Need some help with engineering standards - gear tooth shape

[vlaiv]

I've downloaded and installed FreeCAD software in "preparation" for 3d printer purchase (not more than few months now, just few more installments and I'll be debt free ) and I sort of learned the basics last night and want to do something useful as a practice.

Here is what I have in mind - bits for autofocus unit for my Samyang 85mm T1.5 lens.

So far I've gathered that GT2 standard belts and pulleys are easiest to source for this purpose. From what I was able to find online - follow focus ring is 0.8 module with 102 teeth. Samyang specs say that focus ring is 81.6mm and 81.6 / 0.8 = 102.

I want to make sort of "sleeve" - that will fit onto focus ring and have proper GT2 profile on the outside, but the problem is - I have no idea what sort of shape those teeth have.

Best I can do is this image:

It looks like involute profile? What about pressure angle? How to get this information?

Any pointers are welcome.

[Dr_Ju_ju]

Personally, I wouldn't bother with a "sleeve", instead, after carefully measuring the tooth spacing & depth, I'd just source the required belt and pulleys from https://www.beltingonline.com/ ....  Its what I have done to connect a stepper motor to a Baader Steeltrack focuser 

[Peter-uk]

Open freecad then go to the tools menu

Tools / Addon Manager / Workbenches
then Select fcgear
install

in that work bench you will find all that info

 

Pete

Edited March 15, 2022 by Peter-uk
uodate image

[vlaiv]

1 minute ago, Dr_Ju_ju said:

Personally, I wouldn't bother with a "sleeve", instead, after carefully measuring the tooth spacing & depth, I'd just source the required belt and pulleys from https://www.beltingonline.com/ ....  Its what I have done to connect a stepper motor to a Baader Steeltrack focuser 

I tried doing that and it turns out that pitch is 2.5mm or there abouts and there is T2.5 belt system, but not sure if it will fit as it should.

2GT or GT2 (which ever is proper naming) seems to be more popular, and I want a bit of practice for 3D modeling

 

 

[vlaiv]

Well, here we go:

This should slide onto follow focus ring and provide outer GT2 profile

(I'm not sure if it will match properly as I modeled follow focus gear teeth as standard involute gears with 20 degree pressure angle).

[Peter-uk]

Should of posted this sooner  3 tips that worked well for me with my 3 d printer

1, Use external mosfetto take the high power away from the main control board for the hot bed and the hot end,
this stops the cheap control boards from burning out

 

2, Use a hot bed sticker on the aluminium hot bed BUT NEVER put your hands/fingers on the sticker, doing so will stop your prints from sticking to the bed, If it needs cleaning use rubbing alcohol ie ISOPROPYL ALCOHOL, I cannot stress how important it is not to get any contaminates from your hands onto the hot bed sticker.  It is a real pain.  It will cause no end of grief.

3, Stick a mini greenhouse over your 3D printer to give it temperature control, this will help no end on long overnight prints when the temperature in the room is likely to fluctuate.

 

Pete