hey guys.

have been putting some thought into a bigger and better machine.  i currently have a bp clone with ac servos running mach3.

as great as it is i want better.  more spindle speed, full enclosure, higher pressure coolant and of coarse a tool changer.

i am also wanting a cnc lathe.  converting my 14x36 is an option but i would rather not.  

i have seen plent of machines for sale at some reasonable prices but if i was to buy say an old mori lathe or vmc what sort of result would you expect to get from a conversion to mach3 and how hard/easy would it be.

i understand this depends alot on my experience with machinery and i have very little.  i have never used a plc

what i don't know is does a vmc work on the same sort of design as my knee mill with servos?  eg no glass scale feedback.  sevos drive the screws either through belt or direct drive.  tune the servo for best result.

what i am curious to know is if a vmc would be pretty much just a larger version of what i have already done but just a little more complicated because of the tool changer, auto lube system etc.

i have been reading jh choppers threads and he makes it look so easy.  and seems to get a great result.

would i be better holding out saving my coin and getting somehting newer not needing a retrofit and starting there.  for me it is more the destination not the journey but i also am not flush with coin to throgh at a 30 year old chunck of iron

your thoughts thansk

Hard question really as only you can decide which route is best for you.
 For me it is a no brainer, I would choose an older machine to retrofit every time. I however enjoy doing the retrofits and working out how to do things. You seem to be more concerned with getting it up and running as quick as possible so the newer machine that is running may be the way to go.
 Only thing with going with a running machine is it may not stay running for long, especially if its already fairly long in the tooth. You would then either have to pay someone to fix it or learn to do it yourself and even then getting spares/repairs may be expensive. As an example the Chiron I am currently doing was available because boards had been robbed to keep other machines running as the cost of fixing a single board was upwards of £1000. The owner is very  capable at fixing his machines and finding faults. Repairing drive cards however is another ball game and is a lot more specialised.

Hood

the retrofit of my bp clone has been a big learning curve and i am not against doing it again.  however something turnkey does look attractive but the $$ dont.

does a larger vmc work differently than my bp clone?  the electrical cab was a challange for me but if the same basic principles apply to a vmc compared to my knee mill then that makes me feel a bit better about tackling a vmc to retrofit as i would just more or less just copy what i know works and add tool changer detail etc.

have the knowledge to fix it myself would be a big bonus for sure.

so what would i be looking for in an old lathe to retrofit.

i have seen a mori SL3a for sale that seems in pretty good nick. is cuttently still running bout 84mod

also a nakamura  with everything i would pretty much want also still going strong (around 86mod) that has a fanuc contol on at the moment.  chip conveyor, 12 tool turret etc.

are the servos on these older machines a +/-10v set up or can they take step/dir aswell.  or would i just junk them and get something much newer.

Afraid I dont really know what you did o your Bridgeport, ie did you gut it and replace the drives etc or use what it had, was it servo or stepper based machine etc etc.
With regards to a VMC and a Bridgeport, no difference really in retrofiiting one or the other if you take the same route with both, in other words if you gutted the BP and did the same with a VMC then it should not be any harder, except maybe integrating the toolchanger. If you didnt gut the BP then not gutting the VMC would really not be much more difficult.
 I personally have gone the PLC route for tool changers, mainly because I can do ladders much easier than I can VB script.
 When I did my big lathe there were no controllers available that could be used with Mach to control analogue Amps so I had to go the route of getting new motors and drives. I kept nearly all the other electrics intact however and just interfaced them to Mach.
 Things are much easier nowadays as there are quite a few controllers that can control analogue amps, also they can use 24v I/O etc that the Industrial machines will use. I think the biggest problem would be working out what is what in a control cabinet but having electrical drawings for the machine would make that a much simpler task.
Whether to keep the amps and motors or get new drives/motors will really depend on what the machine has, most industrial stuff is fairly solid but I suppose it is getting on in years if you are talking mid 80's vintage. With the Chiron I am doing  the choice was easy, it didnt have amps so I had to go with new, well second hand actually, so maybe I should have said different. I plan to use the CSMIO/IP-A in this one, its an analogue control and the drives I will be using are analogue.

Hood

i started out with a manual mill and built the conversion for it.  had to work out the wiring and circuits from scratch.  aswell as getting the yaskawa servos running, make mounts for motors, get ground ball screws made etc.

I agree wiring diagrams would help alot.  i have no idea about vb script or plc but how hard can it be?

i guess it just comes down to what i can get for what price and what it  has fitted to it.  like you said if i got something that was all working i may just be able to interface mach3 with the current motors and drives and I/O's.
but if i have little to no info on the drives then wiring them up could be a nightmare. 
from whati  have seen good running condition 80's vintage iron (lathe) runs around the $5000 mark so i would want to pay alot less that that if i was the retro.

then i could have a great setup for less that 10K

i like the user friendlyness of mach 3 so that is an advantage straight up.

Ok so your retrofit with the BP sounds as if it was more than just a basic retro so that is a good step and should make any further retrofits an easier prospect.

Cant really help on price  as the market here is vastly different from over the pond, machines tend to be a lot cheaper here but components seem to be the opposite. My big lathe cost me £300 about 7 years ago but since then prices have increaed quite considerably, now I would be expecting to pay at least £1000 and likely more. I have done a lot to my lathe over the years including adding a servo spindle motor, adding a second turret and then removing the two turrets and making and fitting a single 1 position turret. Not including my time I reckon I have spent well under £3000 total on it.
 The Chiron VMC I am doing cost me nearly 3 times as much and I reckon with all the parts I will fit  it will be about the £2500-£3000 mark when I am finished. I use second hand drives from eBay so that helps keep the cost down.

Hood

yes i agree once it has bee done for the first time any more retrofits will be a lot easier.

i will keep my eyes and ears open for something and see what i can do with it.

i guess i am best keeping in the back of my mind that i may just have to replace all the drive and servos and completely rewire to interface mach3 as a worst case.

how do you guys go moving these suckers.  nearly 4-5 ton of iron must call for some specialist equipment.

I am lucky in that when it arrives I can get it lifted off the lorry by the Boatyards crane. The crane can partially place it into the workshop enough for me to get 25mm dia steel bars underneath the bit thats in the workshop. From there on I just either use a wee winch or a pinch bar and just keep replacing the rollers as they come out the other end. The floor in my workshop is poor so skates tend not to work well but its very easy to move machines around with a pinch bar and steel bars for  rollers.
Hood