Learning about horizontal milling

[rock_breaker]

I have a small Atlas horizontal mill that is new to me that I have completed some very simple work on. Now I want to make "T" nuts using two cutters. The spindle shaft is 7/8' and the ID of my cutters is 1.000" At this point I am making a spacer to hold the cutting discs approximately 9/16" apart for the1/2" "T" nuts. After the spacer will come some bushings for the cutter discs at very tight tolerances.

I have set the compound slide on my Enco lathe at 5` which I believe will let me cut approximately 0.001" when I turn the leadscrew 0.010" . The mill vise will have to be dialed in to be parallel with the table movement. At this point I should mention my S I L brought out some aluminum 1/2" "T" nuts that someone had started but need the shoulders cut on them. Clamping them in the vice seems logical and I want to hold them down with a short bar between the cutters. Obviously a shim about 5/8" thick will have to be under the nuts Hopefully a recess in the hold down bar will prevent end movement. Now if the weather warms up some I think I can get these nuts made.

Have a good day
Ray

 

[brino]

Hi Ray,

Not sure I fully understand....... are you milling the nuts on the lathe, or did you mention the lathe and compound settings for precise control for getting the bushing thickness?

As a double-check, my math says that 5 degrees should give you 0.871 thou. cross feed for every ten thou. on the compound lead screw. For exactly 1 thou. you need the compound angle set at 5.739 degrees, but that's difficult without a vernier protractor....and likely not required.
This only applies if your compound is measured 5 degrees from your lathe spindle axis. (Different machines measure from the cross-slide axis.)

Two thoughts:

1) Any reason not to make the bushings and spacer as one piece?
I suppose you might want to re-use the bushings later as separate pieces......

2) Are the nuts already drilled and tapped?
If so, you could make up a bar to hold in the vise and bolt the t-nuts down thru those holes.

-brino

 

[benmychree]

I doubt that the Atlas has the power to run two cutters; you can use one cutter to do both sides by shifting the cutter from one side to the other if using a plain side cutting cutter or a stagger tooth cutter. Spacers for cutters do not have to be particularly accurate, you can buy a package of steel shims from precision steel warehouse, sold by most any industrial supply to fine tune width of cut when using two cutters. T nuts need not be particularly accurate to size, and should not be snug in the slots to avoid hanging up on chips and burrs. It is irritating to have them sloppy loose, as they do not stand up straight by themselves, but there is a happy medium, perhaps 1/64th to 1/32" undersize, depending on the size.
Ideally, if one is cutting both sides of an object, whether T nuts, or cutting flats on nut or bolt heads, etc., half side cutters are used, they come in RH & LH in pairs, and have both radial and side rake for both sides of the cut, unlike stagger tooth cutters, all the teeth cut on the sides, and the rake of the teeth allows them to cut with less power and results in a smoother cut.

 

[rock_breaker]

Thank you for your comments guys; much sought after discussion. Brino I got my trig book down to look up the tangent of 5` and I get 0.0875 and you are correct about moving the compound 0.10" with the leadscrew, Thanks for pointing that out. My first 2 cutter attempt will be on some precut aluminum nuts already tapped 1/2" 13 TPI. Yes I there is some lathe work to make a spacer and 2 bushings all with the same internal diameter and hopefully just one set up on the lathe
Benchnychree I have 3 half side cutters but they are not the same diameter. Three plain sided cutters came with the machine, all the same diameter. Obviously I need to purchase a half side cutter that will work with one of those I have if possible. The alternative is to turn the nuts over to cut one side at a time. .
Have a good day
Ray

 

[benmychree]

Few folks seem to like horizontal milling, they do everything (nearly) with end mills; both, of course have their place, and horizontal milling frequently takes more setup, but if multiple parts alike are what is being made, it is worth the additional time. When I started my apprenticeship, the shop did not have a vertical mill, only 3 horizontal mills, one with a universal vertical attachment, which was not in the best of condition, and three horizontal boring mills, so horizontal milling was done to some extent, but also a lot of end milling, done horizontally; anyway that was how I was raised, and continue to do so, but also have a vertical mill, and use both to best advantage.

 

[rock_breaker]

Making "T" nuts seems like a natural for a horizontal mill with two cutters, if it has power enough. I will find out next week (company coming this week end). If I do Have to cut the shoulders one at a time it will be done with a half side cutter so I can learn something. The nuts I have made on the mill/drill work ok but just don't have a precision finish, of course they were first timers on the Enco mill/drill. The shop isn't normally heated and we still have our winter coats at hand when out of the sunlight. Even on simple jobs having a mill in addition to my lathes has greatly expanded the scope of my projects.
Have s good day.
Ray

 

[Janderso]

How did your mill work out?
I have a small horizontal mill, "Industrolite" made in Oregon.
Just saw this thread, now i'm curious.

 

[rock_breaker]

Hi Janderso,

I had to go to cutting one side of the "T" nut at a time in order to get close to uniform sides. It turns out that one of the cutters is about .010 smaller than the other cutter I was trying to use. Also the load of 2 cutters may have been to much for the table movement drive shaft. The yoke on the power end broke during the process, finished by hand movement of the table. I am at least the third owner of the mill and there is evidence that someone has had trouble with the U joint before. The "T nuts" work well.
I am new to horizontal milling and followed Rudy Kouhoupt's instructions in his video on the horizontal mill. The video is somewhat slow paced but his techniques are great.
Have a good day
Ray