Stuff your 3D printer has made today...

[Screwdriver]

Well yes, like I said a sketch so the dimensions are not representative of anything other than how Sketchup objects to you trying to draw a spiral. I don't even have any of your dimensions or any idea really what you are trying to achieve or what it's for. I just happened to be sitting here, killing time. In a minute I need to b*gger off and kill something else...

 

[Agroshield]

You tell me you need 45º so for example the linear advance could be 1 inch for 1 turn (as per your design)

You need the diameter of the workpiece to calculate the helix angle, so the above is only true for one specific diameter.

If the part was 1/4" diameter, one inch advance per turn is a very coarse thread. If the part was 24" in diameter, one inch advance per turn is a very fine thread.

On a diameter of one inch, one inch of advance per turn will not give a 45 degree angle - you would need one inch of advance per _half_ turn.

 

[Screwdriver]

You need the diameter of the workpiece to calculate the helix angle, so the above is only true for one specific diameter.

If the part was 1/4" diameter, one inch advance per turn is a very coarse thread. If the part was 24" in diameter, one inch advance per turn is a very fine thread.

On a diameter of one inch, one inch of advance per turn will not give a 45 degree angle - you would need one inch of advance per _half_ turn.

Have a think about that...

 

[Screwdriver]

You need the diameter of the workpiece to calculate the helix angle, so the above is only true for one specific diameter.

If the part was 1/4" diameter, one inch advance per turn is a very coarse thread. If the part was 24" in diameter, one inch advance per turn is a very fine thread.

On a diameter of one inch, one inch of advance per turn will not give a 45 degree angle - you would need one inch of advance per _half_ turn.

Alright I see what you have done there. You are assuming I suggest 1 inch is always the desired linear travel. I do not know what the requirements are therefore I have made a sketch showing a "random" thread with the only caveat being the angle of that spiral (helix angle ) has to be 45º.

I go on to give an example of 1 inch to draw a comparison with thread pitch without knowing what the required linear advance is. The jig just has to be <whatever> equates to 45º. So from my perspective I can uniformly scale whatever diagram I have drawn, to whatever diameter I like and it will still preserve the helix angle because it's just scaling. Naturally that will also scale the linear movement but since that is not specified and I have not claimed it would remain constant, I do not see where "the above" is not true.

 

[Onoff]

Right, a quick bit of CAD. At this point I'd pay somebody to make it. Ideally in 316. Any takers? PM please if you would. Cheers.

 

[ukracer]

Right, a quick bit of CAD. At this point I'd pay somebody to make it. Ideally in 316. Any takers? PM please if you would. Cheers.

View attachment 382524

@doubleboost . any takers.

 

[Agroshield]

Right, a quick bit of CAD.

I think it needs the diameter of the two internal grooves adding. The wall thickness where the external groove passes the internal grooves will be quite thin.

The way it is drawn, the helix does not continue to the top. It stops 1.5mm below the top surface and then the groove exits the top parallel to the green centreline. If that is important, the drawing needs to be made clearer (blown up detail section) as it is easy to misinterpret that part.

You might need to draw a side view to show how the groove terminates.

The helix will only be a straight line at 45 degrees if you unwrap the cylinder into a flat surface. Otherwise, it will look curved (like a stretched letter S) in any side view and any angular dimension is misleading. Look at the seam on an empty toilet roll.

 

[Screwdriver]

Could you 3d print it??

 

[Onoff]

I think it needs the diameter of the two internal grooves adding. The wall thickness where the external groove passes the internal grooves will be quite thin.

The way it is drawn, the helix does not continue to the top. It stops 1.5mm below the top surface and then the groove exits the top parallel to the green centreline. If that is important, the drawing needs to be made clearer (blown up detail section) as it is easy to misinterpret that part.

You might need to draw a side view to show how the groove terminates.

The helix will only be a straight line at 45 degrees if you unwrap the cylinder into a flat surface. Otherwise, it will look curved (like a stretched letter S) in any side view and any angular dimension is misleading. Look at the seam on an empty toilet roll.

