Need help with my lathe

[las3r]

Hey guys I have a grizzly lathe and i have a question that I need help on

when I machine a piece of aluminum I can see that it cuts more on one side than the other, never did that before is there anything I can do to see if my chuck is straight or anything ?

 

[gadget_lover]

A little clarification please.

When mounted in the chuck, Is the left side of the work a different diameter than the right side? ( that's a taper)

Are you talking about one side of the bit cutting more than the other? Generally, it should.

is it a long piece? Are you using a center in the tailstock to support the right end?

Daniel

 

[las3r]

I was doing a 1d mag and I was cutting the two ends of the mag body and once I connected them the 2 pieces were uneven And was not flush with each other

Ill post a pic of what I mean tomorrow

 

[gadget_lover]

I was doing a 1d mag and I was cutting the two ends of the mag body and once I connected them the 2 pieces were uneven And was not flush with each other

Ill post a pic of what I mean tomorrow

A picture and a description of what you expected VS what you found will make it easier to give you some advise. It sounds like you were cutting out the middle to avoid having to re-thread one end. A very small difference in diameter is quite noticeable to the touch when two tubes are joined. I can feel a .001 difference. The most common way to deal with such things is to put a deliberate groove or change in diameter there to camouflage the joint.

A light I bought recently has a prominent gap between the tailcap and the end of the battery tube. There is a decorative groove at the connection to the head too. Neither end has to match the body tube diameter.

Daniel

 

[stjohn]

Hi Las3r,
you have to set the job up before you cut it. You really need at least a magnetic stand and a dial gauge to make sure the work is parallel with your chuck (the chuck should be straight - 'should'). Setting up the job can take longer than cutting it. Also be aware the point of your cutting tool if you are parting off should be exactly at the centre height of the job. If you can always work from a drawing. Many things that would seem to make the job take longer to accomplish actually make it so you only do the job once and the outcome is as you would expect i.e measure and set up properly to get a good result!

cheers, stjohn

 

[350xfire]

Are the jaws on your chuck set correctly? Put them all the way in and see if they line up in the middle of the chuck... I speak from experience.... haha

 

[vestureofblood]

Dude I can tell ya right now. Cutting a worth while set of extensions or doing any long body maglite work on these lathes is a HUGE task.

You have to get the end you are working on perfectly centered and take things slow ( not the turning speed, but the carriage speed and setup). You need to use a barring of some kind. You will also need to protect the finish at the end where you use the barring with something ( I use 3 layers of masking tape).

Here is a video to give an idea of what I am talking about.

http://www.youtube.com/watch?v=tn7A9PqNftY&list=FLn6sN4bKlFUF0YXNbdea7hQ&index=23&feature=plpp_video



I dont use the baring in my tool post any more because even after you center a piece more than a couple inches out you have to stabilize it. I made a barring steady rest for this. Its really tough getting all this figured out ( especially on your own) but once you do it it is possible to put out almost perfectly body/tail alignments. Within a few thousandths anyway.

Another thing that will give you far more stability is if you put a solid piece of aluminum in the end of the light that you have in the chuck so the body does not flex.

Hope this helps.

 

[moderator007]

Las3r are you using a 3-jaw chuck or a 4-jaw chuck? Try checking the face of the chuck first to make sure it is true. If not it could be the chuck or the spindle or both. Mark the chuck and spindle so that you know which side is running out or in and how much before you take it off. Take the chuck off and check the spindle if the face of the chuck is not running true. If the spindle is true its the chuck. If the spindle is out you might be able to place the chuck in a different position to improve the problem if the chuck is also out. When you reposition the chuck on the spindle mount it back up and check the face of the chuck again, if it still reads the same run out in the same position on the spindle as before then the chuck should be true. The spindle is out. If the spindle is out of true you can cut the spindle to true it up. Take close notes on how much and where the spindle is out. If the spindle and the chuck is out its a real pain trying to get it to run true or close to true. You might need to take a little of the face of the spindle to try to compensate for the chuck being out the other way. I have had this problem and it was both spindle and chuck. Took quite a few measurements and cuts off the spindle to ever get it close enough for me. Time consuming with all the disassembly and reassembly but worth the effort since I could not really afford a new chuck.
If the chuck is running true then setup or the jaws could be where the problem is at. What are you using to true the piece in the chuck and are you checking both beginning and end of the piece? The piece will only run true if its setup to run true.
From my experiences maglites aren't exactly true either so that could also be part of the problem.

 

[vestureofblood]

Hey las3r,

I was thinking about this again. If you still want to salvage that mag body while you work on fixing the alinement issue here is a thought.

As long as the parts are not too far out what you could do is take a little extra off the diameter of each side to make a loose fit of the 2 parts. Then fill in the negative space with JB weld and press the parts together with edges aligned. Set something heavy on it to dry and you should still have good contact of the body where the two parts butt together.

Just a thought.