Brutish 4 jaw chucks and/or more creative workholding in the lathe

[becksmachine]

Did a job today that made me think of the ongoing controversy of 3 jaw vs 4 jaw chucks on the lathe.

The photos tell most of the story, this is some kind of adapter in the hydraulic system for an Austin Western grader. Apparently broke just from hydraulic pressure, oil may have been too cold, relief valve set too high or etc?

Anyhow, they wants a new one that isn't broke so they can continue the snow plowing operation. Steel would be a more robust material, at least enough to kick any existing problem down the line to the next weakest component.

The broken part in question.






The raw material, 1 1/2" mild steel plate. Didn't think to start taking pictures until I already had pieces sawn off with the bandsaw.





One side finished, then taken to the bandsaw to make the cuts.

[becksmachine]

One side finished, some excess material removed with the bandsaw.




This is where that "brutish" adjective comes into play. Need to hold on the edge to turn the second side and drill and tap 3/4" pipe, with approximately 1" offset from the diameters on the opposite side.





A 1/4" or less bite that needs to hold during a fairly severe interrupted cut.





Taken while cutting, .100" depth of cut, .015 ipr feed.

[becksmachine]

This is why it stayed in the chuck. Not many 3 jaws would have the snoose to grab something this way even if you could get it positioned correctly in the jaws. For once in this case, chuck jaw rash is actually a good thing






Finished part with hydraulic fitting installed.

[craigd]

Did a job today that made me think of the ongoing controversy of 3 jaw vs 4 jaw chucks on the lathe.

The photos tell most of the story, this is some kind of adapter in the hydraulic system for an Austin Western grader.

Excellent job. Thank you for sharing. What is the controversy of 3 jaw vs 4 jaw chucks on a lathe? Each (and various other work holding devices) has it's application.

[awemawson]

Very nice work, but I'm totally confused regarding your "British" reference ????

Was it a British chuck, or did you think only a British chuck would hold it like that, or mark it like that, or what - most confusing ?????



edit: OK I should have gone to Specsavers !!!!!!!!!!!

[quadrod]

Brutish/British,, either way it was a stout chuck to hold and awkward job.

[Mcgyver]

Brutish/British,, either way it was a stout chuck to hold and awkward job.

funny, until I read your post my eyes saw British as well

Good job becksmachine

[sarge41]

Nice work. I probably would have waited to the last op. to go to the bandsaw, but each to his own. I wasn't aware that there is a controversy about 3 jaw/4 jaw. Each has its own uses.
Sarge

[wierdscience]

Good job,I bet they had a good excuse for ever designing such an oddball fitting.

[boslab]

A realy good job, a tricky shape too, once you get used to a 4 jaw you need little else, the only other way would be faceplate I suppose.
I rarely put a 3 jaw on the lathe, can't be bothered, seem to get along fine with 4, great because I can't even find the 3 jaw, I suspect it's gone myself.
Good job, tidy photos, I've seen lots of CI hydraulic parts similarly broken, lug gone, I think it's cracked during tightening myself, bit of crap under it before tightening the bolts,
Mark

[becksmachine]

Very nice work, but I'm totally confused regarding your "British" reference ????

Was it a British chuck, or did you think only a British chuck would hold it like that, or mark it like that, or what - most confusing ?????

edit: OK I should have gone to Specsavers !!!!!!!!!!!

Apologies to friends across the pond, I did notice the similarity myself. Maybe brutal would have worked better, or not making it the first word so that it wouldn't have to be capitalized? Clear and concise writing is an art.

Good job,I bet they had a good excuse for ever designing such an oddball fitting.

It is one of the unexplainable satisfactions that I get from doing this kind of work. I feel that I am connecting or talking to this poor (clumsy?? ) bastard that designed himself into a corner and had to invent some never before seen gewgaw to save the overall design. Something like the connection I think I have to the members of this board.