 

[daedalusminos]

You're calling out 2 DP... what's the tolerance?

 

[Onoff]

You're calling out 2 DP... what's the tolerance?

"Near enough" , that 13.69 is just where the CAD says the slot will end at.

 

[Agroshield]

...that 13.69 is just where the CAD says the slot will end at.

The 13.69 and the 45 degree conflict or contradict each other. You cannot make the part to both dimensions simultaneously.

The slot starts 1.5mm below the top surface and winds for 90 degrees, or 1/4 of the circumference. Overall circumference is 34 pies, so when you unwind the slot, it runs for 8 1/2 pies or 26.7mm. For it to have a 45 degree helix angle, the drop has to be the same value. 32.0 - 1.5 - 26.7 = 3.8mm from the bottom.

The drawing is wrong both physically and conceptually. You have drawn a line at 45 degrees, so it drops equally to how much it moves to the left. However, when moving left, it is not moving on a flat surface, it is moving on a curve going into the page. The flat drawing makes the actual distance of 26.7mm appear as 17mm. The conceptual mistake is to attempt to use an angular dimension from a flat plane to represent a superficially similar angle on a curved plane.

Edit:

At the risk of labouring the point, you can use the 13.69 dimension in the above sketch in place of the 3.8 one. The 26.7 would then reduce to 15.9 with the 1.5 staying the same. The angle shown above as 45 degrees then becomes arctan(26.7/15.9) = 59.2 degrees.

 

[ukracer]

The 13.69 and the 45 degree conflict or contradict each other. You cannot make the part to both dimensions simultaneously.

The slot starts 1.5mm below the top surface and winds for 90 degrees, or 1/4 of the circumference. Overall circumference is 34 pies, so when you unwind the slot, it runs for 8 1/2 pies or 26.7mm. For it to have a 45 degree helix angle, the drop has to be the same value. 32.0 - 1.5 - 26.7 = 3.8mm from the bottom.

View attachment 382547

The drawing is wrong both physically and conceptually. You have drawn a line at 45 degrees, so it drops equally to how much it moves to the left. However, when moving left, it is not moving on a flat surface, it is moving on a curve going into the page. The flat drawing makes the actual distance of 26.7mm appear as 17mm. The conceptual mistake is to attempt to use an angular dimension from a flat plane to represent a superficially similar angle on a curved plane.

I agree.....

 

[Screwdriver]

I agree.....

Well he is correct. The simple explanation is that the drawing was made in 2d and ignores the curvature.

 

[Onoff]

The drawing is wrong both physically and conceptually.

I'm not wrong. Go figure.

As in the 13.69mm is correct. I know it's not two straight lines for the slot in that view. Doesn't matter for what I'm doing. It's starts where I show it and goes around a quarter of the circumference.

 

[Screwdriver]

I'm not wrong. Go figure.

As in the 13.69mm is correct. I know it's not two straight lines for the slot in that view. Doesn't matter for what I'm doing. It's starts where I show it and goes around a quarter of the circumference.

Having done plenty of modelling for people over the years, I can see what you're saying. There are measurements and parameters you care about and those you do not. I kept away from dimensions with my rough sketch because it was just the concept I was interested in. But if you send a set of dimensioned drawings off to someone for them to interpret, they will need every single issue specified, even (and often especially) the ones you don't care about.

 

[pint]

b&d workmate handle.

 

[MattF]

Printed some of these the other day. File downloaded from thingiverse. Lboxx clips.

 

[Dev]

Today, yesterday, day before that; getting all the bits printed for another CNC homebuild.

really like the finish you get with this matte PLA. Print edged at .3 layers and a lot of infill for strength.

When all the printings done I still need to use the old CNC to cut parts for the new CNC. bootstrapping indeed.

 

[Onoff]

My brother made me a copper pipe phone stand. A bit impractical if you want to charge it up via a lead plugged in at the bottom, as it's too low. Thus some feet in TPU: