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Mixing bushings and bearings?

paradoxum

paradoxum

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Does anyone have any data on the stress points in the gearbox? For example, I was thinking, the spur gear for example is bottom heavy and usually not shimmed up much, whereas the top side is just the shaft and opposite the side taking the most stress from the bevel gear, right? So what about putting a bushing on the bottom, and a bearing on the top? 

And how about the other gears, bushings on side of bevel gear with the teeth, bearing on the other side? Maybe bearings both sides of the sector?

Has anyone mix/matched before like this, any data out there on whether there would be a benefit? I'd like to try it - I might - someday - even sit down one day and mix/match them in lots of different ways and then check for RPS with each setup and log everything - don't suppose anyone has done that before?

Edit: 

I found this on retroarms:

https://www.retroarms.com/news/the-difference-between-bushings-and-bearings

In some scenarios, there is possible combination of the bearings and bushings, for example using bearings on the motor gear and using the bushings on the piston and spur gears. It is only individual and these setups depends on every airsoft technicians, where they prefer different kind of solutions. There is of course the need to count with all forces on every bushings or bearings with wanted lifetime.
Click to expand...


I think I am going to try:

Bevel - bushing on gear side, bearing other

Spur - as above

Sector - bushing on side that grabs piston, bearing opposite

 
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Some manufacturers have indeed mixed and matched. I believe my SOC AR was mixed and matched from factory.

Also P90s tend to have a solid oval bushing and can use bearings for the other two gears. 

Sadly I have no science or knowledge as to why one is picked over the other for specific gears etc. 

 
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Asomodai said:
Also P90s tend to have a solid oval bushing and can use bearings for the other two gears. 
Click to expand...
Yeah I did that with my pulse rifle (thompson). Got steel oval bushings and bearings for the others. That was just to upgrade from the plastic ones it had though and I wasn't thinking about performance like now.

 
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It is a thing, personally i've generally stuck with matched ends (ie upper and lower side if you're looking during assembly).

Bushings on the sector make sense, as it takes the most direct load in terms of the spring and impact loadings and spins at the slowest speeds.

Likewise bearings on the bevel make sense in terms of it having the lowest loadings but highest speeds.

However for the most part i've not really been too fussed about bearings/bushings, but then i'm building my guns to a 1j limit so i'm not as concerned about the mechanical loading on the box.

 
I'm really just trying to min-max as much as possible, I could just go with either or and probably never notice a difference, but part of the fun is tweaking stuff and optimizing it as much as possible for me.

I'll go with bushings on bevel and sector like you say and bearings on spur I guess just to start with.

ZCI steel bushings and EZO bearings

 
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It's not worth overthink TBF. I tend to run bushings because they don't collapse.

If you are building for performance then we don't have the same demands as the USA market. Less motor loading, less gearbox stress.

It is more than possible with the UK 350fps limit to get 25rps with a 7.4v lipo and bushings.

13:1 gears, HT 16TPA motor, S/S 2 teeth on sector, M110 spring or there about. Radius the shells if needed, Grease well and treat it nice and it should run for a very long time without any issues. And it's about all you could ever want from a gun.

Where the wear points are on the sector bushing/bearing. I have no idea. It's not as simple a question as it seems. You have a force from the spur, A force from a spring been compressed, and it's rotating. The rotation causes some strange things when it comes to wear points, and I think a degree would probably be needed to work the answer out correctly. My guess would be the wear point is the top of the bearing due to the main load been from the spring - that force wanting to push to 3 o'clock but the precession in the rotation forcing that to be 90 degrees ahead of the applied force. The sector effectively climbs into the load. You then have a torque been applied both by the rotation, the offset spur force, and the offset mass. That torque is going to want to act at the 3  o clock position on the upper bearing and 9 on the lower... So as a rough guess 12 o'clock to 3 o'clock on the lower bearing, but more like 1 o'clock to 4 o'clock on the upper bearing. It's a crazy guess tho, I'd love for someone to do the proper maths on it.

It's very very complicated in there. But bushings don't collapse.


 

 
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I've always figured that the bevel gear gets bearings and the rest get bushings.

However I would have thought that good bearings could take the forces, I just don't know how good the bearing I have access to are.

 
Tang_Killss said:
Adding a bushing on the bottom and a bearing on the top of a spur gear in a gearbox can potentially help distribute the load and reduce wear, especially if the top side is taking more stress from the bevel gear. However, the effectiveness of this modification would depend on the specific gearbox design and the type of stresses it experiences. It's essential to ensure that the components fit correctly and that the modification doesn't introduce any alignment issues or excessive friction. Additionally, lubrication and maintenance are crucial to prevent premature wear and ensure the gearbox's longevity. To find any parts, you can visit here: Bearing Designations And Dimensions Inquiry System
Click to expand...


View attachment 115439

 
jannickz said:
Your idea of using a combination of bushings and bearings in your airsoft gearbox is interesting and has merit. While there isn't a wealth of publicly available data on stress points specifically, some information exists, and your proposed combination aligns with existing knowledge.
Click to expand...


Are you a fairly well programmed AI? ?

TEST: in a world where crunchy peanut butter exists, what reasons are there to buy smooth?

 
Yes, one of the posts ever made.

At least we know you are human

 
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