Old Techno 4x4 repair/refit

[luv2bsailin]

Hi guys,

I just purchased an old (1991 vintage) Techno 4x4 foot router. It came with a MAC100A controller which, although it seems to work fine, I will probably replace with something more modern. (If anyone needs a MAC100 with two spare driver cards and the Fanuc software, let me know.)

Anyhow, the real reason for my posting here is that I need to find a source for machine parts. For starters I will need at least one ball-nut. The Y-axis one is worn and missing one row of balls. I measured the screw, it is 15mm OD and the threads are spaced at 4mm. I measured the balls at 0.0984 inch and they appear to be all the same.

Are these fairly standard sizes? If so, what is a good source for a replacement ball-nut? The nut has a 2-bolt mounting pattern on one edge but if there is another mounting style more readily available I can probably make it work since I have a small milling machine.

Apparently Techno does not support their older machines, so it looks like I'm on my own. One of their salesmen was kind enough to send me a maintenance manual, but it is pretty generic and covers the whole range of machines.

Thanks,
Jim McMillan

[Montabelli]

techno sells the ball nuts to go with their screws, they are some what adjustable though, if you can put new balls in and get it re loaded onto the screw, you can possibly get some more function out of the existing screws.

Depending on what you plan to use the machine for you might want to consider the pci 400 card for servo control, imo it has very good motion control. closed loop and will work at pretty good speeds.

[luv2bsailin]

Thanks Montabeli.

According to Techno's site, they have what they call a "type one" ballnut that looks like mine. It's listed as 16mm dia, 4mm pitch. I measured the outside of my screws at 15mm, but I'm guessing they are really 16mm. Does that sound right?

I dug in a little deeper and it looks like my Z and Y ball-nuts might be ok. They were packed full of sawdust and dry as a bone, but when I cleaned and re-greased them they seem to roll just fine.
It took some head-scratching and trial and error to figure out how and where to put the balls upon re-assembly. I don't think I lost any balls because the Z and Y axes had the same number (35) but I didn't keep track of where they were placed within the nut. There are 4 turns in the nut, and I wound up with turn one with 18 balls and turn 3 with 17. Turn 2 doesn't work because the "return track" or whatever you call the little plastic insert doesn't allow them to circulate. Turn 4 is open on the end so they'd fall out. Haven't done the X axis yet, but I will be extra careful disassembling it to verify the ball location jibes with I came up with.

The rail bearings were also dry and packed full of dust. Some of them wouldn't move at all until I removed a couple balls for "wiggle room" and soaked them with WD-40 and worked them back and fourth. Once free, lots of rinsing and swabbing cleared them out. I think they'll be ok as well.

Now I gotta figure out what kind of lube to use. There are some recommendations in their generic manual which I will try to source locally. I was going to use some teflon grease I had on hand (Superlube brand) but I think petroleum-base would be better since it can be rinsed out and re-applied periodically to minimize dust build-up.

On the controller question, since it already has steppers on it and I already have a drive (Gecko 540) that I can borrow from one of my other machines, it won't cost me anything to test it in that configuration. I'm not sure, but I have a feeling screw-whipping might limit my max speed before the Geckos do. We'll see. I can always switch to servos down the road if it makes sense.

Any other comments/questions will be most welcome. I will try and document the restoration process here in case anyone finds it helpful.

Cheers,
Jim

[Montabelli]

I believe the techno 16mm screws are available in 4 5 10 and 20 mm pitches, most of the old table tops are 5mm , at least mine are. I assume you are running mach3 on your geko setups, and that should work fine on the techno table if you want to stay with the steppers. there is one other possibility, granite devices has controllers that would allow you to add encoders to your steppers and run them, in a closed loop. it would get you around the biggest problem with steppers.

enjoy