Y Axis Lead Screw Nuts - Poor Design

Questions/answers/discussion about initial setup of your CNC Shark

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Y Axis Lead Screw Nuts - Poor Design

Postby Jim@HeirloomTable » Tue Oct 24, 2017 8:48 am

CNC_Y-AxisRod 18-Oct-17 11-11-20 AM.JPG
Channel Cut for Allen Wrench Access


After two different needs to get in to the set screws holding the y-axis Lead Screw to the motor shaft, we've pretty much concluded that this is an example of design that could be improved.

As you can see in the first picture, it's not possible to get to the screw on the motor side of the connector - it's back inside the hole it passes through.
https://1drv.ms/i/s!Ah_DERvpr7S1gfBfhG_2k0R-CVf9jg

Our fix? - after removing the deck, took a moto tool and ground out an access channel.
https://1drv.ms/i/s!Ah_DERvpr7S1gfBhxyke50puaMYxuA

Now you can get an allen wrench in to the screws. Also put lock-tite in both of them - this took way too long to fix! If you ever have the deck off your machine, I'd highly recommend this modification.
https://1drv.ms/i/s!Ah_DERvpr7S1gfBgCUIDGDUAh-Q8FA

If anyone knows how I can get these images to display, please let me know - I think I've followed all the directions . . . :(
Jim Creighton, Partner
Heirloom Table Home, Hopkinsville, KY
Jim@HeirloomTable
 
Posts: 25
Joined: Sat Oct 24, 2015 11:17 am
Location: Hopkinsville, Kentucky, USA

Re: Y Axis Lead Screw Nuts - Poor Design

Postby Rando » Tue Oct 24, 2017 12:25 pm

Interesting solution to a ever-present problem. I've always assumed I'd just pull the motor off, and attach the connector onto the motor securely before sliding it back into place. Hopefully your connector screws will stay so tight you'll never have to use....right, you already established the dang things come loose...twice! You're right...good idea!

As for how to get the pictures to show in the post, we typically upload the image file, so that it stays with the post, like you did with the first one. Otherwise, if the outside URL eventually goes away, the forum loses that information. Like, say, one day you get tired of storing files in Microsoft OneDrive and move to some tenuous, baling-wire hacked Goo thing. No bias there....LOL. Anyway, you get the idea: URLs go away, files are forever.

The three ones in your post that show up as links look like you might have tried to use the Img or URL buttons, and got the URL when you meant to hit Img. Edit your post (top-right of post) and see if they're URL "tags" in the square brackets around those links. You can see the difference in two references that use the same link text below, but the first is surrounded by url, while the second is by img. The "code" chunks show what it looks like in the post editor's interface

Code: Select all
[url]http://shop.nextwaveautomation.com/images/logo.png[/url]


http://shop.nextwaveautomation.com/images/logo.png

Code: Select all
[img]http://shop.nextwaveautomation.com/images/logo.png[/img]


Image

I'll try it with one of yours:

Code: Select all
[img]https://1drv.ms/i/s!Ah_DERvpr7S1gfBgCUIDGDUAh-Q8FA[/img]


Image

Nope, it looks like maybe OneDrive is returning only the alt-text for the image, or maybe even just the word "image". I'd copy the file out from OneDrive, upload them as attachments (below) and then use the "insert inline" button once the attachment is uploaded. It could be either of them's fault (forum or MS), but MS doesn't care, and the forum developers are long gone. Joyously and with verve we use what we's gots! :D.

One counter-intuitive thing is that if you want to show the full-sized image in the post without forcing the user to click, it has to be stored on the internet somewhere. Images stored locally, as in those we upload, can only be shown in thumbnail form. Which means, yes, images display WORSE when they have more long-term value to the group. Go figure ;-). Maybe they're still trying to punish us because disk storage was expensive...in the 90's.

Hope that helps :D.

Thom
Last edited by Rando on Tue Oct 24, 2017 12:48 pm, edited 5 times in total.
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)
Rando
 
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Location: Hoquiam, WA

Re: Y Axis Lead Screw Nuts - Poor Design

Postby Rando » Tue Oct 24, 2017 12:40 pm

Quick question:

When you put the bed back on, how do you verify it's exactly aligned, not off by even a thousandth? Or, do you even bother? Just curious :D.

Regards,

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)
Rando
 
Posts: 583
Joined: Tue Jan 06, 2015 3:24 pm
Location: Hoquiam, WA

Re: Y Axis Lead Screw Nuts - Poor Design

Postby rungemach » Wed Oct 25, 2017 2:17 pm

I took a different approach and replaced 4 the motor holding nuts with T-nuts.

That way you don't need a wrench under the table to pull the motor off. Just remove the 4 motor screws and pull the motor out along with the lead screw. The carriage will slide forward when you do this as you pull the screw out toward you. The coupler can be tightened easily while the motor and screw are pulled out a few inches.

Use cap screws on the coupler, put a flat on the lead screw if it doesn't have one already, and you should have an assembly that stays tight for some time.

The motor mounting holes must be enlarged slightly for the T-nut body. Use the type with the points made for wood use, and just heat them a bit to let points sink into the plastic. You can do this with the motor out, and work through the large hole to put the T-nuts on.

You can pull your motor and screw out for service very easily, without moving the tabletop. If you unscrew the lead screw it all the way, you will push the bearing off of the far end and have to put it back on, under the table. Not hard to do.
coupler.jpg
motor mounted with T-nuts


Hope this helps
Bob
rungemach
 
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Joined: Mon Aug 02, 2010 8:24 am
Location: Sarasota, Florida


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