Now, if we could only find the right helical gears.... BTW, any response from the AliBaba vendor ?

You will want a little bit of adjustment of the motor forward and back to get the mesh right, the motor shaft and driveshaft will need to be quite accurately orthogonal (so alignment of L brackets needs to be good/adjustable), but as it's helical left/right is pretty tolerant. Looking good.

So I'm thinking that the best anchoring solution would be "L" brackets to the back face both to the front and the back of the motor.

Just a thought- if you didn't mind cutting a hole in the back of the case, could you use something like the wade extruder gears that are two different sizes instead of helical gears?  I think this would let you get more torque, at the possible expense of backlash if they are not very well aligned.  Of course, your best bet is to clean and lube your rods to have as little friction as possible, but there are still people who have had issues with skipping.

Personally, I'm in the process of gathering parts to do a direct drive conversion since I don't mind having the motor outside the case.

Helical gear with a 20° angle of pressure, 45° helix angle, 0.5 module, 18 teeth.  The bore diameter is 5 or 6mm, the hub is ~8mm and is drilled & tapped for a grub screw.  The face width is ~8-10mm.

I'd just forward that to someone on Alibaba and see if they'll make you a couple of samples...

grob wrote:

Looks pretty! Let me know if you find a source for those helicals...

Try this: http://us.misumi-ec.com/vona2/detail/11 … 70/?Inch=0

All you have to do is decrypt all the acronyms and jargon in their configuration selection :-).

Those are too big.

What we're looking for is a helical gear with a 20° angle of pressure, 45° helix angle, 0.5 module, 18 teeth.  The bore diameter is 5 or 6mm, the hub is ~8mm and is drilled & tapped for a grub screw.  The face width is ~8-10mm, and the overall diameter should be about 13.75mm. If we find something with less teeth (16 for example), the diameter will go down to <12mm.

The reason I gave approximate numbers for some of the dimensions, is because most helical gears are custom made, however we should be able to find something close.

The module will ultimately determine the tooth size and pitch, and thus control the overall diameter.  The smaller the module, the smaller/finer the teeth and the more of them you can have on a given diameter.

The gears we're looking for are usually referred to as Miniature, or hobby gears.  They can be found at hobby shops, they're used in clock making, RC cars and helicopters, etc.  The materials are either steel, brass, nylon or even cheap pot metal.

If I were to have a choice, I'd probably get brass.  It has a natural lubrication, and believe it or not outlasts steel, in all but the harshest environments.

Looks pretty! Let me know if you find a source for those helicals...

Try this: http://us.misumi-ec.com/vona2/detail/11 … 70/?Inch=0

All you have to do is decrypt all the acronyms and jargon in their configuration selection :-).

And as usual, awesome CAD work, pirvan!

One of the "off-putting" problems wit the direct drive, at least for me, is the external motor, just hanging out on the side of the frame.  So I've been mulling the idea of the motor being still inside the frame, but instead of using a belt to drive the "Y" rod, use gears.

The problem with simple gears, is they have backlash, so to that extent, I'm using helical gears.  Due to the nature of the tooth engagement of helical gears, backlash is almost non-existent.

I'm currently at work, without access to my SD3, so I don't have any actual dimensions of the existing relations between the frame interior and the "Y" rod, and the sprocket gear for the belts, but those will be worked out later.  This is just a concept of how it would look and work.

Let's hear the comments