1 (edited by Ggalisky 2015-02-09 20:17:06)

Topic: + or - 0.01mm Tolerances

This weekend (2/8/15) I made some 1.75mm MG94 and 1.75mm recycled (80% MG94 20% regrind) filament. Before extrusion I pre-dried both the regrind and MG94 for about 18 hours in this dehydrator Link: http://www.amazon.com/Presto-06300-Dehy … dehydrator .

Here is a good write up about pre-drying I did a while back:

Pre-Drying
Many different types of plastics need to be pre-dried in order to get good quality filament and prints. The plastics that encounter frequently that need pre-drying are PLA, Nylon, TPU, and PC (polycarbonate). There are several more plastics that need to be pre-dried, but for simplicity I only listed a few. I used a food dehydrator I bought off of Amazon to dry all of my pellets. http://www.amazon.com/Presto-06300-Dehy … dehydrator . The dehydrator comes with mesh plates, so you need to find a way to stop the pellets from falling through. I use this: http://www.amazon.com/National-Presto-D … ZNA913RBA. I usually let the pellets dry for about 10-17 hours. After drying I seal the pellets in a zip lock bag with a silica gel packet inside, and add a label so I know what plastic it is.

The end result of the drying was filament with an average diameter of 1.75 with + or - 0.01mm tolerances.

Picture of the dehydrator:
http://i.imgur.com/sjdJl2c.jpg
Picture of the finished filament:
http://i.imgur.com/sun2LDs.jpg

Ulitmaker 2, Form 1 +, Delta format reprap.

My Blog http://ggalisky.weebly.com/
My Youtube https://www.youtube.com/channel/UCXShYo … aDUpebDAOw

2

Re: + or - 0.01mm Tolerances

What did you use to measure the filament width? I'm using a digital caliper (0.01mm resolution) and I'm not expecting accurate readings within 0,025mm.

Good example of accuracy information for digital calipers : http://littlemachineshop.com/products/p … ;category=

3

Re: + or - 0.01mm Tolerances

This is awesome. Seconding the request on how you measured - not only what tool, but how many measurements, spaced over what distance?

CFTechno wrote:

What did you use to measure the filament width? I'm using a digital caliper (0.01mm resolution) and I'm not expecting accurate readings within 0,025mm.

In this case all that really matters is repeatability. Most $10-20 calipers are good to +/-0.01mm repeatability. If he takes 20 samples and they're all +/-0.01mm, then the filament itself is at least that good.

4 (edited by Ggalisky 2015-02-10 05:58:09)

Re: + or - 0.01mm Tolerances

I used these: http://www.amazon.com/Inch-Digital-Cali … l+calipers

Both lengths of filament were about 100g, and I took 10 measurements per 100g coil of filament. Both coils are on their way to wardjr for testing, since I do not currently have a 1.75mm printer.

Ulitmaker 2, Form 1 +, Delta format reprap.

My Blog http://ggalisky.weebly.com/
My Youtube https://www.youtube.com/channel/UCXShYo … aDUpebDAOw

5

Re: + or - 0.01mm Tolerances

Ggalisky wrote:

I used these: http://www.amazon.com/Inch-Digital-Cali … l+calipers

Both lengths of filament were about 100g, and I took 10 measurements per 100g coil of filament. Both coils are on their way to wardjr for testing, since I do not currently have a 1.75mm printer.

Would you like me to verify your measurements?

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6

Re: + or - 0.01mm Tolerances

wardjr wrote:
Ggalisky wrote:

I used these: http://www.amazon.com/Inch-Digital-Cali … l+calipers

Both lengths of filament were about 100g, and I took 10 measurements per 100g coil of filament. Both coils are on their way to wardjr for testing, since I do not currently have a 1.75mm printer.

Would you like me to verify your measurements?

Yes for sure!

Ulitmaker 2, Form 1 +, Delta format reprap.

My Blog http://ggalisky.weebly.com/
My Youtube https://www.youtube.com/channel/UCXShYo … aDUpebDAOw

7

Re: + or - 0.01mm Tolerances

elmoret wrote:

In this case all that really matters is repeatability. Most $10-20 calipers are good to +/-0.01mm repeatability. If he takes 20 samples and they're all +/-0.01mm, then the filament itself is at least that good.

