Fixed endsupports

[lgalla]

Hi I have thk BK-12 end support blocks.
How does one determine how tight to make the end nut and setscrew?
http://www.thk.com/eng/products/clas...pportunit.html
Thanks
Larry

[Zumba]

Tumbleweeds in this forum, eh?

[harryn]

Hi Larry

I made such a long pm to you that I broke it up. Your pm box is now full. Please send me an email and I will send you my long answer to your question. It might even be useful, but that of course is questionable.

Harry

[lgalla]

Nobody has an answer?I might add doing up the nut finger tight and the screw will lock up.
If nobody has an answer,should I throw it in the garbage,switch to R&P for my Z or give it away to a member of the Zone?Where is NC when you need him?
Larry

[BobWarfield]

Larry, should be possible to get it pretty tight without it binding. Certainly well beyond finger tight. Something else is wrong. I'd contact THK tech support for ideas.

Best,

BW

[lgalla]

Thanks Bob for the reply.
I have not heard from THK support and expect not to.I will make some assumptions from the THK PDF.The bearings are JISC5 with adjusted pre load.The PDF just says to put the hex nut on and tighten the set screw.The home made blocks I have seen use the nut for the preload.Perhaps,since the THK's are preloaded bearings the nut is possibly just a retainer.Sucks when you spend mucho denero to do something right and THK won't bother to respond.I suppose support is only for the big guys.
Larry

[BEARINGMAN]

LARRY
according to the THK web site, the bearings in your block are 7001-htdfgmp5.
those would be 12mm bore, ang. contact, flush ground, face to face, medium preload, p5 precision. With a medium preload, I would expect them to feel like they are "locked up" when you try to turn by hand. No matter how tight you make the nut, the preload won't change. The idea of preload is that the more preload the more rigid the unit. Less preload will run faster, cooler, but not as
accurate. Nothing wrong with your bearings, just your perception of how they should turn.

[lgalla]

Thanks a lot Bearingman!
Larry

[lgalla]

Thanks for the help guys.I was wrong on two things.First a nice lady from THK phoned and said something was amiss and suggested I call their tech inToronto.
I think the nut was backwards.One side is flat the other has a ridge to push on the spacer.I am roll'n fine now.
Thanks
Larry

[BobWarfield]

That's great news, Larry. Can't wait to see how your project turns out with those nice ballscrews!

Best,

BW

[lgalla]

Actually BOB,the ballscrews and fixed supports are going to be used for 2 Z axis.
One for spindle and one for drilling.On a 5X10 wood router ballscrews are too expensive and I may go with R&P for X&Y,still undecided.Would Roton's at 1and1/4 dia.at.009/ft be better than R&P?I have 3 BK-15's if I decide to go the ballscrew route.Any insite?
Larry

[BobWarfield]

I have no experience with Rack and Pinion, but I'd have thought it was better suited to plasma cutting due to backlash. That's probably a misconception on my part.

I always thought for the long axes on the router the trick was acme threaded and some of dumpster's preloaded nuts?

Best,

BW