Simple taper turning.

[dr pepper]

I have a myford 7x20 lathe, its the first machine I have had that doesnt have an angle graduation on the top slide, it will adjust to turn a taper shaft, but theres no indication of angle, I know its a dead simple question but how would I go about turning a pulley (I have a pilot bored pulley) to fit on a taper shaft (compressor drive shaft), I have a pair of bevels but there doesnt seem to be a definate register to put them against on the top slide to adjust the angle.
I thought about removing the crank from the compressor and putiing it in the lathe and setting the slide to it but thats a complex job.

[oldtiffie]

Compound slide setting

Use a bevel guage and/or a protractor (tool-post removed for visibility/access):

[Spin Doctor]

Depending on the angle of the taper you can also use a boring head with a morse taper nounted in the tailstock with ball centers. Offset the boring head for the taper you need

[MichaelP]

Instead of using the compound rest angle scale (which you don't have anyway), use the tailstock offset method. It's way more precise, but you'll need to run your part between centers.

If the part needs to taper down from left to right, move the tailstock toward you a certain distance. Control the offset by a plunger type dial indicator. Make sure the plunger is in horizontal position PERPENDICULAR to the tailstock spindle.

You can use either the following formulae to calculate the tailstock offset (in inches):

Tailstock Offset= TPI x OL / 2

OR

Tailstock Offset= OL/TL x (D-d)/2

where
TPI=Taper per Inch
OL=Overall Length of Work (or, more precisely, the distance between centers) (in inches)
TL=Length of the Tapered Section (in inches)
D=Diameter at the Large End (in inches)
d=Diameter at the Small End (in inches)

Before turning make sure the cutting tool is dead on center.

P.S. Naturally, you can substitute inches with any other units of distance, just make sure you use the same unit for every variable including TPI ( TPI will become Taper per Your Unit of Distance Measure, like Taper Per Meter, Taper per Millimeter, Taper per Foot, etc.)

[willmac]

Your Myford should have an angle scale. Is there something missing from your lathe? A picture would help to resolve the problem.

[dr pepper]

Thanks for all the replys and piccies.
Yep, I'm obviously not as experienced as I thought.
I like the offset turning idea, I now understand the concept, and I do have a face/catch plate and drive dogs for my myford, however I think I didnt explain too well, I want to bore a pulley, so its an internal taper bore not an outside shaft taper.
I like the idea about taking off the tool post and removing the chuck jaws and using the bevel, thanks for that, I think thats the way to go for my application, I'll work out the angle with triganometry from micing the shaft.

I got this machine recently and when I tried to use the outside jaws for the 3 jaw chuck I found they are for a different series chuck, ah well I spose I'll find other things like this, I'll use the 4 jaw for this job as its jaws reverse.
As for my machine having an angle guage, it doesnt look as though its ever had one, its a less common ML4, the ML7 and super 7 probably do have angle displays as standard.
I'll put up a photo tomoz, I'm working right now.

[Dragons_fire]

unless i read it wrong, i dont think turning between centers will help much since you want to do a tapered bore im something that is probably fairly short compared to the diameter. i think i would use the protractor, to do it.

[willmac]

ML4 would explain it - an early lathe indeed!

Also in Lancashire - where are you?

[dr pepper]

This is like mine, only mine has a guard over the change wheels, I like the machine, the build quality is what you'd expect from myford, most of the parts are available, and a lot are compatible with the super 7.

Right now I'm in Garstang sat at my bench in work, whereabouts are you then, theres a possibility we've met, did you list an atlas 5 a while back?

[Black_Moons]

You might be able to mount the entire motor in the chuck and dial it in that way (TDI on compound, move compound back and forth and rotate untill TDI stops moving when you move the compound)

Or, once you get it good by eye/protractor/etc (and leave a good chunk of material left) you can use prussion blue dye to 'spot' the fit and see if the angle is too much or too little, then take another pass.

(Basicly just a blue dye that does NOT dry and can be spread very thin and even and transfers well, Its actualy one of the MOST precise ways of mating parts, even if it is a little trial and error, also used in the scraping of tables and ways to the highest precision)

[MichaelP]

its an internal taper bore not an outside shaft taper.

In this case follow Oldtiffie's advice. But I'm sure you realize that the very best approach will be to dial the shaft's taper directly and set the compound angle accordingly.

[Alistair Hosie]

I seem to remember John Stevenson had a really easy way of doing morse tapers using a morse taper to set up.I wish I could remember it.Alistair

[dr pepper]

I'll have to make do with marker blue, but I'll do that once in the ball park.
I dont think total accuracy is called for here, the pulley is ally and its pulled up by a 3/8 nut so it'll fit over the taper if its close.

Oh yeah have a look at this alistair, I found the thread you were talking about by John Stevenson, follow the link and its thread response No.4, I sort of remember something like this in class at college, putting a long piece of square toolstock in the toolpost and taking advantage of using the length of the square stock to match the taper of a bit/reamer in the chuck the wrong way around, crafty, If I could get the compressor pump in the lathe I'd do it.

http://bbs.homeshopmachinist.net/showthread.php?t=16274&highlight=john+stevenson+morse+taper

Post 5 is also quite interesting, need a dti but still very practical, I use the idea about checking the centre height of the cutter on general jobs, it works well with a 6" rule.

[willmac]

Dr Pepper -

Nice lathe. I think I saw a restoration write up on an ML4 a little while back - might be worth looking around the various groups.

I am in Cabus, probably less than a mile from you. Small world.

[Peter.]

I'll have to make do with marker blue, but I'll do that once in the ball park.
I dont think total accuracy is called for here, the pulley is ally and its pulled up by a 3/8 nut so it'll fit over the taper if its close.

Oh yeah have a look at this alistair, I found the thread you were talking about by John Stevenson, follow the link and its thread response No.4, I sort of remember something like this in class at college, putting a long piece of square toolstock in the toolpost and taking advantage of using the length of the square stock to match the taper of a bit/reamer in the chuck the wrong way around, crafty, If I could get the compressor pump in the lathe I'd do it.

http://bbs.homeshopmachinist.net/showthread.php?t=16274&highlight=john+stevenson+morse+taper

Post 5 is also quite interesting, need a dti but still very practical, I use the idea about checking the centre height of the cutter on general jobs, it works well with a 6" rule.

That's pretty cool!

As a variation you could set the compound parallel and put the morse taper in the holder then set the bar you are tuning between centres and off-set the tailstock to match the angle of the taper you're holding. That way you could do your machining with the sliding feed for a better finish.