Atlas 12/36 Question

[ChuckB]

Thanks Pierre for the explaination. I think my tool is a little dull. Between that and the normal springing that certainly explains it.

I still have massive play with the front shim out so I don't think the Belleville washer will work for me. The rear way is tight when the shim was removed enough to make me have to loosen the screws so it wouldn't be too tight. Thinner shim need there.

In my case, being my front way is so worn, even with the carriage tight, unless the play was taken from the top surface of the ways, wouldn't the taper on the work still show up?

I have read about some kind of filler for the ways mentioned in some threads. Will that really work?

 

[pdentrem]

If your frt of the carriage is still too loose verses the back I wonder if there is a groove worn into the plate. I know that mine had. I simply made a new one and shimmed to fit. Yes all the wear is on the top surface of the ways, unless the plate was too tight and wore the underside as well. Not likely. Take a mic and measure the ways from the Headstock area where the carriage does not ride on and at the tailstock end, they should be the same. Now measure along from end to end and you should see the most wear in the first 6" and taper to nothing as you get to about 3/4 along. Most wear is in the first 10".

As for the extra wear in front of the HS, there is only one way to fix it. Grind the ways flat. There have been a multitude of suggestions on how but the best way mentioned was to find a shop that can indicate from the underside of the ways and then work the top surface. Alot of people will then answer that the surface is a ground surface blaa blaa blaa that it will not last and will cause extra wear etc, one still has to finish after grinding ie polish and scrap. The filler is used on the underside of the carriage to lift the carriage up to maintain the fit to the rack which is pinned on the underside.
My Atlas was from the 30s and had been ground a couple times by the previous owners, one being the school board, and it needs it again. There was aleast .070" removed in its life time so far but it still did good work for me. Before I sold it to a machinist friend, I had installed on the underside of the carriage a brass filler strip that I simply screwed into place using tiny countersunk machine screws. This lifted the carriage to regain the proper fit to the rack and realign the leadscrew as well.
My rifle barrels have not complained!
Pierre

PS a really crazy way to rebuild the top of the ways is flame spray but just think of the problems one can get into doing that. Still have to regrind the top afterwards.

 

[ChuckB]

Steve, Taper was probably the wrong word.. I should have said inconsistant diameters.

I imagine that tightening the carriage, by pulling it down, would stop potential chatter, but wouldn't help with uneven cuts being that the carriage still drops into the low area of the ways. Thanks for your and everyone elses input. Chuck

 

[pdentrem]

One thing I should of mentioned is to use a smaller radius tool. The cutting forces are then on a smaller area and thus one tends to get a better sizing as the springing away is reduced, still there but smaller. Have to use a slower/smaller feed rate naturally to match the smaller radius.
Use a large radius tool to hog out most of the metal and then replace with a fresh sharpened smaller radius tool to finish.
Pierre

 

[ChuckB]

Steve.. With my additional adjustments I don't think I have much to complain about. I chucked this up.. took some deep cuts and got 1.4787 at the headstock, 1.4793 in the middle and 1.479 towards the tail stock. I had the carriage feed set at .0078 with the chuck rpm at 345. Used a small triangle insert type bit.


I am a rookie, so sorry if this incorrect, but..I know it is probably sticking out too far and I should have use my tailstock with a live center and the feed/rpms are wrong.. I need to look in my book and set things correctly. Light cuts are not so good. EDIT: (maybe my bit is dull?)

 

[Uncle Buck]

I guess I will live with it for now. I have a SB10L that I am restoring. I will never buy another flat way'ed lathe again or at least an Atlas unless it is in great condition and the price is right. I now truly know most of what to look for when buying a used lathe! I will sell this one and get most of my money back. Thanks for the help. Chuck

You might want to sell those legs separate of the machine as they seem to fetch $200 or more per set last I knew.......Just an idea if you are selling.....

 

[ChuckB]

You might want to sell those legs separate of the machine as they seem to fetch $200 or more per set last I knew.......Just an idea if you are selling.....

:thinking: I don't know.. I'm starting to like this lathe! )

 

[Ulma Doctor]

All machines do this, just some more than others. Every machine has tolerances and moving parts that have some play to allow movement.
What happens when you take a cut and then more metal is removed is a natural reaction called springing. The metal is slightly deflected away from the tool, just as the tool is deflected in the opposite direction. This why one takes a couple passes without moving the tool to remove the extra metal when one gets close to size. One wants to be careful as you get close to finish size as your final cut could be too little or too much.
Also the deflection will be more as the tool gets dull, and as well the further you are from the supported end of the piece. If between centers then the deflection is in the center and if only held in the chuck then the far unsupported end will be deflected.
Pierre

amen to that!, i ruined more pieces buy undercutting rather than making a spring cut.
the things we learn as we go along! )

 

[pdentrem]

You can buy a lot of HSS for the price of carbide. Yes it gives a better finish.

In the work shop, we do not care about spring as we will turn to an oversized diameter and then walk it over to the cylindical grinder and finish to size. Now most all home users do not have that type of equipment so going to finish size with a bit of polishing at the end is what one has to do.
Pierre

PS The Landis 12X24 cylindrical grinder that was listed in the posting about equipment for sale sold for the extremely high price of $330! The owner did drop the ball and did not get in on it. We still need an other one!

 

[ChuckB]

All in all, that is not bad. I see you have a QCTP, that's half the battle. I've always had difficulty getting accuracy less than .001" on my Atlas. I don't even own a micrometer with greater than 1" range. I use dial calipers.

Carbide can stand (make that requires) faster speeds than High Speed Steel, so if it were me, I would at least double the spindle speed and extend the bit a little less from the toolpost. Although, that doesn't exactly explain your measurements, it should give you a smoother finish.

You are correct about the need for using the tailstock in this instance. The recommendation is not to extend the work more than three diameters from the chuck.

Also, Did you make several cuts without advancing the cutter to minimize the springiness?

You don't have anything to apologize about. It's your lathe and your work. The only one you have to please is yourself.

Steve Fox

I just got that tool post and made the adapter for it the other night.. I have only just started using it. I used one of those square turret type holder before and had been using 3/8 carbide bits.. I had all kinds of trouble. I got fustrated and lost interest in my lathe and rarely used it other than lapping races.. I really like the QCTP.. worlds better. I needed to make a simple tool recently and got back into it.. I then realized that the 3/8 carbide bits that I was using were always above center.. and that was the reason for the lousy cuts. I have got back into it and am having fun again!

As far as your question.. a few deepish Cuts.. seems The only good cuts I could make were .006 deep.. any lighter and the finish was grooved and poor. Maybe I just need to practice more. I need to make a quill lock for an older Craftsman drill press.. luck has it that an even older 150 Crafstman drill press uses the same lock, so I have something to copy.. A nice little project that is within my capabilities.


Getting back into this made me want to continue restoring my SB10L.. I started this thread a while ago. but where the thread ended is about the condition of the lathe. I am modivated again and am working on it right now ) I might add to the thread after I paint some small parts..