View Full Version : machine tools, rebuild old
07-22-2001, 04:58 PM
Am working on an Atlas 10 x 36" lathe. Chatter is my main problem. Use of a steady rest helps some which leads me to believe it may be in spindle assy. I'm new at this and would appreciate any help!
07-22-2001, 09:09 PM
Is this the late model with 2 drive belts from the jackshaft to the spindle? I have one of these and may be able to help.
Start by making sure your tool is at center height or a little below.
The crosslide and compound gibs are plastic in mine. if either of these are loose, this could be your trouble.
Chatter is usually due to looseness somewhere. A cutting tool with too wide a contact area is a close second.
Tim in Oregon
07-23-2001, 12:50 AM
My Atlas is mid 50's with taper roller brgs.I have tried all tool positions to no avail. The gibs are steel and tightening does not help. Wide tool contact surly does agrivate the chatter! Jack to spin. is one belt to four step pully. Letting a lead wt. ride on the work while turning will usually minimize my problem. I have built two benches besides the one which came with the lathe trying to sturdy it up but not really helping. A machinest friend says to go slower and slower. Once it starts even turning chuck by hand will chatter! A very small rad. tool and high traverse rate will also work sometimes.
Hoping that many heads are better than one I'll let you ponder.
07-23-2001, 07:27 AM
Put a indicator on spindle yet? Check out end play, shouldn't be over just a little bit, Ideally bout .0005, but machine isn't new. Check it, if you have several thous. you have bearing problems, you might get by with readjusting.
Bed leveled up, any twist?
Keeping tools close to toolpost, little overhang?
What kind of steel, heat treated 4340 likes to chatter on light machines.
Chuck jaws in good shape?
07-23-2001, 07:58 PM
What is material?
What is dia and how long?
What is cutting tool material?
Does a follower rest help?
Does changing the cutting edge of your tool help? Make it sharper to reduce cutting force.
Is your tool post secure? Try attaching tool directly to cross slide.
Many times chatter does not occur because of the condition of the machine tool but because of cutting conditions and setup. Going faster will sometimes help more than going slower.I would like to now more about your set up. If you fix the problem please post your solution.
IMO, when I get chatter, I have misground my tool. Sometimes a touch with a hone is all it takes. The tool should for most work be a tad /RCH(scientific word) under center.
I have a 12" Sears/Atlas in the next room and it will do most of what I wish.
Oh yes, get the tool holder as close to the tool post as possible,#1 chatter generater.
Check out the AXA or up to 12" toolholders from such as Enco,MSC,Harbor Freight.
I appologize to the perpetrator of the method told here. I lost track of the thread and author.
'to get a tool on center, make an oversize cut along the diameter. Stop the machine!Then press a piece of thin hard stock (utility knife blade) between the tool bit and the stock. Vertical shim = on center. Tilted away = too high. Tilted toward tool = too low.
this also is a good way to align the tail stock to the headstock! use centers in both to press the shim. (Unimat book!)
Thanks to the originator,
[This message has been edited by toff (edited 08-05-2001).]
07-27-2001, 12:40 AM
Many thanks for your replys.
Will try to elaborate on my question in answering yours.
The Mitutoyo dial shows not enough movement to uncover the zero line in both planes at the spindle head. The bed is level both ways at head and tail. There was a very slight sway-back which a small screw jack took care of. The Sterratt level ind. about .006" per ft.per grad.line so shouldent be to far off.My cutting tools are mounted solid and are USA HSS m2 grade. Also carbide. The chucks ( 4" & 6" ) are new. In turning 30" by 1 3/4"rolls for a slip-roll out of schedule 80 blk pipe and cold rolled, the only way to cut clean was balancing a lead ingot between toolpost and the work. Tools are ground and honed to proper angles as per my Atlas manual.
toff, I got RCH but you got me with IMO and AXA.
A steady rest adjusted right up allows non chatter and even parting-off but a follow rest isn't much help.
Still scratching head.
07-27-2001, 05:48 AM
Sounds like nothing at all wrong with your machine. Material just too long, you needed a follow rest, but you improvised with chunk of lead. Whatever works, works. It killed the chatter, all that counts.
Hope the slip rolls turn out OK.
07-27-2001, 08:22 PM
It seems to me that the vibration was in your cutting tool not in the work or the machine tool you might try a sharper cutting edge to reduce cutting force and a larger tool if possible.
