Sweep for Bayonet mount

[ninolemann]

Hey everybody, i try to make a Boiler for an espresso machine, and i fail miserably in making the bayonnet mount for the porta-sieve.

I have no idea how to tackle this, but i think the way to go is the sweep+rail function. i saw thatthe guideline can be a spiral, to change a shape (stretch it, scale it) but to get a spiral i am forced to make a spiral body which intereferes with my actual boiler body. i just hvent got the workflow right, and would appreciate some assistance.

So far, i considered myself as a decent CAD-designer, but this is beyond my horizon. must be some sort of rectangle, swept on a circular path, with one side of the rectange getting smaller over the distance of the path... and all this cut out from inside a wall (have a coffee break and ask your barista if he'll let you take a peek underneath his espresso machine, or look at the attached picture)

greetings from zürich

[davebYYPCU]

Yes, a rectangle with a chamfer on the top outside,  inside of the rectangle on centreline, 

pic is not enough, but looks like will be symmetrical, so half turn coil, for the guide rail, centreline edge of the rectangle for the path.

Then mirror, or pattern x 2, coil is temporary, Remove, do not delete it.

Did this one recently, if you search for the post, it has my file attached to pull the Timeline apart.  ( I am on the wrong computer right now) 

[etfrench]

Here's another method that may work. 

The taper will be a few microns different than that produced by the coil method, but I don't think it would impact the functionality.

Note: The chamfer should have been done before the circular pattern, but moving it in the timeline cures that.

[davebYYPCU]

I'll take back what I said, that pic was giving me an optical illusion at first,

took me a while to realise what I was looking at, but after a bit of fiddle, I came up with this, two start custom thread.

The concave fillet is leaving artifacts, so I suppressed it, could be because I am using the coil, (Square coil on centre, 0.4 revolutions,)  made it look right, size from your data to suit,

@jeff_strater can you guys check this out, the suppressed fillet, is not cutting through the top or bottom faces of the coil, but does complete on the end face, 

However the convex one does work. (Here at least) 

[ninolemann]

I Like how this is Going!

Thanks for your replies so far, they were of much help!

I figured i have to cut the bayonet out of solid material, but it is way faster by adding a square  coil and trimming afterwards, similar to daveYYCPU's screenshot. but i stumbled over another

PROBLEM: how can i set the start point of the coil?? i'd like the start point at an angular offset of 42 degrees. can i change the origin ofthe plne?

Thing is, this bayonnet has to be at a certain angle, otherwise the portafiter-handle will point in an unspecified direction and may collide with the housing of my espresso machine...

thanks again for your assistance

[davebYYPCU]

It will be much easier to put the handle on an angle, than to try and reset the start of the coil,

All the coils I have made (not many) seem to start at 3 oclock, on the circle constructed at the beginning of the command,

when the coil is made it can be Move > Rotate, but not while it is being made,

not saying that is how it is, just appears to me to be that way. 

You can set out the angle of the handle from the gaps between the threads, in a top view, and construct the handle at the angle -

42 degrees from where?

presume Revole a half profile.

Might help...

[ninolemann]

Cant do that, because the portasieve is drop-forged, altering the die is way more complicated that changng the boiler, which is CNC-milled.

Is there no way of Rotatijng the Origin for some degrees WITHOUT rotating everything tha is already positioned at certain angles? otherwise i have to start all over and let this inability of the coil tool dictate he positioning of my model...

[davebYYPCU]

Now that the coils sections are done, yes you should be able to rotate, some / any parts you like, 

would need to to check the file, to help any further, any more details?

but I am not understanding your other parts of the boiler fitting,

I know the attaching coffee filter thing has the handle,

but how does the position of the threads change the part on the boiler, it is round stock?

[ninolemann]

I got the exact shape due to my calculations. the thing is: on the other side there will be some valves, hoses, heating, fuses etcetc, so their position over the circumference is very crucial.

as for the handle of the porta-sieve: this thing has two 'wings', each at a right angle to the handle, which will engage in the spiral grooves which i was now able to make. while turning the portasieve, these grooves lead the portasieve in axial direction of the boiler against a large rubber gasket and provide hold and a water(coffee)-tight seal. around a quarter turn should do to lock the portasieve in its position. so the thickness of these wings, the inclination of the bolier helix (and also the softening of the rubber gasket) will determine in which position the handle of the portasieve 'sticks out' of the espresso machine. Preferably towards the user. 

Altering these wings is very difficult as they are drop-forged brass pieces. Building a die is a time and money consuming endeavour. slightly rotating or resetting the pitch of the boiler is way easier.

i was unable to bring the two 'cutouts' of the boiler in line with the beginnig of the two helices. I wanted to do so because i already drew the cutouts on a drawing which was also used for other features, but it seems the start point of a helix is not freely placable, so i got stuck. if i begin with these helixes and go on from there its possible to place all features where i want them.

i'm still concerned how i could rotate these helices without altering everything on the other end, but at lest i can continue with my modeling.

i attached a dummy with my bayonet. if someone can figure out how to rotate these helices, let me know, it wiould be of much help!!!

[etfrench]

Move the timeline back to the coil creation.  Edit the coil feature. Change the operation type to "New Body".  Move the timeline back to the end. Remove the circle patterned copy. Now you can use the Move command to rotate the coil.

[ninolemann]

Aha!

The solution is easy:

i just split the body between the boiler and the bayonet, rotated the free bayonet and reattached the bayonet. that works for me. Thanks for the participation!