Whether this was the case or not, I don't really know for sure, but.........

As for it being a "good" excuse, that would be something of a personal definition depending if you are a cynic or optimist. Was this in response to a deficiency in the overall design? Or something to adapt an existing design to a new application?

Nice work. I probably would have waited to the last op. to go to the bandsaw, but each to his own. I wasn't aware that there is a controversy about 3 jaw/4 jaw. Each has its own uses.
Sarge

I had considered this sequence also, but if the sawing was done last, I wouldn't have had that nice flat side to lay against the bandsaw table. I don't like unstable setups when my fingers are that close to the blade. Says the hypocrite that regularly catches parts with the 6" rule/chuck key handle/screwdriver when parting in the lathe.

Happy New Year to all!

Dave

[garyhlucas]

Nice job. Everytime I see a part like this these days I think "Easy Peasy on the CNC mill!" About 10 minutes to program it in CamBam.

[RussZHC]

I am asking this as someone who is not really any sort of machinist, at best occasionally playing at...in photo # 7, the side view of the chuck jaws holding the work piece, does it make any difference whether or not you back up the work until some solid surface touches the face of the chuck?

My very limited experiences has been that trying to keep a part square while holding it in the jaws with space between the chuck face and the part, the piece often wants to be cocked in some direction. Is it to some degree a function of the size of the chuck in that, to me, the larger chucks can put a lot more pressure on the part, has it to do with the chuck jaws being serrated?

Thanks for the photos and write up, you have a style of writing I enjoy.

[LKeithR]

...It is one of the unexplainable satisfactions that I get from doing this kind of work. I feel that I am connecting or talking to this poor (clumsy?? ) bastard that designed himself into a corner and had to invent some never before seen gewgaw to save the overall design...

Amen to that. We do a wide variety of machining and welding work but I like nothing better than to tear into a machine or part and figure out how to fix it when "standard" parts aren't available or just won't work. Designing and improvising a solution to a problem like this is always satisfying. Sadly, in this day and age people don't "fix" things nearly as much as they used to. The mentality of so many places today is to buy an "assembly" and stuff it in rather than fix one small broken item--if this can't be done of course the whole thing just gets tossed. I'm sure that manufacturers have encouraged this by simply not making many parts available.

And another problem is the knowledge base. I've been doing this kind of work since '69 and over that time I've accumulated a vast "database" if you will, of "tips and tricks" to use when repairing and/or modifying machines, assemblies and parts. With the proliferation of CNC shops--and the younger people who work in them--the pool of knowledge is slowly being eroded (literally, dying off). Aside from the fact that most CNC shops don't want to be bothered with repair work a large percentage of these people simply don't understand "how things work", they only know how to make parts. Give them dimensions and a drawing and they'll make you a hundred parts really quickly and for a pretty reasonable price but ask them to figure out how to make the part or design a replacement and they just can't wrap their heads around it.

...Says the hypocrite that regularly catches parts with the 6" rule/chuck key handle/screwdriver when parting in the lathe....

I do that all the time--isn't that what those things are for? I often find myself doing a power feed parting cut and, having failed to think even a few moments ahead and not wanting to interrupt the cut, have to grab whatever is available to catch the part. If it's a bigger part you don't want to let it drop for fear of dinging the bed--or the part--and if it's a small piece you dare not let it drop because it will take a half hour to sift it out of the nest of swarf which resides perpetually in the catch-tray. That's the nest of swarf which you could have cleaned out before you started the cut if you'd been thinking ahead. I've even caught small parts with my hand when I've found myself in a pinch but that doesn't always work out either because you'd forgotten how hot that little sucker will be and it get's pitched involuntarily across the shop. Hopefully you'll be prepared when you make its replacement...

It's interesting in itself that the part is for an Austin Western grader. They're pretty much antiques since I don't think they've been made since the very early 80s...

[quasi]

I think this is the first 4 jaw I have seen with bolt on jaws.