Bearing Race ID Help Please......

[JoeLee]

This is what started this whole issue of tramming the mills head to such precision. It was this electronic edge finder. When I would zero it off the fixed jaw of the vise and move to my position to drill a hole, I was consistently off my mark by .005 - .006. When I would drill through something I was noticing that there was a difference in distance from the entering hole and the exiting hole. The thicker the part the greater the error. I used ground test blocks to eliminate as much error as I could in tracking this down. I thought that the error was in the probe. Come to find out the error was in the head. It had some slight nod. Less than a half a thou. The error was being amplified by the length of the probe. Once I trammed the head to within a tenth, and it wasn't easy the error disappeared.

JL.....................

[JRouche]

There are 37 different compounds of rubber in a Michelin tire.
Blows my mind how much engineering goes into them.
-Doozer

IMO they make the best tires. All I run on my cars and trucks. JR

[754]

I was just curious. I wouldn't buy one.... not for that price. Besides a new one probably wouldn't be any different.

If I want to get this race flat to the tenth all the way around I will have to find someone with a grinder big enough to handle it. that would be far less expensive than buying a new one at what ??
something like $1200 and the race probably isn't sold separately.

JL.................

what are you talking about put a piece of sandpaper on a piece of glass or something flat and work it down. . It's probably less than 1/2thou to remove..
why pay someone to grind it.....not worth taking the time out of the shop. .. it is called fitting...

[Doozer]

....If I want to get this race flat to the tenth all the way around I will have to find someone with a grinder big enough to handle it. ....

JL.................

Just let it hang off the front edge of your mag chuck,
grind as much as you can,
then rotate the race maybe 90° and grind another strip,
Keep grinding and rotating the race until it is all cleaned up.
Check it on the surface plate. It will be near perfect.

-Doozer

[Bented]

what are you talking about put a piece of sandpaper on a piece of glass or something flat and work it down. . It's probably less than 1/2thou to remove..
why pay someone to grind it.....not worth taking the time out of the shop. .. it is called fitting...

10 X more accuracy is required, -.0001" , everything a person dreams of or more.

[tom_d]

So, in one way, tramming to the "table" is as wrong as anything else, since it is table MOVEMENT that you may want to be aligned relative to.

Yes. When setting up a machine you first qualify the motions of the machine, not the accessories attached to it. Once the machine's movements are known, then the accessories can be brought into position. A loose and distant analogy would be where, when setting up a lathe, you level the bed and eliminate any twist in the casting BEFORE setting the tailstock so the lathe cuts a true, non tapered cylinder.

[Noitoen]

Here is the big brother to the small race pictured on my mill. As you can see it's turned into a catch all.

This one measures about 16" in dia. The inner race ID is 8". That's one big electric motor to have an 8" dia. shaft.

JL......................

That bearing alone does not work in a motor. It goes next to another in a motor mounted vertically and acts as a trust bearing

[JoeLee]

That bearing alone does not work in a motor. It goes next to another in a motor mounted vertically and acts as a trust bearing

I'm not sure of it's exact configuration in the motor but I was told it came out of an electric motor. A fiend that worked in a motor repair shop gave it to me.

JL...............

[dian]

This is what started this whole issue of tramming the mills head to such precision. It was this electronic edge finder. When I would zero it off the fixed jaw of the vise and move to my position to drill a hole, I was consistently off my mark by .005 - .006. When I would drill through something I was noticing that there was a difference in distance from the entering hole and the exiting hole. The thicker the part the greater the error. I used ground test blocks to eliminate as much error as I could in tracking this down. I thought that the error was in the probe. Come to find out the error was in the head. It had some slight nod. Less than a half a thou. The error was being amplified by the length of the probe. Once I trammed the head to within a tenth, and it wasn't easy the error disappeared.

JL.....................

not completely shure what you are saying, but im getting the feeling you z-axis/quill is off.

[JoeLee]

not completely shure what you are saying, but im getting the feeling you z-axis/quill is off.

Your correct in your assumption. The head had about .0005 nod. that was the whole reason for the problem I was having with the edge finder and hole accuracy. Some people would just brush off .0005 error in head tram, but for me it made a noticeable difference.

JL......................

[754]

Tram should be checked, moreso on a machine new to you. Keep in mind. .. this is for double swivel turret mills.
turret
Tram should be checked often.... it should only take about a minute or two..
Tram should be corrected, IF NEEDED ., BUT more Important .. in a manner that Relates to your work.. and tolerances. .
They can and often go out over time.

In other words consider the job it's doing....... drills holes for bolts 1 thou in 6 inches is fine.
Doing engine case repair, or die work , it may not be fine..

.....Don't sweat getting the last few tenths, 90 per cent of the time.

[JoeLee]

Tram should be checked, moreso on a machine new to you. Keep in mind. .. this is for double swivel turret mills.
turret
Tram should be checked often.... it should only take about a minute or two..
Tram should be corrected, IF NEEDED ., BUT more Important .. in a manner that Relates to your work.. and tolerances. .
They can and often go out over time.

In other words consider the job it's doing....... drills holes for bolts 1 thou in 6 inches is fine.
Doing engine case repair, or die work , it may not be fine..

.....Don't sweat getting the last few tenths, 90 per cent of the time.

Yes, very true.......... it only takes a couple minutes to check it, but can take several to adjust it to the degree of accuracy that I did.
It can go out over time. I think what had happened in my case is I moved the beam out one day and never bothered to check the tram after returning it to it's original position.
that could have very well been the reason.

I wouldn't worry about being off .001 on the exit side of a 6" deep hole.
I was finding myself being off almost that much in a 1/2" deep through hole. To me that was messing up a few things and wasn't acceptable.

Now that I have corrected the problem I'll know what to look for should the situation arise again.

Now even my milling / swirl pattern looks better.

JL...............