The motion buffer is good. I'm stuck with a 2 command buffer. I'm using an ancient baldor card, just "upgrade" from the euosystem to euroserver, ie from servo x and y, stepper z to all servo. The card sold but quite good, it'll interpolate 3d moves it's self and do circular arcs in 2 axis. I've got it arcing in x and y but want to extend to the other axis. I drip feed via RS232 but it's slow. My timings showed max 100ms, the current version of software uses 70ms as the limit which all seems to be working very stabally. The problem with servos is you cant just stop them, theres a ramp to consider so the current software works this out, this is crucial for multiple points at the same velocity I find. The motion buffer is only 2 moves and the next one has to be available for smooth motion. Think I've got teh balence just about right now. You have to optimise the moves, 1000 line encoders, 4mm pitch and quadrature gives me 1000 steps per mm, so it's quite possible to send it 50 distinct positional moves and only have it move 1mm! So theres sort of a sense and reason algorythn that tries to get rid of sill small stuff and interpolate it a circluar arcs. Very short but neccessary moves are allowed to ramp up and down. But it'll do quite intricate stuff now at 30mm/s which is good enough. The data packets I am stuck with, there is a command set and a checksum to add and then you should get a reply within 10ms that all has been recieved and understood. The advantage with the card is it was free, and with the right optimisation can run pretty fast. The next version of the soft will cater for circular interpolation in y/z and x/z allowing faster parallel finishing. It runs on an old 486 on XP and seens OK, no what you mean though, event based, it doesn't do what it's told, only what it feels like doing, which is why the software takes into account the time to transmit and recieve and guesimates wether the next command will be there in time, if not, I have a special command that tells the card to not assume constant velocity so it can ramp. It also does this if the angle of motion change is too much as this upsets the controller as wel. My other option is a spare eprom that has MINT on it. I could write a load of code for it and build in a buffer, say 100 positional moves. The move buffer though would still be 2 moves and the code still has to be there if the buffer runs dry. Its really pretty annoying 2 1/2 hours through a job to get a sudden following error! I think steppers are better in this respect, they're not really bothered where they are, this card is obsessed with where it thinks it is, to 0.001 of a mm! I have set this now to 1 mm, experience has taught me it's either spot on or crashed. The code used to read simple CAMgl as a tool path but this is only 2 1/2d really so I went to APT to envisage full 3D. Working stably at the moment so, and no joke, it'll be the first time in 10 years I can confidently design something and cut it!

I have a little sherline lathe for stuff i used to do in a previous life, I bought and old (55 years) worn myford just to pat off bits to put in the sherline. Being me, I the spent more time making parts for the myford than actually doing anything productive! A project in itself! So I sold it and bought a new big lathe, that you can just switch on and use, First job, yes, make new motor mounts for the NC mill and rebuild it!

I want to rewrite the software to do circular arc in the other axis, I wwant to do it now. But I am going to be good and going to bang out some cribbage boards and stick them on ebay to demonstrate to the wife my garage and all the junk in it has a use!

If my source is any use you are welcome to have it, it's very nerdy, no commments, pascal, D7, very readable. Reads APT file from Rhinocam and posts it to my own format, (the cam gl stuff is probably still there somwhere), which can then be drip fed. I did write loads of RS232 stuff but now use a Baldor dll which also has access to good stable RS232 comms commands.

Garage bekoning!

Tom