Question Ball Screw replacement for wearing thread nuts

Hi Doug,

I think the problem with vertical axes is that because of the low friction, a heavy assembly could back drive the ball screw and let the whole lot descend gracefully (or not as the case may be!!) to the base plate or whatever it hits first.

With a stepper motor drive, hopefully there is enough residual magnetism to keep things in check - I've tried mine with it unpowered and one can definitely feel the poles. A case of suck it and see - not a problem once it's recognized.

Peter.

Afraid the news is not very encouraging - the Zapp Automation ball nut doesn't match the standard ball/lead screw!! At least 1/4mm backlash and an altogether poor fit.

Assembled and dis-assembled the setup a few times to try to what was going wrong, and at the last time a couple of balls dropped out - so now I have the unenviable task if getting them back!! Going to have to make a jig to do that as the GTEN design is very non-standard (and novel) as far as I can tell. Three individual return paths, one from each of three threads if I understand the construction correctly.

Ball diameters are 1.71mm, and the Stepcraft screw looks to be able to accommodate nearer 2mm (cant measure this exactly). I can only conclude that the Eichenberger ball nut uses a larger size since the original experimenter reported little or no backlash.

I am wondering whether to risk £90 on one of the Eichenberger ball nuts !!! Motivation not high at the moment!!

Peter.

I hate to say I told you so. Just buy the matching precision thread from ZAP automation and be done with it - if you want it to work

peterg1000 wrote: Afraid the news is not very encouraging....

I am wondering whether to risk £90 on one of the Eichenberger ball nuts !!! Motivation not high at the moment!!

Peter.

Really sorry to hear that. I probably would have stuck with the Eichenberger since it appears those worked, and then only tried 1 axis to verify it. It sucks taking a risk like that, plus all the work to change the part.

Were you able to make the adapter ok? I'd still like to know if the Eichenberger ball nuts will work but don't have the resources to try it myself right now. Let us know if you decide to try.

Hi Proto,

I think I might have a chat to the sales manager at Moore - might be able to either get hold of an externally damaged Eichenberger ball nut or persuade him to try my Z ball screw in one on his premises. Nothing ventured etc!!

I did get as far as partially machining a mounting adapter - it needs the mounting spigot turning and tapping once the height of the ball screw centre is determined. Easy to do in a 4 jaw chuck on my lathe. The M18 x 1 thread was much easier than I thought - a taper tap in aluminium worked wonders!!

GTEN ball nut and part finished adapter.

Hi Peter.

I'm genuinely sorry that this modification didn't work out. It was certainly worth a try IMHO, but it's not a cheap punt is it?

Do let us know how you get on.

I just finished setup and tuning of my machine and I'm pleased and relieved. That must be three weeks on and off (mostly off since I was on holiday for 9 days over October half term).

Doug

Hi Doug,

This might be on the back burner for a few weeks, but I haven't given up hope of getting hold of an Eichenberger ball nut by fair means or foul!!

I have a partly complete wooden clock that has been on hold for a while - really must get that finished before I embark on another major investigation.

Glad to hear that your SC is virtually complete and "tuned" - your patience and diligence will pay dividends in future.

Peter

I completely Gave up and bought all this
[img size=500,200] www.cnczone.com/forums/attachment.php?attachmentid=337470&d=1477405398&thumb=1 [/img]

My Build blog is in here:

Nick's Big Build

All looks juice finch (Nick). Although the picture is a small thumbnail and I need to be logged in to CNC Zone to see the full size version. My digital footprint is far too big already to be registering for yet another forum

Doug

All looks juicy finch (Nick). Although the picture is a small thumbnail and I need to be logged in to CNC Zone to see the full size version. My digital footprint is far too big already to be registering for yet another forum

I kind of lost the plot a little. I forgot that the original mod linked to used an Eichenberger ball nut not the £43 Zapp Automation ones.

