Resources covering model design guidelines

classic Classic list List threaded Threaded
20 messages Options
Reply | Threaded
Open this post in threaded view
|

Resources covering model design guidelines

fcwilt
Hi,

Now that I have undertaken to design my own 3D models, rather than use other
folks work, I understand that there is much I will have to learn.

As part of that learning I need some basic info.

When a machinist wishes to drill a hole for an M3 machine screw to pass
through there are many places where he can look for that information and he
will find that there are suggested hole sizes for a "close fit", a "normal
fit" and a "loose fit".

Likewise if he needs to drill a hole for tapping for that M3 machine screw
he will find that there are suggested hole sizes for 50% threads and 75%
threads.


So my question is when working with different kinds of 3D printing
technologies and materials used in those type of machines are there places I
can go to find that same kind of information?


As a simple test I used the dimensions I would use for aluminum to create a
test part over at Shapeways using their "Versatile Plastic" material which
has proven, using other folks designs, to be very good for the type of parts
I have been making.

As I expected the holes were too bit too small although the linear
dimensions were quite good.


So if anyone has this knowledge or links to this knowledge I would be most
appreciative.

Thanks.

Frederick



--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Jamie Bainbridge
On 23 July 2018 at 08:37, fcwilt <[hidden email]> wrote:

> Hi,
>
> Now that I have undertaken to design my own 3D models, rather than use other
> folks work, I understand that there is much I will have to learn.
>
> As part of that learning I need some basic info.
>
> When a machinist wishes to drill a hole for an M3 machine screw to pass
> through there are many places where he can look for that information and he
> will find that there are suggested hole sizes for a "close fit", a "normal
> fit" and a "loose fit".
>
> Likewise if he needs to drill a hole for tapping for that M3 machine screw
> he will find that there are suggested hole sizes for 50% threads and 75%
> threads.
>
>
> So my question is when working with different kinds of 3D printing
> technologies and materials used in those type of machines are there places I
> can go to find that same kind of information?
>
>
> As a simple test I used the dimensions I would use for aluminum to create a
> test part over at Shapeways using their "Versatile Plastic" material which
> has proven, using other folks designs, to be very good for the type of parts
> I have been making.
>
> As I expected the holes were too bit too small although the linear
> dimensions were quite good.
>
>
> So if anyone has this knowledge or links to this knowledge I would be most
> appreciative.

3DHubs have an article and infographic about designing for different
manufacturing methods, including FDM printing:
https://www.3dhubs.com/knowledge-base/key-design-considerations-3d-printing

Different printers and materials and slicers and tuning produce
different results, especially at the lower end of the market where
machines and filament vary, or where people do not take the time to
properly learn how FDM printing works and tune correctly.

You can print test parts to see how your machine and settings fare,
the Maker's Muse tolerance test is one such method:
https://www.youtube.com/watch?v=TYuLVN3YHw8

Specifically for metric screw holes, I made this calibration plate:
https://www.thingiverse.com/thing:2221050

Jamie

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

nophead
In reply to this post by fcwilt
You want the target hole size to be the same as for machining. If the Shapeways process is accurate then you have to consider the fact that STL files only have faceted holes. I.e. a round hole will end up polygonal, with its vertices on the circle. That means the sides of the polygon will be inside the circle and thus the hole is too small. You need to increase the radius by dividing by cos(180 / n) where n is the number of sides.



On 22 July 2018 at 23:37, fcwilt <[hidden email]> wrote:
Hi,

Now that I have undertaken to design my own 3D models, rather than use other
folks work, I understand that there is much I will have to learn.

As part of that learning I need some basic info.

When a machinist wishes to drill a hole for an M3 machine screw to pass
through there are many places where he can look for that information and he
will find that there are suggested hole sizes for a "close fit", a "normal
fit" and a "loose fit".

Likewise if he needs to drill a hole for tapping for that M3 machine screw
he will find that there are suggested hole sizes for 50% threads and 75%
threads.


So my question is when working with different kinds of 3D printing
technologies and materials used in those type of machines are there places I
can go to find that same kind of information?


As a simple test I used the dimensions I would use for aluminum to create a
test part over at Shapeways using their "Versatile Plastic" material which
has proven, using other folks designs, to be very good for the type of parts
I have been making.

As I expected the holes were too bit too small although the linear
dimensions were quite good.


