Three Jaw Chuck Flaw

[dehn0045]

Newb here, so sorry if this is a silly question. I have a new 6" D1-4 3-jaw chuck that came with my lathe. I decided to completely disassemble it for cleaning and found what looks like a small flaw in the casting of the backplate. It's about 1/4" wide, 1/4" deep and 1/2" long. I'm not sure what level of concern I should approach this with - like "no prob, they look like that all the time" or "holy $#*! Send that thing back", or more likely somewhere in between. I am leaning toward contacting the vendor and see what they say, but thought I would try to get a little more knowledge before talking to them.

 

[ACHiPo]

Welcome! That doesn’t look catastrophic to me. Disappointing quality, but in a low stress region.

 

[brino]

There are no bad questions, that's how we all learn!

First I'd need to be sure of what you're asking about........



The blue circle contains what appears to be a slight over-cut from the machining operation (EDIT: or better said, rough grinding out an inclusion) when they cleaned-up the edge of that relief feature in the casting. I'd say that's nothing. It's likely too little to affect balance.

The green circle contains something I cannot see well enough to comment on.
Is it a crack between two thru holes? (that could be structural and cause for concern!)
Are there meant to be holes there?, are they a feature for something?
Or were they drill by the manufacturer to attempt to stop a crack/flaw in the casting from continuing to crack?

Is it just a step in that surface from two offset passes when they cut that slot? (that could be removed with a file, no problem)

I'd need some pictures from different perspectives to be sure.

-brino

 

[dehn0045]

@brino thanks for the detailed response! It is the blue circled region that is my concern. The green circled area is just an artifact of the photo, some grease/glare or shadow, but nothing structural.

The bottom of the gouge (blue circle) is rough, similar to the red painted area, I assumed that this is un-machined casting. But again, I am a total newb and don't really have any idea how these things are actually made - other than watching youtube videos on "awesome machines" lol.

I should have said that I will be far from pushing the limits of my machine or chuck for a long time. My assumption is that this flaw won't likely present any concerns at lower speeds with softer materials. Also, my understanding is that 6" chucks are less prone to catastrophic failures. My intent is to purchase a higher quality (non-Chinese) 8" 4-jaw chuck in the relatively near future.

 

[RJSakowski]

It looks like a casting flaw. The adjacent surfaces are too rough to be machined. Possibly a slag inclusion that was removed when cleaning the casting. It shouldn't compromise the chuck.

 

[RJSakowski]

I suspect that this type of flaw is more common than we realize. Many of them in non critical areas are just filled in for cosmetic purposes.

 

[dehn0045]

thanks @RJSakowski !! Makes a lot of sense, I guess that it one of the big differences between good/bad casting -- and why all the stuff from Harbor Freight has so much bondo covered with paint that chips away after a couple years.

 

[ACHiPo]

There are no bad questions, that's how we all learn!

First I'd need to be sure of what you're asking about........

View attachment 340859

The blue circle contains what appears to be a slight over-cut from the machining operation when they cleaned-up the edge of that relief feature in the casting. I'd say that's nothing. It's likely too little to affect balance.

The green circle contains something I cannot see well enough to comment on.
Is it a crack between two thru holes? (that could be structural and cause for concern!)
Are there meant to be holes there?, are they a feature for something?
Or were they drill by the manufacturer to attempt to stop a crack/flaw in the casting from continuing to crack?

Is it just a step in that surface from two offset passes when they cut that slot? (that could be removed with a file, no problem)

I'd need some pictures from different perspectives to be sure.

-brino

I was commenting on the blue circle area. I agree it doesn't look fatal. The green area I didn't notice before. That looks sketchier, but can't really tell from the photo.

 

[dehn0045]

Sorry didn't get this out sooner, I was able to snap another photo this evening and shows that the green circle area is an artifact of the photo due to the small recess and the angle the photo was taken.

Thanks for all of the input from everyone!