Massive Runout on my new D1-4 5C Collet chuck. Suggestions???

Don't know why I didn't see it before,but the back surface of that chuck looks messed with. WHAT are all those file marks about? That surface should be pristine grinding marks,not all file marks.

Ray,what do you mean the other parts are meaningless? They all contribute to how true the collet holding surfaces run. I think someone has messed the back up. I am more and more drawn to SEND IT BACK!!!!!!

O.K.,with that in mind, IF IT WERE DO OR DIE,I'd chuck a VERY TRUE piece of precision ground shafting(NOT DRILL ROD!!!) in a collet-the LARGEST size possible that will go clear through the collet. Clamp the protruding rod in the FRONT end into a 4 jaw chuck. The collet chuck would be facing the 4 jaw. First having removed the D4 pins. I also would have FIRST taken a light grind with a GOOD tool post grinder across the face of the 4 jaw jaws in insure parallelism. Otherwise something held close to the chuck could indicate true,but away from the chuck it could waggle.

Having prepared the 4 jaw to maximum parallelism,chuck your precision ground rod. There must be enough room allowed to get an indicator between them. You MUST get the rod indicated to .0001" if you want your collet chuck to be that accurate. And,don't forget to use a collet that is KNOWN TO BE TRUE. Have any Hardinges?

Take a very light grind across the rear end of the chuck until it JUST cleans up. Remember,you first had to make sure the mating surfaces of the spindle and chuck did work,and you don't want to change that. You might get away with taking A FEW THOU off the back of the chuck. I am concerned that the chuck might then not mate up. As stubborn as I am,I'd carefully remove the whole assembly,turn it around,and with thin blue,check it against the spindle and re grind he taper as necessary after truing the back surface with those file marks.

I dunno,I think it really would be best to send it back.

Any argument to my last procedure here? With the low forces of grinding,I doubt rigidity would be a problem. But,I stress,use a GOOD tool post grinder. And an ACCURATE piece of precision ground shafting. Drill rod looks nice,but it has lobes on it and it just isn't good enough. My favorite grinder is my new Themac.
 
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I bought a Bison for the shop at work. I got it to hold to .0001" believe it of not. To get it to hold that accurately,it came down in the end to selectively torquing the already REAL TIGHT bolts holding it to the backing plate I mounted it to.

Things can get strange when working to those extremely tight tolerances. So many things have to be right when achieving that kind of accuracy.

I have not had one of these Asian collet chucks,nor do I have the need for one. My HLVH at home is a giant collet chuck!!:) And,I have a Cushman that is for the 16" lathe. It uses a larger type collet that can reach 1 1/2" dia. stuff.

I did read an article where a guy bought an Asian chuck. It was pretty full of chips and trash when he took it apart. IIRC,it did better when he cleaned all the junk out of it. I don't recall how true it ran in the first place,though. Some of the chucks being mentioned here are totally out of any reasonable tolerance. I can't see that cleaning the junk out of this chuck would make a huge difference,but he could try it.
 
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flutedchamber said:
Avayan,

If you don't mind me asking, what brand is the chuck?
Click to expand...

Will be tough to give you an actual brand, but I think I can offer a category such as "IMPORT". I bought it on eBay and you can see the posting here:

http://www.ebay.com/itm/5C-Collets-...w-/321217843874?ssPageName=ADME:X:RTQ:US:1123

It is an eStore so I am thinking this link will be alive for quite a while.

I think I will return this unit. The reason why I need a Collet Chuck is because it is one of the ways to hold a shoulder screw that I need to machine. Since I wasn't able to do it as intended, I changed the design and was able to get the job done.

It will cost me about $40 on S&H to close this behind me, if the seller honors the return. So if all works out, I will have learned a $40 lesson which can be coded as:

if ((lucky == true) && (your_luck == ONE_TRILLION_INFINITY))
{
precision = IMPORT;
accuracy = IMPORT;
}
else
{
you_are_screwed = true;
kiss_your_money_goodbye = true;
how_much_time_did_you_waste = UNKNOWN;
}

Sorry, I am a programmer ;-)
 
Returning it is an option, but the postage is probably a lot and, if you want another from the same place, you'll have to pay postage on the second one too. If you choose that path, I'd put a secret mark on the returned chuck just to be sure you don't get the same one back.
If I had to fix it myself (and I'm not nearly as expert as many on this forum) I would first determine if the runout is eccentric where the CL of the collet is parallel to, but not coincident with the axis of rotation. A bar placed in the collet would give the same runout along its length. Or if the runout is due to the axis of the collet being at an angle to the axis of rotation in which case the bar would swing in a conical manner with the runout increasing as you move away from the collet. In case 1, it may be just a matter of loosening the screws holding the halves together and tapping until it line up. Of course, the "match" of the OD on the two halves will no longer line up. In the second case; if you're sure that the OD of the mounting plate runs true, I'd split the chuck and see if there's runout on the face surface of the mounting plate. If so, it's probably not too hard to correct by machining in situ. We're not talking about a lot of material here. While things are split I'd also look for something obvious like a chip between the mating surfaces. Again we're not looking for anything big. If that's not the problem then there must be something tweaked in the collet mounting plate and without holding it and thinking about it for a while, I'm not sure how I'd approach it, but I'm sure there's a way. Hope you can figure it out.
 
Sometimes a $40 lesson is money well spent. God knows I've had quite a few lessons that cost me way more than that.:bawling:
 
Try paying $75.00 EACH WAY for a messed up guitar described as "Excellent" from Gruhn guitars in Nashville!! I visited their store when called out to the Hall of Fame as a consultant. They knew who I was,and that I was a builder,but still sent me a Gibson Super 400 with 7 or 8 cracks in the lower body where it had obviously been dropped. Those cracks were NOT NEW,either(not dropped in shipping). It also reeked of pot. I'll NEVER buy anything from them again. They are supposed to be big time vintage guitar dealers. He later got caught in a scheme of selling doctored up NEW Les Paul guitars to look old,and sell for SIX figures. Made up by some guy in Florida,IIRC. He claimed he couldn't tell!!! And,he bills himself as a top expert. I don't think he got convicted of fraud in the case,but being a cognoscenti myself in instruments,I can't help wonder WHY he could't tell.

So far,I have never had a problem on Ebay,though I did have to return a phonograph to California. It was missing parts and the woman just didn't know. No trouble getting money back,and I left no feedback.

Rant over.
 
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Could the chuck have been reassembled with the front half turned 120 degrees off from it's original manufacture? Meaning, if you disassembled the front/back split, and turned it 120 degrees (one bolt hole) and reassembled, I wonder if that would fix it?

It depends on the order of operations of the original build, and when things were trued up.

Bernie
 
THey have learned to make them look pretty, and ground on all visible surfaces. Sadly, they are often not ground square in relation to it's other surfaces. Ready for Ebay!!

Bernie
 
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