So if anyone has this knowledge or links to this knowledge I would be most
appreciative.

Thanks.

Frederick



--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Jamie Bainbridge
https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/undersized_circular_objects

I use cylinder_outer() so much I made my own library for it:

https://github.com/superjamie/handyscad

Jamie


On 23 July 2018 at 08:57, nop head <[hidden email]> wrote:

> You want the target hole size to be the same as for machining. If the
> Shapeways process is accurate then you have to consider the fact that STL
> files only have faceted holes. I.e. a round hole will end up polygonal, with
> its vertices on the circle. That means the sides of the polygon will be
> inside the circle and thus the hole is too small. You need to increase the
> radius by dividing by cos(180 / n) where n is the number of sides.
>
>
>
> On 22 July 2018 at 23:37, fcwilt <[hidden email]> wrote:
>>
>> Hi,
>>
>> Now that I have undertaken to design my own 3D models, rather than use
>> other
>> folks work, I understand that there is much I will have to learn.
>>
>> As part of that learning I need some basic info.
>>
>> When a machinist wishes to drill a hole for an M3 machine screw to pass
>> through there are many places where he can look for that information and
>> he
>> will find that there are suggested hole sizes for a "close fit", a "normal
>> fit" and a "loose fit".
>>
>> Likewise if he needs to drill a hole for tapping for that M3 machine screw
>> he will find that there are suggested hole sizes for 50% threads and 75%
>> threads.
>>
>>
>> So my question is when working with different kinds of 3D printing
>> technologies and materials used in those type of machines are there places
>> I
>> can go to find that same kind of information?
>>
>>
>> As a simple test I used the dimensions I would use for aluminum to create
>> a
>> test part over at Shapeways using their "Versatile Plastic" material which
>> has proven, using other folks designs, to be very good for the type of
>> parts
>> I have been making.
>>
>> As I expected the holes were too bit too small although the linear
>> dimensions were quite good.
>>
>>
>> So if anyone has this knowledge or links to this knowledge I would be most
>> appreciative.
>>
>> Thanks.
>>
>> Frederick
>>
>>
>>
>> --
>> Sent from: http://forum.openscad.org/
>>
>> _______________________________________________
>> OpenSCAD mailing list
>> [hidden email]
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
>
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

boxcarmib
I think what you maybe referring to is the topic of “engineering fit”… here’s a link to the wikipedia article on it…

https://en.wikipedia.org/wiki/Engineering_fit

My personal experience is that with an FDM printer you don’t have anything close to the accuracy, repeatability and precision needed to achieve anything but the most coarse levels of engineering fit… but then again, if you have parts that fit in other parts you have to start somewhere.

I think you may find the following wikipedia page particularly useful in explaining the components that are involved in machining and when you consider the inconsistencies of filament flow, temperature regulation, extruder positioning etc.you can appreciate that there’s no simple fix.

https://en.wikipedia.org/wiki/Accuracy_and_precision

Anyway, I hope you find the link as useful as I did.

