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MK3 M3 Nut sizes or print tolorence issue  

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Geakster
(@geakster)
Eminent Member
MK3 M3 Nut sizes or print tolorence issue

I have a working MK3 i built my self from sourced parts. It prints really good how ever when I print the parts to make another MK3 my M3 nuts do not fit in to the printed parts. I started off with a home built reprap and printed MK3 parts, when i printed with the reprap I had the same issue, so I heated the nuts up to push them in place in the printed parts so that I could get the printer going. I thought that maybe my reprap wasnt as accurate but the MK3 i built has the same issue, in some of the smaller holes the M3 nuts simply wont fit, they are too thick.

 

now am i missing a setting? the MK3 calibrates its self and its pretty darn accurate. So is it the M3 nuts im using? do they make a slimmer M3 nut? Just to be clear im NOT talking about the square nuts although them didnt fit either.

Please remember I built these myself and I tried to order every thing to spec. I used to have a bunch of the prusa i2 long ago and loved them now im trying to go with the MK3. Thanks in advance.

Posted : 05/12/2019 2:36 am
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

No one knows this answer? :*(

 

Prusa really must have special M3 nuts they hide from the world lol...

Posted : 06/12/2019 12:15 am
Mick
 Mick
(@mick-4)
Eminent Member
RE: MK3 M3 Nut sizes or print tolorence issue

Is it the outside size of the nut or its thickness?

Nuts are manufactured for different uses, the standard being a "full nut". You can also get a "half nut" which is thinner. This can also be called a lock nut, thin nut or jam nut. They are typically used with a full nut to stop it from moving.

I hope this is of some use.

Regards

Mick

Posted : 06/12/2019 7:17 am
Geakster liked
Chocki
(@chocki)
Prominent Member
RE: MK3 M3 Nut sizes or print tolorence issue

Could it just be the shrinkage of the material?.

I found that if you try to print a 4mm hole and a 4mm peg there is no way they will fit together (Using PETG T-Glass printed at 260 Deg C).

Even if the calibration was off the same error would be applied to both the peg and hole so in an ideal world, they would fit albeit with a tight fit, in reality I have to print the hole at 4.3mm with the peg at 4mm to get a fit that does not require unreasonable force.

The same recently for a drill guide for a 4mm drill, the holes had to be printed at 4.3mm else they were much too small. I did look at adjusting the steps /mm value to get finer resolution for adjusting my prints, but on the 8 bit board there simply isn't the processing capability to deal with a finer step value required as it would be too much for the EINSY to process during fast movements, so you should do some test prints for sizes and adjust your designs to get the correct real world values where accuracy matters.

In slicer there is an setting which you can adjust to compensate for shrinkage which I believe is used for holes, but I have not actually played with this yet, maybe someone whom has could shed some light on how it works, or do what I have been doing and measure prints, and adjust my drawing to allow for the difference between real and design measurements.

You may want to buy one of these: 150mm / 6 inch Dial Plastic Vernier Caliper Measurement Gauge

They are good enough for most 3d printing and invaluable to get prints made to fit properly, and start from only a few £'s if in the UK (Amazon), and require no batteries so can be left for long times without that usual, the batteries are dead again feeling.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.

Posted : 06/12/2019 7:45 am
Geakster liked
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

@michael-f27

it is the thickness is the issue, sorry I should have clarified that. I tried looking for thinner nuts but dosnt seem to be some thing i can find for the M3 size.

Posted : 06/12/2019 9:18 am
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

I am currently trying to print it at 02.mm as it is suggested spec instead of 0.1mm to see if that might be the issue?

Posted : 06/12/2019 9:32 am
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

@chocki

I dont think its shrinking but it is always a possibility. I've tried a couple different materials

Posted : 06/12/2019 9:33 am
JoanTabb
(@joantabb)
Moderator
RE: MK3 M3 Nut sizes or print tolorence issue

Hi Cevans, 

there are at least two thicknesses of square nuts, 
Prusa use the thin one! 

is this the issue?

Thin Nuts  (1,8mm Thick)

https://www.ebay.co.uk/itm/M2-5-M3-M4-M5-M6-M8-M10-THIN-Square-Nuts-A2-Stainless-Steel-Type-DIN-562/292079244600?var=591053828452&hash=item4401479538:m:m2DzBq-PQSihZnQVhOYKgGg

 

Thick nuts (2.4mm thick)
https://www.ebay.co.uk/itm/M3-M4-M5-M6-M8-M10-Sqaure-Nuts-Square-Machine-Screw-Nut-Stainless-Steel/202766171808?var=502907620070&hash=item2f35ce3ea0:m:mWPvkHJ2jZhB3q42cbkWZlQ

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 06/12/2019 9:49 am
Geakster liked
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

@joantabb

its not the square nuts, its the hex nuts that are too thick.

Posted : 06/12/2019 10:10 am
JoanTabb
(@joantabb)
Moderator
RE: MK3 M3 Nut sizes or print tolorence issue

@cevans9921

How thick are your Hex nuts?

https://www.ebay.co.uk/itm/M3-M4-M5-M6-M8-STAINLESS-STEEL-A2-HEXAGON-HALF-LOCK-THIN-NUTS-FOR-BOLTS-SCREWS/121544225928?hash=item1c4c99b488:m:muD8kUkxf4_hbkrFgvXntjA

 

this site gives you a picture of assorted M3 fasteners
https://www.westfieldfasteners.co.uk/A2_Nut_M3.html

 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 06/12/2019 10:47 am
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

@joantabb

when i use the micrometer it shows my hex nuts are 2.32mm thick

Posted : 06/12/2019 10:53 am
JoanTabb
(@joantabb)
Moderator
RE: MK3 M3 Nut sizes or print tolorence issue

M3 thin Locknuts are 1.8mm thick

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 06/12/2019 11:29 am
Geakster liked
Geakster
(@geakster)
Eminent Member
Topic starter answered:
RE: MK3 M3 Nut sizes or print tolorence issue

ahhh that is the issue then, I appreciate it 😀

 

Posted : 06/12/2019 3:22 pm
JoanTabb
(@joantabb)
Moderator
RE: MK3 M3 Nut sizes or print tolorence issue

@cevans9921

Good luck. Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 07/12/2019 5:44 pm
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