Need advice for the best Raft Settings in Cura

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Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Feb-Sun-10-Feb

Hi Printrbot nation,

I've been using my printrbot simple metal for a few months now and is been really sweet. I've been using the brim option for a while, but I am trying to go back to raft to avoid wrapping print. I've done some research on the best raft setting around the internet and I am using these settings (pictures below) for now. The problem is that after the first two layers, the three and final layers of the raft didn't seem to "completely filled the area". And when the print is finished the raft is difficult to snap off and stuck to the bottom of the print.

Any expert can show their setting for raft in Cura that can snap easily and print in shorter time would be appreciated. I have been with this problem for weeks!!! Thank you.

{P.S I can post more pictures if you don't understand what i meant about the problem with the raft setting. It's really difficult to show when the machine is printing}
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Need advice for the best Raft Settings in Cura

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Re: Need advice for the best Raft Settings in Cura

Postby Mooselake » 2016-Feb-Sun-13-Feb

Rafts are used to compensate for warped beds, and date back to the very early days of 3D printing. They're not really intended for curling problems. Brims are used to increase the amount of area the plastic sticks to and help hold it in place, so your use of one should have helped. Perhaps it's time to investigate the cause rather than attacking the symptom.

What type of plastic are you printing? Are you using a cooling fan? What temps are you using? Do you have a heated bed? What temperature is it set at? What's the room you're printing in like? Cool, warm, drafty, or a garage where you're dodging icicles?

Curling's caused by the plastic contracting as it cools, and can be worsened by using print settings that stretch the plastic as it's laid down. Too much cooling can increase the tendency towards curling, as can starting at too high a temperature. Some times of filament curl more than others. It's hard to offer advice without enough information.

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Re: Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Feb-Sun-19-Feb

Mooselake wrote:Rafts are used to compensate for warped beds, and date back to the very early days of 3D printing. They're not really intended for curling problems. Brims are used to increase the amount of area the plastic sticks to and help hold it in place, so your use of one should have helped. Perhaps it's time to investigate the cause rather than attacking the symptom.

What type of plastic are you printing? Are you using a cooling fan? What temps are you using? Do you have a heated bed? What temperature is it set at? What's the room you're printing in like? Cool, warm, drafty, or a garage where you're dodging icicles?

Curling's caused by the plastic contracting as it cools, and can be worsened by using print settings that stretch the plastic as it's laid down. Too much cooling can increase the tendency towards curling, as can starting at too high a temperature. Some times of filament curl more than others. It's hard to offer advice without enough information.

Kirk


Hey Kirk,

Sorry for the typo but you were right. I am using raft for compensating for warped prints because when I printed larger prints using brim (at 15/20 brim lines), the corner still has warping problems.

Here's the print setting I use right now.
Plastic: PLA
Cooling fan: Enabled 100% at third layer
Temps : 190 C without heating bed on with white masking tape and glue stick ( It makes the print sticks really well so that's nothing wrong with that)
Room Temp: around 18 - 20 degrees

I have calibrated the printer and it runs fairly well on Brim setting for that time being (except for the warping problems like I mentioned). But Once I changed to Raft setting, as i said the Raft layers are not completely filled and the raft part is not easy to snap off.
Are you using the raft option often on Cura Kirk? Maybe you can share your setting on Cura too :)
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Re: Need advice for the best Raft Settings in Cura

Postby bbrown64 » 2016-Feb-Mon-06-Feb

I would suggest 60 degree for the bed temp. I believe that heated bed will help hold down the corners. I do use a brim occasionally, however I have my line count down to just 3. This has been my experience anyway. I do not need to use anything to help hold down a print on my heated bed.
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Re: Need advice for the best Raft Settings in Cura

Postby Mooselake » 2016-Feb-Mon-11-Feb

By warp I mean a print surface that's not flat, not a print curling off the bed. Check it with a straightedge in several places, and look for a gap underneath.

Bill's suggestion of heating the bed (assuming you have a heated bed) is a good one, 60C is a good temp or PLA. I haven't tried a cold bed for years, mine hits 60 in a minute or two.

3M blue tape is used more than the more common tan colored tape, since it has a special coating (to keep paint from seeping underneath) that plastic likes to stick to. For any type of tape it needs to be clean, perhaps replace your tape and give it a wipe with isopropyl alcohol or similar (I've used denatured alcohol or acetone, but keep them on hand) before applying your glue stick. I'm a glue stick fan (use it on double strength window glass, but we don't probe here), but find it needs to be washed off every now and then. Warm water works fine, I remove the glass and clean it off in the sink, but you might need to use wet paper towel or similar.

