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davidh
01-17-2009, 02:55 PM
its snowy and cold and i need to get off my a** and make the adjustable tool height center locator guide today. but my mind needs help. . .

i have the base, the vertical rod and im going to make the two adjustable height guides so i can use it but, , , the question is

how do i set the height gages to the actual dead center of my spindle ?

my thought would to use a needle point something, chucked in the chuck and use my finger to feel the point being dead on the top of one of the height guides..right ?

would i use the exact same techneque to "feel the top of the tool at the tool post in relation to the top of the height guide ?

my eyes are pretty crappy so a "visual"comparison would not be any better than im doing right now which produces some pretty poor results.

i feel really dumb asking such a basic question but i am having a real big brain fart. . . . .:(

lane
01-17-2009, 03:07 PM
.015 one way are the other want make that much different. I just use a 6 inch scale against the work and touch tool to it . If tool on center scale will be vertical ,if high are low it will tip one way are the other.

Mike Burdick
01-17-2009, 03:08 PM
A suggestion...

Chuck up a piece of scrap material and turn it down to a point using the compound. This will find the exact center of your lathe's spindle that will not depend on the chuck's accuracy. Use a magnifying glass, or by "feel" if your eyes are bad, to match the gauge to this point. One note here: Most likely you can't get it "right on" so make your error on the LOW side since this will insure the tool bit won't "rub" before the cutting edge.

Another idea that you might consider is to find the center height of your spindle using a very thin sharp pointed tool and then using that to scribe a very small and thin line on the tail stock ram. This makes a very handy gauge that is always very easy to find! ;)

.

Frank Ford
01-17-2009, 03:10 PM
I just chucked a piece of scrap in the lathe and faced it repeatedly, adjusting the tool until it crossed center perfectly. Then I made the tool setting gauge from a cheap "not quite square" to fit the tool height:

http://www.frets.com/HomeShopTech/Tooling/ToolHeightSet/toolheightset.jpg

barts
01-17-2009, 05:21 PM
I made this one the other evening after a long day at work... a nice way to relax. I just set it from a pointed rod held in the chuck... As an aside, I used to wonder why people found such jigs handy; as my vision has gotten poorer I find such aids a big timesaver... and those bifocal safety glasses are a wonderful invention!

http://smaalders.net/barts/lathe-tool.jpg

Peter N
01-17-2009, 05:37 PM
Got a Vernier or digital caliper?

OK, chuck a bit of stock, any size you like, and take a few cuts until you a nice smooth finish. Measure the diameter with the vernier, divide by 2 and write down the reading.
Move the cross slide underneath the stock, use the 'depth' leg of the vernier and put the sharp end :D on the cross slide or the top slide then bring the other end down to rest on top of the bar you just turned.
Then subtract the number you just wrote down from that reading and you have the exact centre height of your lathe from the plane you measured from.
Write this down somewhere (mines on a wall next to the lathe) and just set and lock your caliper to this reading the next time, and use the vernier in the same way from the same plane to set your tool tip on centre.
It's even simpler with a height gauge, but not always quite so accessible.
Of course if your centre height is more than 6" or you use a huge diameter bit of bar, you'll need a bigger vernier.

Peter

barts
01-17-2009, 05:43 PM
Peter, that method works - but I don't like setting the tail end of my vernier calipers on the business end of a carbide cutter. If I have to take a surfacing cut on my height gage in a year or two, no harm done....

dp
01-17-2009, 05:44 PM
my thought would to use a needle point something, chucked in the chuck and use my finger to feel the point being dead on the top of one of the height guides..right ?

Put a piece of 1/2" or so stock in the chuck and using the compound set to 30 degrees, turn the end to a point - raise or lower the cutter to get a perfect point. When finished that point is the center of your chuck. Align your height gage to that as best you can. Use plenty of light and a lens can help. Once you remove that center from your chuck it is pretty much useless as you'll be hard put to get it back where it was, but once your gage height is set it should remain accurate until the first time you drop it :)

airsmith282
01-17-2009, 06:59 PM
i cant be of much help but make sure your cutter is nice and sharp and then line it up by eye.. i do it this way most of the time but for a few cutters i made a few tool post holders that are dead on and i have a few adjustable holders that dont often get a different cutter in and i just sawp out the cutters and realine when i need to... iam farsited i guess you call it ,,so i see fine detail up close with and with out my glasses so i never seem to have a problem and i usualy set just a hair line below center i find that right dead on center is not always best so a hair line below works great..

Peter.
01-17-2009, 07:08 PM
I have 'screwcutting in the lathe' and in there the author describes how to set the tool to exact center-height.

Put a piece of round stock in the chuck and find a thin strip of plate, and trap it between the cutting edge of your tool and the workpiece. Adjust the height of the tool until the strip is held dead vertical when trapped by the cutting edge of the tool.

oldtiffie
01-17-2009, 07:13 PM
Its easier than that.

Either get a piece of scrap that had had the end faced off and has little or no "tit" left on it. Set the tool height to the centre of the "tit" - by "eye". You will pretty close. If you are fussy, take a facing cut and keep adjusting the tool height until there is little or no "tit" left.

I can do it quicker than I can type it.

As said, if you are +/- 10>20 thou it won't matter much most times although I tend to set my tool "just a smidgen" below centre height for outside work and just above it for internal/boring work.

barts
01-17-2009, 09:00 PM
I have 'screwcutting in the lathe' and in there the author describes how to set the tool to exact center-height.

Put a piece of round stock in the chuck and find a thin strip of plate, and trap it between the cutting edge of your tool and the workpiece. Adjust the height of the tool until the strip is held dead vertical when trapped by the cutting edge of the tool.

This works beautifully w/ positive rake tools, particularly HSS; a old 6" machinist's scale is perfect for this task.... my usual trick is to drop the scale into the swarf in the chips bin, though :o

oldtiffie
01-17-2009, 09:24 PM
This is one I made a while ago. Just put a bit of tool steel or anything with a flat edger on it an use it as a "scratch" guage. I sized it with a vernier height guage (to the top), took off half the diameter, re-set the height guage to the centre height, checked it, looked OK and made the centre height guage to suit. I guess I have used it about a dozen times - but it works very well.

http://i200.photobucket.com/albums/aa294/oldtiffie/Part_off1.jpg

aboard_epsilon
01-17-2009, 09:24 PM
Here's my ten min KISS wonder

http://img.photobucket.com/albums/v190/aboard_epsilon/smart%20and%20brown/centredoofor.jpg

All the best ..markj