventional tooling - I was trying the boring bar to give better visual access but it looks like it's a no no.
Despite the video giving the impression that the work is rotating in the wrong direction, it is in fact rotating clockwise looking at the chuck, cutting force being down onto the insert (tool behind the work).
awemawson:
So I removed the long boring bar, but without resetting the machine over travel limits (due to the shorter chuck) I still had to use an axial tool with more stick out than desirable. However finish is dramatically improved so a basis for experiments and tests :thumbup:
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