> On Jul 22, 2018, at 4:26 PM, Jamie Bainbridge <[hidden email]> wrote:
>
> https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/undersized_circular_objects
>
> I use cylinder_outer() so much I made my own library for it:
>
> https://github.com/superjamie/handyscad
>
> Jamie
>
>
> On 23 July 2018 at 08:57, nop head <[hidden email]> wrote:
>> You want the target hole size to be the same as for machining. If the
>> Shapeways process is accurate then you have to consider the fact that STL
>> files only have faceted holes. I.e. a round hole will end up polygonal, with
>> its vertices on the circle. That means the sides of the polygon will be
>> inside the circle and thus the hole is too small. You need to increase the
>> radius by dividing by cos(180 / n) where n is the number of sides.
>>
>>
>>
>> On 22 July 2018 at 23:37, fcwilt <[hidden email]> wrote:
>>>
>>> Hi,
>>>
>>> Now that I have undertaken to design my own 3D models, rather than use
>>> other
>>> folks work, I understand that there is much I will have to learn.
>>>
>>> As part of that learning I need some basic info.
>>>
>>> When a machinist wishes to drill a hole for an M3 machine screw to pass
>>> through there are many places where he can look for that information and
>>> he
>>> will find that there are suggested hole sizes for a "close fit", a "normal
>>> fit" and a "loose fit".
>>>
>>> Likewise if he needs to drill a hole for tapping for that M3 machine screw
>>> he will find that there are suggested hole sizes for 50% threads and 75%
>>> threads.
>>>
>>>
>>> So my question is when working with different kinds of 3D printing
>>> technologies and materials used in those type of machines are there places
>>> I
>>> can go to find that same kind of information?
>>>
>>>
>>> As a simple test I used the dimensions I would use for aluminum to create
>>> a
>>> test part over at Shapeways using their "Versatile Plastic" material which
>>> has proven, using other folks designs, to be very good for the type of
>>> parts
>>> I have been making.
>>>
>>> As I expected the holes were too bit too small although the linear
>>> dimensions were quite good.
>>>
>>>
>>> So if anyone has this knowledge or links to this knowledge I would be most
>>> appreciative.
>>>
>>> Thanks.
>>>
>>> Frederick
>>>
>>>
>>>
>>> --
>>> Sent from: http://forum.openscad.org/
>>>
>>> _______________________________________________
>>> OpenSCAD mailing list
>>> [hidden email]
>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
>>
>>
>> _______________________________________________
>> OpenSCAD mailing list
>> [hidden email]
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Neon22
And pragmatically - your extruder will ooze a little based on temp,
layer height, and viscosity of the specific filament.
So in practise even if you manually account for inside holes vs outside
holes (your stl will not know) then you need to test your own equipment
and filament to work out the final fiddle factor to make it fit well.

Or drill it out :) (if its small)


On 7/23/2018 12:09 PM, Hugo Jackson wrote:

> I think what you maybe referring to is the topic of “engineering fit”… here’s a link to the wikipedia article on it…
>
> https://en.wikipedia.org/wiki/Engineering_fit
>
> My personal experience is that with an FDM printer you don’t have anything close to the accuracy, repeatability and precision needed to achieve anything but the most coarse levels of engineering fit… but then again, if you have parts that fit in other parts you have to start somewhere.
>
> I think you may find the following wikipedia page particularly useful in explaining the components that are involved in machining and when you consider the inconsistencies of filament flow, temperature regulation, extruder positioning etc.you can appreciate that there’s no simple fix.
>
> https://en.wikipedia.org/wiki/Accuracy_and_precision
>
> Anyway, I hope you find the link as useful as I did.
>
>> On Jul 22, 2018, at 4:26 PM, Jamie Bainbridge <[hidden email]> wrote:
>>
>> https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/undersized_circular_objects
>>
>> I use cylinder_outer() so much I made my own library for it:
>>
>> https://github.com/superjamie/handyscad
>>
>> Jamie
>>
>>
>> On 23 July 2018 at 08:57, nop head <[hidden email]> wrote:
>>> You want the target hole size to be the same as for machining. If the
>>> Shapeways process is accurate then you have to consider the fact that STL
>>> files only have faceted holes. I.e. a round hole will end up polygonal, with
>>> its vertices on the circle. That means the sides of the polygon will be
>>> inside the circle and thus the hole is too small. You need to increase the
>>> radius by dividing by cos(180 / n) where n is the number of sides.
>>>
>>>
>>>
>>> On 22 July 2018 at 23:37, fcwilt <[hidden email]> wrote:
>>>> Hi,
>>>>
>>>> Now that I have undertaken to design my own 3D models, rather than use
>>>> other
>>>> folks work, I understand that there is much I will have to learn.
>>>>
>>>> As part of that learning I need some basic info.
>>>>
>>>> When a machinist wishes to drill a hole for an M3 machine screw to pass
>>>> through there are many places where he can look for that information and
>>>> he
>>>> will find that there are suggested hole sizes for a "close fit", a "normal
>>>> fit" and a "loose fit".
>>>>
>>>> Likewise if he needs to drill a hole for tapping for that M3 machine screw
>>>> he will find that there are suggested hole sizes for 50% threads and 75%
>>>> threads.
>>>>
>>>>
>>>> So my question is when working with different kinds of 3D printing
>>>> technologies and materials used in those type of machines are there places
>>>> I
>>>> can go to find that same kind of information?
>>>>
>>>>
>>>> As a simple test I used the dimensions I would use for aluminum to create
>>>> a
>>>> test part over at Shapeways using their "Versatile Plastic" material which
>>>> has proven, using other folks designs, to be very good for the type of
>>>> parts
>>>> I have been making.
>>>>
>>>> As I expected the holes were too bit too small although the linear
>>>> dimensions were quite good.
>>>>
>>>>
>>>> So if anyone has this knowledge or links to this knowledge I would be most
>>>> appreciative.
>>>>
>>>> Thanks.
>>>>
>>>> Frederick
>>>>
>>>>
>>>>
>>>> --
>>>> Sent from: http://forum.openscad.org/
>>>>
>>>> _______________________________________________
>>>> OpenSCAD mailing list
>>>> [hidden email]
>>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>>
>>>
>>> _______________________________________________
>>> OpenSCAD mailing list
>>> [hidden email]
>>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>>>
>> _______________________________________________
>> OpenSCAD mailing list
>> [hidden email]
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