Autoleveling isn't perfect. If it's always the same section of the bed that fails to stick then try shimming the bed (closer to) flat. Try moving the print to a different location on the bed, or rotating it, to see if that helps. If if fails in the same place on the bed then you know where the issue is.

Is this issue with just one print, or all of them? Is it size related, i.e. smaller prints stick but bigger ones don't? Is it always in one area of the bed, or does it move around?

I don't use Cura very often, but they have an active user community and a good manual. You shouldn't need a raft; it's more likely a setup (first layer needs to be close, but not too close, so it's squished into the bed but not so far it jams the hot end and it can't extrude properly), the bed not flat, or perhaps your tape/glue combination isn't working as well as it should. Try stopping a print that doesn't work after one layer and posting a picture or two. Don't use raft or brim for it.

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Re: Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Feb-Tue-21-Feb

bbrown64 wrote:I would suggest 60 degree for the bed temp. I believe that heated bed will help hold down the corners. I do use a brim occasionally, however I have my line count down to just 3. This has been my experience anyway. I do not need to use anything to help hold down a print on my heated bed.


Hey Bill,

I tried with heated bed before with Kapton tape but right now i'm using white masking task (cuz is free and sticks better with glue sticks) to make the print stick better. Just want to know if the temperature of the heated bed will make the tape shrink or wrinkle? I asked someone and they said you shouldn't turn the heated bed on if you're on masking tape/blue tape, is that true?
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Re: Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Feb-Tue-21-Feb

Mooselake wrote:By warp I mean a print surface that's not flat, not a print curling off the bed. Check it with a straightedge in several places, and look for a gap underneath.

Bill's suggestion of heating the bed (assuming you have a heated bed) is a good one, 60C is a good temp or PLA. I haven't tried a cold bed for years, mine hits 60 in a minute or two.

3M blue tape is used more than the more common tan colored tape, since it has a special coating (to keep paint from seeping underneath) that plastic likes to stick to. For any type of tape it needs to be clean, perhaps replace your tape and give it a wipe with isopropyl alcohol or similar (I've used denatured alcohol or acetone, but keep them on hand) before applying your glue stick. I'm a glue stick fan (use it on double strength window glass, but we don't probe here), but find it needs to be washed off every now and then. Warm water works fine, I remove the glass and clean it off in the sink, but you might need to use wet paper towel or similar.

Autoleveling isn't perfect. If it's always the same section of the bed that fails to stick then try shimming the bed (closer to) flat. Try moving the print to a different location on the bed, or rotating it, to see if that helps. If if fails in the same place on the bed then you know where the issue is.

Is this issue with just one print, or all of them? Is it size related, i.e. smaller prints stick but bigger ones don't? Is it always in one area of the bed, or does it move around?

I don't use Cura very often, but they have an active user community and a good manual. You shouldn't need a raft; it's more likely a setup (first layer needs to be close, but not too close, so it's squished into the bed but not so far it jams the hot end and it can't extrude properly), the bed not flat, or perhaps your tape/glue combination isn't working as well as it should. Try stopping a print that doesn't work after one layer and posting a picture or two. Don't use raft or brim for it.

Kirk


Hey Kirk,

Some quick answers for you
1. I know blue tape's better, but I've got white masking tape for free with LOTS OF SUPPLIES and I don't mind removing it once and awhile
2. Glue stick is perfect for smaller prints but it just doesn't work as well to compensate wraping in large prints (eg. 10cm *10*cm *10cm)
3. Raft seems to have a make a more signficant effect to compensate the print from wrapping so I want to stick to this option. The problem i have is removing the raft parts from the print.

Can you elaborate more what do you mean by shimming the bed (closer to) flat, I don't understand what you mean. So far I think the auto-leveling is working well but is worth a shot to take a look. And I will post some picture of the raft and first few layers of print without raft if i'm able to. Thank you.
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Re: Need advice for the best Raft Settings in Cura

Postby RetireeJay » 2016-Feb-Tue-21-Feb

Count me among the non-raft users. I've printed things nearly 18cm in one axis without raft, so I know it's possible. Heated bed, CLEANLINESS, and fresh glue stick are the keys. In fact, with the glue stick you probably don't need the painter's tape at all. Maybe the tape is the problem. I'm using glue stick on glass, with heat, and it works great. (But then again, I'm not using the same plastic that you are.)

