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Jakeddesign

Getting Better Dimensional Accuracy - Calibration

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12 hours ago, Jakeddesign said:

When I started at this company they told me they didnt have a use for a printer...then I convinced them to buy and 6 months later this thing NEVER stops printing.  Its crazy....my full time Engineer gig is now more than 50% printer technician!

That sounds good! What is it used for mostly, if you don't mind me asking? 

 

9 hours ago, yellowshark said:

When I say measured I did this by manually extruding 10mm of filament and cutting it off and measuring the diameter.

Do you mean you extruded the filament not printing on a bed, but just catching it from the air? Wouldn't it stretch because it is still soft / warm and it just hangs there?

 

9 hours ago, yellowshark said:

I have no idea if they test each new machine and recalibrate that setting if required.

We do! I don't think we calibrate stepper motors, as they should all be good and consistent. But we do check them, and if they don't pass our calibration test and quality assurance, it is not going out until it does. 

 

@ghostkeeper, can you say a little bit more about the post processing script; post stretch script? I can imagine there also lies a partial solution here re the ID of holes. Do we know of a speed / temperature / layer height which is ideal for an accurate ID? I could imagine, a small layer height, at a low temperature and not very fast so the amount of filament you extrude is small and therefor cools fast and is minimally stretched along the nozzle tool path? @Jakeddesign , did you try this script as well? (it can be found under extensions > post processing > modify g-code. 

 

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40 minutes ago, SandervG said:

 

 

10 hours ago, yellowshark said:

When I say measured I did this by manually extruding 10mm of filament and cutting it off and measuring the diameter.

Do you mean you extruded the filament not printing on a bed, but just catching it from the air? Wouldn't it stretch because it is still soft / warm and it just hangs there?

Hi @SandervG, that is a fair point. What I do first is to extrude 30-40mm to ensure all is extruding well and as it should be, which does mean that on the first cut it is not totally hanging as it is laying on the bed before the cut is made. BUT that does not apply to the subsequent cuts (although as I said above the measurements were cconsistent). I do not think that measuring it  printed on the bed is reliable as that will depend on how squished you have the filament set to via the bed to nozzle distance. Visually it looks right, i.e. once the first tens of mm have been extruded the width of the extruding filament, from the nozzle tip to the bottom looks consistent BUT that is not the same as using a vernier! I guess the good thing for me is that this "stretched" filament was fatter than the specified nozzle diameter and using .45 was better than using .40. Your point though does make me think that I will have another play and maybe try 0.47 or even 0.5 and see what happens.👨‍🎓

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6 hours ago, SandervG said:
18 hours ago, Jakeddesign said:

When I started at this company they told me they didnt have a use for a printer...then I convinced them to buy and 6 months later this thing NEVER stops printing.  Its crazy....my full time Engineer gig is now more than 50% printer technician!

That sounds good! What is it used for mostly, if you don't mind me asking? 

 

I work for a prosthetics company, we focus mostly on lower limb, but are getting into upper limb prosthetics as well.  Any plastic components were order through Statasys, which is a great service, but quite expensive and long leadtime (unless you pay even MORE money).  We have one product that I have printed 4-5 versions using the UM3 - something we would not have done if we were ordering prints from a vendor.  Saved a lot of money on mold change costs too, since even printing such complex parts on an FDM printer we were able to identify some pretty serious overlooks.

 

The printer runs for at least 40 hours a week, and if I time prints just right, I can hit 100 hours.

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On 5/8/2018 at 12:18 AM, yellowshark said:

Oh dammit, @LaserBrain, my comments were based on your test cube but if your are printing circular geometries then the inner diameter will have a tolerance close to what your stating , i.e. smaller; of course you may already know that ! but I just wanted to be clear.

No Problem @yellowshark, I've been super busy so not had a chance to reply. However, thanks for your info. Round parts are a struggle, especially when they have to fit, I've had to slightly overscale a couple of items to get them to fit, otherwise they are too snug.
As for the calibration cube, I'll try some of the suggestions and see where it leads too. The hardware looks all good, gave it a once over today, belts etc. 
Cheers,

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