I beg to differ :-)  in this case repeatability is not a an "property" of the caliper but an indication of how consistent the user is using it when doing it's measurements.

The filament I extrude is measured using the sensor that [fillip] build for the lyman v5 extruder. First thing I noticed is that the behavior of the fluctuation is in the form of <long same width><short under or above width><long same width>  Sometimes those under/above widths were so short that I missed them while watching the sensor data on the lcd screen. So I rewrote the mackerel software to keep track of the min and max values and display them every 5 second. 

If I would take the filament produced and re-measure it by hand because of the cadence in which the "blobs" appear it's not likely that I will be measuring at exactly the same spot where those "blobs" are and hence would report better results for the filament then it in reality has.

8

Re: + or - 0.01mm Tolerances

Fillip sent me one of those sensors as well. It is definitely not as reliable as calipers. I was not impressed by it.

If you measure several dozen times along a length, statistically you'll catch at least one of those + or - widths. That's the whole idea behind simple random sampling.

9

Re: + or - 0.01mm Tolerances

elmoret wrote:

Fillip sent me one of those sensors as well. It is definitely not as reliable as calipers. I was not impressed by it.

Can you explain in a bit more detail why you were not impressed?

elmoret wrote:

If you measure several dozen times along a length, statistically you'll catch at least one of those + or - widths. That's the whole idea behind simple random sampling.

it's one of the things I'm trying to find out if that is indeed the case, by changing the software a complete audit trail for an extruder run can be generated and then some calculations can be made how large that chance really is.

10

Re: + or - 0.01mm Tolerances

I was not impressed because a piece of steel rod that was a uniform 1.58mm in diameter, checked with calipers, registered 1.53-1.63mm. It was not repeatable enough to be useful.

11

Re: + or - 0.01mm Tolerances

elmoret wrote:

I was not impressed because a piece of steel rod that was a uniform 1.58mm in diameter, checked with calipers, registered 1.53-1.63mm. It was not repeatable enough to be useful.

Thanks!

The BOM for version 3 of the sensor includes a drill rod (1/16) and during the calibration routine it will correctly measure the diameter...(well it did each and every time I tried) Only issue I see is that it's rather slow/lagging. When placing the drill rod only from the 3th measurement forward the value is correct and stable, same when removing it, only from the 3th measurement onward the value reaches 0 and stays 0.

12

Re: + or - 0.01mm Tolerances

Does anyone have links to this sensor by Fillip?

13

Re: + or - 0.01mm Tolerances

bbriggsgeek wrote:

Does anyone have links to this sensor by Fillip?

http://www.thingiverse.com/thing:454584

14

Re: + or - 0.01mm Tolerances

Ggalisky wrote:

Pre-Drying
Many different types of plastics need to be pre-dried in order to get good quality filament and prints. The plastics that encounter frequently that need pre-drying are PLA, Nylon, TPU, and PC (polycarbonate). There are several more plastics that need to be pre-dried, but for simplicity I only listed a few. I used a food dehydrator I bought off of Amazon to dry all of my pellets. http://www.amazon.com/Presto-06300-Dehy … dehydrator . The dehydrator comes with mesh plates, so you need to find a way to stop the pellets from falling through. I use this: http://www.amazon.com/National-Presto-D … ZNA913RBA. I usually let the pellets dry for about 10-17 hours. After drying I seal the pellets in a zip lock bag with a silica gel packet inside, and add a label so I know what plastic it is.

Sorry for keeping asking questions but really trying to learn as much and as fast as possible smile  Do you use the heater when drying and at what temperatures? The datasheet for the ABS I'm using says 2-4 hours of drying is needed at 80C.  At this site http://www.ptonline.com/knowledgecenter … pic-Resins they state that for ABS "•Internal moisture can not be removed with hot air alone"

15 (edited by Ggalisky 2015-02-10 23:13:11)

Re: + or - 0.01mm Tolerances

The dehydrator just blows hot hair over the pellets. It worked for nylon, acrylic,  and polycarbonate, so it proabaly works with ABS.

