Tips to align LM8UU bearings on y-carriage plate?

[Paul]

Hey folks,

I'm building my first MendelMax 1.5 and have run into a small issue.  I'm using a standard y-carriage with LM8UU bearings and this plate: http://store.terawattindustries.com/27-terawatt-industries-universal-y-axis-plate.html .  When I slide a single bearing along one of the smooth rods, it moves smoothly, and while it isn't silent, isn't too loud either.  Placing two bearings butted up against eachother move along the rod well too.  When I assemble the plate and slide a rod through a pair of bearings, however, there is a lot of noise and it isn't nearly as smooth as I think it probably should be.  I can only imagine that this is because the bearings are not aligned.  

I tried keeping all of the socket head screws loose, placing the smooth rod in, then tightening them down, hoping that the rod would help align the bearings, but it didn't fix the issue.  I'm thinking of opening up the holes slightly in the plastic stand-offs to see if the extra wiggle room can give me a degree of freedom to find that "sweet spot", then tighten down the bolts, but figured I'd ask here since I'd guess that this is a common problem.

Thanks for any guidance!

Paul

[Lee]

The problem is likely that the printed parts which hold your y-axis rods are not perfectly matched to the spacing of the plate. It is unfortunate that you cannot adjust the rod spacing with the printed parts, but you should first make sure that your y-axis rods do not move at a slight diagonal across your printer. 

Use a caliper to check that the printed rod holders are directly across from each other across the y-axis. You can "pad" the inside of the printed parts where the rods are held to move the rods closer together by small amounts if you need to.

[Paul]

Hello Lee,

Good tips, but actually I'm not even at the point of installing the plate into the base yet.  I have the plate sitting upside down like this: http://mendelmax.terawattindustries.com/assembly/pix/assembly/large/MM15-BuildGuide-0_1-240.png , and am trying to align the bearings to the rod.  At first glance, it appears that the bearings are at a slight angle.

[GrtBaldini]

Until you get it mounted in place, you won't know for sure. Did you get the plastic from the same place? maybe contact them and ask which holders work the best with their plate. You can fine tune the holes a tiny bit to fit the plate but you want them snug. I made my own plate but made a template with the hole layouts, etc and it works well and I'm using 4 similar holders. good luck!

On Tuesday, April 9, 2013 12:20:35 AM UTC-5, peabody1929 wrote:

I would make sure the inside of the plastic bearing holders are clean and smooth.  A bit of extra plastic can make the bearing sit at an angle.  Hope you solve the mystery!

[Paul]

I took peabody's advice and lightly sanded down the bearing holders using a dremel and sanding cylinder.  While the bearings slide in smoother, it didn't fix the issue.

GrtBaldini, the plate came with its own bearing holders and standoffs, as it is sold as a complete "kit".

I ended up slightly opening up the holes in the bearing mounts by around 200 microns.  After some finagling, the plate slides much smoother on the rails now.  I'll see if I can post a video to ask the community whether or not it is acceptable to continue the build.

[GrtBaldini]

We like new builds! Just watch out for that Larry guy... :-) :-P

[Larry Knopp]

Ha!
:)

On Wed, Apr 10, 2013 at 9:42 PM, GrtBaldini <fishn...@gmail.com> wrote:

We like new builds! Just watch out for that Larry guy... :-) :-P

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