Originally Posted by Willyb  Hello NinerSevenTango
Congratulations on purchasing your New Tormach CNC Mill. Have a couple questions. |
Thanks, Willy.
Which circuit board was it that let go? The Parallel Port Breakout Board? Did you find any reason for it to crispy crittered? When this happens with a New Machine, you have got to wonder is it a wiring problem? Did you look the other way when powering it up the second time? |
Yes, it was the parallel port breakout board. I think it fried because there was a trace on the circuit board a little too close to a fuse clip. Ordinarily it would be all right but mine must have gotten vibrated a little much in shipping, allowing it to wear through the insulation. The replacement board has been redesigned so nothing like that can ever happen. Look the other way? No, I watched closely the second time! I work with high voltage, high power electronics, and this one is pretty tame by comparison. Besides, I had a pretty good idea the second one couldn't do what the first one did.
2-1/2 thousandths is more than the inspection sheet suggests. I wonder if you might have some looseness in your Z Ball Screw Bearings? If you installed a Counter Balance how much do you think the Z Axis Gib could be loosened up? |
Yes, I can tighten the bearing preload to take some of that out, and I bought the spanner wrenches to to that. On the other hand, I don't want to over do it on the preload, because I know what will happen then. So my thinking was that if I can neutrally balance the assembly, it should glide like the other two axes, and I should be able to relax the gib without having to overtighten the bearings. I predict that when the gravity load is taken off, the thing will become as accurate as the other two axes. If not, only then I will start cranking on the bearing mount.
I did the math, and I'm uncertain as to whether to use a compressed air system and a cylinder instead of a dead weight. There wouldn't be much cost difference, and the air system would be more compact and not add inertia to the system. Inertia complicates the drive algorithm a little (but so does stiction!). Looks like a 2" cylinder and a 5 gallon air tank at around 60 psi would work. On the other hand, the dead weight is dead simple, and only has two or three roller bearings and a cable to ever fail or wear out. I'll let all that roll around in my head for awhile before I decide what to do. Usually the simpler solution is better. If I can come up with an elegantly simple solution, and it works like I hope it will, I'll share it here.
For now the thing works just fine the way it is. It's getting quite a workout for break in, having peck drilled around 1000 holes so far. That's a lot of up and down motion!
If you don't mined me asking, what are all the aluminum plates for? |
The aluminum plates are to be used as locators to hold small pins. 150 of these pins will be put into a plate, then the plate gets put into an induction hardening machine. The machine raises the plate full of pins up to an inductor, the inductor is energized with high frequency at high power, and the pins all turn orange hot within seconds, after which they are quenched with a water based solution to quickly cool them down again. The result -- each pin is hardened exactly half way down. The pins end up in a transmission. Our customer puts three of them into a plate, and rivets the soft end over to permanently affix them. The hardened end drives another plate for some purpose or other.
How are you locating the Tooling Plate so that it goes back onto the Mill Table in the same position once it has been removed? |
I intend to leave the tooling plate in place. If it gets moved, I'll have to use an edge finder, and move the model in my drawing, I guess.
Sounds like you are very happy with your New Tormach CNC Mill. I am saving up for one and hope to be ordering soon. Can't wait. Thanks for the help with my questions. |
So far I am having a lot of fun with it. I'm working on creeping up on maximum feeds and speeds, and trying to remember all the little tricks I taught myself 5 years ago when I had a HAAS. I'm not a machinist by trade, and experienced machinists know a lot of tricks and tips that I have to stumble upon the hard way. But the learning is the fun part for me. I hope you get to order yours soon, I know you'll be impressed.
--97T--