Ebay ballscrew coupler connection

[Dan911]

Hello all,

I'm upgrading my Z axis and replacing my leadscrew with a 1605 ballscrew I purchased on ebay. I was wondering if anyone was filing a flat spot on end of ballscrew similar to a nema34 shaft for a better hold in coupler? I will be using a Oldham coupler I purchased from cncrouterparts. Will tightening coupler and set screw be enough?

Thanks for any input/advice,
Dan

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[Fluxion]

I filed a flat on mine, I used loctite on the set screw as well.

[Dan911]

Thanks Fluxion, I will do the same.

[UA_Iron]

Oldham Zero Backlash Couplers | CNCRouterParts

Is that the coupler you purchased?

It's called "zero-backlash" for two reasons:
1. There's an interference fit between the polymer center piece and each of the aluminum hub ends
2. Each of the aluminum hub ends clamps over the circumference of each shaft

Given point 2, you will not want a flat on the shaft. This could potentially work against you as now your clamp is engaged with less surface area.

flats are required for set screw mounts and can experience backlash

[Fluxion]

I guess I should have mentioned that the flat I put on my ballscew is probably about 3/16" wide, I never did measure it. I might also mention that my ball screw end is 12mm and cncrouterparts.com doesn't offer a hub with a matching bore so I ordered a 10mm and bored it on my lathe. The bore was a snug fit to press on by hand and I am sure the set screw would mar the end of the ballscew making removal difficult. If oldham manufactured the coupler halves with the set screw I am sure they intended them to be used. I don't really see a reason that would require the use of both the set screw and the clamping screw,, I am sure the clamp is plenty good. That being said, I did tighten the clamping bolt first then the set screw, I figured using bothe wouldn't hurt as long as there hub fits the shaft correctly.

[Dan911]

Oldham Zero Backlash Couplers | CNCRouterParts

Is that the coupler you purchased?

Yes it is, I was surprised and disappointed when received the 1/2" end (Nema 34) had a set screw but the other end didn't. After reading your post now makes sense why. I my not file a flat but I think a set screw will leave less chance for slipping.

Thanks for your input,
Dan

[A_Camera]

I filed a flat on mine, I used loctite on the set screw as well.

Loctite? ...and what if you want to or need to remove it? I am a bit of a skeptical to using Loctite, especially on aluminum. Perhaps I am wrong and should use it more often.

[bhurts]

Loctite is awesome. It will keep you from having to retighten everything as it vibrates loose over time. It comes in 3 basic types. They hold to varying degrees depending on your needs. Even the red permanent loctite isn't really permanent. You can break loose any loctite connection by either a heating the area with a torch or b putting a soldiering iron on the screw and getting it really hot. The loctite is broken down by heat. The blue doesn't even need heat to break loose just a little extra torque to break the connection.

Ben

[wizard]

Yes it is, I was surprised and disappointed when received the 1/2" end (Nema 34) had a set screw but the other end didn't. After reading your post now makes sense why. I my not file a flat but I think a set screw will leave less chance for slipping.

Thanks for your input,
Dan

If the coupling hub has a set screw then it needs to press against a flat. In order for that set screw t hold it needs to be aligned square to the flat. Often hubs will come with two set screws set 120 degrees apart, in such a case at least one set screw should be on a flat. Ideally two set screw would be bearing against two flats but you just can file them as they need to be an accurate number of degrees apart.

As for which is better, clamps are great on precision ground shafts but terrible otherwise. To prevent slippage the clamps must be a precision fit on the shaft to begin within.

Set screws can be notoriously bad though. Often slipping or grooving a shaft. I often attribute this to undersized set screws and a lack of proper installation. You can get away with slightly sloppier fits with set screws though. Another issue with set screws is that they can result in a pulley or coupling rocking on an axis, this can then be seen as backlash, but be hard to diagnose.

[wizard]

Loctite? ...and what if you want to or need to remove it? I am a bit of a skeptical to using Loctite, especially on aluminum. Perhaps I am wrong and should use it more often.

Loctite can be over done. I know some Japenese machines we use literally have every single nut and bolt Loctited in place. That is a real pain.

Realize though that there are different Loctites out there including specific materials for mounting bearing and collars to shafts. It isn't just a material for threaded fasteners. I wouldn't use the stuff until you have the machine finalized though. Even with heat you may find yourself having a hard time removing parts.

[A_Camera]

Loctite can be over done. I know some Japenese machines we use literally have every single nut and bolt Loctited in place. That is a real pain.

Realize though that there are different Loctites out there including specific materials for mounting bearing and collars to shafts. It isn't just a material for threaded fasteners. I wouldn't use the stuff until you have the machine finalized though. Even with heat you may find yourself having a hard time removing parts.

That's about how I see it as well. Loctite can be a real PITA if you need to remove a screw, but sure, if you are 100% sure you don't need to remove a screw than it is a good idea.

[A_Camera]

Loctite is awesome. It will keep you from having to retighten everything as it vibrates loose over time. It comes in 3 basic types. They hold to varying degrees depending on your needs. Even the red permanent loctite isn't really permanent. You can break loose any loctite connection by either a heating the area with a torch or b putting a soldiering iron on the screw and getting it really hot. The loctite is broken down by heat. The blue doesn't even need heat to break loose just a little extra torque to break the connection.

Ben

Thanks. I had no idea that Loctite can be removed with heat. Though, a torch on a machine isn't really a good idea, at least not if the machine is greasy... I am saying this because I am right now fighting a screw on my pillar drill which I need to remove but can't. I can't use a torch because that would set fire to the whole thing, including my home, so I am afraid I have to give it up and drill it out. A "little extra torque" won't help, the screw is too weak and I am afraid of breaking the head off and causing more problems.

[bhurts]

If flame is a problem use a pencil soldering iron. It will have the same affect but takes a little longer to heat up.

Ben

[A_Camera]

If flame is a problem use a pencil soldering iron. It will have the same affect but takes a little longer to heat up.

Ben

I think a hair dryer should be more efficient, especially in my case, since the only soldering iron I have is for electronics and I don't thing that it could ever hear up a 5mm stainless iron screw which is stuck in a stainless pipe with 5mm thick walls. Anyway, in the end I managed to remove the screw I was fighting with without heat, just by using more torque than I could apply by hand. Never the less, I will keep in mind that heat will help if needed. Thanks.

[Dan911]

I ended up filing a small flat spot with the file edge on ballscrew. The small amount of surface area this took away from clamp and replaced with set screw seem to me to be a lot less chance of slippage. I lined up and clamped first than tightened set screw with blue Loctite.

Thanks,
Dan