Page 2 of 3

Re: Upsizing - the 2x4Oko build

Posted: Fri Feb 22, 2013 5:00 pm
by WillAdams
(re: threaded rod through Makerslide)
Improbable Construct wrote:I believe that the consensus was that it would just cause the makerslide to bow out and not add any structural stiffness.
Okay, well that's out --- I wonder if there's some other technique which could be used which would be lightweight, strong and reversible?

Perhaps a length of cable passed through doubled up Makerslide? You'd just need fastener(s) to connect the ends --- maybe the connectors used for stainless cable balustrades?

Re: Upsizing - the 2x4Oko build

Posted: Fri Feb 22, 2013 7:51 pm
by northbear
Improbable Construct wrote:
WillAdams wrote: I'm thing I've been wondering about is if one would get any sort of increased stiffness by running a length of threaded rod down the middle of each length of Makerslide and fastening it w/ nuts from either end --- can't recall having seen mention of that (if I missed it, I'd love to be pointed to it).
There was some discussion of that somewhere on here...
I think it was off topic so i can't for the life of me find it but,
I believe that the consensus was that it would just cause the makerslide to bow out and not add any structural stiffness.
The only discussion I could find was:

"suspension bridge"
http://www.shapeoko.com/forum/viewtopic ... 5317#p5317

"bar across the back"
http://www.shapeoko.com/forum/viewtopic ... 763&p=6240

Re: Upsizing - the 2x4Oko build

Posted: Fri Feb 22, 2013 8:07 pm
by Improbable Construct
Unless I had a very detailed conversation with my self about it, (which is very possible) I remember a conversation about tensioning threaded rod to try and create a stressed member sort of approach.
I looked on the old google groups and couldn't find it there either.
Strange...

Re: Upsizing - the 2x4Oko build

Posted: Fri Feb 22, 2013 8:09 pm
by cvoinescu
There's one more thing I remember (or maybe it's on one of the threads linked here). Someone used dual-X rail with a third piece of extrusion between the two X rails, all three bolted together at intervals. The person who did it used 20mm x 20mm extrusion, so he got a channel for the cables in the bargain; I'm not sure how useful that is in terms of resisting vertical deflection, though, so I'd go with a third piece of MakerSlide, or 20mm x 40mm extrusion, to make a sandwich 60mm wide and 40mm tall (plus the Vs).

Still, I believe that, for lengths shorter than about 75cm or 1m, two pieces of MakerSlide bolted together in several places are be hard to beat, and there's not a lot to gain from adding even more support to the X rail and making the carriage even wider (which makes it more flexible, unless reinforced).

Re: Upsizing - the 2x4Oko build

Posted: Fri Feb 22, 2013 9:32 pm
by WillAdams
cvoinescu wrote:two pieces of MakerSlide bolted together in several places are be hard to beat
How does one do that? I've seen mention of it a few times, but no details.

Re: Upsizing - the 2x4Oko build

Posted: Sat Feb 23, 2013 6:32 am
by mjohn
More progress tonight. Had to come up with a solution for the m5 70mm bolts (Inventables didn't have any). And neither of my home stores had the m5 in anything longer than 50mm. So I got two 1' lengths of threaded rod (10/24 IIRC) cut them to size and bolted each end and put the wheels and spacers between both plates. Lock washers, thread lock and looks good.

X axis with one makerslide..
Image

And two makerslides..
Image

Full Table..
Image

And the belts.. Everything moves smoothly.
Image

Was shorted servo cable so I need to make another run tomorrow for that. Then Electronics and I'm ready to test.

Re: Upsizing - the 2x4Oko build

Posted: Sat Feb 23, 2013 12:21 pm
by zerblatt007
WillAdams wrote:
cvoinescu wrote:two pieces of MakerSlide bolted together in several places are be hard to beat
How does one do that? I've seen mention of it a few times, but no details.
I was wondering that too. Can not see anything like that on the pictures, so it must be like t-nuts connecting the makerslides with a pice of metal on the bottom side?

The cable in the middle of the makerslide was a cool touch :D

Re: Upsizing - the 2x4Oko build

Posted: Sat Feb 23, 2013 3:06 pm
by Will Winder
zerblatt007 wrote:
WillAdams wrote:
cvoinescu wrote:two pieces of MakerSlide bolted together in several places are be hard to beat
How does one do that? I've seen mention of it a few times, but no details.
I was wondering that too. Can not see anything like that on the pictures, so it must be like t-nuts connecting the makerslides with a pice of metal on the bottom side?

The cable in the middle of the makerslide was a cool touch :D
I would drill through both pieces of maker slide in one of the T-Slots, then bolt it together using a T-Slot nut on one side.

Re: Upsizing - the 2x4Oko build

Posted: Sat Feb 23, 2013 4:05 pm
by mjohn
zerblatt007 wrote:The cable in the middle of the makerslide was a cool touch :D
Can't take credit for that, wish I could. Saw it floating around in another members' build photos. :)

---

I'm thinking that bolting the X makerslides is becoming more and more necessary. Event though I have them right up against each other there is still the smallest gap (probably so small I can't see daylight, but still there.) It's not causing any problems with the gantry rolling, but I can see the need for at least one bolt in the middle. It's sturdier than one, but but two didn't seem to make much difference other than the benefits to Z. This is not a mod for the un-dual-y-motor-less.

Thanks for the rec IC, I did line up the makerslides with the outside gap on both slides on the bottom. A hole and a bolt should go in there perfectly.

Fastening Makerslide pairwise

Posted: Sat Feb 23, 2013 4:33 pm
by WillAdams
Rather than a bolt is there some sort of extrusion which would fit in the slots?

Failing that, one should only need to drill one piece --- unless there would be a mechanical advantage in alternating pairs:

- in from left side @ top, in from right side @ bottom
- in from right side @ top, in from left side @ bottom

and going across in a zig-zag pattern --- how close would the holes need to be for a given span?

Openrail uses 50mm spacing, but that's chosen to acommodate bolting a flat piece against an extrusion, bolting extrusion to extrusion shouldn't afford as much flex, so double at least?

Hate to use more hardware than necessary.

Or, could one forego mechanical fasteners and use epoxy? It's almost time for me to buy more JB Weld....

William