Adventures with a Flashforge

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Re: Adventures with a Flashforge

Post by SimonWood » Sat Dec 19, 2020 9:32 am

Trevor Thompson wrote: Fri Dec 18, 2020 8:53 pm I wonder how it will come out from a resin printer?
I look forward to finding out when you try it!

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Re: Adventures with a Flashforge

Post by philipy » Sat Dec 19, 2020 11:43 am

SimonWood wrote: Sat Dec 19, 2020 9:31 am
But a little part of me wants to spend far more time than that "fixing" the problem, either by messing with the STL files to compensate the drawing, or to fiddle with the slicer settings to find out why holes come out too small..

I don't know anything about your Flashprint, but I'm not at all sure that a slicer can do the sort of editing that you need, to fiddle with adjusting things like Lego studs and holes. Certainly Cura can flip, multiply, move, etc and the scale function allows scaling by different amounts in the three planes, but I doubt that adjusting one small element of an stl file is possible. I think you need to go back to a CAD file to do that. I know it is possible to import stl's into Sketchup but don't know if Tinkercad can accept them.
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Re: Adventures with a Flashforge

Post by ge_rik » Sat Dec 19, 2020 12:17 pm

philipy wrote: Sat Dec 19, 2020 11:43 am ......I know it is possible to import stl's into Sketchup but don't know if Tinkercad can accept them.
You can import .STL, .OBJ and .SVG files into TinkerCAD

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Re: Adventures with a Flashforge

Post by SimonWood » Sat Dec 19, 2020 12:39 pm

philipy wrote: Sat Dec 19, 2020 11:43 am I don't know anything about your Flashprint, but I'm not at all sure that a slicer can do the sort of editing that you need, to fiddle with adjusting things like Lego studs and holes. Certainly Cura can flip, multiply, move, etc and the scale function allows scaling by different amounts in the three planes, but I doubt that adjusting one small element of an stl file is possible. I think you need to go back to a CAD file to do that. I know it is possible to import stl's into Sketchup but don't know if Tinkercad can accept them.
I have already augmented an STL file in TinkerCAD - adding to a Lego block. (This is one reason making Lego appeals to me - the ability to create new pieces, or converters - a bit like this Duplo to Brio adapter.)

I can definitely scale in FlashPrint, and duplicate and (I think) mirror. Maybe scaling differently in the 3 planes will resolve it? But I'm hoping there's some universal setting I can find... I've discovered "elephants footing" this morning, and read up on solutions, but on examining the prints I'm doubtful that's the problem. Think I need to keep looking...

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Re: Adventures with a Flashforge

Post by Trevor Thompson » Sat Dec 19, 2020 11:11 pm

Simon

The Flashforge slicing software will allow all of the general manipulations like scaling, duplicating and so on. But you will have to go into the CAD package to adjust specific parts such as the pip size.

I have been looking more carefully at shrinkage and I think it is a lot less than I said last night - I think I got my math wrong. More on that in the place I posted it last night.

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Re: Adventures with a Flashforge

Post by Trevor Thompson » Sat Dec 19, 2020 11:36 pm

Trevor Thompson wrote: Fri Dec 18, 2020 9:44 pm Some information on shrinkage.

I have just measured the victorian milk churn in sketchup - and the 9 of them I have printed.

Height in the software 45mm. In reality between 45.56 and 45.67mm.

diameter in the software 27.95mm - in the printed versions fairly consistently 26.14mm in on direction and 26.26mm in the other.

So the model is about 10% too high, about 93.5% of the width it should be and 93.4% deep.

So suggesting 5% shrinkage in the plane of the bed is about right.

trevor
I have thought about this again.

I did the maths in a hurry and made stupid errors.
The error in the height of the milkchurn - 0.5mm out in 45 mm - so 1mm out in 90 mm - that is something near 1.5% not 5%.
the error in the diameter 0.8mm out in 28mm - so 2.4mm out in 86mm - that is in the order of 3%. I have to admit that measuring the diameter accurately was difficult.

I have measured the first part of the Goods shed - a section of the side of the building, That should be 139.95 x 105.57 but when printed is 139.45 x 105.66mm. So on the long side (across the printer) it is 0.5mm too short - in 140mm - so even in my head I can see that is about 0.3%. The short side (front to back on the printer) it is 0.09mm too long in about 100mm so that is about 1% too long. So the error in this component is negligible.

I have also measured the Ashbury Coach. The drawing says it should be 151.97mm long over the body, it is actually 150.71 long. It should be 73.5mm wide over the body, and it is actually 74.13mm. So that is 0.75mm too wide in 74mm so about 1%. I also measured the wheel diameter - should be 24mm diameter and is 23.86mm - that is about 0.6mm too small. That is about 2.4%.

So as a conclusion I am convinced that in practical terms when just creating a scale model the dimensions of components are mostly within 1% of the design size. There is a bigger error on tall objects - it is probably around 1.5%

I wonder what the manufacturing tolerance on a Lego brick is!

