Robotdigg Rails
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Yeah I've tried so hard to find a good way to use rails on 4040 but most of the ways I could think of leave more room for error than just sticking with delrin. Has anyone seen noticeable improvement with the rails over standard v slot delrin?
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Why not bolt rails to your 4040 extrusions? The rails will be slightly off centre, but apart from a small change in the maximum sideways angle of the arms in one direction (which I don't think will matter at all if you use Haydn's magnetic joints), I don't think it will affect the kinematics - as long as you bolt the rails on the same side of each extrusion, either all to the left, or all to the right.
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@dc42 I guess because the motor and idler mounts will then be offset by ~10mm?
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@t3p3tony said in Robotdigg Rails:
@dc42 I guess because the motor and idler mounts will then be offset by ~10mm?
That's a very good point, I hadn't thought of it!
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Yeah, and given the varying standards/types of the rails it's hard to find one that has 2 sets of screws 20mm apart and also a block with a 20mm square set of holes.
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I've gotten their rails a few times. They're hit and miss. I've gotten some bent. I've gotten some filled with sludge instead of oil. Most have been usable after a tear down and re-build of the carriages, and polishing the rail itself. (Only one was too bent to bother trying to save)
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I could see some spacers made from acrylic and a laser cutter. Would you have the room to move the carriages ~15mm closer to the bed?
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@number40fan what do you mean?
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If I was on my other computer I could draw you a better picture, but hopefully you get the idea.
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Can't figure out how to edit my posts, but needing to move the carriages closer will really depend on how your setup is now.
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@number40fan Yeah I get where you're going, though at that point you could almost just use it as a jig to drill holes in the center really. But introducing potential for error either way. I think at that point I'd rather just buy 2040, vertex and new linear rails. The only real alternative is parallel rails which I'm not sure there's anything that would work in this scenario.
Btw what are the 'best' linear rails from robotdigg? I know they said they can do custom lengths.
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@mysta said in Robotdigg Rails:
@number40fan Yeah I get where you're going, though at that point you could almost just use it as a jig to drill holes in the center really. But introducing potential for error either way. I think at that point I'd rather just buy 2040, vertex and new linear rails. The only real alternative is parallel rails which I'm not sure there's anything that would work in this scenario.
Btw what are the 'best' linear rails from robotdigg? I know they said they can do custom lengths.
The std steel ones can vary in Quality like most Chinese Clones but all the Stainless ones that I know about no-one has said there bad!
Such as these MGN12-1500 ones in SUS440C
They may even do double width ones so you could alway ask Derek what he can do for you?
Doug
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@dougal1957 Thanks I'll ask. I do like the idea of a 4040 with rails. And my current setup prob has a little more weight on the carriage than I'd like.
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Whatever you used to make the spacers, you would have a little wiggle room, just like you would with T-nuts in an aluminum extrusion. The linear rail would be stiff enough to help align everything vertically if you loosely assembled the spacers first.
Even with the best made extrusions, you are not guaranteed to not have a slight bend/twist in them.
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@mysta Will be interesting to see if they have them in stock, every time Ive ordered from them they've not had them, and other sellers on Ali took the order and then asked for more money, which I refused.
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@dadiy For what, the 440C?
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@mysta they didn't have anything in the 1.5m lengths even though they were advertised, hopefully that's changed now, please let us know if you go for it.
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Alright I'll give it a shot,t hey usually don't reply until like 3am so I'll see. If they do I'll prob get like 1350 or somewhere around there as I won't need the full length with my 500mm arms.
