Milling task.

prasad

prasad

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I want to mill a large size aluminum tube (8" OD, 4" ID and 1" long). My plan is to make a 6" square as you can see marked in the picture attached. I will have to mill the tube equally on 4 sides. I can start on one edge and once I have that side formed I can flip it around and mill the opposite edge. I should get both sides parallel.

I am not sure what I must do at this point to get the remaining two sides at 90 degree square. Please can you advice me?

Thank you and Happy New Year 2015 to all,
Prasad
Wynnewood PA

CAM00103.jpg
 
Depending on what you have as far as equipment goes,here's the quick and dirty way. Because of the diameter your vise probably won't accept the part laying flat so that narrows down your options. ( if it is big enough let us know and you can go to option 2). First I would bandsaw all the extra material off to eliminate as much height as possible. Put the part in the vise vertically and mill top and bottom as you suggested. Then rotate part 90 degrees and hold a machinist square against the machined side while tightening the vise. Mill and then flip it 180 and repeat. Because of the height sticking out of the vise don't go crazy with depth of cut and feed.

Regards
Darrell
 
If you have rotary table you could grab the tube from the inside and rotate every 90 degrees, and mill all 4 sides. Or set it in your vise, mill 1 flat to the desired size, flip it 180 degrees and mount it on parallels. this will get 2 sides parallel to each other, once you have 2 opposite sides done turn 90 degrees in the vise and line up one of the milled sides with a square, you now have 3 sides parallel to each other the 4th side should be simple enough to mill, with the opposite side sitting on parallels in the vise
 
clamp the tube to the table of your mill on top of some spacer blocks (123 blocks if you have them). advance the mill's x axis to mill one flat, move the y axis to the point of the parallel side, and advance the x axis again, but in reverse. This will provide two parallel sides. Now, clamp the two sides that were just milled, and remove the other two clamps. repeat the same previous steps but instead advance the y axis. if your mill is not big enough, you will have to do four separate setups, each time indicating off a previously milled edge. hope this is clear.
 
18w said:
Depending on what you have as far as equipment goes,here's the quick and dirty way. Because of the diameter your vise probably won't accept the part laying flat so that narrows down your options. ( if it is big enough let us know and you can go to option 2). First I would bandsaw all the extra material off to eliminate as much height as possible. Put the part in the vise vertically and mill top and bottom as you suggested. Then rotate part 90 degrees and hold a machinist square against the machined side while tightening the vise. Mill and then flip it 180 and repeat. Because of the height sticking out of the vise don't go crazy with depth of cut and feed.

Regards
Darrell
Click to expand...

Darrell

My mill is a Grizzly Mini-mill G8689. I have a good vise from LMS but my until I cut the ring to 6 inch size the job is too big for vise to hold. I do not have band saw or a rotary table. My plan is to lay it horizontal on the bed of milling machine and mill two side to get them decently flat and then move it upright in the vise to do fine cuts. I am lost at this point. I will try the machinist's square as suggested by you.

Thanks
Prasad
 
Prasad, my method was just a simple method using the vise only. If you are setting the piece up flat on the table on blocks just mill the 2 sides in the x axis and do as was suggested by mzyad3. If your mill has too small of travel in the y axis just rotate the part 90 degrees and put a indicator in your quill and use it to align your part by placing the indicator on one of your milled sides and moving your y axis table back and forth to align your part while reclamping it. If you do it in the vise instead of using a square you could also use the indicator again in your drill chuck or collet and sweep the newly machined side that is now standing vertically in your vise after rotating it. Hope this isn't too confusing. It is easier to do than explain.

Regards
Darrell
 
prasad said:
I want to mill a large size aluminum tube (8" OD, 4" ID and 1" long). My plan is to make a 6" square as you can see marked in the picture attached. I will have to mill the tube equally on 4 sides. I can start on one edge and once I have that side formed I can flip it around and mill the opposite edge. I should get both sides parallel.

I am not sure what I must do at this point to get the remaining two sides at 90 degree square. Please can you advice me?

Thank you and Happy New Year 2015 to all,
Prasad
Wynnewood PA
Click to expand...

I was reading all the replies that were posted. All are very good and sound advice.

One more approach I have used. I have used steel dowel pins that were the diameter of the Tee slots as parallels. Tap them in one slot them clamp the piece using strap clamps. After you cut your first side use it to establish a true edge. Remove the clamps and rotate the part then mill the other side. After that I would lock the table and start cutting one side perpendicular to first side. The final side I would unclamp the piece and mount the third side against the dowel pins. Mill the fourth side.

Clear as mud, sorry if it sounds confusing, but it does work just be sure to remove any burrs that might keep the surface away from the pins.
 
Bill C. has a very good idea... very simple which is always best. If you still have trouble, sometimes a phone call can can simplify things. I am leaving for the evening but will be available tomorrow if you still are having troubles...which I doubt after Bills solution. PM me with your number if you still need help.


Regards
Darrell
 
Prasad
If you have a milling vice, which it sounds like you do. If you make the cuts on the two sides as you stated, that will get the two sides parallel to each other, Then remove the jaws from the inside of your vice and mount on the outside. Even a 3" milling vice should have more than enough opening with the jaws on the outside to hold a 4" wide piece of material. Then just make your cuts with the Y axis feed on the right side, then cut the left side. You may not even have to remove from the vice to cut both sides if your vice is smaller than 4" If your vice does not have provisions for mounting on the outside , then you will need to try something else. I would also ensure you had one side flat prior to making the squaring cuts. Clamp in the vice if large enough (jaws outside) or to the table with hold down clamps and fly cut (or large end mill) one side. That will be your reference side so everything comes out square in all directions.

Mitch
 
I was wondering why you couldn't center and perimeter clamp the 1" thick round plate to the table on top of something to space it off the table surface, and go around the perimeter while moving the perimeter clamps from the side you were doing. Then I went to your introductory post to see what equipment you have, which is a Grizzly G8689 mini mill with the following specs.


  • Table travel (longitudinal): 7-5/16"
  • Table travel (cross): 4"
  • Table size: 3-5/8" x 15-3/4"
It appears that you can only mill one side on the longitudinal axis with most of the plate you are milling hanging off the front of the table.

I wonder if you can clamp it to the table with the first edge you want to remove hanging slightly off of the back of the table. Mill that edge and then rotate the plate exactly 90°, which would be confirmed by sweeping the flat edge that you just milled with an indicator. Then mill the back edge, rotate , and repeat for the next 2 edges. Cutting most of the unwanted metal off with a bandsaw, hacksaw, or sawzall would probably speed things up.

hope this advise is a help to you.
I'm a novice myself.


Chris
 
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