Another topic about a gap

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Fortross
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Another topic about a gap

Postby Fortross » Thu Dec 20, 2018 6:18 pm

Hello everyone.

I've recently bought the brand new Raise3D Pro2 with a dual extruder set. I bought this printer for purposes of prototyping and low series manufacturing. Material - ASA with HIPS as a support.
The problem is trivial - warping of a model. Yes, I've searched community forum trying to find the solution, read some topics and realized I'm not the only one who has this kind of issue. I measured and remeasured the glass table and found that it's warped in the center of the surface, and furthermore needs to be readjusted. I also found a shop which could make me precise and ground thick aluminum table. But! The thing is while I was trying to adjust a gap between a nozzle and a surface of the table I found that the gap is not constant. For example, I adjusted the gap in the center of the table to be 0.2 mm. After moving the extruder head around the table (no matter manually or not) and then move it back to the center, the gap has changed. I did it lots of times and usually received a different result. Finally, I tried to measure the bending of the guide rails and realized that they are bending down under the weight of the extruder head, mostly at the center of the table. The max bend value of the rails I acquired was 0.18 mm! Thus, at the corners of the table, the gap has sometimes reached enormous 0.75 mm (including "straightness" of the bed) . This uneven bending could cause and actually caused unexpected scratching of the table or a model by a nozzle which some people experienced.
I understand that I'm a newbie in 3D printing but I have got a lot of experience working with CNC machines, turning and milling centers and I really don't understand how I can reach stable and repetitive results with this sort of guide rails playing not to mention warped table. I couldn't even imagine how these rails play while printing at high speeds.
I appreciate any suggestions on how to deal with this trouble.

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Vicky@Raise3D
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Re: Another topic about a gap

Postby Vicky@Raise3D » Fri Dec 21, 2018 12:24 am

Did you feel any resistance when trying to move the print head around?
Can you see any obvious wiggle on your rods when moving print head around in all directions?

Fortross
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Re: Another topic about a gap

Postby Fortross » Fri Dec 21, 2018 9:42 am

Yes, there is some resistance when moving the printhead around. About playing... Yes, they play. It's pretty obvious to see with the naked eye. And all of this is not about bearings or untighten screws, I revised all of them.

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Vicky@Raise3D
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Re: Another topic about a gap

Postby Vicky@Raise3D » Fri Dec 21, 2018 8:08 pm

If your rods wiggles a lot, especially can see jumping up and down with eyes, I'm thinking whether you have a bent rod or not. If so, you may need to consider get replacement for it.

Fortross
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Re: Another topic about a gap

Postby Fortross » Sat Dec 22, 2018 12:59 am

I didn't mean these rods wiggle really "a lot", there is some wiggling which is enough to obtain unconstant gap. It's hard to diagnose these rods while they're mounted. I'm thinking about examination in laboratory conditions. It will cost some money, but then I'll understand if they aren't straight or they're too thin to support the printhead without bending or It's me crazy.

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Vicky@Raise3D
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Re: Another topic about a gap

Postby Vicky@Raise3D » Mon Dec 24, 2018 12:29 am

If you'd like to take a video which can see the abnormal you can see and share with our technician at http://help.raise3d.com, they can help diagnose.

zemlin
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Re: Another topic about a gap

Postby zemlin » Mon Dec 24, 2018 3:03 am

Fortross wrote: or they're too thin to support the printhead without bending or It's me crazy.

Any beam under load will bend. Larger beams bend less.
I did some beam calculations for 8mm diameter rods and an estimate of the weight of the gantry - I don't remember the exact numbers, but they were comparable to the gantry sag of the N2 printers.

I don't, however, find that this leads to any warping of parts, as it's only very small amount of sag. With larger parts and larger nozzles I can get a good first layer without issue. With smaller parts I work in a smaller area of the bed. Using a raft can also be helpful as it builds a surface that will compensate for any sag in the gantry, so if you want to run a bunch of small parts covering the table, printing on a raft could be a good practice.

I've never printed with ASA, but a quick google says it prints a lot like ABS. I have printed a lot of ABS, and warping with that isn't something to blame on the printer - it's the nature of the material and you have to be on your A-game to get good results. Sounds like you might be expecting too much too soon. Perhaps it's worth getting your head wrapped around the process using easier materials to start off.

A good print might still be warped once you pop it off the plate. FDM printing can leave a lot of internal stresses in a part. If you want it truly flat after printing, you might need to look into an annealing process to stress relieve the part before popping it off the bed.

Fortross
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Re: Another topic about a gap

Postby Fortross » Mon Dec 24, 2018 3:50 pm

Vicky@Raise3D wrote:If you'd like to take a video which can see the abnormal you can see and share with our technician at http://help.raise3d.com, they can help diagnose.


