# 3D Printing a Spindle Nose Protector



## MyLilMule (Jan 30, 2021)

I'm trying to design a spindle nose protector for the 1-7/8-8 spindle on my 13". I created something in Fusion 360, and using their thread modeler, printed a part that is supposed to be 1-7/8-8 threads, but it won't thread on the spindle. Anyone here have any success in 3D printing large threads? Is there a trick to tell Fusion to make them looser than standard?


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## Technical Ted (Jan 30, 2021)

I know nothing about 3D printing, but I find this a very interesting topic and would like to learn more myself for when I decide to take the plunge and buy a printer.

I do know Fusion 360 and have watched several videos on printing... I'm wondering if it could be a scaling issue??? Are the rest of your dimension spot on or are they a little under size as well? If all your other dimension are exactly correct, I have nothing to offer, only a lot to learn! 

Ted


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## silverhawk (Jan 30, 2021)

Check the inner diameter and root of the protector to make sure it didn't scale poorly.

joe


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## martik777 (Jan 30, 2021)

You have a lathe, why don't you make one?  Hardwood would be easy to thread and "machine"


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## ttabbal (Jan 30, 2021)

I suspect you got some shrinkage while cooling. Happens sometimes with prints. Maybe scale up 5% or so?


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## 7milesup (Jan 30, 2021)

You will almost certainly have some percentage of shrinkage.
What material are you printing with?


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## brino (Jan 30, 2021)

You could try printing the male thread and seeing if it would mate with your chuck/backplate.,,,,and female thread.

Alternately, if you send me an *.stl file for a 1-1/2-8tpi for my southBend 9" then I'll print that and try it.
I do not fancy trying to coax Fusion-360 to do what I want it to do........I don't have days to waste on that.......

-brino


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## MyLilMule (Jan 30, 2021)

silverhawk said:


> Check the inner diameter and root of the protector to make sure it didn't scale poorly.
> 
> joe


I checked the thread pitch and it seemed spot on. I didn't measure the diameter and root internally. I don't have the tools to do that yet.


martik777 said:


> You have a lathe, why don't you make one?  Hardwood would be easy to thread and "machine"


My lathe is undergoing a restoration and is in pieces. I just want to protect the spindle threads whilst moving/removing/storing the spindle. I will make one at some point, just can't for the moment.


7milesup said:


> You will almost certainly have some percentage of shrinkage.
> What material are you printing with?


PLA.


brino said:


> You could try printing the male thread and seeing if it would mate with your chuck/backplate.,,,,and female thread.
> 
> Alternately, if you send me an *.stl file for a 1-1/2-8tpi for my southBend 9" then I'll print that and try it.
> I do not fancy trying to coax Fusion-360 to do what I want it to do........I don't have days to waste on that.......
> ...


Good idea on printing the male side. I might give that a try just to see what I get.

I found a "solution" of sorts. Printed a bunch of test pieces. Found out that if I make the thread 1-15/16-8 and then scale the whole thing to 98.4% (halfway between 1-15/16 and 1-7/8) it threads on with just the right amount of tension.

I've attached an STL file of the spindle protector with 1-1/2-8 threads. I have also attached a smaller section to print first that you can use as a test. These are both at size. Confusion 360 isn't that bad. Too me 10 minutes to draw this part.

Here's what it should resemble when complete:


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## silverhawk (Jan 30, 2021)

Well done, sir! Even when you don't have the tools, trial and error can still get you close enough!

joe


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## brino (Jan 30, 2021)

MyLilMule said:


> Confusion 360 isn't that bad. Too me 10 minutes to draw this part.



Wow, that was fast.......
You are as a god to me!

I am still NOT over their change to the damn ribbon interface.........just when I thought I knew where things were........

I just started a print, and will report on the fit tomorrow.

Thanks!
-brino


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## brino (Jan 31, 2021)

@MyLilMule

Thanks for the model!

Here's the one I printed last night from your model:


it is PLA with 100% infill.

it looks great and the thread pitch looks perfect:



However I could only screw it onto the lathe spindle about half a turn before it got tight.

Measuring the internal thread diameter gives 1.367" to 1.373" depending on direction/location.
Which looks good according to the charts:




....but there are some boogers on the threads:






I believe these line-up where the printer ends one layer and/or changes direction.

I am going to try cleaning up those defects and see if that does it......

