Printing change gear

[ibrich]

Hello all,

I am the owner of a Harrison M250 metal lathe. It is missing one 80 tooth change gear and I have heard it is possible to 3d print a replacement gear. Most of my change gears are steel but two are fiber so I am thinking it will work. Has anyone here printed a change gear and if so what filament was used? Did it work to your satisfaction? I have found the STL file online btw. Thanks in advance.
Regards,
Richard

[Michael G]

G'day Richard. Welcome to our forum.

It can be done, but how long it will last will depend on a lot of things - load on the gear, how well the printer is set up, what material is used and so on. If you have a printer then try it and see. If not, I'd be hunting around for a metal gear. If you have a mill and a method of dividing, it is not difficult to do. A number of us here make up our own gears. We are in Australia, but there should be someone in the US who could help.

Michael

[Ray-s]

Richard, welcome to the forum.
I don't have a mill and have used 3D printed change gears a couple of times very successfully.

My first experience was to produce a set of gears for an ancient Senecca Falls machine that allowed me to cut metric threads.
These were printed with PLA ( I can't recall the exact settings but being my first attempts at 3D printing they were printed with a fine layer height and I overdid it on infill percentage and outer layers - something like 18 hour print time per gear from memory).
They are surprisingly strong and I have produced some very nice metric threads with them. These were printed in 2018 and have been left oily - they appear to be undamaged with time and oil to date. One other thing I have done that is not recommended is to use these gears meshing with another PLA gear - that was required with the conversion and so far it hasn't had any obvious drawbacks.
396611

During one of our COVID lockdowns here I produced a fancier version of these (contoured profiles with the tooth count embossed) just because I had time to burn.
396612


I was making a oil filler plug on my Hembrug lathe and discovered I was missing a 30 tooth gear required for the particular imperial pitch I needed (I actually needed two 30 tooth gears and only one had come with my used machine.
In that case I quickly drew up the required 30 tooth metric gear and printed it with pretty basic settings (still a fine layer height but not overboard on outer layer thickness and infill - you can see the tiny gaps in the centre of each tooth if you zoom in on the picture).
However, this worked just fine for the job in hand and as you can see on this machine the change gears run in a very oily environment that hasn't had any obvious negative effects on the PLA gear to date.
396613

If you don't have access to the equipment to produce your own metal change gear then I wouldn't hesitate to try a 3D printed one - I have only used PLA so far but would like to try PET-G to see how they came out.
One thing I have tried with good success with post-printing cleanup is to chuck the printed gear up in the lathe and run a reamer through the bore to ensure the bore is nice and square to the gear when tidying up any 'elephants foot' in the lower section of the bore.
Ray

[russ57]

The Drummond user group has several users of 3d printed gears, no reports of issues. Particularly useful for older gear where spares are "unobtainium".
Some available via ebay etc, and possibly made to order.