Do not worry about asking too may questions, I would not have learned as much as I have with out asking questions.  The only time questions become problematic is when the answers can be found on a google search.

Ulitmaker 2, Form 1 +, Delta format reprap.

My Blog http://ggalisky.weebly.com/
My Youtube https://www.youtube.com/channel/UCXShYo … aDUpebDAOw

16

Re: + or - 0.01mm Tolerances

Ggalisky wrote:
wardjr wrote:
Ggalisky wrote:

I used these: http://www.amazon.com/Inch-Digital-Cali … l+calipers

Both lengths of filament were about 100g, and I took 10 measurements per 100g coil of filament. Both coils are on their way to wardjr for testing, since I do not currently have a 1.75mm printer.

Would you like me to verify your measurements?

Yes for sure!


Pretty well verified at this point.  I measured both rolls at 12" along the entire length and in only one spot (on both rolls) did I find the tolerance to be +.02 out of spec so I would say the + or - .01 statement to be absolutely correct.

Printit Industries Model 8.10 fully enclosed CoreXY, Chamber heat
3-SD3's & a Workbench all fully enclosed, RH-Slic3r Win7pro, E3D V6, Volcano & Cyclops Hot End
SSR/500W AC Heated Glass Bed, Linear bearings on SS rods. Direct Drive Y-axis, BulldogXL
Thanks to all for your contributions

17 (edited by parto 2015-09-08 07:36:53)

Re: + or - 0.01mm Tolerances

Hi,
I've built a filament extruder similar to the filastruder. See pic  http://soliforum.com/i/?IlkL7lV.jpg
I've extruded  3mm ABS only and have been running my first tests with MG94. Everything has gone pretty well. The filament surface finish is very good except I can't get better tolerances that +/- 0.1mm. My set up is as follows:
Nozzle dia 2.5mm.
Dried filament for 4 hours at 85 Deg C (recommended temp in data sheet for MG94 is 80-90 Deg C)
Nozzle Temp 182 Deg C.
Barrel Temp 150 Deg. C  (I have a second heater installed on the barrel )
Auger  running at 5 RPM.
I'm using the laser detector and a modified version of the filawinder.
The main thing that jumps out at me from the data is a repetitive frequency of max and min diameter values. I have attached excel file of the data.  See a quick pic of  diameter output from excel file ----> http://soliforum.com/i/?3azO5At.png These peaks  occur on average every 108 seconds. At first I though that these peaks would coincide with the auger RPM but no. There doesn't seem to be any relationship. From my calculations a peak filament diameter occurs every 9 turns of the auger.
Anyone got any ideas what's going on here???

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filament data 182C_5RPM.xls 239 kb, file has never been downloaded. 

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18 (edited by CFTechno 2015-09-07 19:50:10)

Re: + or - 0.01mm Tolerances

Which sensor are you using? I'm asking because I learned the hard way that you should make sure that you can trust the data from the sensor before making any assumptions.

19

Re: + or - 0.01mm Tolerances

Which sensor are you using? I'm asking because I learned the hard way that you should make sure that you can trust the data from the sensor before making any assumptions.


I am using two different sensors one  (see http://www.thingiverse.com/thing:699308) taking a measurement as the filament exits the extruder  and another (http://diy3dprinting.blogspot.ie/2014/0 … ensor.html) taking a final measurement once the filament has hardened before it is wound on the spool. I have checked these sensors and am confident they are reading correct. I am also using the the ATtiny85 filament sensor on my printer to compensate for variations on my DIY filament. It is a similar sensor to Flippers one but using an micro processor that can be programmed using the arduino software.

20 (edited by parto 2015-09-17 09:31:18)

Re: + or - 0.01mm Tolerances

Hi,
I've sorted out my filament tolerance issues. I have documented all the findings, graphs and all in the attached word doc. In summary, just a few degrees C. off my setpoint of 182 C. was responsible for  my poor +/- 0.1mm tolerance. Hope the data helps others.

Post's attachments

Filament tolerance issues and the eventual solution imbedded pics.doc 516.5 kb, 15 downloads since 2015-09-17 

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