1 Topic by w_smith

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Topic: SD4 broke Lawsy carriage!

So it just keeps getting better!  Either because I:

- had the X belt too tight
- Used too much acetone cleaning the bed, and the vapors rotted the carriage
- have a lot to atone for in a previous life

Or some combination thereof, the bolt that holds the X pulley on the right Lawsy carriage broke the lower attachment point (and then cracked the upper one).

I managed to use Krazy Glue to hold the upper attachment together, and painted that part of the assembly with acetone to hopefully weld it together.

I then went down to my local machine shop, had a good laugh about putting him out of business, and had him make a reinforcing plate to hold the bolt in place.

It's printing again, but when I switch back to ABS I'm going to be printing off spares of everything!  And I'll probably add some more material to the pulley bolt attachment.

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2 Reply by wardjr

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Re: SD4 broke Lawsy carriage!

Maybe a little insight to your situation....
Good chance you had the belt too tight and maybe you had poor layer adhesion or chose to use less than 100% infill.
Acetone will bond ABS stronger than anything you could ever print so the vapor definitely didn't cause your problem.  It is always a good idea to have spare parts on hand.  You are not alone we have all been there and done that wink

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3 Reply by jagowilson (edited by jagowilson 2015-02-27 01:48:57)

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Re: SD4 broke Lawsy carriage!

Ha, nice idea. Yep it definitely helps to have spares wink

When you print those print them 100% infill. Make sure your extrusion multiplier is dialed in well or the bearings won't have a tight fit.

Edit: dammit ward

4 Reply by AZERATE

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Re: SD4 broke Lawsy carriage!

**Disclaimer: I sent OP the carriage**
I think the tension must have been too tight. Wardjr did mention the infil being less than 100%, which "could be the case, since I print all my carriages at 70%, but that specific part was printed immediately after the original which has been installed and running for close to 200 hours without problems.
Either this part was a fluke structurally speaking, or the tension played a significant role.

BTW...nice idea!

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5 Reply by mdrVB6

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Re: SD4 broke Lawsy carriage!

The number one rule of 3D printing should be have a spare of EVERYTHING!  Especially printed parts.  I think we have all found this out the hard way before, I know I have.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed

6 Reply by w_smith

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Re: SD4 broke Lawsy carriage!

Yeah, but "Never lick a gift horse in the mouth" 8*) the carriages were a donation from another forum member, so I can't really complain.

Last time I tried 100% infill Slic3r blew up, but maybe the new one fixes those bugs.

I'm printing a bed stabilizer (in PLA, don't get me started!) before I switch to PLA, and I've got the part-cooling fan ready to go, so hopefully I can spend next week turning out spare carriage parts.

7 Reply by jagowilson

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Re: SD4 broke Lawsy carriage!

I don't recommend printing printer parts in PLA. it gets hot enough in my (properly sealed) enclosure to melt PLA parts.

8 Reply by mdrVB6

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Re: SD4 broke Lawsy carriage!

+1, PLA is not a good choice.  I've seen the recent thread on bed stabilizers.  I don't know about the wooden beds, but the aluminum bead holder on my SD2 is about the one part this is solid and has never given me any troubles.  Really, unless some part of the Z axis is broken, you should not need a bed stabilizer.  Even if you can wobble it by hand, that is not a motion that happens during printing so its a non-issue.  There are so many things that can be done to improve your prints before doing a bed stabilizer.  Just my opinion.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed

9 Reply by w_smith

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Re: SD4 broke Lawsy carriage!

mdrVB6 wrote:

+1, PLA is not a good choice.  I've seen the recent thread on bed stabilizers.  I don't know about the wooden beds, but the aluminum bead holder on my SD2 is about the one part this is solid and has never given me any troubles.  Really, unless some part of the Z axis is broken, you should not need a bed stabilizer.  Even if you can wobble it by hand, that is not a motion that happens during printing so its a non-issue.  There are so many things that can be done to improve your prints before doing a bed stabilizer.  Just my opinion.

