Z Axis Nut

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Z Axis Nut

Postby nixtacy » Mon Dec 24, 2012 4:43 pm

Hi, I didn't want to clutter the ACME vs threaded rod Z axis post, but I was curious what you all thought of what I did.
More specifically, I'm concerned about potential Z wobble.
Since I don't have access to a 3D printer, I tried fabricating as many solutions as possible out of more commonly available stuff.

For my Z block, I just bought some standard Tee nuts and embedded them in some aluminum angle.
I was very impressed with how smoothly the tee nuts threaded on and off the threaded rod. VERY smooth.

So, I just drilled a large hole in the center to accept the Center boss of the nut, then drilled 4 small holes to accept the spikey ear things. Then I just hammered them over (2 spikey ears to the left, 2 spikey ears to the right) to ensure they would capture the angle.
Then I stuffed an earplug in the Tee nut before painting the completed angle assy.

From your experiences, what issues may I have with this setup?

Image
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Re: Z Axis Nut

Postby cozmicray » Mon Dec 24, 2012 6:08 pm

What is wrong with the standard Ordbot nut Block?

You don't have access to a 3D printer but you are working on a 3D printer?
Did you build up your Ordbot from scratch?

Is it too difficult for you to thread a piece of plastic for a Z-axis nut
Is it too difficult to use a nut captured in some bracket?
How about a Tee nut in a piece of wood or plastic?
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Re: Z Axis Nut

Postby madmike8 » Mon Dec 24, 2012 10:18 pm

cozmicray wrote:What is wrong with the standard Ordbot nut Block?

You don't have access to a 3D printer but you are working on a 3D printer?
Did you build up your Ordbot from scratch?

Is it too difficult for you to thread a piece of plastic for a Z-axis nut
Is it too difficult to use a nut captured in some bracket?
How about a Tee nut in a piece of wood or plastic?


Having a bad day?
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Re: Z Axis Nut

Postby nixtacy » Wed Dec 26, 2012 3:23 pm

cozmicray wrote:What is wrong with the standard Ordbot nut Block?

Nothing. Other then being a printed part. And I don't have a printer.
cozmicray wrote:You don't have access to a 3D printer but you are working on a 3D printer?

Yes. Clearly.
cozmicray wrote:Did you build up your Ordbot from scratch?

Yes. Clearly.
cozmicray wrote:Is it too difficult for you to thread a piece of plastic for a Z-axis nut

Yes. Well, No. But, for the sake of your question, yes.
cozmicray wrote:Is it too difficult to use a nut captured in some bracket?

Yes. As it just might promote Z WOBBLE.
cozmicray wrote:How about a Tee nut in a piece of wood or plastic?

How about a Tee Nut into an aluminum angle?

Now that you answered my question, with six of your own, maybe some one with some experience with these printers can post and relate their experiences.
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Re: Z Axis Nut

Postby madmike8 » Wed Dec 26, 2012 3:39 pm

I'm not going to be much help since I'm building mine up from parts too, but I'm basically doing the same thing your doing with some acme threaded rod and delrin nuts from ebay mounthed on some aluminum angle. I'm using a bit thicker angle than you though. I'd say go with what you have. If there is any issues then find or maybe print the nut. The only thing I would have done different than what you have is I would have inserted the nut from the bottom so that the weight of the z axis is supported by the shoulder of the nut rather than the bent over spikes.

Good Luck
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Re: Z Axis Nut

Postby canadianavenger » Wed Dec 26, 2012 3:45 pm

Interesting solution with the tee nuts. My only concern would be that they may work lose over time, introducing backlash. But looks like a good "bootstrap" solution, to print the designed in parts.
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Re: Z Axis Nut

Postby REdington » Wed Dec 26, 2012 4:57 pm

When I got my 1/4-20 threaded rods, they were bent so I bought some 3/8-12 ACME and made a few sets.
Here is how I make all my no-backlash nuts.

http://bbs.homeshopmachinist.net/thread ... e-easy-way

For the 3/8 acme, I drilled a 7/32nd hole in a piece of 1/2" thick Delrin and took it to the bandsaw and cut it

Image

And then heated some extra acme rod.

Image

I used a Dremel with a cutoff disk and cut a few teeth in a piece a acme and ran it through a few times.

I turned the end down on one end to 5 mm and made the couplers out of 1/2" alum and bored and reamed to 5mm.

Image


I've printed a few parts and so far they look super. I'm still working getting it calibrated to almost perfect

Rodney
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Re: Z Axis Nut

Postby Cre8ivdsgn » Wed Dec 26, 2012 5:43 pm

I have been idly wondering about something regarding this design: with the occasional mention of Z axis binding, would it simply be better to drive the motors from the top and allow gravity to hold things in alignment on the Z? It just strikes me that with the rod ends sticking up and unsupported at the undriven end, the slightest propensity to splay the twin rods yields binding issues and if the rods were hanging down, you would have half as much trouble.

I have a feeling this issue is a bit like the airplane "tail-dragging" versus "tricycle" landing gear. I haven't looked at things carefully at this point and I could be very wrong.

All of you here on this site are very gifted folks and I think someone could easily try mounting the motors for the Z up on the support handle. Hmmm... maybe this is my cue to finally build my own 3D printer! (I've literally built hundreds of pieces of CNC automation over the last twenty years or so - more than 20 years! - but never a 3D printer.)
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Re: Z Axis Nut

Postby Cre8ivdsgn » Wed Dec 26, 2012 5:53 pm

Oh, I also think that the original T nut idea was fine and if anything the split block idea was almost excessive! Because gravity is working in one direction, anti-backlash (spring loaded or otherwise) is a bit redundant. The metal-metal interface of the T-nut might lead to more binding if the threaded rod is insufficiently lubricated and the pitch of the motors versus the nuts are off. In that case the plastic nuts are better.
We all have various bits of tools and tooling in our garages and certainly some things are easier than others given what tools we have on hand!

Happy New Year! (Its not too early to say that, is it?!) Happy pending new year... happy new year to come... happy incipient new year... ahhhh, you folks get the idea! :D
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Re: Z Axis Nut

Postby cozmicray » Wed Dec 26, 2012 6:59 pm

Bravo for building 3Dprinter with kitchen utensils!

Always amazed me how John Harrison build a precise clock with hand tools to win the Longitude prize.
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