Here's a neat idea for homemade linear bearings...


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Thread: Here's a neat idea for homemade linear bearings...

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    Default Here's a neat idea for homemade linear bearings...

    While doing my usual nightly internet searching I came across this blog post...

    http://www.bg-cnc.com/wordpress/?p=372

    I thought it was an excellent idea for a DIY linear bearing. Unfortunately there was no description with the pictures. I emailed the site owner. He responded super quick but couldn't provide any information on them. I knew they were made from a drill press pipe drilling guide but wasn't sure which one or how much they cost. A quick Bing search later and I found the guide at good ol' Harbor Freight for $9.99. It's a little less that six inches long so that may be a little short for some folks use. Here's a link to the HF part...

    Self-Centering Drill Press Jig

    I'm not sure it's right for what I'm thinking of building but it definitely has merit...

    Regards
    Greg

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    Default Re: Here's a neat idea for homemade linear bearings...

    Sorry to dig up an old thread, but I really like this bearing idea using a self-centering jig. Greg (if still on) or anyone else have more info on what size shaft/pipe will work with this linear bearing? Also are the bearings on guide 608's? Thanks!



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    Default Re: Here's a neat idea for homemade linear bearings...

    Cool idea...would it spread under load??



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    Default Re: Here's a neat idea for homemade linear bearings...

    Not sure, but really like how perfect the centering jig is as a starting piece. What would be the best way to drill square holes on the angled sides?



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    Default Re: Here's a neat idea for homemade linear bearings...

    Make a jig probably.

    Quote Originally Posted by runninfarmer View Post
    Not sure, but really like how perfect the centering jig is as a starting piece. What would be the best way to drill square holes on the angled sides?




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    Default Re: Here's a neat idea for homemade linear bearings...

    Make a jig to drill into a jig, I like it! Hahaha



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    Default Re: Here's a neat idea for homemade linear bearings...

    The big problem with this design is the same problem you have with all unsupported pipe or rod designs, that is the rods will deflect and vibrate significantly. The longer the span the worse it will be from the standpoint of deflection and vibration. Frankly I wouldn’t even bother unless you can find a way to fully support the running shafts.

    I actually have a similar drilling jig in my cellar right now (not an exact copy) and a couple of concerns come to mind right away. First is that you will need a mill to make the slots for the lower bearings. Those two bearings need to be precisely located and the slots obviously to allow the Bearings to pass through. The precision is required to keep the bearings parallel to the mounting surface. The second problem would likely be thread retention on the 4 upper bearings mounted on the 45 degree walls. The stock is pretty thin aluminum so my confidence in its long term ability to hold is low.

    I’m not sure if you noticed or not but the mounts for the 4 upper bearings are on eccentric spacers. This is a requirement to get a good fit especially on highly variable pipe. Spring loading might be a better approach. Just realize that you can have significant variability (for a linear bearing) in diameter and smoothness. The little bearings used in these designs don’t handle the changes in load well at all.

    In any event the creativity in this design is good but the idea of wasting ones time on a build with unsupported pipe or rod isn’t. What might work is to calculate the max diameter rod this design can handle and then see if that makes for a cost effective way to make a supported rail. In the end you will be screwing around trying to solve the pipe flex issue especially on any sizeable machine. There have been many guys that have gone the pipe linear bearing route on these forums and other sites that eventually have had to upgrade. Frankly supported round rails and their bearing blocks are not that much more expensive in the end. If you don’t want to go with supported round rod linear bearings I’d seriously consider some of the lower cost linear bearing solutions that don’t use unsupported pipe. Some of these might even allow the use of these V block fixtures. Angle iron on a well supported plywood base for example has more potential if you have the machinery to mount the angles parallel. The ability of these home grown systems to work depends a great deal upon ones ability to build them to an acceptable level of precision. This is where mounting supported linear rails on flat surfaces have a huge advantage. The flat surface provides one reference point in 3D space.



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    Default Re: Here's a neat idea for homemade linear bearings...

    DIY bearings are a great concept and I looked at doing that myself. But i finally ordered the SBR16 rail and trucks for my build and got going much, much faster with significantly less effort and less mechanical issues.

    Quote Originally Posted by wizard View Post
    The big problem with this design is the same problem you have with all unsupported pipe or rod designs, that is the rods will deflect and vibrate significantly. The longer the span the worse it will be from the standpoint of deflection and vibration. Frankly I wouldn’t even bother unless you can find a way to fully support the running shafts.

    I actually have a similar drilling jig in my cellar right now (not an exact copy) and a couple of concerns come to mind right away. First is that you will need a mill to make the slots for the lower bearings. Those two bearings need to be precisely located and the slots obviously to allow the Bearings to pass through. The precision is required to keep the bearings parallel to the mounting surface. The second problem would likely be thread retention on the 4 upper bearings mounted on the 45 degree walls. The stock is pretty thin aluminum so my confidence in its long term ability to hold is low.

    I’m not sure if you noticed or not but the mounts for the 4 upper bearings are on eccentric spacers. This is a requirement to get a good fit especially on highly variable pipe. Spring loading might be a better approach. Just realize that you can have significant variability (for a linear bearing) in diameter and smoothness. The little bearings used in these designs don’t handle the changes in load well at all.

    In any event the creativity in this design is good but the idea of wasting ones time on a build with unsupported pipe or rod isn’t. What might work is to calculate the max diameter rod this design can handle and then see if that makes for a cost effective way to make a supported rail. In the end you will be screwing around trying to solve the pipe flex issue especially on any sizeable machine. There have been many guys that have gone the pipe linear bearing route on these forums and other sites that eventually have had to upgrade. Frankly supported round rails and their bearing blocks are not that much more expensive in the end. If you don’t want to go with supported round rod linear bearings I’d seriously consider some of the lower cost linear bearing solutions that don’t use unsupported pipe. Some of these might even allow the use of these V block fixtures. Angle iron on a well supported plywood base for example has more potential if you have the machinery to mount the angles parallel. The ability of these home grown systems to work depends a great deal upon ones ability to build them to an acceptable level of precision. This is where mounting supported linear rails on flat surfaces have a huge advantage. The flat surface provides one reference point in 3D space.




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Here's a neat idea for homemade linear bearings...

Here's a neat idea for homemade linear bearings...