Fitting Vee Guides to the Fanuc Tapecut Model M Wire EDM

[awemawson]

A few days ago I was glancing through old  threads and re-read my series on rebuilding my Fanuc Tapecut Model M Wire EDM machine. Now apart from playing about, frankly that machine has hardly been used - why? Well threading the wire is an ABSOLUTE PAIN 

The wire has to be passed through upper and lower guides that are hole in rubies - wire 0.25 mm hole in ruby 0.255 AND you had to thread from the underneath only being able to see the hole in a mirror. So perhaps you see why it has only had infrequent use !

Original thread HERE:

https://madmodder.net/index.php/topic,10085.msg113699.html#msg113699

Now while I was rebuilding the machine I'd had the opportunity to rob a Model L as it was being scrapped - a very similar machine but this particular one was equipped with 'Vee Guides' - no holes, just a sharp Vee shape into which the wire falls held by tension - a slightly less accurate method but VASTLY easier to thread !

Why did I never fit them Well both machines had been heavily modified over the years and the method of fitting the guides was qite different between them, and the Vee guides were missing all the plumbing for the ionised water electrolyte. Perhaps I should explain, not only does the guide assembly (upper and lower incidentally) have to hold the wire in a precise location, it has  to convey the cutting current to the wire, and direct a jet of water along the wire to stop it melting and flush out cutting debris.

Now the current is applied to the wire by it sliding over a polished tungsten carbide stationary roller - relatively easy to engineer. The water is slightly more complicated as the water guide has to be able to open and close to admit the wire when threading. The original (missing) parts are complicated mouldings - but HEY - I HAVE A 3D PRINTER !

Now having had this thought I then could not find where the heck I'd put the Vee guides - I searched high and low, and it wasn't until someone wanted a TG100 collet from me that I went searching in my container and found a mystery ammunition box - and guess what was inside 

So, over the next few weeks I plan to try and come up with a design that allows me to relatively easily swap between the two type of guide, and hopefully get it working.

I made a start today with a 'Psychological Clean Up' - a good hoovering to get the dead flies and dust off, then a sponge down with phosphoric acid to remove dried on bits that I been cutting, followed by a good rinse. Always better to work on a clean machine!

Workshop time is severely limited at the moment as Abi(gail) our new Viszla puppy joined us yesterday and needs constant attention - we are 'time sharing' hour on - hour off !

[awemawson]

Well the good news is that it seems that the mechanical mounting for the Upper Vee Guide is identical to the existing Ruby guide.  So it looks like just a bit of re-jigging of the water and electrical connections will sort that when I've 3D printed the rest of the jet.

For the Lower Vee Guide it's a bit more complicated, but I've found one small bit of stainless that forms half of the water jet for the lower head. If you read the rebuild thread you may recall I had to totally re-make the mounting as the original had largely dissolved away in the de-ionised water over the years. Now the good news is that I reused the blue insulating machinable ceramic spacer that it all sits on so hopefully mounting holes will be the same - with a bit of luck I can once more re-make this mount ensuring that it is compatible with the Vee mount, and much of the objective will have been achieved. It will still need the rest of its water system 3D printed but it should be possible.

(amazing what you can do in short gaps between puppy sitting  )

[AdeV]

Would it not be possible to lathe up a simple cone, which fit onto the underside of the lower guide, which would aim the cut piece of wire into the ruby? Or would that have been too easy? 

PS: Manual arrived safe & sound last week, thanks; I forgot to mention it! Or maybe it was the week before - time seems to be flying by right now! I blame the baby...

[awemawson]

Glad arrived Ade 

The problem is access - there is very little room under the lower ruby (actually I think I may be wrong, they may be artificial sapphires).

[awemawson]

Another 'blast from the past' - steaming up the
wire EDM machine the other day and realising what a pain wire threading is using the ruby hole guides (0.25 mm wire to be threaded through 0.255 mm hole upside down in an invisible place) I decided to knuckle down and sort out the fitting for these guides.

As far as I can tell the bits I have are mechanically complete but are missing the removable half of the de-ionised water fittings. They probably stayed on the scrap machine when these used Vee guides were obtained. So the task is to 3D print them.

So far I think I've got the lower guide sorted and a 99% fill version is printing as I type - I've been using 13% fill ones for prototypes getting the shape right.

A few hurdles along the way: Not used Fusion 360 for several years so it insisted on being updated - still not an intuitive program (for me at least). Eventually got what I thought was right, exported it to the Cetus 3D printer and in the process of trying to get is sat on the right plane to avoid printing loads of scaffolding ended up printing a mirror image  Still as I say final version now printing in Pet-G.

Will start modelling the upper nozzle surround over the weekend hopefully.