Hello, First time posting, and just building a new LEAD CNC. I want to know if this is a BAD thing to do the tensioning the way I did.. Since the longest acme screw I could find was a 1557MM 8MM screw (It is the one for a Workbee V2.), I tried to come up with a way to put the tension on the lead screw, use the thrust bearings on both sides. What I have come up with, to no need to move the stepper motor away from the plates more then it is now, and keep the parts as close to normal as possible is this: Mount thrust bearing between flexible connector and the top plate, using the flexible connector to hold the thrust bearing tight. Add the Thrust bearing and a locking collar to the bottom of the lead screw to add and hold the tension on the lead screw.. Once done, I left the bottom 2 lock collars loose, added a nut to the end of the lead screw, and stepped the motor to tighten the nut. turning the nut, just to the point of the stepper motor giving out, then tightened the outer lock collar, followed by the inner lock collar. Does any one see a reason why this will fail? This, when done, will be a 1515 LEAD with all screws, a HIGH Z mod, Multiple Z actuators, one with a 3kw Water Cooled spindle (Full Length of the Z) and a 2nd shorty on the back for a laser/drag knife.
Search for tingle system that is exactly the method also research bulkmans method but I suspect that you already have looking at the thrust bearings. Edit for..... clarification only on x and y axis not x also you don't really need on x axis y is the one that really flaps around
At over 1500mm long, an 8mm screw isn't going to perform well no matter how far you tension it. It should be at least a 15/16mm screw, preferably a 20mm screw (especially if you're rotating the screw and not the nut). Five-plus feet is no joke. The design of the tensioning itself seems ok, though I'd add Belleville washers to hold the tension and I'd probably find a better way to tension than just turning the motor- 2-3 Nm isn't gonna do much to it, you're getting maybe 200-300lbf on the screw- pretty much what you could get just by pulling on it as hard as you could. Maybe locking the inner collar a couple mm away from the plate, and using it as a spot to get a pair of vise grips or maybe even a pipe wrench around. You want somewhere around 500-1000lbf on there- and at that point, you need to be sure the extrusion isn't gonna bow or buckle.
Thanks! Never thought of the Spring Washers, but that's a great IDEA! As for the tensioning, I was trying to figure out a way to generate more torque on the screw, but don't want to clamp to the lead screw.. I will play and see if I can get more. I will say, the lashing of the lead screw has dropped considerable compared to before, but still room for better.
Is it pretty much 1. Get lead screw tightened onto motor 2. Pull lead screw on the other side with a lot of force 3. Tighten tension nut while keeping up that force ? Many thanks y’all
Nope, that's the last thing you do. Feed in the lead screw and set the thrust bearings each end. On the motor end tighten the flex coupler on the screw and pull it against the thrust bearing. Put the nut on the other end and tighten the assembly. Once you have the tension desired on the screw, then you tighten the motor into the flex coupling. You should not be pulling on the stepper motor in any way. The tension exists between the inside face of the flex coupling at one end and the nut at the other. As an additional point, when setting the thrust bearings, look at the two washers. One will have a slightly larger hole than the other. The one with the larger hole goes against the plate in the bearing pocket and the one with the smaller hole goes toward the end of the screw, against the nut or the flex coupler.
BTW, I forgot to mention the Shim - 12 x 8 x 1mm. You'll need one at the coupler end between the thrust bearing and the coupler to keep the coupler from rubbing the plate. You'll probably need one at the nut end too so just plan on two each actuator.
Am I taking crazy pills? I can’t for the life of me get these tension nuts on. I’ve removed the set screw and I just can’t get them to go on.
I had a couple of questions regarding lead screw tensioning method to piggyback onto this thread rather than launch another. I thought this thread had the best additional advice for implementing this on an existing OB system with 8mm leadscrews (thanks @Rick 2.0), supplementing these references: Tingle-Tension-System-Manual.pdf (bulkman3d.com) (good install video) First the questions: Torque applied: Can anyone recommend a target range of ft/lb or N-m of torque that should be applied to the brass Tension Nut? Results: Has anyone noticed change in machine "running noise" using a tensioned leadscrew? And will this have impact on the GRBL max speed (i.e. $110/111/112) and/or max acceleration (i.e. $120/121/122) limits and need to re-optimize? My scenario: I have been slowly building a 1010 Sphinx from Kyo's plans (pre-OB kit availability) and noticed both my Y-axis lead screws under compression whipped and also bowed near end of travel by the motors. I want to resolve this before I finish a system enclosure that I am building (and hardware adjustments are a bigger ordeal) -- I noticed the new tension nut and thrust bearings and heard about tensioning. With the 1040mm OB leadscrew length (shorter than the SPAM Tingle upgrade leadscrews), I have built out the leadscrew tensioning based on advice in this thread -- I only did this for my Sphinx Y-axis leadscrews: Motor end: NEMA23 --> Motor Coupler --> thrust bearing --> motor leadscrew end-plate --> flanged bearing --> precision washer --> 5/16" split-collar leadscrew shaft clamp Opposite end: Tension nut --> precision washer --> thrust bearing --> leadscrew end-plate --> flanged bearing --> precision washer --> 5/16" split-collar leadscrew shaft clamp Notes: Per Rick's suggestion, I directed the smooth surface side of thrust bearing's middle brass bearing holder toward the tension nut or the motor coupler. With 1040mm length lead screw, you have to make sure you have ~6-8mm available hanging out once assembled for the motor coupler to grab it well I upgraded to 5/16" split-collars on the interior side of the endplates to hold the flanged bearings in place. I am simply snugging these against the flanged bearing to hold in place, and not applying excessive force against the flanged bearings that might create an additional bind around each endplate due to the tension nut or motor coupler applying tension. I had to move my Y-Axis endstops to avoid making contact with the 5/16" collars set screws. Rick pointed out above that you should not apply the tension nut with the Motor coupler attached to the NEMA23. I re-did my initial tensioning setup after I tried to do it with NEMA23's attached/energized as per other installation advice on the web. With the Y-axis motors unhooked, while tightening the tension nut I wasn't sure how to "hold" the motor coupler stationary as I applied tension with the new brass nut -- I had the screw rotate some. With the 40mm spacers forming a cage around motor coupler, I stuck an allen wrench into a motor coupler set screw forming a wedge against a 40mm spacer to keep the leadscrew from rotating on coupler end while I tightening the tension nut at the opposite end. This worked well, but I am uncertain if I have "same" tension on each Y-axis leadscrew and how critical those need to be matched (thus my Questions #1 & #2). Outcome thus far: The Good: Very little Y-axis leadscrew whip, straight-as-an-arrow while moving in Y for either of my Y-axis leadscrews. I have eliminated the leadscrew warping that I previously observed near end of travel under compression. I can only deflect the leadscrews a few millimeters by hand. No binding of Y-axis moving plates when motors off and manually turn leadscrews. Concerns: Machine seems "louder" on y-axis. I have yet to optimize my machine for GRBL $110-112/120-122 for my system -- using $111 = 2000mm/min and $121= 10mm/sec^2 for my Y-axis. I ran 20min gcode to draw concentric squares/circles and perimeter from 100mm to 600mm diameter and ran OK with 1000mm/min feed rate. However, at the very end of this job one of Y-axis leadscrews binded up while the other tried to drive onward -- I stopped the job before the X-axis rail was too canted. Help/Advice?? I may just need to play around with Y-axis $111/$121 settings with this new setup -- I haven't done this and maybe one of my Y-axis motors just stalled when it binded during the job above. My 2 questions about tensioning and my description above of how I performed this are to see if anyone recommends that I should re-do any hardware setup again before proceeding further. I'd appreciate any advice. Happy New Year, too.
For my 1st question on a recommended torque setting for the Tension nuts — I might buy one of these inexpensive torque wrenches to recheck tension on the Y-axis tension nuts and try to balance them. I have no idea what tension in N-m/ft-lbs that I am shooting for doing this “properly”. EPAuto 1/4-Inch Drive Click Torque Wrench (20-200 in.-lb... https://www.amazon.com/dp/B01LX4ND65/ref=cm_sw_r_sms_api_glc_fabc_jDI7FbXH3M3YY?_encoding=UTF8&psc=1
Not sure where you are seeing this. I'm not really sure if it matters which way the brass holder faces. Main issue is getting the washer with the larger hole up against the mounting plate. As far as what specific torque to put on these systems let me make one thing perfectly clear.... $2 thrust bearings are basically crap. The balls are not ground to any significant level of precision. And the more tension you put on the system, the more compression you put on the balls and the more the irregularities are going to cause your system to bind. Snug tight is all you want to achieve here. You want to remove all the slack possible, taking out any play in the system but not creating significant tension in the lead screws. Am I suggesting you shouldn't use $2 bearings, of course not. They fill a niche in the hobby market at a reasonable price. If you must have proper bearings, ones that can handle the forces you desire to put in the screws be prepared to drop some serious $$$$.
LOL, I paid for my bearings, they are on their way from China (should be here, in Canada, in less than 2 weeks), less than $2 for two of them. I guess once they're installed I'll see how much tension I can put on them, if any, and if I'll have to just toss them to the garbage.
Hi! I just put my (chinese fake) 1500 CNC under tension, I was lucky to have thought to have ordered the OpenBuild Motor Endplates[0] (4point) to replace the (fake) plates (2 points) and was able to make it work because they are thinner ( 6.4mm vs 12.2mm ) and provide *just enough* enough room for the lock collar. A couple important tips 1) Do not use open build tension nuts with non-open build ACME screws. The nuts are 7.8mm not 8mm because open build acme screws are 7.8mm 2) When ordering, send them an email to ask for Loose fitting flanged bearings[1] (7.9mm will just barely fit the fake 8mm ACME screws).. get a few extras just in case. 3) Probably add a few couplers just in case you strip/mess up your couplers 4) Before putting it under tension, verify the motor fits nicely 5) I forgot to order spacers, so I used drop in t-nuts and they worked great... though I did have to measure alot of them to find 3 sets of four that were very close in thickness... [0] C-Beam Motor Mount Plate [1] Flanged Bearing 688ZZ 8x16x5 Hope this helps!
