Screw Holes and Solid Infill

I am working with fusion 360 and a Creality Ender 5.
I have items that need to be bored and threaded. This does not work because once the wall layers are penetrated I enter the sparser Infill area which does not take the threads. I have improved results with a 100% Infill but I find that this infill does not really result in closely spaced runs of plastic (I don't know of any way to make and actual Solid item). Of course I don't want to use inserts for the screws.

Can someone tell me what I am doing wrong here? I thought that the generating software would make the screw holds with thicker walls but apparently not..

Thanks
Fritz

In Fusion 360 in the sketch tool box there is a thread command that adds a thread to the inside of a hole or the outside of a cylinder if you use this with the "modeled" option set you will get a thread with no need to drill and tap. We have used this feature down to M3 internal treaded. otherwise set your wall thickness enough to allow for the thread. PS Use the hole expansion feature in the slicer to get the right thread clearance.

Thanks for your reply. I do not know of a "sketch tool box" or "modeled option" in Fusion but perhaps these have changed --I am using 2.0.9937 Fusion. This has a sketch " toolbar", and "Design" option.

But there is a "hole" option of course on the Design page and it does allow one to specify threading. I did this originally but the Gcode ( I use Fusion instead of a slicer for this) did not give a very large wall. So I had to increase the wall as you mentioned. Of course you have to set ALL the walls for the complete part and cannot do it for just the hole. This works. (I also note that if I generate and STL and process it with Cura I still to not get a solid wall). Bottom line-I just need to use larger wall surfaces all round.

I am happy on what you are reporting about using regarding using the hole feature--I am new to 3d printing and still resort to taps, reams and other things but I guess the little machine I have here is more accurate than I realized. I will try using it to do the taps in the future.

Thanks again!
Fritz

Hi Sorry I was a bit lax with the instructions familiarity breeds contempt!!!
If from the "design" page you select "Solid" and select the "Create" drop down menu the "Thread" option is just below the hole option you are using. Selecting thread gives a pop up menu with several options .

my version of Fusion 360 is also 2-0-9937

Aha--Now I see. Not your fault--there are so many menus, right-clicks, left-clicks, drop-downs. pop-ups and so on that it becomes a labor just to keep track of them all. I need a spreadsheet for this. I think--but am not sure--that the "thread" option duplicates the options in the "Pop-Up" that appears when you institute a hole. It has one icon there that specifies threading. At any rate you were a great help and I will try using the machine to develop threads. I always "chase" after a manufacturer in real steel for example so if they are a little tight etc that will get corrected-

thanks again!
Fritz

If it is any help we mostly use M3 to M6 threads from the thread pop up menu "modeled" ( also in thread pop up)using nylon 6 and cura slicer with 0.1mm hole expansion. Because of the equipment we design we also use BSP threads G8 G4 but we do chase those to get a good fit.

Thanks! that is useful
Fritz

if you increase horizontal perimeters in the slicer. it will put solid walls around any holes.
That's mostly what i do and let the bolt cut it's own thread.
You don't need to pre-thread it.

CA, I’m interested in this too so would appreciate some detail of how you do that in Cura please? Can you do it, or something equivalent, in OpenSCAD instead?

Terrypin-not sure which you are asking about -the reaming or making a hole with walls. I will assume the latter. In scattering of menus in CURA:
>>In the upper Right is a toolbar with 3 small "bars". Click on the bars to expand the menu
>>in the lower right of that menu is a "button" that says "CUSTOM". Click this
>>A set of dropdowns with names like "Quality, Shell,Infill ......" will appear
>> Click on "SHELL"
>> You will see "Wall Line Count" as an option. Keep increasing this and use the "Preview of Cura to see the resulting walls. You need to pick on that gives you enough thickness to accept your threads. How thick is, of course, empirical---try about 10 for starters.

With all the menus, dropdowns, buttons, bars, right-clicks and everything else in modern software it is no wonder that takes a 3"thick manual to document it!

I hope this helps- I am learning a lot of this along with you!
Fritz

Many thanks Fritz. Yes, that's the part I'm particularly interested in. From CA's sentence:
"if you increase horizontal perimeters in the slicer. it will put solid walls around any holes."

I'll try those steps you describe shortly. Not sure I'd have found them without your details!