Although I never print with raft, I do sometimes have to print with support, and I always hate having to do so because the support rarely breaks away totally cleanly (or even easily!). I can't imagine that raft would be any different; it's just "support" for the entire base of the object.

You can look at the numbers you get from the auto-leveling to see how far your bed is tilted with respect to the X-Y plane of printing. If you have more than a millimeter of tilt, you'll probably benefit from shimming the bed to get it closer to the plane of printing.
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Re: Need advice for the best Raft Settings in Cura

Postby Mooselake » 2016-Feb-Wed-14-Feb

tonychan1488 wrote:Some quick answers for you
1. I know blue tape's better, but I've got white masking tape for free with LOTS OF SUPPLIES and I don't mind removing it once and awhile
2. Glue stick is perfect for smaller prints but it just doesn't work as well to compensate wraping in large prints (eg. 10cm *10*cm *10cm)
3. Raft seems to have a make a more signficant effect to compensate the print from wrapping so I want to stick to this option. The problem i have is removing the raft parts from the print.

Can you elaborate more what do you mean by shimming the bed (closer to) flat, I don't understand what you mean. So far I think the auto-leveling is working well but is worth a shot to take a look. And I will post some picture of the raft and first few layers of print without raft if i'm able to. Thank you.

1. Free's not free if it doesn't work. Either skip the tape completely and use glue stick, or get blue tape.

2. PLA shouldn't warp. I've printed nearly 200x200 prints with PLA without warping. I've used many different types of print surfaces, and many types of coatings (including none at all). I use glue stick because it works at least as well as anything else I've tried, and it's easy, relatively mess free, and easy to remove (soap and water, no peeling it off).

3. If you're having warping with PLA (not wrapping, that's what you do with presents. Warp means it's not printing flat on the bed like you expect. 3D printer people have their own language :) ) then something is wrong. You should fix the problem rather then fiddling with rafts. Expect a bad looking surface and to have to file, sand, or otherwise clean it up with rafts or support.

You can attach a picture (use the full editor), but probably not link to it yet. It would be really interesting to see what's happening.

Kirk
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Re: Need advice for the best Raft Settings in Cura

Postby bbrown64 » 2016-Feb-Thu-05-Feb

Heated bed does not cause any tape issues, that I have run across. I remember when I was using a glue stick/ blue tape combination I had a difficult time removing parts from the bed. Rafting also does not leave a nice finished surface on the bottom. If your prints corners are pulling up from the bed that is what I call warping. Then the issue is the filament is not sticking down when the hotend makes the corners. That has to do with setting for the first layer. At least I think that is correct. As of now my PLA temps are as follows. 200/ 60 I do not have any problems with warpage at all. The best purchase I have made was to buy a Zebra Plate, everything sticks to it without any supplementary glue or tape needed. Here are my setting even though I never use a raft.

Image
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Re: Need advice for the best Raft Settings in Cura

Postby ktfergus » 2016-Feb-Thu-17-Feb

The problem i have is removing the raft parts from the print.


Sometimes when I need to keep a large or thin print from warping, I'll design in "pads" which only connect to the part at several small points. They're easier to remove than a full brim, but you still need to do some sanding to clean up where they break off.

Here's a pic:
Image

Can you elaborate more what do you mean by shimming the bed (closer to) flat, I don't understand what you mean


Shimming/leveling the bed means mechanically adjusting (raising or lowering) each corner of the print bed, so that the bed is perfectly perpendicular to the z axis/hotend. Basically, you can move the nozzle to any point on the bed & it will be the same distance from the print surface to the nozzle. Some people use washers others use small springs to shim; I fall into the latter category. With a flat (unwarped) and "leveled" bed you really don't need the auto-leveling feature, & I no longer use it. In fact, I found that once my bed was physically leveled, the auto-leveling actually made my prints worse.
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Re: Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Apr-Sat-01-Apr

ktfergus wrote:
The problem i have is removing the raft parts from the print.


Sometimes when I need to keep a large or thin print from warping, I'll design in "pads" which only connect to the part at several small points. They're easier to remove than a full brim, but you still need to do some sanding to clean up where they break off.

