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Tool Cool Project

Tool
Tomc938

Tomc938

Ultra Member
Yesterday I was working in the shop when I came across what I thought was a small piece of scrap aluminum. I looked at it close, and saw engraved on one side: "0.010 on the cross feed removes 0.001 on the diameter" and indications that one side goes up against the chuck and the other side on the cross slide. Sure enough, when I put the one side on the face of the chuck and the other side on the "face" of the cross slide 0.010 feed on the cross slide removed exactly 0.001 from the diameter!

I got my lathe and milling machine from a retired tool maker. He also threw in a couple of Kennedy boxes full of tools and some small scraps of metal. This jig was in a toolbox and I guess I thought it was just a block and put it into my scrap pile.

I'm glad I found it! It's going to prove very handy when I need to take precise amounts off stock.

If I'm reading Machinery's Handbook correctly, the angle is 5° 43'.

The block makes this setup quick and repeatable. You might want to look at making a block like this for yourself.

(On a side note, I was wondering when I brought the lathe home why he had the cross slide lined up with the axis of the lathe rather than the normal 30 degrees I usually work with. I'm guessing his normal position for the cross slide was off by 5° 43' and I just didn't notice the slight difference)


Picture 1.jpgPicture 2.jpg
 
I agree! And being able to dial in 0.001-whatever with tenths accuracy with a 2 minute setup is amazing.

I knew about using trig to get this kind of accuracy, but the block is so slick.
 
It's a sine thing, sets the compound to 5 degrees, then you advance the compound ten thou which effectively is the same as moving the cross slide 1 thou but more accurately.
Replace my numbers with Toms.
 
Susquatch said:
I am feeling really thick today Tom. I can't see how that block works. Can you be a little more pedantic for me?
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If you look at the first picture I think it will make sense. The block is held up against the face of the chuck and then the cross slide is loosened and brought up against the other side of the block. The sides of the block are not parallel, but off by 5 degrees and 43 minutes. (I exaggerated the angle in the drawing. The block is indicated with dotted lines.)

When the cross slide is advanced 0.010", it moves 0.005 closer to the axis od the lathe, not 0.001 as I indicated on the drawing.

Block.jpg
 
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Tomc938 said:
If you look at the first picture I think it will make sense.
Click to expand...

The tool post was hiding too much of it. But I think I understand now. The idea is to butt the compound up to the wedge, turn it until the faces mate, and then tighten it. Doing so sets up a 10:1 movement of the tool via the compound. In other words, 10 thou on the compound equals 1 thou on the tool.

Interesting.

I assume you have to lock the cross slide to achieve any real reasonable accuracy. Obviously, the chuck face has to be square too.
 
Susquatch said:
The tool post was hiding too much of it. But I think I understand now. The idea is to butt the compound up to the wedge, turn it until the faces mate, and then tighten it. Doing so sets up a 10:1 movement of the tool via the compound. In other words, 10 thou on the compound equals 1 thou on the tool.

Interesting.

I assume you have to lock the cross slide to achieve any real reasonable accuracy. Obviously, the chuck face has to be square too.
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You are correct on all counts! But I guess it's actually 20:1 as the TOTAL removed from the work piece is 0.001.
 
Dabbler said:
@Tomc938 can you please upload the pictures again? I cannot view them from post #1
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I'll do one better: the original photo wasn't easy to make out with a shiny chuck face and a shiny piece of Al.

I'll colour the block and take another photo.

The guy labelled the top as the taper is not super evident. And the face that goes to the church and the face that goes to the compound.

I think it is a cool, simple accessory that if you take the time to make accurately can give you a crazy level of control when it comes to removing metal. Like tenths. And repeatable.


Block.webp
 
FatherWes said:
By my math the angle should be 5.7392 degrees (5 degrees 44.4 minutes) to get a 10:1 difference between cross slide and the axial travel of the bit. So, with a 5.7392 degree angle, 10 thou movement of the cross slide would take off 2 thou off the diameter.
To get 0.001” change in diameter for a 0.010” change in cross slide, the angle would have to be 2.866 degrees.
Or am I messing up my trig?
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Trig looks right. My dial takes off .001 when I dial in .001, so .010 takes off a thou. Not sure that that kind of dial is called. (Direct read?)
 
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Tomc938 said:
Trig looks right. My dial takes off .001 when I dial in .001, so .010 takes off a thou. Not sure that that kid of dial is called. (Direct read?)
Click to expand...

Not sure what they are called either. But there are two kinds - one measures diameter (like mine) and the other measures radius. If I had my druthers, I'd rather read radius.
 
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