Time to replace the leadscrews and leadnuts. With what?

[FXC]

I bought a 10-year old Taig and have been using occasionally for the past few months, spending more time with upgrades and adjustments than actual work (I'm not bashing the machine.)

I bought a Keling kit featuring KL8060 drivers with royally oversized 570 oz-in steppers (I know, I know) and I can't manage to reliably go beyond 35 IPM. The best configuration I found is to drive those beasts at the minimum current (2A); otherwise they stall, screaming like a pig.

I'm trying to do some precision milling and the leadscrews + nuts just won't let me. There's really nothing more I can do, i.e. adjustments, to get rid of the backlash because the screws are unevenly worn. This means that if I tighten the nuts too much, I can hear the pigs as soon as the nut hits an unworn spot. On top of everything, the screws are bent, too and they wiggle like... a wiggler.

Now, therefore, I reached the conclusion that it's time to replace these screws and also get some anti-backlash nuts. I'd like to go for 5 or 10 TPI max but there aren't any nuts out there, especially self-adjusting zero backlash ones, or at least I can't find them. I hereby request your help in finding a solution, even if it includes custom made stuff. Consider this an RFQ as well - I need the screw ends turned down to size, as well as some nuts cut and threaded for them. Delrin, maybe, with a flexible end?

THANK YOU!

[lsces]

FXC

As you say the machine is 10 years old, does it CURRENTLY have adjustable nuts on the lead screws? I thought they were a more recent development. My own machines run quite happily day in day out at 60IPM on the closed loop controller, but 40IPM is more reliable with open loop steppers. I would suggest that simply buying a new set of lead screws and adjustable nuts from Taig would be a good investment. We change them on 'production' machines once they get to the point where backlash is getting unacceptable in the middle of the screw when you have trouble getting to the ends. Jewelers and the like tend to do a lot of work in the middle 2 or 3 sq inches

One thing that is always worth doing before starting work is simply to jog the machine from corner to corner on the bed a couple of times. Helps 'wake it up' and gets the oil well distributed.

[Jeff-Birt]

I bought a Keling kit featuring KL8060 drivers with royally oversized 570 oz-in steppers (I know, I know) and I can't manage to reliably go beyond 35 IPM. The best configuration I found is to drive those beasts at the minimum current (2A); otherwise they stall, screaming like a pig.

This is a classic case of not buying motors that are suited to the machine being used. The steppers, power supply, stepper driver, and drive on the machine all have to work well together for the machine to function well. What you've done is put a semi engine (big, slow motor) in a sports car that is designed for a small hi RPM engine.

My own machines run quite happily day in day out at 60IPM on the closed loop controller, but 40IPM is more reliable with open loop steppers.

I can do 100 IPM all day long with my 'little' 166 oz-in steppers and my open-loop driver box with a G540 drive. I have the motors tuned down to 40 IPM as the spindle is limited to 10K RPM. If I had a hi-speed spindle I would crank it up for doing things like PCB milling.

[lsces]

I can do 100 IPM all day long with my 'little' 166 oz-in steppers and my open-loop driver box with a G540 drive. I have the motors tuned down to 40 IPM as the spindle is limited to 10K RPM. If I had a hi-speed spindle I would crank it up for doing things like PCB milling.

The kress spindle hasn't been off my machine in some time

[FXC]

This is a classic case [...]

Jeff, in my first post I put "I know, I know", anticipating exactly the response you gave. I know now... but I didn't know then. All I wanted was to get rid of the DOS environment I was forced to use due to the controller's age. As it is now obvious, I had no idea what I was doing and now I'm in "damage control" mode.

To use your analogy, here I am with these Cummins Turbo Diesels mounted on a Mustang. I'm thinking of changing the tranny, since it's worn out anyway and I just can't find one. That is, I need some 5 TPI screws and nuts but I don't think there's anyone making them, is there?

[lsces]

Jeff, in my first post I put "I know, I know", anticipating exactly the response you gave. I know now... but I didn't know then. All I wanted was to get rid of the DOS environment I was forced to use due to the controller's age. As it is now obvious, I had no idea what I was doing and now I'm in "damage control" mode.

To use your analogy, here I am with these Cummins Turbo Diesels mounted on a Mustang. I'm thinking of changing the tranny, since it's worn out anyway and I just can't find one. That is, I need some 5 TPI screws and nuts but I don't think there's anyone making them, is there?

FXC - If you had a Microproto controller already, then the easiest first step would have been to simply upgrade it to step and direction ... Kurt has a board for that OR there is the TurboTaig board if Peter still has any left. The space between table and bed does not provide enough room for the easy installation of ball screws - you may need a mill to machine some extra space out

[Jeff-Birt]

Jeff, in my first post I put "I know, I know", anticipating exactly the response you gave. I know now... but I didn't know then.

Sorry, I wasn't trying to preach to the choir. Just wanted to explain to anyone else reading what the issue with the large motors was. The tendency in the DIY CNC community is to try and fit the largest motors possible or the largest motors a particular drive will handle and that seldom benefits anyone but the guy selling the motors

You can find leadscrews from lots of different industrial suppliers but then you'll have to have them ground to fit the Taig and you'll have to make the split nuts for them. There is very little clearance under the saddle, not enough for a typical lead nut. It would probably be faster, easier and less expensive to get a new set of stock Taig screws, split nuts and better suited steppers. While your at it I would also suggest thinking about replacing the two ball bearings that support each screw. There is no telling what shape they might be in after 10 years and you'll have it all apart anyhow. The bearings are very common and can be supplied by a Taig dealer or most any local bearing house.

[rowbare]

By far the easiest thing to do is to replace the lead screws and nuts with original Taig bits.

The biggest problem you run into is that you have to spin the motors pretty fast to get decent speed with a 20 TPI screw and your big steppers run out of ooomph at higher speeds. However you have tons of torque down low so it might be worth your while to make a belt drive speed increaser in the 2:1 to 3:1 range. That would get your motors in their sweet spot. This might be more expensive than new motors though.

bob