JordanBrown
In reply to this post by fcwilt
https://makezine.com/2015/07/22/tips-3d-printing-press-fit-parts/

It's not exactly what you were asking about, but I found this article to have some interesting tips on building press-fit parts, and in particular on making pegs that go into holes.

The conclusion in a nutshell:  don't try to put round pegs into round holes.  The tolerances are too tight and the processes too inexact.  Instead, put hollow octagonal pegs into round holes, so that the pegs and the holes can deform a little as they're pressed together.


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

fcwilt
In reply to this post by Jamie Bainbridge
Thanks to everyone for the wealth of information.

Many good ideas and much to read.

Frederick





--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

fcwilt
In reply to this post by Jamie Bainbridge
Jamie Bainbridge wrote
> Specifically for metric screw holes, I made this calibration plate:
> https://www.thingiverse.com/thing:2221050
>
> Jamie

That seems to me like a very good idea.

I will have to have one printed up for me.

Frederick





--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

RobWLakes
In reply to this post by Neon22

Hi folks,

This is of interest to me as well. I have successfully threaded quite a few holes in 3-D models and found it very satisfactory.  Choosing the right hole though is somewhat hit or miss for me, and I will print Hugo's plate with different holes as a better indication of what my own printer (at its settings) makes holes.

I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled Threaded Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I am hoping to slip them on my soldering iron tip and insert/melt them into my models.  Hugo's plate with the graded holes will help here as well.

Rob


On 23/07/18 10:27, Mark Schafer wrote:
And pragmatically - your extruder will ooze a little based on temp, layer height, and viscosity of the specific filament.
So in practise even if you manually account for inside holes vs outside holes (your stl will not know) then you need to test your own equipment and filament to work out the final fiddle factor to make it fit well.

Or drill it out :) (if its small)


On 7/23/2018 12:09 PM, Hugo Jackson wrote:
I think what you maybe referring to is the topic of “engineering fit”… here’s a link to the wikipedia article on it…

https://en.wikipedia.org/wiki/Engineering_fit

My personal experience is that with an FDM printer you don’t have anything close to the accuracy, repeatability and precision needed to achieve anything but the most coarse levels of engineering fit… but then again, if you have parts that fit in other parts you have to start somewhere.

I think you may find the following wikipedia page particularly useful in explaining the components that are involved in machining and when you consider the inconsistencies of filament flow, temperature regulation, extruder positioning etc.you can appreciate that there’s no simple fix.

https://en.wikipedia.org/wiki/Accuracy_and_precision

Anyway, I hope you find the link as useful as I did.

On Jul 22, 2018, at 4:26 PM, Jamie Bainbridge [hidden email] wrote:

https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/undersized_circular_objects

I use cylinder_outer() so much I made my own library for it:

https://github.com/superjamie/handyscad

Jamie


On 23 July 2018 at 08:57, nop head [hidden email] wrote:
You want the target hole size to be the same as for machining. If the
Shapeways process is accurate then you have to consider the fact that STL
files only have faceted holes. I.e. a round hole will end up polygonal, with
its vertices on the circle. That means the sides of the polygon will be
inside the circle and thus the hole is too small. You need to increase the
radius by dividing by cos(180 / n) where n is the number of sides.



On 22 July 2018 at 23:37, fcwilt [hidden email] wrote:
Hi,

Now that I have undertaken to design my own 3D models, rather than use
other
folks work, I understand that there is much I will have to learn.

As part of that learning I need some basic info.

When a machinist wishes to drill a hole for an M3 machine screw to pass
through there are many places where he can look for that information and
he
will find that there are suggested hole sizes for a "close fit", a "normal
fit" and a "loose fit".

