Bushing into nylon press fit question..........

I need to press an oilite bushing into a nylon gear. Gear hole measures 1.000. Bushing OD measures 1.003, ID .562. Is that too much of a press or am I good to go. Any danger of splitting the gear. Is warming the gear a good idea? Thanks..........Bob

I think you’ll be fine but I’m sure someone has more experience with nylon. A little heat would certainly help it start better, as would a little lead in machined in the gear or bushing.

Warming that nylon gear will make a 0.003'' bush fall in (plastics have a high rate opf thermal expansion) and they also creep / stretch so IMHO&E keeping the bush in place will need circlips etc etc.

Limy Sami said:

Warming that nylon gear will make a 0.003'' bush fall in (plastics have a high rate opf thermal expansion) and they also creep / stretch so IMHO&E keeping the bush in place will need circlips etc etc.

Click to expand...

Being it's oilite/nylon I'm guessing some kind of loctite is a waste of time. Yes/No? The bushing will be held in place by it's mounting but I'm thinking maybe a bit of straight knurl to give the bushing some bite. Yes/No?....Bob

Knurling might help (I've no experience) but a lot will depend what the loading is on the gear.

I think Loctite is purely a metal to metal job.

Gear is a change gear on a Sheldon lathe. Not heavily loaded I'm guessing. Now I'm thinking of a couple or three set screws drilled and tapped axially into the bushing and gear....Bob

plastics are pretty slippery. When I did something similar with a delrin gear I turned the end of a set screw down to the minor thread diameter, drilled a hole with the tap drill through both gear and bushing, then tapped the delrin. Might not have been necessary, but I'm a belt and braces guy sometimes

I think any kind of "glue" is going to be iffy. If I was doing it I would probably cut a keyway in both components and split the difference with a key. Pretty quick and easy job with things with those dimensions and material.

that needs knurls or teeth and a sort of ultrasonic welding to insert it and hold being its a gear. if not it will spin inside the other part.

Understood on the slippage. Question is.......Is the .003 press fit OK? Do I have to worry about splitting the gear during the press with that much interference?...........Bob

Here is a more complex but, I think, more structurally sound driving method:

A method to prevent bearing spin might be to silver solder a (guessing dimensions by looking at photo) 1.75” diameter “washer” to one end of the bushing. The washer would be drilled with a bolt circle of four .093 or .063 holes at a radius of .687. Loctite (or soft solder) 4 drive pins in the holes. Then bore the some bolt circle into the nylon.

The pins both drive and radially constrain the nylon gear. Keys and spline will tend to weaken and spread the gear. These drive pins( long enough to penetrate the gear 3/4 of its thickness) will only work if you have enough headroom or if you let the drive washer into the gear. The shoulder bolt that mounts the gear will keep the bushing seated in the gear.

Added a couple hrs later: Actually, using the brazed washer and a single driving pin rather than 4 would probably be adequate in most cases.

Denis