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Re: Adventures with a Flashforge

Post by FWLR » Sun Dec 20, 2020 8:18 am

That is very interesting to know Trevor thank you. Shrinkage is not worth bothering about is it, when there are such small differences in the finished part.
But then I guess the rivet counters would still find something to say don't you think.... :lol: :lol: :lol:

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Re: Adventures with a Flashforge

Post by ge_rik » Mon Dec 21, 2020 8:35 am

I've been pondering about the discussion about shrinkage etc. Doesn't it depend on how your printer has been calibrated?

There are so many variables at play between drawing and printing - but at the end of the day, isn't what comes out on the printbed dependent on how each printer has been set-up? I'd imagine that, for example, over time, the belts controlling the position of the print head will stretch. I've already had to tighten them on my newer printer. And on my old printer, those who cloned its design from the original on which it's based, replaced the fancy screw threaded rods for the Z axis with ordinary (cheaper) M8 threaded rod and so must have recalibrated the software to compensate.

I found this about calibration. I've not tried it out yet, but it looks interesting
https://all3dp.com/2/how-to-calibrate-a ... explained/

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Re: Adventures with a Flashforge

Post by FWLR » Mon Dec 21, 2020 9:30 am

I have tried to open the site Rik, but it wants me to allow adds. So I did but it still wants me to allow adds again. I have allowed the site on my ad-blocker so it should allow them for that site.... :scratch:

Anyway my thinking is, with screw threads they are more likely to keep calibration than belts. When I was setting CNC machines, the old belted one's had to be calibrated on a regular basis and the screwed ones not that much, although they too had to be calibrated also. Don't these machines have a calibration program that will do it automatically, especially if they are screw threaded ones.

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Re: Adventures with a Flashforge

Post by SimonWood » Mon Dec 21, 2020 10:53 am

Trevor Thompson wrote: Sat Dec 19, 2020 11:36 pm So as a conclusion I am convinced that in practical terms when just creating a scale model the dimensions of components are mostly within 1% of the design size. There is a bigger error on tall objects - it is probably around 1.5%

I wonder what the manufacturing tolerance on a Lego brick is!
Whilst I guess Lego bricks have to be precise enough to clip together reliably 99.9% of the time, the tolerances there are fine for our kind of work, I think!
FWLR wrote: Sun Dec 20, 2020 8:18 am That is very interesting to know Trevor thank you. Shrinkage is not worth bothering about is it, when there are such small differences in the finished part.
But then I guess the rivet counters would still find something to say don't you think.... :lol: :lol: :lol:
It's not so much the modelling (and rivet counting) that interested me but the functional aspects - e.g. my prints of the Loco Remote track not clipping together as designed. It's not so much a problem in the sense of being an issue for my purposes as being a puzzle...
ge_rik wrote: Mon Dec 21, 2020 8:35 am I've been pondering about the discussion about shrinkage etc. Doesn't it depend on how your printer has been calibrated?
I'm sure it does - and the page you link to looks fascinating, but I must confess it's going to take me some time to get my head around it, as all I've done it hoik this machine out of its box and plug it in. Really all I'm doing right now is exploring where I seem to be bumping up against its limitations - but these are a long way from affecting what I really want to do with it... the same curiosity will, I'm sure, lead me to explore the calibration more fully. In particular, I wonder if providing the filament diameter (and fiddling with the temperature settings) might make the pips fit the holes...

In the meantime, on the Lego wagon I used tabs. There I noticed that for a tab drawn at 64mm I needed a slot drawn at 64.8mm for it to fit into. Tab and slot were both drawn and printed in the same plane...

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Re: Adventures with a Flashforge

Post by SimonWood » Mon Dec 21, 2020 11:15 am

IMG_8423.jpg
IMG_8423.jpg (18.96 KiB) Viewed 5104 times
To give a balanced picture of the printer... I should probably post pics of the problems, not just the successes!

I've mentioned the 'curling' issue - that is, the edge(s) of the raft lift up, and so the print is not on a flat base...the print is uneven, with some parts getting compressed in the Z axis - in this case the sleeper printing too high, the rail not high enough, the sleeper won't sit flat and more importantly flanges will hit it:
IMG_8451.jpg
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Then, I'm not quite sure what to call this, although it seems to be quite common - sometimes it looks like it would be easy enough to hide with filler, sometimes not so much:
IMG_8450.jpg
IMG_8450.jpg (39.44 KiB) Viewed 5104 times
My guess is this is probably due to my printing ABS when the ambient temperature is too low and the side door of the printer is off to allow me to feed it from a 1kg spool...

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Re: Adventures with a Flashforge

Post by philipy » Mon Dec 21, 2020 11:39 am

SimonWood wrote: Mon Dec 21, 2020 11:15 am
To give a balanced picture of the printer... I should probably post pics of the problems, not just the successes!
Ahh...spaghetti..been there, done that, got Tee shirts galore!