Terry

depending on your nozzle size your wall count will have to vary. With the standard nozzle of 0.4mm a wall count of 10 will give you a rather thick 4mm wall! I have been using 2mm walls with threads up to G4 (1/4 inch BSP 10mm hole) with no trouble larger than that use the modeled feature in Fusion 360 even if you have to case it afterwards. We use this system for nylon pressure vessel caps up to 6 Bar

Thanks for your reply Gambo.
I suppose the thread vs holding power for various materials is what is needed here but I recall from reading years ago that it gets pretty buried in equations and not altogether useful-hands on experience like yours is useful. I am never confident in the holding of PLA threads due to the layered buildup nature of the parts.

You are working with nylon-something I always wanted to try--it looks to be a lot stronger and more temperature resistant than PLA and apparently the layers have better holding strength. It is advertised as printable in the low cost desktop machines that a lot of us buy--not sure why it isn't more of a standard.
Do you post treat the nylon assemblies? I know that PLA leaks in water (I do a lot of aquatic work) and usually is pre-treated with methylene chloride to meld the layers. I forgo printing and use a desktop CNC and delrin for cases like that.

thanks
Fritz

Thanks Gambo. ‘Layer height’ I understand! But I must read up further to grasp other terms I’ve encountered like ‘wall count’, ‘number of perimeters’, ‘perimeter width’, ‘top & bottom surface thickness’ actually mean! Particularly for the main type of model I’m focusing on at this early stage. Namely boxes with screw on lids, slide-on side panels, holes for switches, pillars for PCBs, etc.What would be useful would be a web page showing illustrations of simple models (ideally a box!) with the important printing factors like those identified,

In Cura if you hover over a parameter say wall count it will pop up a brief description. support.ultimaker.com has a full manual on line.All nylons are not equal and the ones that easily printable are premium products for instance the one I use most is Spectrum Filaments (Poland) PA6 Low warp which costs 41.22 euros inc VAT per Kilo from the factory or £55.00 from a UK retailer. I have tried a good number of Nylon Filaments and with the exception of the US made Taulman Bridge and 230 filaments which cost much the same in UK have not had a lot of success. Having said that between them they offer the range different flexibilities we require for our needs. Spectrum PA6 Low warp prints at 250- 260C nozzle temp and 55C bed onto a dry and sanded sheet of Tufnol (garolite in US) I use a 1mm thick Tufnol sheet clamped to a glass bed because the adhesion of the nylon to the Tufnol is very strong and you need to flex the sheet to get the work released.

PS
I don't post treat assemblies other than chasing some larger threads. Very large threads like those securing bottle Tops are spiral objects individually drawn in Fusion 360 and sometimes need a little cleaning up because of limitations in the overhang printing capability of FDM we have not yet found it necessary to use support structures when using PA6 LW.

Thanks again. I don't even know if this information is buried somewhere else. You should write a book! 3D printing is a big industry these days but a quick look at Amazon does not reveal anything that seems to present the information that you mention. There are a lot of industrial and research users out here now, many with low end but perfectly usable machines, and a technically detailed book on plastics, orientation strategy, post-treating, best feed rates, issues like Terrypin are asking and all else is sorely needed. I learned "crank" machining largely by trial and error and it is a shame to do this all over again 50 years latercheersFritz

Thanks for the compliment. I'm sorry I do tend to lecture but I am glad you found the information useful

Colin

I agree with CA that I typically just let the bolt cut it's own threads, but it takes some experimentation to get the printed hole sized right to make this work. I've also found that the finer pitch on metric bolts is far easier to do this with than with equivalent imperial sizes. For example, I find it far easier to thread in an M3 bolt than a 4-40 bolt.

Hi Terry you have got to the wrong screen in Cura. This screen is the one allows you to set the parameters which can be changed from the advanced screen one layer of popup back

Hi Terry you have got to the wrong screen in Cura. This screen is the one allows you to set the parameters which can be changed from the advanced screen one layer of popup back

If you go to the print settings screen and use the 3 bars to set it to Advanced mode. at the top of the settings menu are a whole lot of setting to set wall thickness and top and bottom thickness. Settings like line width, wall line count and wall width are interconnected and auto recalculate on the latest change you make.

