On Monday 31 July 2017 07:13:05 Tomaz T. wrote: > For my future project (cnc router) I will have to use helical rack and > pinion system on two longer axis (2 and 3.5m). There are some designs > where pinion is forced against rack with spring tensioner, on the > other side, if I follow Atlanta's installation manual for their > system, they forbid tensioning pinion against rack as it would cause > wear and tear or rupture of teeth (they suggest pre-load pinion > shaft).
If they are pre-loading to full contact, I fail to see the diff between a spring load and a pre-load. With a spring, it might have enough give to ride over a wood chip falling on the pinion. > In my case this will be used for woodworking cnc router, so I'm not > looking for very high precision, but anyway if there is anyone heaving > experience with this would be nice to hear. Not with this per sei, but I found precise in woodcarving was a matter of taste, in my case when carving some green and green style box joints in mahogany. In order to get a fit I could finish sand and draw or hammer together, I had to cheat on the fit by telling the machine the 1/4" bit I was using, was only about .247" in diameter, otherwise the fit was so tight it wiped all the glue off in front of it as I drove the joint together, and as the carbide bit dulled, I had to increase the clearance by telling the software the bit was as small as .245". This was using the max speed the G0704's spindle could muster, about 2750 revs with my controller. A genuine router motor doing 25k rpms probably wouldn't have needed the extra clearance. > Example of tensioned pinion: > > https://www.google.si/search?q=rack+pinion+cnc&source=lnms&tbm=isch&sa >=X&ved=0ahUKEwi8g8ziqrPVAhVE6xoKHf02A3gQ_AUICigB&biw=1536&bih=735#imgrc >=Yrj6s6vvjL--WM: Looks good to me. I might use a longer, softer spring, or a tension spring, if adjustment needed, adjust the springs anchoring hook. One of the other pix at that link shows that IIRC. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