Likewise if he needs to drill a hole for tapping for that M3 machine screw
he will find that there are suggested hole sizes for 50% threads and 75%
threads.


So my question is when working with different kinds of 3D printing
technologies and materials used in those type of machines are there places
I
can go to find that same kind of information?


As a simple test I used the dimensions I would use for aluminum to create
a
test part over at Shapeways using their "Versatile Plastic" material which
has proven, using other folks designs, to be very good for the type of
parts
I have been making.

As I expected the holes were too bit too small although the linear
dimensions were quite good.


So if anyone has this knowledge or links to this knowledge I would be most
appreciative.

Thanks.

Frederick



--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org



_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Rob W
Lake Tyers Beach,
Victoria, Australia
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Jamie Bainbridge
On 23 July 2018 at 14:07, Rob Ward <[hidden email]> wrote:
> I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled Threaded
> Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I am
> hoping to slip them on my soldering iron tip and insert/melt them into my
> models.

That is common but I've never liked these for a few reasons:

* It's difficult to precisely place something when you're melting it
into plastic with a soldering iron. FDM printing is accurate to
~0.25mm or so, but then human hands forcing a big insert into a
too-small printed pocket with a lot of heat are less accurate.
* If the hole is not easily accessible on an outside face of the part,
it's difficult to install the knurled insert. For example, on the
axles of this Kossel effector:
https://www.thingiverse.com/thing:2297083
* I'm never sure how much force I can apply to the knurled insert once
it's melted in place. Do I need to be fragile like when threading into
plastic? Will it eventually let go over time if held in tension by a
spring?

Where a captive thread force is required, modelling in a captive nut
or nyloc is far more preferable. For example, Johann's Kossel
effector: https://github.com/jcrocholl/kossel/blob/master/effector.stl

To go into a flat face, you need a small square hole to insert the
nut. You can easily find dimensions of metric ISO nuts. The hole needs
to be tight enough to stop the nut rotating. If you intend for the nut
to be removable then add a hole on the other side to poke the nut back
out with a paperclip or something.

You could also model an insertion/removal cube with more clearance and
then a hexagonal nut trap which the nut pulls back into.

If this description isn't clear, let me know and I can model it up for you.

Jamie

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Neon22
In reply to this post by RobWLakes

FWIW these two stores work well for me and also have the threaded inserts which is an alt to soldering iron push designs. Check out the rest of the h/w they sell.
- Chang-Da store:
    https://www.aliexpress.com/item/100pcs-lot-Brass-insert-M2-M2-5-M3-Through-thread-brass-insert-nut-knurled-nuts-for/32840519444.html
- Zhong-Fa store:
    https://www.aliexpress.com/item/100pcs-lot-M3-L-OD-4-2mm-M3-Through-hole-brass-insert-nut-knurled-nuts-for/32853029322.html

Not an affiliate link.


On 7/23/2018 4:07 PM, Rob Ward wrote:

Hi folks,

This is of interest to me as well. I have successfully threaded quite a few holes in 3-D models and found it very satisfactory.  Choosing the right hole though is somewhat hit or miss for me, and I will print Hugo's plate with different holes as a better indication of what my own printer (at its settings) makes holes.

I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled Threaded Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I am hoping to slip them on my soldering iron tip and insert/melt them into my models.  Hugo's plate with the graded holes will help here as well.

Rob




_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

RobWLakes
In reply to this post by Jamie Bainbridge
They are good points Jamie.

My main concern was if I used the soldering iron tip to push them in
they may very well come back out on the soldering iron seeing they have
a thread that could grip the tip. I think I will look into a simple
"push" fit with a tool (ie a mounted M3 thread on a handle like a
screwdriver, or even a mini press) and try various hole sizes. That way
I can address your concern about the orientation better than pushing
something into sloppy melted plastic. After that I might try a slight
touch of the iron just to get the spikes to settle into the plastic
after insertion.

I have used holes with "hidden" nuts and they do work well.

