Fitting two plastic parts 3

[TheMotionGuy]

Hello, my first time here on the forum.

Anyhow, I deal mostly with the optical inspection systems here at work and I've been doing that for quite a while...but my boss asked me to prototype something for him that is out of my realm of expertise...

It is simply a 4" round disk, 3/8" thick of ABS -- inserted into the top of it will be a 1/2" DIA rod of ABS about 6" long. In reality, the rod measures between 0.5020" and 0.5050" along the shaft.

I need to design the interface between the disk and the rod. And i have to be able to do it myself with our limited equipment.

I don't know much about press-fits nor do I think i have the required skills to get the tolerances right in addition to the limited equipment. Would an 1/2" DIA end mill 0.3" deep and an adhesive be a good route to take?


Thank you for your help, I appreciate any insights you might have!

-Dale

 

[mcgyvr]

That will work... But does it all need to be optically clear or is it just something to store your wedding ring on. depending on the wear of the end mill,etc.. you are not guaranteed to make a .500" hole with a 1/2" end mill. Heck no need for the end mill, just glue the rod on the face of the disk.

 

[TheMotionGuy]

The device will eventually have a cleaning polymer on the bottom of the disk and a grip slid over the nylon shaft. It will be used as a manual cleaning device for a very specific application. I don't think it would be strong enough to simply "glue the rod to the face of the disk" do you?

But the end mill will be brand new, as I don't have a 1/2" one that I can find laying around.

 

[MadMango]

You should get close enough. I'd break the edge of the rod and drive it into the disk with a mallet. The ABS will give.

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[TheMotionGuy]

What do you mean break the edge?

 

[MiketheEngineer]

Round it off just a bit - like a few passes with light sandpaper.

 

[btrueblood]

I'd still squeeze a few drops of acetone or MEK into the crevice after press fitting, to solvent "weld" the two pieces together.

 

[TVP]

I agree with all of the above-- press fit should be ok, lightly break the edges using sandpaper, and solvent bonding/welding using a few drops of acetone or MEK.

 

[TheMotionGuy]

Alright, thank you everyone very VERY much!

My parts just arrived about 30 minutes ago, so I am going to get to work!

You've been quite helpful!

Regards,

-Dale

 

[TheRocketScientist]

They sell screws in your neck of the woods? Or can't you penetrate the disk for some reason?

 

[TheMotionGuy]

It is imperative that the bottom surface be rigit and extremely flat... Or I would just countersink a screw through to the rod.

 

[KENAT]

Um, if there is no precision alignment required then just make the blind hole in the 'disk' a tiny bit over sized on diameter compared to the 'shaft' and use adhesive. If you can afford to have a fillet of adhesive between the shaft and disk even better.

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