Smoothie M2

[Tim]

interesting that you have no play, comparing it to what jim posted... how old is your machine?

Well, okay, I was posting messages from my bedroom instead of my basement. Now that I'm sitting next to my printer and seeing just how much I can move the bed up and down by pushing on it, I guess there is about a half millimeter of give on it. As Jim noted, it doesn't appear to come from any one source, but is distributed over the entire Z stage assembly. I wouldn't call it "loose", though.

[insta]

I think it's actually flex in the aluminum piece that holds the bed spider to the linear rail.

[jimc]

Yeah i agree. Thats a steel 1/8" thick plate. Pat and i were talking about that prob 2 years ago. He was going to have it made from something thicker to try but never got around to it i guess. I wouldnt mind doing that myself and changing the liner slide to a proloaded misumi just to see if there is a difference. I bet it helps but i think it wont make as big a difference as i am thinking. The stock makergear stuff, even though there is a little play, does a pretty good job.

[PcS]

I never did the thicker plate because after more hillbilly testing my opinion pointed me in the direction of a pre-loaded bearing or two rails in parallel. Ultimately though I just figured with the great print quality I am getting I could not justify my time to do it. If I ever retire watch out I will mirror the m2 and have dual z rods .

[ednisley]

you can watch the linear bearing move when you do this ... certainly with less force then the movement of the carriage would create...

It's remarkably easy to push very hard with a fingertip.

To produce 0.1 N·m at the end of a 100 mm lever arm, you apply 0.1 N·m / 0.1 m = 0.01 N = 0.001 kgf = 1 g of force. Call it 1/30 ounce. That's essentially nothing, but that's what the platform acceleration applies.

Also, you're probably pushing near the +X edge of the platform, where the Y-axis motion can't generate any force at all. Apply a calibrated 1/30 ounce to the +Y edge and see how much deflection results.

Prediction: not much! [grin]

Adding a second Y-axis rail will produce a severely overconstrained mount. The X axis of my Thing-O-Matic had exactly that problem, which required un-wedging the design:
http://softsolder.com/2011/04/10/thing- ... -follower/
http://softsolder.com/2011/04/20/thing- ... installed/

If you insist on rigid-izing the Y axis, at least do it with a kinematic mount!

Seeing as how you have the urge to tinker and a shop to do it in, you might be amused by my Thing-O-Matic re-engineering project, which started with a disturbing realization:
http://softsolder.com/2010/12/26/makerb ... tor-abuse/
Fast-forwarding through the next six months will cover most of the many improvements.

The M2 didn't present nearly as many, ah, opportunities...

[jimc]

i just ordered a misumi preloaded bearing for the y on one of my older machines. ill do a test print for ringing before i change it out and one after using the same gcode and we will see if there is an improvement. if it makes a difference then ill get one for the other machine as well. they have so many bearings and figuring out their part # system isnt the most fun. here is the part # to order if anyone is interested. SSEBT13-295. this should be a direct replacement.

[innkeeper]

I spent a good 3 hours disassembling parts of the machine and looking where the play is along with trying out some some fixes that had no effect.
in short, my bearing does have play, but it is totaly within its spec. so id not call it "bad" but needs to be better if keeping the current design... yea also spent time looking at loaded bearing and high precision rails today as thats the quick and easy way to improve it.

Jim i'll defiantly look into the one you have on order.
the ones i am leaning toward are "gothic arch" design were there are 4 rows of ball bearings at 45 degree angles upwards and downwards. from what i am gathering it handles these kinds of loads better, but.. need to read more

the other place i could find play was in the screws going into the spider, there actually loose and allow for some vertical and horizontal movement., the holes on the steal place allow for some axial movement.
the bolts i have were threaded all the way to the head, putting in bolts that have a few mm of unthreaded body fixed that, though it was a temporary fix... the bolts i had were too long.... i'll order the right ones. but its a cheap and easy fix.

i'm not sure the play in the tapped part of the spider is a big deal as its under load virticly from the springs. but it does add t the axial play even loaded.

any other play i could find other then the bearing, the threaded holes in the spider and the holes in the steal plate required some force and flexing of components. and frankly i don't think the forces generated are enough for that to be a factor except for perhaps resonance oscillations.




t

[innkeeper]

It's remarkably easy to push very hard with a fingertip.

cant disagree with you...what your saying makes perfect sense.
i did tear it down and and confirmed the play in the bearing.. though it seems it is within spec.. just leads to movement at the end of the spider.

i'm not saying that some of the movement i see at the end isn't flex, i am sure it is. but in the same token, if i can get rid of some of the play in the bearing it cant hurt.

those are some cool mods on your site....

The M2 didn't present nearly as many, ah, opportunities...

yea modifying the m2 gets very expensive very fast... which... is actually back your point on price / performance.

[Tim]

cant disagree with you...what your saying makes perfect sense.

I call it "The Tao of Ed". You listen to that guy. He dispenses wisdom.

[PcS]

Looking forward to the results of your test jimc.