Rob

On 23/07/18 15:21, Jamie Bainbridge wrote:

> On 23 July 2018 at 14:07, Rob Ward <[hidden email]> wrote:
>> I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled Threaded
>> Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I am
>> hoping to slip them on my soldering iron tip and insert/melt them into my
>> models.
> That is common but I've never liked these for a few reasons:
>
> * It's difficult to precisely place something when you're melting it
> into plastic with a soldering iron. FDM printing is accurate to
> ~0.25mm or so, but then human hands forcing a big insert into a
> too-small printed pocket with a lot of heat are less accurate.
> * If the hole is not easily accessible on an outside face of the part,
> it's difficult to install the knurled insert. For example, on the
> axles of this Kossel effector:
> https://www.thingiverse.com/thing:2297083
> * I'm never sure how much force I can apply to the knurled insert once
> it's melted in place. Do I need to be fragile like when threading into
> plastic? Will it eventually let go over time if held in tension by a
> spring?
>
> Where a captive thread force is required, modelling in a captive nut
> or nyloc is far more preferable. For example, Johann's Kossel
> effector: https://github.com/jcrocholl/kossel/blob/master/effector.stl
>
> To go into a flat face, you need a small square hole to insert the
> nut. You can easily find dimensions of metric ISO nuts. The hole needs
> to be tight enough to stop the nut rotating. If you intend for the nut
> to be removable then add a hole on the other side to poke the nut back
> out with a paperclip or something.
>
> You could also model an insertion/removal cube with more clearance and
> then a hexagonal nut trap which the nut pulls back into.
>
> If this description isn't clear, let me know and I can model it up for you.
>
> Jamie
>


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Rob W
Lake Tyers Beach,
Victoria, Australia
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

nophead
I make a lot of things with heatfit inserts and they work very well for me. They don't look like the Aliexpress ones above that are intended for injection moulding. They start with a plain section that is slightly smaller than the hole you insert them into, so they are guided all the way down and don't drift. https://www.insertsdirect.com/acatalog/heatfit-insert.html

I use a soldering iron set to 200C (which is a lot less than for soldering) with a conical bit that hasn't even been used for solder. I hold the iron for a few seconds before giving a firm push. I twist anti-clockwise before pulling back to stop the bit catching in the thread.

I have seen Warner Berry use a custom turned bit with a shoulder and the iron mounted in a drill press to keep it all parallel. That is probably the best way to do it, but as I use four different sizes I prefer the conical bit.

Using polyholes I get better than 0.25mm accuracy with FDM, close to 0.1mm. Good enough for heatfit, tapping, press fit and clearance holes. For higher precision like pulley bores I print them undersized and then ream with an H7 reamer in a drill press set to low speed. That gives a nice snug fit on a motor shaft. When you drill or ream soft plastic holes come out very slightly undersized, so a reamed plastic pulley is a little tighter than an aluminium one. However when you get to such tight tolerances as H7 temperature has a significant effect on the size.

On 23 July 2018 at 07:26, Rob Ward <[hidden email]> wrote:
They are good points Jamie.

My main concern was if I used the soldering iron tip to push them in they may very well come back out on the soldering iron seeing they have a thread that could grip the tip. I think I will look into a simple "push" fit with a tool (ie a mounted M3 thread on a handle like a screwdriver, or even a mini press) and try various hole sizes. That way I can address your concern about the orientation better than pushing something into sloppy melted plastic. After that I might try a slight touch of the iron just to get the spikes to settle into the plastic after insertion.

I have used holes with "hidden" nuts and they do work well.

Rob


On 23/07/18 15:21, Jamie Bainbridge wrote:
On 23 July 2018 at 14:07, Rob Ward <[hidden email]> wrote:
I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled Threaded
Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I am
hoping to slip them on my soldering iron tip and insert/melt them into my
models.
That is common but I've never liked these for a few reasons:

* It's difficult to precisely place something when you're melting it
into plastic with a soldering iron. FDM printing is accurate to
~0.25mm or so, but then human hands forcing a big insert into a
too-small printed pocket with a lot of heat are less accurate.
* If the hole is not easily accessible on an outside face of the part,
it's difficult to install the knurled insert. For example, on the
axles of this Kossel effector:
https://www.thingiverse.com/thing:2297083
* I'm never sure how much force I can apply to the knurled insert once
it's melted in place. Do I need to be fragile like when threading into
plastic? Will it eventually let go over time if held in tension by a
spring?

