Total Newbie question.

[cuemaker]

I feel slightly stupid for asking the following question.

let me preface this by saying that I have poor math skills. I know what I need to know and do well with it, but learing new stuff takes time and repitition for me.

Now the question.

My cross slide has graduations upto 200. Is this thousands? and how to I convert that to say .125's of an inch and such.

[IOWOLF]

Zero the cross slide and count the lil lines, although lathes vary as to actual cut depth or o.a.diameter.or get a dial indicator.

[cuemaker]

so no set standard for actual graduation? I must figure it for my self.

I do know that i did 90 graduations and got about .210 of a cut. is that almost a quarter inch deep cut?

[zl1byz]

<font face="Verdana, Arial" size="2">Originally posted by cuemaker:
so no set standard for actual graduation? I must figure it for my self.

I do know that i did 90 graduations and got about .210 of a cut. is that almost a quarter inch deep cut?</font>

With a bit of latteral thinking and guessing. When you say .210 of a cut. Do you mean the cut is .210 deep or .210 was removed of the diameter of the material. If it is the latter, allowing for some error maybe 100 graduations gives you .100 DOC or .200 off the diameter?

John.

[This message has been edited by zl1byz (edited 07-16-2005).]

[hammerhead74000]

Nope. Could even be metric - or worse, inaccurate!

Do this: put your dial indicator on the bed (or saddle, whichever is more convenient) with the probe up against the cross slide. Zero the hand-wheel, and zero the DI's face. Crank one full revolution on the hand-wheel, and read the DI. Divide the reading by 200 (the number of divisions on the hand-wheel scale) and that's your distance per graduation. Multiply by two to get your diameter reduction (because you are removing stock from both sides with a lathe).

To convert graduations to inches, just divide the distance to go by the distance per graduation.

[zl1byz]

I guess one question is what make, model of lathe?

John.

[cuemaker]

Thank you for your help.

Lathe is a Clausing Colchester student model II or MKII


The .210 was a the difference in measurement on my material. Measure one side, measure the other, and subtract, which was almost 90 graduation marks on my cross slide. And my cross slide was perpendicualr to my work.

[This message has been edited by cuemaker (edited 07-16-2005).]

[wierdscience]

Some lathes read the amount to be removed from the diameter(direct reading) and some read the amount to be removed from the radius(indirect)

On the direct type,if you set the dial to .01" you will remove .01" off the diameter of the part.

On the indirect type,if you set the dial to .01" you remove .02" off the diameter.

The 200 divisions you mention are most likely .001" (Thousandths)The fact that you got .210 from a setting of .098 suggests that it is the indirect type of dial.
If you want to remove .125" from the diameter of the part,you would zero the dial and advance it in 62-1/2 divisions(62.5 x 2 =125).
If you are using digital calipers,you can set the calipers to the desired measurement of the part,then zero them,measure the diameter and the result you get you would divide by 2,that will be the amount to set the dial in.A little less than half gives you a safty factor in case your setup isn't 100%.You can always take material off,but putting it back on is another story

The fact that your readings aren't exact can be the fualt of several things.Your tool could be set to high or too low,it could be springing under load,or as mentioned you could have a machine with metric screws and inch dials.In either case a magnetic base indicator will help you see exactly what you have.Hope this helps.

[Tin Falcon]

another way tell is to check the pitch of your cross slide screw.For example if the screw has a pitch of twenty, one complete turn of the handle would move the cross slide .050 or 1/20th of an inch and remove .100 from the diameter of the stock. A ten pitch would move the cross slide .100 and remove .200 off the diameter. Also some lathes the dial is calibraded for diameter ie howmuch total stock is removed others ar calibrated as to the tool movement.

[cuemaker]

Wierd,

That is exactly the info I needed. Thank you! My measurements that I gave where rough estimates. The .210 is pretty close, the 90 part is what I think I did. I was trying to get somewhere and not really keeping track.

Now, for all you helpfull people, does .210 translate to almost a quarter of an inch?

[wierdscience]

.250 is 1/4",look at it this way,if 1.00" is divided into 1,000 parts (thousandths) then 1/4 of that would be 250 thousandths or 1/4 of an inch.

[zl1byz]

<font face="Verdana, Arial" size="2">Originally posted by cuemaker:
Thank you for your help.

Lathe is a Clausing Colchester student model II or MKII


The .210 was a the difference in measurement on my material. Measure one side, measure the other, and subtract, which was almost 90 graduation marks on my cross slide. And my cross slide was perpendicualr to my work.

[This message has been edited by cuemaker (edited 07-16-2005).]</font>

Gee this is great. When you say cross slide do you mean the main slide built into the saddle of the lathe, which can't be rotated or the top slide (compound slide) that can be rotated to differnt angles?

I think the graduations are thousands of an inch and that on the slide you are using they represent the DOC (depth of cut) which you multiply by 2 to get the amout of material removed from the diameter of the material.

The reason you got .210 off the diameter for 90 graduations is just an error in your measuring, you say you measured both sides. What are you using to measure with?

I have a Colchester here, not a clausing. It has duel dials so I can work metric or imperial. For imperial 200 grads per revolution on the cross slide and 100 grads per rev on the compound (top) slide. The cross slide measures the change in diameter and the compound measures DOC. Seems logical to me.

John.

[zl1byz]

<font face="Verdana, Arial" size="2">Originally posted by cuemaker:
Wierd,

My measurements that I gave where rough estimates. The .210 is pretty close, the 90 part is what I think I did. I was trying to get somewhere and not really keeping track.

Now, for all you helpfull people, does .210 translate to almost a quarter of an inch?</font>

I know you are learning but pretty close & rough estimate, no wonder your confused.

.250 is 1/4 inch. So is .210 almost 1/4 inch? Not in my book!

John.

[john hobdeclipe]

If you're having trouble relating decimal measurements to fractional measurements, do this:
A. Get a fractions / decimals conversion chart, study it, refer to it often, keep it handy all the time. Eventually, as you work with decimals enough, you remember the ones you use a lot, soon it all becomes second nature.

B. Get a set of feeler gauges and literally "feel" them. Feel what .002 is (literally a hair,) see what .063 (1/16")looks like, etc. Again, do it enough and it gets easy to grasp the measurements in your mind whether they are decimals or fractions.

During my years in furniture and millwork shops, I regularly had to take drawings dimensioned in fractions, mentally convert to decimals since we used dial calipers, then make adjustments to machines with only metric readouts. It was a real pain at first, but became routine after a while.

Hope this helps.

[IOWOLF]

Why didn't I say that.