"Origami" CNC Plasma Build - folding 1200 x 600mm cut area

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05 Jul 2021 08:53 #213750 by Joco
Bit of a question for the likes of tommy, rod and anyone else who has experience with the shaped linear rail systems.  I had been planing on a single 15mm rail on the X axis.  My logic being that the forces on the Z carriage are not that high in the scheme of things.  Nothing like would be happening for a router.  However looking at Rod's X axis build I can see dual rails.  Am I heading into an area of frustation with "waggle" on the Z if I only have a single rail on X?  Should I be biting the cost bullet and have two?   I had been hoping to avoid the weight as well as the cost.
Is a single rail on the with some bearings as runner wheels to provide some extra support an option? 

Open to advice and education on this.

Thanks - James.
 

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05 Jul 2021 09:32 - 05 Jul 2021 09:34 #213751 by rodw
I think if I did mine again, I would just use one rail and a helical rack and pinion which would "key in" to help with axial loads.. I'd probably use a larger rail, probably HGR25 becasue its easier to buy but from memory HGR15 would meet the loads. I used 80x40x4mm aluminium RHS for the rail.

Oh and if you go to my website, there is an email in the footer. I did round up that assembly for you this morning. Send me an email so I can share it with you from Google Drive.

Oops. go here www.vmn.com.au/
 
Last edit: 05 Jul 2021 09:34 by rodw.
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05 Jul 2021 09:53 #213752 by Joco
Email sent.

That RHS section looks exactly like what I had been planning on. 

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05 Jul 2021 09:58 #213754 by tommylight
15mm rail should be more than enough, the only unknown is how many times would it survive ramming it into the slats at full speed ! :)
I used a single 25mm HiWin rail and a single carriage on many machines, they are still in perfect working order despite the owners not cleaning them ever!
But if a spec of plasma dust gets inside it will lock the carriage, so a bit of care should be taken when installing the carriage to the rail.
As a general rule, mount the rail at the bottom of the gantry, use screws in all the holes on the rail, have the gantry at least 15 to 20CM above slats, make the Z axis have at least 15cm of movement as it comes handy for cutting designs on square tubes.
Plenty of info here:
forum.linuxcnc.org/plasma-laser/35349-cn...fo-and-guide?start=0
forum.linuxcnc.org/plasma-laser/38974-di...rything-in-one-place

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05 Jul 2021 16:00 #213770 by BigJohnT

JT - re the axis being perpendicular to each other I guess other than being careful on construction that next part is getting the racking on the X under control. Dual motors and independent homing with adjustable home reference points being key to that exercise?


Sounds like a good plan to me.

JT

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18 Jul 2021 00:29 #215191 by Joco
 A little progress this weekend.  Got the Y axis linear rails cut in between the rain.  Also printed these aignment jogs that I was shown bby a friend that he used on his hypercude 3d printer.  So after some looong print time as these are significantly bigger I have two.  And they work a treat. Instant alignment to within sub 0.06mm. 
Mounted rail


An alignment bracket
 

Checking how accurate it is to top of rail
 

Setting middle of rail to zero as reference point
 

Right then Left tavel check.   Pretty good at 0.02mm from zero.  In sweeping across the length and bearing in mind this is hot rolled steel with primer on it there is 0.05 to 0.06 of variation.  I would say that is pretty dang good given how this is all being put together.
 
 

I think a pretty good start to getting these rails lined up and ultimately in place. 

Cheers - James.
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18 Jul 2021 09:05 #215212 by Joco
Getting things mounted up.
 
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18 Jul 2021 09:33 #215213 by RNJFAB
Good Work James,

Looks like it's really coming along now 

Cant wait to see the gantry on and how you go with the z axis

Cheers

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18 Jul 2021 10:35 #215219 by Joco
Here are some draft images of a Z axis design.  I am trying to make as low profile as I can manage with components that are either readily available or not too challenging to create on a lathe or mill.

Cheers.


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18 Jul 2021 16:29 #215235 by tommylight
Check my Z build here, one set of rails needed for floating head is done with about 7 euro in material and it works perfectly fine:
 forum.linuxcnc.org/show-your-stuff/38547...plasma-build?start=0

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