Where a captive thread force is required, modelling in a captive nut
or nyloc is far more preferable. For example, Johann's Kossel
effector: https://github.com/jcrocholl/kossel/blob/master/effector.stl

To go into a flat face, you need a small square hole to insert the
nut. You can easily find dimensions of metric ISO nuts. The hole needs
to be tight enough to stop the nut rotating. If you intend for the nut
to be removable then add a hole on the other side to poke the nut back
out with a paperclip or something.

You could also model an insertion/removal cube with more clearance and
then a hexagonal nut trap which the nut pulls back into.

If this description isn't clear, let me know and I can model it up for you.

Jamie



_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

ednisley
In reply to this post by Jamie Bainbridge
On 07/23/2018 01:21 AM, Jamie Bainbridge wrote:
> melting it into plastic with a soldering iron

I set the hole OD to the insert knurl OD, (optionally) butter the knurl
with epoxy, use a screw as pilot, and ram it into the hole with a drill
press to keep it perpendicular.

Dry, showing the drill press:

https://softsolder.com/2016/03/07/vacuum-tube-leds-noval-tube-on-a-platter/

An early attempt with epoxy:

https://softsolder.com/2016/03/14/knurled-inserts-epoxy-anchoring/

The 3D printed hole will be at the right location, so using epoxy
eliminates melting-plastic distortion / misalignment and ensures great
bonding to the rough hole walls.

I tried adding recessed rings to the hole for more bonding surface, but,
given the overall lack of strength, that seemed like gilding gold.

Tedious if you're in production, no big deal for my onesie-twosie parts.

--
Ed
https://softsolder.com

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
 --
Ed
softsolder.com
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

nophead
Each to his own, but the ones I use are designed to be hot pressed into thermoplastic and the correct hole size is specified. I have never had one fail or more out of alignment enough to matter. Nearly everything I print nowadays uses them.

On 23 July 2018 at 14:54, Ed Nisley <[hidden email]> wrote:
On 07/23/2018 01:21 AM, Jamie Bainbridge wrote:
melting it into plastic with a soldering iron

I set the hole OD to the insert knurl OD, (optionally) butter the knurl with epoxy, use a screw as pilot, and ram it into the hole with a drill press to keep it perpendicular.

Dry, showing the drill press:

https://softsolder.com/2016/03/07/vacuum-tube-leds-noval-tube-on-a-platter/

An early attempt with epoxy:

https://softsolder.com/2016/03/14/knurled-inserts-epoxy-anchoring/

The 3D printed hole will be at the right location, so using epoxy eliminates melting-plastic distortion / misalignment and ensures great bonding to the rough hole walls.

I tried adding recessed rings to the hole for more bonding surface, but, given the overall lack of strength, that seemed like gilding gold.

Tedious if you're in production, no big deal for my onesie-twosie parts.

--
Ed
https://softsolder.com


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org


_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Jamie Bainbridge
In reply to this post by nophead
This is great info. You should write a blog post about this so it's
not lost in the annals of historic forum posts which few will ever
read.

On 23 July 2018 at 18:43, nop head <[hidden email]> wrote:

