thread mill sim hits bottom of drilled hole but no red crash warning

[rickg5056]

hello everyone

im checking to see if this is a problem or if my work around should be observed when i do this, i hate breaking tools

is a blind drill cycled hole followed by a single point thread milling.

capture1  in the sim the thread mill is clearly crashing into the stock at the bottom of the drilled  hole,  but im not getting a crash warning, 

capture 2 i used the same thread milling cycle but adjusted the bottom height by 2mm and the threadmill shows it clears the bottom of the hole with no crash warnings either. 

am i missing something .. 

[DarthBane55]

I could be wrong, but your threadmill is feeding near the bottom isn't it?  In that case I think Fusion would not say it's a crash.  You'd have to turn on "comparison" mode in simulation to see the model violation.  If it was rapiding down straight to the bottom I think it would show a red mark in the lower bar.

[rickg5056]

yes sir, near the bottom it transitions to feedrate. 

i lowered the safe distance in safe linking to .001 and i get a crash warning in the same stock that i didnt get one before.

so i should employ capture number 2 by adding some distance to the bottom height in my case 2mm  and any other time im thread milling a blind hole.  or am i just flat out doing this wrong 

1. it would be great if there was an adjustment in the passes tab or the end user could select if the tapped hole is a drilled hole or full depth hole.  then maybe fusion could detect how far to push the thread mill down based on the geometry of the drill bit tip

2. thread distance in the thread milling tab

3. i simmed 10 different size holes and it looks like offsetting the bottom by thread pitch+.020 clears safely everytime, 

[DarthBane55 · Accepted solution]

If solution 3 works out most of the time, you can create the equation in the bottom height and make it the default for threadmilling.  But not all blind holes need the thread to go right to the bottom.  When it needs to, I know it's tight so I pay close attention and look from the side in wireframe mode to see that there is no problem at the bottom.  Because there are times when pitch +0.02 is not deep enough too.  I think it's hard to make this a solid rule (pitch +0.020).  It really depends on the drawing specs, so not sure I would want to let Fusion decide for me how deep to go.  That being said, try the equation if that works out most of the time for you!

[rickg5056 · Accepted solution]

it was pretty naive of me to think that would work everytime, especialy because i never leave it to chance, i alway check in sim when i know its close. i didnt think that fusion would disregard the modeled hole thread and just thread to bottom of the hole or to the tip of the drill bit which is what is causing the problem, maybe ill put in a feature request. 

i guess ive grown accustomed to how easy fusion make things and it blew my mind that there was not a distance to thread to in the thread milling tab 

i will  check always and adjust the bottom up to make sure the thread mill is not hitting the stock at tthe bottom of the hole. thank you for your fast response.

[rickg5056 · Accepted solution]

for anyone else having this problem i did some more testing and it looks like at least on my end, 

the only thread milling that will work is to use the HOLE tab  then using the SIMPLE option on both hole types and on DRILL POINT selecting ANGLE ,  one these holes the threadmill will clear because of the bevel left by the drill point

if you try to thread mill any other type of hole, whether its an extruded pocket from a sketch, or any ether selection type of hole from the HOLE tab, the tip of the tool will hit the bottom of the hole. the work around is to offset the BOTTOM to in HEIGHTS TAB to limit how far down the thread mill goes or only use drilled holes for where you want or need to threadmill