Home |
Search |
Today's Posts |
|
Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
|
|||
|
|||
Before I replace my chuck..
Hi Doug I had the same problem with a chuck on my old McDougal lathe and I followed Brown and Sharps instructions to lap the jaws flat again and it made all the difference in the world. I will post the link to the thread if I can locate it. Bill D "Doug Warner" wrote in message ... Myford ML7, small 3-jaw chuck. No matter how tight I crank down on it, pushing sideways on the end of a 8" bar will cause the bar to shift, and the end to run untrue. Merely loosening and retightening it will lose centering, at least at the far end. Repairable, or do I have to buy a new chuck? It's not the spindle bearing, since I don't see the same problem with a smaller bar in a collet. To reply, please remove one letter from each side of "@" Spammers are vermin. Please kill them. |
#2
|
|||
|
|||
Before I replace my chuck..
Before you give up on it, I'd do two things:
1. Disassemble, clean, grease and reassemble the chuck. There's an article in HSM magazine on how to do this but nothing tough here. You wouldn't believe the amount of swarf plugging everything up. 2. Theres a good chance your jaws have been whacked by a MAJOR shmuck. Look at this site for how to retrue the jaws: http://www.loganact.com/tips/chuck-jaw.htm This would make make sence for what you're seeing. One or more jaws is banana shape and not holding the entire length. Karl |
#3
|
|||
|
|||
Before I replace my chuck..
Hi Doug I found the thread that I am sure has applicability to your problem. I have posted the two messages that relate. The first describes the problem that I had and the second outlines Brownsharp's solution that I followed. Hope this solves your problem. Bill D ********************************************** Message 1 in thread From: BillDarby ) Subject: Chatter while parting off a 5/8s rod View this article only Newsgroups: rec.crafts.metalworking Date: 2000/08/09 Chatter while parting off a 5/8s rod. I was parting off a 5/8 rod using my 10 inch MacDougall lathe and I was getting an unbelievable amount of chatter while doing so. I was using a 6 inch three jaw chuck on an L00 spindle. Everything was tight and the lathe itself is very sturdy for the size of swing. The cutter was a .093" wide tool, sharp, short, center height and an 1/8 of an inch from the face of the jaws. When I supported the outboard end in a steady the lathe began to cut the rod as if it were butter. (????) I have had that lathe for some time but have never done any parting on it that I can recall. The observation that I dismissed the other day may have a great deal to do with this problem. I was measuring the movement of the carriage coming under load with a tenths indicator and at one point I had the indicator on the spindle nose. At the same time, I gave the back end of the spindle a push sideways. That spindle is 27 inches long and the push on the far end caused a 2 tenths movement on the indicator on the nose. Well that was a very fruitful trip out to the shop. I just slipped out to confirm the 2 tenths reading and also to see how much deflection I would get on the nose with me leaning on an 14 inch rod in the chuck. Under a good hefty load the indicator on the side of the chuck registered 5 tenths. That did not seem to be enough to cause the chatter that I was seeing. So I moved the indicator out to the one inch SS rod that I had in the chuck and had it set "just" in front of the jaws. Would you believe?? Ten ot twelve thou movement in any direct ion that I pushed!!!! I could not believe my eyes. When I looked close I could see a sliver of light between the rod and the jaw appearing and disappearing as I heaved on the bar. I thought perhaps the jaws were moving in the chuck but when I indicated to the jaws, none was moving more then the half thou that I found the chuck itself to be moving. So, when I began this post I had a suspicion that my spindle bearings needed snugging up. Now I think that the major problem is only that the face of the jaws have distorted into something akin to a canoe shape and simply need to be ground flat. Some time ago someone stated that you could get enough load on your jaws in order to grind them by running at high RPM. The best this lathe will do is 1550 RPM. Do you think that's high enough to produce a good load? A most profitable evening (morning). Night all. Bill Darby BTW My apology to the spelling police for breaking my brake in a recent post. It will not be the last. Darn spell checker doesn't see errors like that. ********************************************** Message 7 in thread From: BillDarby ) Subject: Chatter while parting off a 5/8s rod View this article only Newsgroups: rec.crafts.metalworking Date: 2000/08/09 Hello All Well you are looking at one "very happy" dude. I used a 1.25 inch brass rod two feet long with valve grinding pasteprepared, as per the post in order to straighten my chuck jaws. I have to say that it was an unqualified success! As soon as I cleaned the paste from the chuck I chucked up anidentical piece piece of 5/8s stock and the cutter literally fell through it. I could not crank the cross feed fast enough tokeep up with the ease of cutting.Thank you brownnsharp!Bill DarbyBTW The cutting speed was not 600 it was 460RPM.REF:Subject: how do i check my spindle to see if it is true on mysheldon; Date:Fri, 28 Jul 2000 04:43:29 GMT;From: ********************************************** "Doug Warner" wrote in message ... Myford ML7, small 3-jaw chuck. No matter how tight I crank down on it, pushing sideways on the end of a 8" bar will cause the bar to shift, and the end to run untrue. Merely loosening and retightening it will lose centering, at least at the far end. Repairable, or do I have to buy a new chuck? It's not the spindle bearing, since I don't see the same problem with a smaller bar in a collet. To reply, please remove one letter from each side of "@" Spammers are vermin. Please kill them. |
#4
|
|||
|
|||
Before I replace my chuck..
Doug Warner wrote:
Myford ML7, small 3-jaw chuck. No matter how tight I crank down on it, pushing sideways on the end of a 8" bar will cause the bar to shift, and the end to run untrue. Merely loosening and retightening it will lose centering, at least at the far end. Repairable, or do I have to buy a new chuck? It's not the spindle bearing, since I don't see the same problem with a smaller bar in a collet. To reply, please remove one letter from each side of "@" Spammers are vermin. Please kill them. Use an indicator on the chuck body and each of the chuck jaws while you try that push test. If they move, then either the chuck body isn't seating right on the spindle or the jaws and their slots are well worn, and you'd be better off replacing that chuck. If the chuck and jaws stay put, then you probably need to true up the contacting surfaces of the jaws, because they've probably become curved through wear. If you search around you'll find references on how to do that, including how to support the jaws during the operation. You can dress them with a Dremel tool with a rotary stone in it clamped to the toolpost, while the chuck is rotating at a slow speed. That's what I've done more than once. Jeff -- Jeff Wisnia (W1BSV + Brass Rat '57 EE) "If you can keep smiling when things go wrong, you've thought of someone to place the blame on." |
#5
|
|||
|
|||
Before I replace my chuck..
If all else fails..I have a "New Old Stock Myford" 3 jaw, and a 4 jaw
chuck, still in the greased wrappers, that I will be putting up for sale, if someone can give me an idea what they normally sell for on Ebay, etc etc. Gunner -- The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary. --James D. Nicoll |
#6
|
|||
|
|||
Before I replace my chuck..
William G Darby wrote:
Hi Doug I found the thread that I am sure has applicability to your problem. I have posted the two messages that relate. The first describes the problem that I had and the second outlines Brownsharp's solution that I followed. Hope this solves your problem. Bill D ********************************************** Message 1 in thread From: BillDarby ) Subject: Chatter while parting off a 5/8s rod View this article only Newsgroups: rec.crafts.metalworking Date: 2000/08/09 ********************************************** Message 7 in thread From: BillDarby ) Subject: Chatter while parting off a 5/8s rod View this article only Newsgroups: rec.crafts.metalworking Date: 2000/08/09 Hello All Well you are looking at one "very happy" dude. I used a 1.25 inch brass rod two feet long with valve grinding pasteprepared, as per the post in order to straighten my chuck jaws. I have to say that it was an unqualified success! [snip] I'm afraid I can find no trace of theis posting! Can anyone suplly me with a copy? thanks, Dave |
#8
|
|||
|
|||
Before I replace my chuck..
On Wed, 10 Sep 2003 14:42:14 -0700, Grant Erwin
wrote: Your jaws might be bellmouthed. If that is the case you can try to get new ones if they are standard or you can try grinding them - you have little to lose! If it's a Burnerd (standard Myford fitment) then new jaws are available.... They cost about the same as a new chuck :-( Mark Rand RTFM |
#9
|
|||
|
|||
Before I replace my chuck..
In article , Doug Warner says...
I disassembled and cleaned it (before all these replies), and had already re-ground the jaws by running a stone in the tailstock through them. Upon close examination on the bench, they're still bellmouthed. If the jaws have more than a thou or so of slop in the body of the chuck, in the slots, as it sounds like from your description of trying to stone them, it is most likely trashed. That is, if you can grasp them by hand and rock them in an angular fashion so that one end moves more than a thou, it's toast. Jim ================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================== |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Where to get right angled chuck? | UK diy | |||
magnetic chuck problem | Metalworking | |||
Cuemaking-Metal Lathe Chuck Question? | Metalworking | |||
bought a chuck on ebay from marjenmachine | Metalworking | |||
Jacobs Chuck removal from 1/2in. drill | Metalworking |