I've found that one little glitch while printing the first layer (a bump or divot in the kapton, or poor adhesion) can cause the head to hit the resulting bump on succeeding layers, which shakes the bed, Rinse Later Repeat.

I can see the bed shake, so I'm going to do what I can to reduce it.  The Z rods are held in place properly, but I can grab one of the rods and cause the bed to rotate around the other rod.  I mean, c'mon, there's a 12-inch moment arm from the Z rods to the front of the bed, how can you expect that to be stable to within 0.1mm?

And I've officially given up on waiting for the proper connectors from SD tech support, I'm going to switch over to ABS and work my way up to the E3D hot-end over the next week.

10 Reply by mdrVB6

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Re: SD4 broke Lawsy carriage!

w_smith wrote:

The Z rods are held in place properly, but I can grab one of the rods and cause the bed to rotate around the other rod.

These two statement are in conflict with each other.  If they were held in place properly, you would not be able to rotate the bed like that.  Its not your fault, it sounds like you just got a shitty bed and/or frame where the operator had an off day when he drilled your holes in the case.  Unfortunately, solidoodle QC often leaves much to be desired.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed

11 Reply by w_smith

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Re: SD4 broke Lawsy carriage!

mdrVB6 wrote:
w_smith wrote:

The Z rods are held in place properly, but I can grab one of the rods and cause the bed to rotate around the other rod.

These two statement are in conflict with each other.  If they were held in place properly, you would not be able to rotate the bed like that.  Its not your fault, it sounds like you just got a shitty bed and/or frame where the operator had an off day when he drilled your holes in the case.  Unfortunately, solidoodle QC often leaves much to be desired.

Actually the ends of the rods are well secured, but the rods flex or bend just enough to allow the front of the bed to move.  The stabilizers (see other thread) work so well that the back of the bed has more slop than the front now!

12 Reply by grob

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Re: SD4 broke Lawsy carriage!

w_smith wrote:

Actually the ends of the rods are well secured, but the rods flex or bend just enough to allow the front of the bed to move.  The stabilizers (see other thread) work so well that the back of the bed has more slop than the front now!

Sorry VBR. I'm with smith on this one, the 3/8" rods bend.

There's about a 6:1 leverage on the front of the bed to the shafts, and due to the mounting through the thin sheet metal, the shafts are basically pin jointed at the ends (see 4th diagram below) rather than fixed as many assume (see 6th diagram below), so about 4x as flexible as you might think...

http://www.grantadesign.com/images/solutions.figa2.gif

I feel that most of the flexibility in the system is actually coming through the bed (and also the extruder mounting). I've always intended to mount a shaft up the front of the case to do the stabilising; haven't quite got around to it yet.

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
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13 Reply by mdrVB6 (edited by mdrVB6 2015-03-02 14:33:15)

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Re: SD4 broke Lawsy carriage!

I thought that "the rods rotate around each other" meant that OP was having the bed swing in a circle around the Z axis?  If that was the case then I would say it would have to be indicative of oversized holes or undersized rods.  But if he is having the rods bend then I agree that it is an overall rigidity problem that could solved by simply using more robust components.  The solidoodle is not exactly known for its premium construction.

The rods rotating around each other is different than the rods bending, so we are not really in disagreement here.  Haha, I haven't seen statics diagrams like that since college (civil engineer, but not structural focused).

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed

14 Reply by w_smith

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Re: SD4 broke Lawsy carriage!

Potato, Potatoe, the front of the bed was very wobbly before the stabilizer, and doesn't move at all after.  Bed shaking during printing is essentially eliminated.

15 Reply by grob

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Re: SD4 broke Lawsy carriage!

Hehe thanks. When you rotate the bed around z (e.g. apply a force in x at the front of the bed), the rods actually bend to allow the rotation (even if the bearings/bushings have no slop). That's all I was trying to point out.

And no argument, mainly just wanted to post a diagram haha. smile

SD3. Mk2b + glass, heated enclosure, GT2 belts, direct drive y shaft, linear bearings, bowden-feed E3D v5 w/ 0.9° stepper
Smoothieboard via Octoprint on RPi