Rohm independent chuck 8"

[jmh8743]

Hey guys,
I've got a Rohm 4 jaw which was lotsa $, which I bought due to inability of the bundled 4 jaw to repeat. It has several issues; but the most significant is inability of the jaws to contact workpiece uniformly. Manf says that's normal. I don't know what "normal" is.


My biggest concern is regarding the jaw contact. By the by, all jaws are same. It's as if they are tapered inward toward the front. Very noticeable with alum, and apparent with SS or carbon steel.


What do you think? Need some advice here. Thanks


Mike, Remlap Al

 

[Desburnett]

Hi Mike
You say the original would not repeat but the "independent" in the title indicates the four jaws are independent of each other and are not self centering? If it is a self centering chuck and the jaws are not square to the backplate then you could attempt to bore them true. If the jaws are not true due to a quality issue the hardness of the jaws should not be an issue as the manufacturer would have scrimped here too. If you need info on how to bore the jaws true using rings let me know.
regards
Des

 

[OldMachinist]

I have two 10" four jaw chucks, a old Skinner that has had lots of use and a very little used South Bend. On both of them the jaw faces are 90 degrees to the body of the chuck.

 

[flutedchamber]

I'm not familiar with Rohm chucks, but If the jaw surface is perpendicular to the slot in it's side, then the slots in the chuck are on an angle. Are the jaws loose in the slots in the chuck?

I have a Buck 10 inch 4 jaw and a Bison 8 inch three jaw that are over 40 years old and well used (but not abused) that don't do that.

 

[ScrapMetal]

Did you buy it used or new? It almost sounds like someone had used the chuck on the inner diameter of a pipe and tightened it to the point where it "sprung" the jaws a bit.

-Ron

 

[jmh8743]

Thanks for all your responses. I was not fully explanatory.

Did you buy it used or new? It almost sounds like someone had used the chuck on the inner diameter of a pipe and tightened it to the point where it "sprung" the jaws a bit.

Ron: The chuck is new. Came that way and the manf responded this is normal. Intuitively, being a novice, I did not think so. And I did not Ron.

I'm not familiar with Rohm chucks, but If the jaw surface is perpendicular to the slot in it's side, then the slots in the chuck are on an angle. Are the jaws loose in the slots in the chuck?

Flute: checking this today. I'll put it on the mill table. good thought. Jaws are NOT loose. Dont fit tight.
With the back of the chuck on the mill table, I can run an DI cross the slots. You all have helped. The manf says this is "normal". I presumed they were "preloading" cutting the jaws.

I have two 10" four jaw chucks, a old Skinner that has had lots of use and a very little used South Bend. On both of them the jaw faces are 90 degrees to the body of the chuck.

Thanks for the pics. Great help. To the mill table today and I'll do the same thing.


Hi Mike
You say the original would not repeat but the "independent" in the title indicates the four jaws are independent of each other and are not self centering? If it is a self centering chuck and the jaws are not square to the backplate then you could attempt to bore them true. If the jaws are not true due to a quality issue the hardness of the jaws should not be an issue as the manufacturer would have scrimped here too. If you need info on how to bore the jaws true using rings let me know.
regards
Des


DES: The Rohm chuck is independent. The "bundled" chuck was independent and would not repeat.
I then purchased the Rohm on advice from a local. Let me make the tests shown and then I'll "fix" the blasted chuck.

This is my thought: As a novice, my biggest task is to acheive enough experience with tools that work. Instead I have been trying to correct deficient tools. Much of it my fault. Much not.

I thought (Dad used to say "Son, a thought would bust your skull") I was assuring myself I had a good chuck. Dad was right.

Hope I cleared it up.....on a mission.

Mike

 

[jmh8743]

This is where I am:




I did this for all 4 jaws using a TI 0.0005'" min
Jaw delta
1 0.012"
2 0.013"
3 0.004"
4 0.0075"

I know this is not loaded. The directions also matter. They were ALL out.

1 + 3 = 0.016"
2 + 4 = 0.020"

Then removed from lathe and moved to mill:



All surfaces about 3/10

then jaws 2 and 4





These are loaded and contacting at the bottom. By the by the contact marks on the work is reverse of this.



Mike.

 

[Jeff in Pa]

The last pic, what size feeler guage fits in the opening? Get that answer, and send the pictures to Rohm in an email. That is totally unacceptable. I have over 30 years experience in the trade and that chuck surely seems to be out of spec.

 

[jmh8743]

Thanks for your help. I tried Rohm and this is their response. This individual explained to me I had 1 year warranty. I have all the details why bore you'all, BUT:

Hello Mr. Hillman,
Happy New Year to you too dear Sir.

• You can send this chuck for repair evaluation and quote.

• Chuck was delivered to you on UPS tracking#1z3244130350621404-02/24/2012.

This chuck cannot be returned at this time.

Best regards,

Goran Handac
Technical Sales Regional Manager SE
RÖHM Products of America, Inc.
5155 Sugarloaf Parkway, Suite K
Lawrenceville, GA 30043
Office: 770-963-8440
Cell: 404-432-2488
Toll free: 800-445-7646
Fax: 770-963-8407
www.rohm-products.com


I have determined the slots are parallel to the backplate AND the front plate. I documented my procedure carefully. The opening at the top of the jaws is 0.014" for those that asked. If I send it back they will charge me for their error. I asked for reconsideration. No response to that email. BUT it is what it is.

It appears to be the jaws from what I did this morning. Once more I'm S--------. Is nothing delivered as described? This is not a mainland china chuck.

Would it be of value to someone? This is way beyond my expertise and I found you cant fight city hall with my experiences with JET as detailed herein. If I had bought it from MSC, I'd have no problem.



This was my procedure. The slots in the body are ok. Then butting on the table....close.




then look at this in the chuck.



and this




Between the inside of the jaw to the top about 0.010".

So I guess I'm in the market for an accurate 4 jaw independent. These jaws appear for another chuck.
I know I cant advertise here and wont.

What I can say is that the first posts you guys gave me was a clue. Proven your point "OldMachinist" and others.

Mike

 

[tarmo120]

From what I see it looks that the slots in the jaws are misaligned.

But check this video out. He shows how to re-surface chuck jaws.

http://www.youtube.com/watch?v=WRznOOpCaNg

[video=youtube;WRznOOpCaNg]http://www.youtube.com/watch?v=WRznOOpCaNg[/video]