"4x KGT 10x3 FGR RH S A G Eichenberger Carry Nut"

So these babies are £90 a piece? Phew. But they will almost certainly work with the stock Stepcraft lead screws if we believe this guy so £270 + effort of machining your own adapter. Hmm.

Doug

Time to resurrect this.

CNC4You.co.uk has ballscrews and ballbuts for sale. Would any of these be suitable for retro-fitting to the Stepcraft machines? I presume not since the ballnut design looks different...

www.cnc4you.co.uk/Ballscrew/Ballscrew-with-Fitted-Anti-Backlash-Ballnut-RM1605-C7-16mm

£55.99 + supplement for different length ballscrews:

RM1605-C7
1300mm Total Length 1362mm (+£24.00)
200mm Total Length 262mm
250mm Total Length 312mm (+£1.00)
300mm Total Length 362mm (+£2.00)
350mm Total Length 412mm (+£3.00)
450mm Total Length 512mm (+£5.00)
500mm Total Length 562mm (+£6.00)
550mm Total Length 612mm (+£7.00)
600mm Total Length 662mm (+£8.00)
650mm Total Length 712mm (+£9.00)
700mm Total Length 762mm (+£10.00)
750mm Total Length 812mm (+£11.00)
900mm Total Length 962mm (+£14.00)
1000mm Total Length 1062mm (+£16.00)
1100mm Total Length 1162mm (+£18.00)
1200mm Total Length 1262mm (+£20.00)

They have other ballnut options:

www.cnc4you.co.uk/Ballscrew/20mm-Ballscrew-with-Fitted-Anti-Backlash-Ballnut-RM2005-C7-20mm

£77.99 + options

Doug

Hi Doug,
I’ve been reading this thread with great interest. I’ve just bought a 600/2 with the intention of some aluminium machining and ballscrews seem like a worthwhile upgrade.
Have you progressed any further?
With the introduction of the ‘Black’ machine the Nema 23 motors, these sound appealing too.

Hi , I was willing to take a chance and buy the ball nuts and test if the machine worked with them (I had already made the adapters and requested budget of the ball nuts eichenberger to its distributor in Spain), but then I saw that the manufacturer had made the black edition, equipped with adjustable nut, and I have decided to wait for this nut to be sold. I suppose the nema motors 23 have been fitted because with the adjustable nuts increases friction with the lead screw and consequent loss of power. So I'll wait and when adjustable nuts and motors are on sale, I'll switch them to my stepcraft.

Greetings,
Alberto

Hi guys,

I decided to buy ( SKF Ball Nuts ).
Quite expensive especially if you want to buy four of them but I was tired of my endless issues with machine backlash so wanted to give a try

Now please don't laugh I printed ball nut holders from PLA plastic, just to test how ball nuts will work on standard s600 v2 lead screws.

All works surprisingly well. Machine has no backlash at all on all axes. Velocity on X and Y axes up to 6500mm/min (UCCNC), not during the milling or cutting of course. Amazing.

I bought piece of aluminium 6082t6 (eBay) and decided to make these holders from aluminium, just in case. Plastic holders worked very well but I prefer aluminium

Cheers. FaFiNoS.

Here few photos:

More photos:

Even more photos:

And two more photos:

FaFiNoS,
That's really great news! Thanks for all the effort and pictures. Looks there are only 2 ballnuts left in stock right now. Hoping I can find time/money to do this. Thanks again for sharing.

The SKF Ball Nuts working with the original Stepcraft threads without modifications?

Kolja-Ki wrote: The SKF Ball Nuts working with the original Stepcraft threads without modifications?

Hi,

I did only one small modification. Because these nuts are very tight I removed 2 balls from each nut on Y axis. Before this I could not achieve that high travelling speed. I always check maximum traveling speed to make sure lead screws are well aligned and stepper motor is able move axis without any problems. Of course this is just to check. My standard milling/cutting speed is much lower and depends of the type of work.

One thing which is extremely important is the thread inside ball nut holder. When you make a thread a tap 18x1 must go perfectly straight into the hole. That's all.