PS when you are on the print setting menu don't click on the little pop up gear wheel !!

the problem with perimeter/layer numbers and thickness is that different slicers do it differently.
Some let you set and actual thickness - say 0.8mm.
And some let you set the number of layers.
So you need to know the diameter of your nozzle and the thickness of the ;layers you are printing.

If you print at 0.3mm layer height and with a 0.4mm diameter nozzle.
then:

3 top and bottom layers = 3x3 - 0.9mm 'skin' on the top and bottom of a model
3 perimeter shells - 3x0.4 - 1.2 mm walls/perimeters/shell around the sides of the model and ALSO around any holes in the model.

Print at 0.1mm layer height and to get the same top and bottom skin thickness and you need 9 top & bottom layers.

I find that a 2.75 mm hole will print slightly smaller than 3mm bolt and will be a tight and snug fit.

It's also best to screw in once and then leave it. If you repeatedly screw the bolt in and out you will eventually wear the threads away and each time you remove and re-insert the hold is slightly less.

I also add a drop of uhu all purpose glue to theb hole prior to screwing the bolt in. Best glue for pla I've found.

Why isn't nylon used more by home 3d printer owners.
because it can be a total bastard to print with.

It's really stringy, so print speeds and retractions ahve to be slowed right down. It expands when hot and shrinks when cooling so can be a bugger to get to stick to stuff.
And the good stuff - ie: that shrinks less and prints easier - is comparitively expensive.

The two best nylons I've tried are: Mymat nylon, which is about as good as it gets. No shrinkage, prints clean and sticks to just about anything.
And taulman nylon 230.

Like eevry type of printing filament - not all nylons are the same.
Most of the cheap stuff out of chine is really bloody difficult to use. And requires higher printing temps and an enclosed build volume.
So you tend to go for the more pricey - but easier to use taulman products. They - literally - have a nylon for all occasions.

Then there's the fact that nylon is pretty soft. So for many uses pet-g is an excellent and easier to use alternative.

And these days a fairly stiff polypropylene is not only cheaper but just as tough and much much easier to print with.

Books wise - well, people tend to find that they can make more money recording youtube videos these days - so technical books on 3d printing have almost dried up.

The one I bought - about 8 years ago, was excellent and covered everything from software to machines, as well as designing and modifying designs.
But the chap has not updated it and whiole the basic information is still valid, the details are all well out of date.
https://www.amazon.co.uk/Practical-3...7722000&sr=8-3

One of the problems is the sheer speed that ALL aspects of rapid prototyping and 3d printing is advancing.
Back when I got my first machine - you had abs and pla. And pla was considered weak and brittle - took me 6 months to realsie that was wrong - even then.

Now - 8 years later, you can pick up a printer for under £100, there are dozens of different types of material to print with and the technology of the machines themselves has moved forward so fast that a book printed last year would be out of date less than a year later.

I like books I grew up learning from books and I still prefer to have a book in one hand and the computer mouse in the other.

But 3d printing is one of those things where there is no substitute for trial and error.
It's a lot more user friendly than when i started, but soceity has become ncreasingly more impatient and people don't believe they have to actually 'learn' anything to be able to use tools any more.
For that we have smart phones to blame. When you make a complicated product that has no manual - not only do most people never use a fraction of the devices capabilities - they assume that nothing else 'needs' a manual either - so they just get out of the habit of learning HOW to use things.

Anyway - rant over :-)

Great Rant how I do agree!!!!

HI CA \On the subject of Nylons you are right the Taulman Nylon Bridge and 230 are soft and very flexible but the Spectrum PA6 LW is as easy to print but much harder and less flexible in fact when printed resembles Delrin.

Hi Gambo: Thanks, you were quick off the mark! I realised my mistake shortly after posting and deleted the post ;-)

Thanks @Gambo for these informative messages. I am a beginner and new here. I have this Prusa MK3s that I use every day and as I will be away from my laser for weeks at a time, I think I will need something to occupy want remains of my mind. I plan to study some programs [Fusion360] and learn a couple new ones like Meshmixer.I am liking the Ender 5 . The Pro model incorporates most of the mods that people have been doing to the Ender 5 for a reasonable price so I think that is a no brainer. I would assemble it and try it and see if it needs more modification and then remove the four vertical extrusions for compacting.I started this hobby with a Creality 10 and it was a good printer and then moved to the Prusa which is a great printer. Am I right?