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View Full Version : Ground ballscrew bargain... and a hexapod?!



bikepete
19-04-2016, 11:50 AM
Just a heads-up on some ballscrews which are so good I can't help but share the link...

Take a look here on ebay (http://www.ebay.co.uk/itm/191840572508)...

Brand new THK precision-class ground, 32 diameter 10 mm pitch, long pre-loaded nut... 300 mm usable travel or a smidge over. The details don't seem to be in the current THK catalogue but going by the model code on the packaging, they seem to be a slightly 'custom' version of the EIK model listed in this catalogue in German (page 108):

http://hsb.org.pl/Katalogi/Kugelgewindetriebe%20301-1G.pdf

The end machining is a bit short for standard BK25 blocks but I think by removing one seal (and making other arrangements to keep crap out) it'll work...

I ordered one and when it came ordered two more. They come in the original THK boxes with an inspection certificate. Lovely smooth, tight action when turning by hand. For 71.50 inc postage each it's a steal...

I have no connection with the seller except as a happy customer. He says he has plenty of them - they were spares for a now discontinued motion platform (he has two of those too if anyone wants one - hexapod mill maybe?):

18229

komatias
19-04-2016, 03:07 PM
Whats the preload class on these?

bikepete
19-04-2016, 03:20 PM
Not entirely sure. The feel is of a sort of light/medium preload I'd say - tight but not notchy at all. The PDF I linked to above says (in the table on p. 108) that the preload (Vorspannung) is 1.3 kN - but I'm not sure how that is measured. P. 49 says the preload is achieved through pitch offset of the different races within the single nut.

bikepete
19-04-2016, 03:27 PM
In case it helps the entire model number code is:

EIK3210S-6RRG0+535.5LC5

and the one I have in front of me has serial number KX04K05797 - that is also the only thing etched onto the ballnut itself.

Mmm, just found more in another THK catalogue (p. 15-248) (https://tech.thk.com/en/products/pdf/en_a15_174.pdf):

S is presumably 'Special'
6 is six ball circuits
RR is labyrinth seals both ends
G0 is "zero or less" axial clearance i.e preload
535.5L is threaded length
C5 is accuracy class

komatias
19-04-2016, 03:36 PM
Very nice indeed! I keep having to remind myself to stop drooling over things like this for a while http://www.sherv.net/cm/emoticons/fighting/bash-head.gif . After all I am having a clearout.

Boyan Silyavski
20-04-2016, 12:31 AM
so 6 of these and i will feel exactly like this guy on the video


https://www.youtube.com/watch?v=PEZCZzghGFE


/just before my wife comes home and throws me out/