-brino


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## 7milesup (Jan 31, 2021)

That's awesome Brino.  Excellent work.


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## MyLilMule (Jan 31, 2021)

Nice. I am not having the same luck. I printed one last night as described. Oversized threads and shrink when printing. I had to clean out the threads from all the scaffolding that ended up in them. It threads on, but gets a little tight at the end, same as yours. But I’m just going to leave it as is. Does what I need it to do.

Thanks for at least confirming I created the model right. Lol.








Sent from my iPhone using Tapatalk


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## brino (Jan 31, 2021)

7milesup said:


> That's awesome Brino. Excellent work.



To be clear and fair, all the real work was done by @MyLilMule !
I just started a print from his model and went to bed.

Update:
I do not have a 1-1/2"-8TPI tap, but I did find a 1"-8TPI tap.
I used it (by hand) to basically scrape the threads with the cutting edge:



and now it fits the lathe spindle nose much better!

-brino


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## MyLilMule (Jan 31, 2021)

Glad it worked for you. I don't have a tap that big or I would try it myself. I am still perplexed why my printer seems to be printing undersized. It's new to me, as is 3D printing, so not sure if I set something up wrong. Might need to give Dremel a call.


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## ttabbal (Jan 31, 2021)

I bet your printer is fine, but the plastic shrinks a bit as it cools. It depends on the filament. Some shrink more than others. It's possible that the printer needs calibration though. There are some guides out there for adjusting the e-steps. A machinist could handle the measuring easy enough. You just tell the printer to move some amount, measure how much it actually moved, and drop it into a formula to figure out the new steps value. 

If steps are set properly, you can adjust for the shrink by printing little test cubes, measuring them, and scaling the print in the slicer to get the right size.


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## Grendel (Feb 27, 2021)

from my experience with 3d printers, make any holes the nozzle diameter oversize, most printers print external dimensions corectly, but holes are always tight, my printer has a 0.4mm nozzle so to get a 20mm hole I would design it to 20.4mm for a tight fit.


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## jocat54 (Feb 27, 2021)

brino said:


> To be clear and fair, all the real work was done by @MyLilMule !
> I just started a print from his model and went to bed.
> 
> Update:
> ...


  I watched a video the other day from Old Tony--he tapped a larger internal id than the tap was (same tpi). I have never tried it but made sense watching the video.


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## jwmelvin (Feb 27, 2021)

Yes my experience is the same. It seems like the break in the perimeter loop causes enough of a bump to make fits a bit tight.


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## malleusmagnus (Mar 4, 2021)

brino said:


> Wow, that was fast.......
> You are as a god to me!
> 
> I am still NOT over their change to the damn ribbon interface.........just when I thought I knew where things were........
> ...


Any thoughts on the effort?  Ignore my last; just saw page 2.  

If you have a spare lying around, I'd take it off your hands.  I'm restoring my 1938 9" and also need a little something to protect the spindle nose during the process.


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## aliva (Mar 6, 2021)

Maybe a dumb question but, Since I don't have a threaded nose on my lathe, why is a nose protector needed?


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## Technical Ted (Mar 6, 2021)

I have a South Bend with a threaded spindle and I don't really consider the nose piece as much of a "thread protector" as a means of removing the collet adaptor from my spindle taper. I prefer that rather than driving it out with a rod through the spindle.

Ted


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## brino (Mar 6, 2021)

aliva said:


> Maybe a dumb question but, Since I don't have a threaded nose on my lathe, why is a nose protector needed?



I have never used one before, but I believe the fear is that while turning a part that's held in a (perhaps Morse-taper) collet that is itself held directly in the spindle nose with a draw-bar thru the spindle that the lathe cutting tool could accidentally come in contact with the spindle threads and damage them.

-brino


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## aliva (Mar 9, 2021)

a


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## SLK001 (Mar 9, 2021)

You guys are equating "fear" with a simple desire to protect the threads on the spindle.  Also, to run a tool into the spindle threads, the operator must be either:
1) asleep,
2) gone to the restroom, or
3) just plain stupid.


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## MyLilMule (Mar 10, 2021)

Um, I did this for fun, because I just got a lathe, and I just got a 3D printer. I needed a project. This whole thread, was about threads (pun not intended - mostly) not about the usefulness, or lack thereof, of any part I was making.


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