Page 2 of 4

Re: best rigidity mods for SO2?

Posted: Wed Aug 20, 2014 10:08 am
by WillAdams
That's something we still haven't reached a consensus on.

My inclination is to try the Makerslide joining clips once I get a 3D printer calibrated: http://www.shapeoko.com/forum/viewtopic.php?f=12&t=1810

http://www.thingiverse.com/thing:74301

The alternative is to drill holes in at least one of the pieces --- we've discussed it quite a bit, but don't have as many links here: http://www.shapeoko.com/wiki/index.php/ ... ide_X-Axis as there should be.

Re: best rigidity mods for SO2?

Posted: Wed Aug 20, 2014 11:36 am
by cvoinescu
ijv wrote:Whats the best way of bolting the x-axis together? Also are there any bolting locations on the x-axis that gets you the most rigidity for the hole? :)
There is no "best" way -- or, there is, but best for what?

I find my method is a good compromise: it requires only simple dirlling with no particular accuracy, no tapping, and no gouging the sides of the T-slot to clear larger bolt heads; and it's not permanent like glue (or welding -- wouldn't that be overkill?), so later adjustment is still possible. It's not the most rigid way, but M3 screws are surprisingly tough nonetheless.

Re: best rigidity mods for SO2?

Posted: Wed Aug 20, 2014 12:00 pm
by Woodworker
I can't see where a piece of plastic joining both pieces at the end is going to significantly increase the resistance to twist. Perhapse if they were metal and were the same length as the rail? What are the setup costs to have something like this made from aluminum?

Re: best rigidity mods for SO2?

Posted: Wed Aug 20, 2014 12:06 pm
by ronniemcd
Woodworker wrote:I can't see where a piece of plastic joining both pieces at the end is going to significantly increase the resistance to twist. Perhapse if they were metal and were the same length as the rail? What are the setup costs to have something like this made from aluminum?
That's the beauty of them, you stack them in as many as you like to increase the hold they have.

Re: best rigidity mods for SO2?

Posted: Wed Aug 20, 2014 12:20 pm
by Woodworker
The instructions say to "hammer them in the ends", so I have a 900mm X axis and would like it joined in the middle. So I get a 500mm rod and drive them all the way to the center? I'm not try to be a pain I'm just trying to gather info for my next upgrade. This seems like a good idea for shorter lengths of rails.

Re: best rigidity mods for SO2?

Posted: Tue Dec 23, 2014 2:03 am
by Halfdead
I went ahead and bolted my x axis together, now I'm wondering where I can find the right length spacers, it's 52.7 mm between the two plates. Times like this I wish I had a metal lathe...

Re: best rigidity mods for SO2?

Posted: Tue Dec 23, 2014 3:23 am
by chomdh
I'm also curious about how to reduce the amount of "twist" the z axis mounting plate has. My z axis v-wheels are pretty tight against the rails, but I notice a fair amount of motion when I push on it with my thumbs. I'm thinking this could be a source of some inconsistencies in my parts and carvings.

Re: best rigidity mods for SO2?

Posted: Sun Dec 28, 2014 2:25 pm
by chomdh
When I further examine the v-wheel assemblies, the bearings seem to have a larger than expected amount of internal clearance (space between the balls and races). When they manufacture the balls, they are sorted by size before they are assembled into the races so that you can buy different internal tolerance classes. Does anyone know what internal clearance class the v-wheel bearings have?

I've ordered a 5th and 6th v wheel kit for my z axis plate which haven't yet arrived but if going to a reduced internal clearance bearing is an option I may try that as well. Since the z axis v wheel bearings move so slowly I don't believe reducing the internal clearance will have any negative side effects.

Re: best rigidity mods for SO2?

Posted: Sun Dec 28, 2014 3:37 pm
by WillAdams
Unfortunately, we don't know what the ABEC rating for the bearings which Inventables sources is. (Article about skateboard bearings here: http://skateboard.about.com/od/gear/f/ABEC_Bearings.htm )

I'd really like to get a bit written up for this for the wiki:

- ABEC rating
- minimum ABEC rating for usage --- what is the point of diminishing returns?
- does a particular axis benefit from a better rating? (My thinking is the Z- wants the best, then X-, and Y- last or the same as X-)
- how does the usage of eccentric nuts influence this? I'm thinking that if one were to tighten an eccentric nut up so that a bearing was trapped so that the smallest ball bearing in the races was at that point it would be locked there and induce additional wear

Interesting link discussing this sort of thing in a CNC context: http://solsylva.com/cnc/bearing_trials.shtml

And of course, there's a thread on CNC Zone: http://www.cnczone.com/forums/diy-cnc-r ... -abec.html

Re: best rigidity mods for SO2?

Posted: Wed Dec 31, 2014 3:39 pm
by galyion
there should be almost no measurable play in the bearing themselves. maybe .0005" tops.