Here's a pic:
Image

Can you elaborate more what do you mean by shimming the bed (closer to) flat, I don't understand what you mean


Shimming/leveling the bed means mechanically adjusting (raising or lowering) each corner of the print bed, so that the bed is perfectly perpendicular to the z axis/hotend. Basically, you can move the nozzle to any point on the bed & it will be the same distance from the print surface to the nozzle. Some people use washers others use small springs to shim; I fall into the latter category. With a flat (unwarped) and "leveled" bed you really don't need the auto-leveling feature, & I no longer use it. In fact, I found that once my bed was physically leveled, the auto-leveling actually made my prints worse.


Thanks man. I have used the aluminum heated bed with glue stick and without tape and to print now. Without raft it is sticking really well. IN fact, it is too well that sometimes it is difficult to remove it by scrapper. So from your experience, is there any easier way to remove the print?

Also,I'm still confused of your bed shimming method, I think i have a slight incline of my bed and i need to shim it to make it level. I don't know what you mean by using washers and spring to level it. Can you explain a bit more please? It would be very helpful. Thank you
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Re: Need advice for the best Raft Settings in Cura

Postby bbrown64 » 2016-Apr-Sat-05-Apr

Tony, do not use so many brim lines to help hold down a print. I have found that 3 brim lines is sufficient to hold down anything I have printed. Anything more is just a waste of plastic. Here is what I have. Image
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Re: Need advice for the best Raft Settings in Cura

Postby tonychan1488 » 2016-Apr-Sat-11-Apr

bbrown64 wrote:Tony, do not use so many brim lines to help hold down a print. I have found that 3 brim lines is sufficient to hold down anything I have printed. Anything more is just a waste of plastic. Here is what I have. Image


Hi there. No I have not even used brim because the print sticks so firmly on the bed now. In fact, sometimes it can get too stuck and I have to use a lot of force to remove it out of the bed. I don't know if that's the same for you but I can show you my profile for print to have some comparison to see if there's anything i did it right or wrong. Thank you.
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Re: Need advice for the best Raft Settings in Cura

Postby Mooselake » 2016-Apr-Sat-16-Apr

Tony, try experimenting with your Z offset, and reduce (by that I mean I think I mean increase since it's negative, move the head a little bit farther from the bed), for example if it's -0.3mm make it -0.25mm. I don't have a probe (another discussion for another time), forgive me if I got the numbers wrong. You want to find that sweet spot where you squish the filament just enough into the bed, too much and it'll stick to hard (until you get really too close and you'll just jam the extruder), too far and it'll come off. Try some simple thin prints to test with, it should go pretty quick.

I have an old cheap small pocket knife that I use on stuck prints, just push the point against the base of the print and tap it (I have one of those kex key sets stuck in a chunk of plastic, works great), working around the print if one place isn't enough. I use glue stick on glass, hard to scratch and the glue will keep the print from pulling chunks out of the glass. YMMV, of course

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Re: Need advice for the best Raft Settings in Cura

Postby ktfergus » 2016-Apr-Sun-20-Apr

So from your experience, is there any easier way to remove the print?


I like to use blue tape on the print surface, even if it isn't there to aid adhesion, just so there's a thin layer of material between the print bed and the print. That way, if a print is difficult to remove, there's still a small space to get a putty knife under the print to pry it off. In the past, I liked to print on a thin layer of ploy-carbonate, which I could remove from the printer and then flex to remove a part. I believe Build Tak serves a similar purpose. I now print on 8.5" x 11" magnetic sheets. I've been meaning to write up a post about this latest mod, but I basically installed a steel print bed so the sheets will stick to it. Then after a print I simply lift the sheet off the bed & peel off the part; I haven't used my putty knife in weeks. (Larger prints can still curl up, but I have a work around for that I'm going to try next week)

Also, as Moose points out, you can adjust the z offset to find a "goldilocks" setting with just the right amount of adhesion.

Also,I'm still confused of your bed shimming method, I think i have a slight incline of my bed and i need to shim it to make it level. I don't know what you mean by using washers and spring to level it. Can you explain a bit more please?


Basically, you want all four corners of your print bed to be at the same elevation, relative to the nozzle (like the four corners of a building's foundation). If one of those corners is lower than the other three, it needs to be physically raised up to match the others (not unlike putting sugar packets under one leg of a wobbly table). to do this on a Printrbot, you'll need to first remove the print bed by taking out the four M3 screws connecting the bed to the rod ends. I like using springs or disc springs which lairb linked to in this thread about bed levelling, because you can manually adjust each corner, as needed. Here's one of the "springs" I printed out to shim my bed:

Image

Place a spring/washer between the bed and rod ends at each screw & you will be able to raise and lower each corner of the bed by turning the M3 screw.
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