> I make a lot of things with heatfit inserts and they work very well for me.
> They don't look like the Aliexpress ones above that are intended for
> injection moulding. They start with a plain section that is slightly smaller
> than the hole you insert them into, so they are guided all the way down and
> don't drift. https://www.insertsdirect.com/acatalog/heatfit-insert.html
>
> I use a soldering iron set to 200C (which is a lot less than for soldering)
> with a conical bit that hasn't even been used for solder. I hold the iron
> for a few seconds before giving a firm push. I twist anti-clockwise before
> pulling back to stop the bit catching in the thread.
>
> I have seen Warner Berry use a custom turned bit with a shoulder and the
> iron mounted in a drill press to keep it all parallel. That is probably the
> best way to do it, but as I use four different sizes I prefer the conical
> bit.
>
> Using polyholes I get better than 0.25mm accuracy with FDM, close to 0.1mm.
> Good enough for heatfit, tapping, press fit and clearance holes. For higher
> precision like pulley bores I print them undersized and then ream with an H7
> reamer in a drill press set to low speed. That gives a nice snug fit on a
> motor shaft. When you drill or ream soft plastic holes come out very
> slightly undersized, so a reamed plastic pulley is a little tighter than an
> aluminium one. However when you get to such tight tolerances as H7
> temperature has a significant effect on the size.
>
> On 23 July 2018 at 07:26, Rob Ward <[hidden email]> wrote:
>>
>> They are good points Jamie.
>>
>> My main concern was if I used the soldering iron tip to push them in they
>> may very well come back out on the soldering iron seeing they have a thread
>> that could grip the tip. I think I will look into a simple "push" fit with a
>> tool (ie a mounted M3 thread on a handle like a screwdriver, or even a mini
>> press) and try various hole sizes. That way I can address your concern about
>> the orientation better than pushing something into sloppy melted plastic.
>> After that I might try a slight touch of the iron just to get the spikes to
>> settle into the plastic after insertion.
>>
>> I have used holes with "hidden" nuts and they do work well.
>>
>> Rob
>>
>>
>> On 23/07/18 15:21, Jamie Bainbridge wrote:
>>>
>>> On 23 July 2018 at 14:07, Rob Ward <[hidden email]> wrote:
>>>>
>>>> I am also going to try these "M3 x 3mm Solid Brass Cylinder Knurled
>>>> Threaded
>>>> Round Insert Embedded Nuts" (search eBay?) as an alternative as well.  I
>>>> am
>>>> hoping to slip them on my soldering iron tip and insert/melt them into
>>>> my
>>>> models.
>>>
>>> That is common but I've never liked these for a few reasons:
>>>
>>> * It's difficult to precisely place something when you're melting it
>>> into plastic with a soldering iron. FDM printing is accurate to
>>> ~0.25mm or so, but then human hands forcing a big insert into a
>>> too-small printed pocket with a lot of heat are less accurate.
>>> * If the hole is not easily accessible on an outside face of the part,
>>> it's difficult to install the knurled insert. For example, on the
>>> axles of this Kossel effector:
>>> https://www.thingiverse.com/thing:2297083
>>> * I'm never sure how much force I can apply to the knurled insert once
>>> it's melted in place. Do I need to be fragile like when threading into
>>> plastic? Will it eventually let go over time if held in tension by a
>>> spring?
>>>
>>> Where a captive thread force is required, modelling in a captive nut
>>> or nyloc is far more preferable. For example, Johann's Kossel
>>> effector: https://github.com/jcrocholl/kossel/blob/master/effector.stl
>>>
>>> To go into a flat face, you need a small square hole to insert the
>>> nut. You can easily find dimensions of metric ISO nuts. The hole needs
>>> to be tight enough to stop the nut rotating. If you intend for the nut
>>> to be removable then add a hole on the other side to poke the nut back
>>> out with a paperclip or something.
>>>
>>> You could also model an insertion/removal cube with more clearance and
>>> then a hexagonal nut trap which the nut pulls back into.
>>>
>>> If this description isn't clear, let me know and I can model it up for
>>> you.
>>>
>>> Jamie
>>>
>>
>>
>> _______________________________________________
>> OpenSCAD mailing list
>> [hidden email]
>> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
>
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Troberg
In reply to this post by fcwilt
I'd probably just make it easy for myself and simply put a dimple where the
hole should be, then drill it afterwards. That way, you'll get precise
dimensions.



--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

Jamie Bainbridge
On 27 July 2018 at 01:44, Troberg <[hidden email]> wrote:
> I'd probably just make it easy for myself and simply put a dimple where the
> hole should be, then drill it afterwards. That way, you'll get precise
> dimensions.

Then you don't get perimeters around the hole, so the part would be
weak against the compression of the fastener.

To avoid this you could use the part modifier function of the slicer
to print 100% infill just around that drill area. Both Cura and Slic3r
have the ability to do this. S3D does not afaik, I think it can only
do multiple processes based on layers not areas, maybe I am wrong.

You also would need a drill press to get straight holes through thick
parts. That would matter if you're mating to something else precisely
made, such as using an M3x50mm screw to hold a NEMA17 motor against a
thick part.

Jamie

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
Reply | Threaded
Open this post in threaded view
|

Re: Resources covering model design guidelines

fcwilt
In reply to this post by fcwilt
Just an update.

Based on some of the information I got here I created a model for a part
attempting to duplicate an existing part printed from a 3rd party model.

Long story short using ShapeWays and Versatile Plastic (which was used on
the other part) the result was spot on and the holes and hexnut recesses
were most satisfactory, no work needed, The part could be used just as it
was printed.

Except to use the part I need two more.

Frederick




--
Sent from: http://forum.openscad.org/

_______________________________________________
OpenSCAD mailing list
[hidden email]
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org