# Trying to make a worm gear

Trying to make a worm gear but i get some strange behavior when trying to create the grooves. For example, i create the grooves of the gear against the flat side of a cylinder, i then rotate one face of the cylinder to create the rotated groove. When i do this though the cylinder arcs inward reducing the diameter in the center.

Hi - this is quite strange. Are you able to readjust the radius of the cylinder after it reduces?
Here’s a video on designing a gear(not exactly a worm gear) using the app:

Hoping you can get some insights from the video on how the grooves were created in the app.

No, the center of the cylinder is having its radius reduced. The ends are maintaining the correct diameter.

Please can you attach a screenshot showing your design to help us better understand the issue. Thanks!

Add > Construction Axis [to your Cylinder in this case]

The Height will determine the length of the ‘Worm’.
Don’t worry about it being too long it will only be effective over the actual Length of the Cylinder.
so ‘begin early’ and ‘end late’ as appropriate.

this was done using a loft but rotating afterwards

Are you saying that the result shown in your last post is that required?
If that is the case then do not bother reading any further.
Be aware that the terminology surrounding this subject is in disarray, this is only one version of many possible.
My input was to direct you toward creating a Worm/Worm Gear [not to be confused with Worm Wheel/Gear Wheel hobbed or cut to match the Worm].
Both items together being described as a Worm Gear Assembly, Worm Gear Set or Worm Gear Pair.
A Google Search for Worm Gear will reveal a multitude of Worm shaped Gear variations:

The first is by far the most popular, the second is of a type used to force meat through the Plates of a Butchers Mincer or Grinder. The third image is of a Worm Wheel made to suit a specific Worm.
The purpose of a Worm Gear is to provide dramatic speed reduction.

My picture is close to the end result im looking for. The radius of the cylinder needs to uniform throughout the model.

I used worm gear to provide a recognizable close to what I’m looking for example. From what u see in my picture i need to rotate the channel +90 degrees. Then i need to rotate a new channel -90 degrees so that all channels are connected. like a zigzag.

If you “unwrapped” the cylinder the channels would look exactly like a zigzag

You could follow:

Helix around Cylinder

To create the Four Helixes you need.

Then Sketch, on the Base of the Cylinder, the Four Closed Shapes needed to create the Grooves.
The following demonstrates how it is possible to Tools > Sweep the Four Shapes along the Helixes although NB: The Axis shown will be replaced by the Helixes you create in this case.

I keep getting, spin would produce a self intersecting surface.

What does that mean and how should I resolve?

Long time since I have experienced a similar message.
It usually shows when a Revolved Object would collide with itself.
E.g., If you were cutting a Screw Thread with a Pitch of 1.5mm and your ‘Cutter’ measured 1.5mm high [along that Pitch] in theory it should be OK.
In reality there is absolutely nil clearance and inevitably after a few Turns of 360 degrees it will likely fail.
Scale the ‘Cutter’ to 0.99 or 0.98 usually it will clear the problem.

Relate the above to what you are doing to find possible conflicts.
If unable to achieve the solution give full detailed description of what you are doing and when the problem occurs, adding a few ScreenShots could be very useful.

No luck. i need a square, not a circle. I dont get options to modify the angles until i successfully complete the revolve

No luck with this.

or this

this also didn’t work

no go with this either

a bit closer here but the square face is facing the wrong way

If this Curve is right for you concentrate on this last ScreenShot.

Select the Construction Plane [CP] carrying the ‘Closed Shape’ ‘square’.
Transform > Move/Rotate the CP so that the ‘square’ is parallel to the Cylinder Base.
Appropriately position the ‘square’ so that it ‘cuts’ through the Edge of the Cylinder.
Don’t worry about anything outside the Cylinder because that will disappear.
Compensate for this ‘loss’ by adjusting the ‘square’ to a ‘rectangle’.

Perhaps these will help:
A Triangular Closed Shape + Tools > Revolve is used to create the Curve required:

A.shapr (132 KB)
Tools > Subtract used to remove the Triangular Body leaving the Guide for Tools > Sweep

A Rectangular Closed Shape is used to create the Groove required.
NB.This is positioned 0.1mm below the Base Face of the Cylinder to ensure complete Selection prior to Sweep. Following the Sweep it will be necessary to ‘push through’ the thin portion remaining at the top of the Groove.

B.shapr (244 KB)

Then you will have to repeat four times, or if you are up for it set up the other three Grooves and create then in unison?

That is what im looking for but I don’t follow how you got to that point. Could you give more detail and or screenshot each step?

The last ScreenShot was to show the result of the .shapr Files you should be able to pick up the clues from the Files.