I agree with halfnut; as long as you have good rolls it does not matter how you got there and good luck.
07-29-2001, 12:40 PM
IMO is In My Opinion. I'm 'clueically challanged' about AXA.
PS: Oh, yeah, IMHO is 'humble' opinion
[This message has been edited by Ron LaDow (edited 07-29-2001).]
07-31-2001, 01:38 PM
I could be wrong but I believe that AXA was a reference to a size of toolpost for smaller lathes (up to 12"). Aloris is perhaps the originator of the nomenclature but others have adopted it or use variations of it. See http://www.aloris.com/. Aloris was quick to send me their catalog.
08-02-2001, 11:49 PM
While I am admittly a self taught amature, I have had quite a bit of experience on my Logan 10" lathe. When I first started out I had problems with chatter also. I ground my tool bits as shown in South Bend's "How to Run a Lathe," or so I thought. I also tried Carbide thinking that mak be the answer. Bad idea! I finally bought a Diamond Tool Holder like those advertised in Home Shop Machinist. Wow! What a difference! The chatter disappeared. The tool works great and is really easy to sharpen correctly. Point is, the tool bits were ground wrong, for my use anyway. Since then I have learned by reading a lot, observing the cuts with the Diamond Holder and practice, how to grind bits that work well. My guess is that you have too much radius on the bit and possibly too much contacting the work while turning. I hope this helps or at least encourages you to try some different shape bits. Let us know how you make out.
08-21-2001, 03:23 AM
One source of sympathetic vibration is the dovetails and the lathe ways. Make sure you lubricate them well before use. I had problems like that before a pro smacked me in the head and told me what "I was not doing". The oil dampens the vibration making it less severe. You should also use a follow rest (well lubricated!) for the longer jobs as you get deflection even with light cuts.
08-21-2001, 09:57 PM
As halfnut and c. tate advised it is the result that counts. There are two cartoon panels in "Machine Tool Reconditioning" by Connelly that say it very well. See pages 7 & 61. J.R. Williams's did some great work in OUT OUR WAY about 50 years ago.
I did finish the slip rolls and my sons and grandson use it "building tin". If anyone is interested I have a picture I could post. As I am somewhat of a perfectionest I still look and anyalize to pinpoint the chatter cause.
09-08-2001, 04:01 AM
Let me try to summarise. Chatter occurs when the edge of the cutting tool moves down under the force of the cut,and then SOMETHING happens to move the tool away from the work or viceversa. The tool springs back, and the process repeats itself. In this case the cure by using a "diamond" toolholder suggests one
of two causes. 1) The new toolholder or the tool itself may be held less firmly than before. If so, the old toolholder may have been undersized for the job, the clamping screw for the bit, or the square hole in which the bit is clamped may allow movement that should not take place. Cause 2) is that the cutting angles on the new tool are more suited to the work, reducing all the cutting forces, and preventing chatter.
A test to distinguish between 1) and 2) would be to improvise a very rigid tool holder - e.g. a solid block mounted directly to the compund rest, holds the cutting edge on center, the tool being clamped between the block and an equally solid top, by 4 10-32 or 1/4 capscrews, two on each side of the tool, and spaced along the length of the tool by a little less than the legth of the tool itself.
I might perhaps add that I have been using a home made quick change toolpost rather like to OMNIPOST advertised in HSM by KRF of St. Joseph MI. I didn't case harden mine but made it a bit bigger than the OMNIPOST to gain more rigidity. It was not hard to make,
but I did use a milling machine. However, if a workholder were imrovised to mount the workpiece to the compound rest, I think a somewhat less adjustable toolholder could be made using the Atlas lathe alone.
09-08-2001, 04:04 AM
I have a typo in my previous - I should have said the new tool is held MORE firmly than before.
09-09-2001, 09:31 PM
You are the first guy that I have heard describe how to get a tool bit on center that way, other then the man who showed the procedure to me about 35 years ago.
When things like this happen I always
check the moon faze first!
09-29-2001, 02:44 PM
If your still having chatter problems, I have a fix for you. Take one of your carbide tools and bend the shank up about 35 to 45 degrees. Now resharpen The front to provide clearance. set the tool up below center,try about an 1/8th inch. Turn relatively slow and use coolant. I'll send you a picture if you don't have a clue what I'm talking about!