King Midas mill conversion

[Jonathan]

What's the dimension I've marked with '???':



Pretty minor, but I changed the end bearing surface from 7mm to 9mm since the bearing is 10mm wide and it's best not to have the bearing resting on too much thread.

[Robin Hewitt]

latest draft -version for X -screw is here

The X screw is best held in tension, suggest you put a thread and one bearing at either end.

I have found 31pcs of the 12mm Belleville washers I used...
www.bellevillesprings.com pn: D2812215

You are welcome to half a dozen, just shout.

[Jonathan]

Was going to mention adding the second thread for tensioning but for some reason I thought that drawing was for the Y-screw...oops. I've got a thread on both ends of my router X-axis screws for the same reason.

Do you reckon the D2812215 Belleville washers would be suitable for preloading RM1204 ballnuts? The screw I have here is actually 11.60mm diameter so it's going to close... Apparently 10-15% of static thrust rating is a good compromise for preload, so 1KN. I probably need a lower spring constant for that as such a small deflection will be hard to measure.

[Robin Hewitt]

Do you reckon the D2812215 Belleville washers would be suitable for preloading RM1204 ballnuts?

I used them with 1204's on my Roland mill at considerably lower pre-load than on the Warco. I don't go above 5mm tooling on that.

Works okay, but agree a lighter section washer would be easier to adjust and give you more take up.

[Gary]

Looking at the drawing is seems over complicated.
If you want zero backlash and don't want any movement on the support bearing just go for a good quality FK12, the gten R1605 ballscrew and the R1605T3-FDID-P1

This is the link to the datasheet for the FDI and FDU type ballnuts and it is 34mm between the flats, so it is actually 6mm difference.
http://www.zappautomation.co.uk%2Fpd...%2FFDU-FDI.pdf

The ballnut is already pre loaded for zero backlash and has been tested on the screw.

you will need ti install chinese fonts in acrobat.

[Robin Hewitt]

The ballnut is already pre loaded for zero backlash and has been tested on the screw.

That looks interesting, is it shimmed or does it have springs? The data sheet is vague.

[Gary]

No its a spacer between the two nuts.
I dont know of any commercial double ballnuts that use a spring.
All the manufactures i have worked with use a spacer to pre load the double ballnut, and there are reasons for this.

That looks interesting, is it shimmed or does it have springs? The data sheet is vague.

[Robin Hewitt]

All the manufactures i have worked with use a spacer to pre load the double ballnut, and there are reasons for this.

Good point, I forgot to mention that John will need to leave room to fit an oil pipe to the nut. I use 4mm OD nylon tube and standard push fittings which are a bit sticky out and it will drip