Probably the bed isn't hot enough and/or the initial layers are too cool and/or to fast. Final issue I've found is that sometimes a blob of filament has stuck to the nozzle and the filament then sticks to it and curls round as it extrudes, then it doesn't stick to the bed and just extrudes the spaghetti,
SimonWood wrote: Mon Dec 21, 2020 11:15 am
Then, I'm not quite sure what to call this, although it seems to be quite common - sometimes it looks like it would be easy enough to hide with filler, sometimes not so much:

My guess is this is probably due to my printing ABS when the ambient temperature is too low and the side door of the printer is off to allow me to feed it from a 1kg spool...
I think that is a function of printing temperature and probably drafts, plus possibly print speed. Basically one layer of filament has cooled down before it could fuse properly to the layer underneath, and then subsequent layers have stuck to each other and warp as they cool. If the print speed is slightly higher it might have time to fuse before it cools.
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Re: Adventures with a Flashforge

Post by -steves- » Mon Dec 21, 2020 3:24 pm

I have a simple answer to warping and it work's. Pritt Stick (or Tesco equivalent which also works just as well but is loads cheaper). The first time you put it on it doesn't always work that well after it's been cleaned, but subsequent applications are hard to get off the magnetic base, only thing is you need to wash it and scrub it once in a while or it ends up too bumpy with all the glue. I use this ALL the time and I get no warping issues after the first application each time. :thumbup:
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Re: Adventures with a Flashforge

Post by Trevor Thompson » Mon Dec 21, 2020 5:00 pm

Ah Simon

I have had these problems as well. They are more common (probably) with ABS than PLA.

Firstly when the raft fails to bond to the bed. Try cleaning with Acetone and if that isn't enough acetone with ABS in it. As I said before be careful it will really stick if you overdo the ABS. So much that you can damage the flexible bed plate.

The splits in the components printed on edge. Firstly the component may be too thin - in as much as it will improve the situation if the component is thicker. As Philip said it is a cooling issue. You could manually reduce the print speed a bit in the "more options menu". You can adjust the temperature of the extruder a bit - to 235 which is as high as it will go perhaps.

As for calibration. I don't think we have any calibration controls apart from setting the height of the extruder in its zero position. I have not calibrated mine - and I have done a huge amount of printing on it. If you find out how to do it (and if it is necessary) let me know!

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Re: Adventures with a Flashforge

Post by Trevor Thompson » Mon Dec 21, 2020 5:04 pm

Just realised Philip said raise the print speed and I said lower the print speed. Obviously try both as an experiment but I think lower will give it longer to fuse to the lower layer.

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Re: Adventures with a Flashforge

Post by philipy » Mon Dec 21, 2020 5:21 pm

Trevor Thompson wrote: Mon Dec 21, 2020 5:04 pm I think lower will give it longer to fuse to the lower layer.
True. I was thinking that increasing the speed would get the head back again before it had cooled too much! As you say, try both. :D
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Re: Adventures with a Flashforge

Post by SimonWood » Mon Dec 21, 2020 7:53 pm

So far I've got around the curling problem cleaning with nothing more than IPA but I think the ambient temperature has been warmer.

Meanwhile...
SimonWood wrote: Mon Dec 21, 2020 10:53 am In the meantime, on the Lego wagon I used tabs. There I noticed that for a tab drawn at 64mm I needed a slot drawn at 64.8mm for it to fit into. Tab and slot were both drawn and printed in the same plane...
On Rik's Southwold short van the side (digital height 80mm) has printed out at a real-world height of ~79.5mm. The gap it fits into in the van end has printed out a height of ~78.5mm. Again, nothing a file can't fix...

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Re: Adventures with a Flashforge

Post by Trevor Thompson » Mon Dec 21, 2020 11:07 pm

I suppose I have avoided the issues of making one part fit into another by avoiding the issue. Looking at what I have made I make most things as flat plates when I can. So each side and end separately then glue them onto a base. So the issue of shrinkage and so on is just not apparent.

It explains why I have only crossed it with holes for axles and wheel centres, which I just machine anyway.

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Re: Adventures with a Flashforge

Post by philipy » Tue Dec 22, 2020 7:59 am

Trevor Thompson wrote: Mon Dec 21, 2020 11:07 pm

It explains why I have only crossed it with holes for axles and wheel centres, which I just machine anyway.

Thinking about it, thats about the only time it's bothered me, as well. I normally fudge it, if necessary, with drills, files, etc. I don't have a lathe and haven't used one since about 1965/6 at school, when my one and only effort was a brass cannon barrel about 3" long!
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Re: Adventures with a Flashforge

Post by SimonWood » Tue Dec 22, 2020 11:47 am

It's good to know that it's not just me. As I say it's quickly resolved with a file (or a lathe!) but if it were the case of it being 5 minutes tinkering with the settings if only I knew how, I'd learn how before I made any more prints! As it seems to be more of a case of nothing is perfect, but it improves as you get to know your printer, I'll just keep getting to know my printer!

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