First Major DRO Job

[Susquatch]

The Rego info is quite clear to me Is it becasue I am born in EU? Not sure.

I didn't land on an individual product page. I landed on a generic info page for the entire collet set in a chart that was sort of like the LMS info. I can't seem to find it now.

 

[Susquatch]

The 6.35 drill bit does not fit in the 6-5. (I suppose it could be forced but why?)

I believe doing so will damage the collet.

But I confess to trying to make a 17/64 drill fit in a 1/4 collet. It's sooooo close! However, I couldn't get it to go in with reasonable effort and I didn't try to force it, so it didn't happen!

 

[Susquatch]

I should have added that the 5/16 collet did hold the 17/64 drill just fine. It was within the specified range that the collet was designed for. It didn't slip and it did the job. It was just painful and felt wrong to have to crank on the nut that much.

 

[Susquatch]

look forward to a picture of this whole contraption your building mounted

As promised, I finished the job I had on my lathe and so I mounted my triple spider and took a photo.

The purpose of the spider is to be able to align a part axially in perfect alignment with the axis of the spindle. Not just centered, but centered in two locations so that the entire part is axially aligned.

Two sets of jack screws are used to dial in the part.

My spider has three sets of jack screws so that it can be used with short or long parts. You just choose which two of the three sets to use and back off on the third set.

The part mounted in the spider in the photo just happens to be the dumbbell I used to test my Spindle alignment. I am using the front two sets of Jack's screws here.

 

[jcdammeyer]

As promised, I finished the job I had on my lathe and so I mounted my triple spider and took a photo.

The purpose of the spider is to be able to align a part axially in perfect alignment with the axis of the spindle. Not just centered, but centered in two locations so that the entire part is axially aligned.

Two sets of jack screws are used to dial in the part.

My spider has three sets of jack screws so that it can be used with short or long parts. You just choose which two of the three sets to use and back off on the third set.

The part mounted in the spider in the photo just happens to be the dumbbell I used to test my Spindle alignment. I am using the front two sets of Jack's screws here.

View attachment 26990

I'm still puzzled as to why this is any better than a 4 jaw chuck?

 

[Susquatch]

I'm still puzzled as to why this is any better than a 4 jaw chuck?

A four Jaw can only align the part at one place along its length. It cannot align the entire axis.

Yes, it can do it for a part that has the outside diameter concentric with the ID, but only if the outside is already concentric and only if the OD is parallel and only if the jaws are also parallel.

The spider allows you to "perfectly" align the part regardless of its outside OD concentricity, and regardless of how parallel the Jaws and OD of the part are.

 

[Susquatch]

I'm still puzzled as to why this is any better than a 4 jaw chuck?

It might help to understand if you consider mounting a bar in the 4jaw. Usually, the bar can be centered, but the far end will wobble. The spider allows you to eliminate the wobble.

Alternatively, you could machine the bar to be concentric as this is the intrinsic purpose of a lathe.

But, if you don't want to turn the part and just want it dialed in as is, you need a double spider.

 

[jcdammeyer]

It might help to understand if you consider mounting a bar in the 4jaw. Usually, the bar can be centered, but the far end will wobble. The spider allows you to eliminate the wobble.

Alternatively, you could machine the bar to be concentric as this is the intrinsic purpose of a lathe.

But, if you don't want to turn the part and just want it dialed in as is, you need a double spider.

So I did follow that idea but implementation has me puzzled.
1. You grab a piece of CRS say 3/8" diameter and put it into the 4 jaw with 4" extended.
2. Dial indicator on the part right by the jaws, 0.2" from the jaws, allows you to adjust until the dial indicator reads true.
3. Dial indicator on the end at the 3.9" point shows 0.025" wobble.

OK. The traditional way of course is to first drill a center hole with the part protruding 0.25" and the dial indicator at the 0.2" spot. Turned true and then center drilled.
Now extend out and again true at the 0.2" from the jaws and then set the center into the end which keeps the 4" end from wobbling. But clearly it would be stressed then since the opposite end sticking out the back end of the spindle might not be centered. Right?

So we start again with step 1 but into the spider.
Which screws do you adjust first? Inner or outer? And where is the dial indicator put first? The outer end?

 

[Susquatch]

Turned true and then center drilled.

Now extend out and again true at the 0.2" from the jaws and then set the center into the end which keeps the 4" end from wobbling. But clearly it would be stressed then since the opposite end sticking out the back end of the spindle might not be centered. Right?

All that assumes you can machine the outside to true the part.

In this case, that isn't allowed. For argument sake, just assume it's a polished part that is already at final diameter. That may or may not be the case but it suffices to explain the process.

Although it isn't strictly required, I always start at the end nearest the chuck. I adjust the closest set of jack screws until the indicator reads zero runout. Then I move the indicator to the far end and adjust the far left jack screws until the indicator reads zero runout. Then I repeat the process again nearest the fixture, then furthest, then nearest...... Until both locations read zero runout. Now I know the part is running concentric to the lathe axis and I can proceed to do whatever work was required.

If the part is long enough, the triple spider is not required. You can use a four jaw with gimbals and a rear spider at the other end of the spindle to do the same thing.