I'll try to make the video in short time.

zemlin wrote:
Fortross wrote:


Thanks for your respond, zemlin.

To be honest, I just try to figure out if there is something wrong with the printer or the filament or with me. Your experience in ABS printing made me a little more optimistic in this case.
I started my experience in 3D printing making the same model with stock PLA which I received with the printer and models were absolutely perfect. But It's PLA. ASA just starts to warp immediately after starting printing and no matter if there is a raft or not. I tried to use blue scotch, kapton tape, hairspray, printed ugly warped ABS deflector for the extruder cooler to avoid fast cooling, printed on the glass side of the bed, printed rafts and brims and nothing helped to prevent model unsticking from the bed. Sometimes it doesn't stick to the bed at all. Right now I can't print a simple 76 mm diameter cylinder with 2 mm wall thickness and 20 mm height without warping. On the other hand I can't move to other more easygoing material because of hardness, durability and chemical resistance requirements specified to the part.

After countless hours of trying I started to measure the rods and the bed. That's the story.

Could you please write what the manufacturer of the filament you use? And your settings for printing ABS? Maybe the point is there.

Appreciate your kind answer in advance.

zemlin
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Re: Another topic about a gap

Postby zemlin » Tue Dec 25, 2018 2:12 am

I have had good results with Hatchbox ABS and eSun ABS Plus. Between the two I prefer the Hatchbox. It's a little more prone to warping, but the finish and colors are a lot nicer than the matte finish from the eSun ABS Plus. I've had availability issues with Hatchbox, however, so when I was doing a lot of printing there were times when I couldn't get the material.

When printing ABS I print on a PEI print bed. You don't want to over-squish the first layer with ABS on PEI or you'll have a tough time getting it off. With a good first layer, however, the PEI is a great surface for ABS. I also like the PEI for PETG material. PETG prints a lot easier than ABS, but it can be stringy.

Fortross
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Re: Another topic about a gap

Postby Fortross » Wed Dec 26, 2018 8:22 am

Unfortunately, the Hatchbox doesn't produce ASA and isn't introduced to the EU market, but we do have eSUN filament here, thanks, I'll try it. I invested some money in buying different filament - Fillamentum, Zortrax, and eSUN, which I ordered yesterday on the basis of your experience. I'll try all of them out. Thanks again.

It looks like PEI needs a lot higher temperatures of an extruder and a bed than ABS and even ASA, (300 C+ for the extruder and 120C+ (sometimes even 140 - 160 C) for the bed) this is exactly what I read in different sources. Do you use significantly improved printer? How do you combine these materials in one print?

I'm using HIPS as a support for my prints just because of comparable printing conditions, but, unfortunately, it warps the same way as ASA does. Here is the best result I've got with ASA and HIPS after one hour of preheating and some hairspray on the surface of the bed. The unresolved problem is that an outside wall of the part begins to unstick immediately after printing started (no matter is there raft or not) while the inner part of the wall preserves its position. Is it caused by the printer? Or is the temperature of the bed too low for ASA? Or is it bad quality material? I don't know.
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zemlin
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Re: Another topic about a gap

Postby zemlin » Wed Dec 26, 2018 1:22 pm

Are you running ASA with the fan covers on - you don't want any cooling with that material.

regarding PEI - I'm not printing it - I'm using a sheet of it for the build surface.

There seems to be some helpful info about ASA here: https://www.simplify3d.com/support/materials-guide/asa/

Fortross
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Joined: Thu Dec 20, 2018 3:25 pm

Re: Another topic about a gap

Postby Fortross » Wed Dec 26, 2018 2:07 pm

I'm running ASA without layer cooling at all. For the nozzle cooler, I printed a deflector to avoid any atmosphere movement next to the model.

Anyway, thank you for your attention paid and for the info. I'll go on searching for the solution. It should be somewhere.

cullymoto
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Joined: Tue Jan 31, 2017 7:32 pm

Re: Another topic about a gap

Postby cullymoto » Sun Dec 30, 2018 3:40 pm

I second the recommendation for using pei as a build plate surface. I've used the same 0.40" sheet for well over 1 year on my n2+.
All it ever needs is a quick light sanding, and cleaned with alcohol.
https://catalog.cshyde.com/viewitems/3d ... /ultem-pei
I get my pei here and it's the single greatest upgrade I've ever made to any of my printers. I cannot recommend this stuff enough

Fortross
Posts: 7
Joined: Thu Dec 20, 2018 3:25 pm

Re: Another topic about a gap

Postby Fortross » Tue Jan 08, 2019 2:06 pm

Well, the question is settled.

Zemlin's link was decisive, thank you very much! There was just overheating problem working with ASA. I made some changes and printed absolutely good parts without any warping at all.

So, the printer is OK. My apologies for the disturbance.


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