Matching a Taper?

[mcman56]

I need to make a tapered collar to match the taper on a motorcycle flywheel. Measuring with a standard protractor, it is 5 1/2 degrees per side. I'm trying to cut it with an enco 1340 lathe. The protractor and angled slide adjustment are not high precision so it is not working out well. I have even tried simply trying to bump a 1/2 or 1/4 degree, cut and try but the flywheel always rocks on the taper I cut. Is there a better way or any suggestions?

I'm planning to mount the flywheel on the mill and spin it on the stator to simulate the ignition in action. The large end of the taper faces down so the collar would pull up on an arbor. The flywheel is much like a standard lawn mower flywheel with tapered shaft. This is a test set up for short runs up to maybe 3000 rpm so perfection is not needed. I just want it to run true and not come flying out.

i did set it up on a lathe by holding the flywheel on the chuck but it has much momentum at high speed and I do not have good feel to know that I'm centered and not dragging the stator on the flywheel.

[warmstrong1955]

I've done some tapers, using my compound., so assuming that's what you are doing.....
A protractor will get you into the ball park.
A dial indicator, will get you dangerously close.
Then you need some sacrificial material to make a test run, and measure it, or in my case....some test runs...after some tweaking.

First time out, I got it spot on with a dial indicator, but when I cut a test piece, it was a few thou off.
Takes a bit of adjusting to get 'er spot on....or close enough to it.
Trial & guess...if there's a way to do it without a hit & miss & tweak....I haven't found it yet. Although, the first time took me a half a dozen 'practice' pieces. Last one....was one.


Bill

[mcman56]

How exactly do you use an indicator? Thanks

[warmstrong1955]

Put the dial indicator on the tool post.
You have to trig out that the taper will be. The longer you calc the length, the more accurate you will be, even if the overall length of the taper you need is shorter.
Set the compound with a protractor if you need a starting point.
Run the indicator up against a work piece, after checking the work piece to make sure it is true, and run the compound the calculated length.
Missed a bit...you loosen the compound, and gently tappity tap tap it, and try again. Be nice to our indicator!
After you tighten it back down....tappity tap tap it again, and then test.

When it all comes out honkey....as well as dorey....carve up a test piece, and see what you actually get.
I always measure with the indicator again if I miss it, before I tweak the compound. It' surprising how stuff moves around oh so slightly when you put the tool to the work.
It gives you an idea what to go for the next time...and the next project....it has for me anyway.

It's a trial & guess thing....at least it has been for me.

Maybe someone here has a better method...


Bill

[mcman56]

Maybe I'm getting it I could mount the flywheel
In the lathe and adjust the compound till I get no variation with an indicator on the taper at that point I could put a shaft in the chuck and cut with the angle. Is that the idea

[Patio]

Mcman, I once, did a repair on a set of flywheel tapers, that had been damaged. I don't know if any of that information will help you or not, but here is a link to the process. I used the sprocket shaft, that fit in the flywheel hole, held between centers, to help set the angel of the compound.
https://www.chaski.org/homemachinist/vi ... r&start=24

In answer to your question about using the flywheel in the lathe to set the compound angle. Yes you could do that, but you would need to know that the flywheel is setting perpendicular to the axis of the lathe, and that the hole is actually in the center of the flywheel.

Does this test you want to do, with the stater next to the flywheel, need to be done on the mill or could it be done on the lathe also? Do you need to turn at 3,000, as I doubt your lathe goes that fast. Does your mill go that fast?

If it could be done in the lathe....chuck the flywheel(using softjaws if necessary and available), devise a method to hold the stater, in place of your tool holder, use the carriage to set the distance between the two, and you should be able to get a result. Just some thoughts.

I will watching to see how this works out. Please keep us informed of your progress.

[Harold_V]

Maybe I'm getting it I could mount the flywheel
In the lathe and adjust the compound till I get no variation with an indicator on the taper at that point I could put a shaft in the chuck and cut with the angle. Is that the idea

No. That will lead to a false sense of orientation. If you miss the centerline, and you will, the setting you achieve won't result in the taper you desire. Two reasons. The indicator won't be dead on, nor will the cutting tool, each introducing a minor amount of error.

The information you've been provided is quite good, but you have to know when and how to apply the indicator. The changes you'll make will be miniscule, so you can't guess. You must make calculated moves, which you will read by using a dial indicator that is placed against the compound, always at the same location. When you turn the compound to make minor adjustments, you'll move a given amount (indicator reading), take a test cut and check to see if you've accomplished your mission. If not, you make another adjustment and repeat. If you do this without an indicator, you'll chase the setting endlessly unless you happen to hit right on it.

Checking the resulting taper. Measure, to get in the ball park, but when it's time to fit the taper, use Prussian Blue. A VERY thin coat, something you can barely see, then fit one piece to the other. See where it "patterns" (transfers blue), which will be where it's tight. You'll want a full pattern, end to end, before accepting the setting. Once established, DO NOT REMOVE THE TOOL YOU USE TO MACHINE THE CUT. Any change in its relationship to the centerline will result in a change of the taper.

Make sure the gib on your compound slide is snug. You should be able to move the slide, but if it moves too easily, the cut will vary, depending on which direction you move the compound.

H

[mcman56]

Part of the challenge is measuring the taper in the flywheel. All I have is a protractor.

[warmstrong1955]

Part of the challenge is measuring the taper in the flywheel. All I have is a protractor.

Take a gander in your Machinery's Handbook. You can measure the taper in the flywheel using a couple of ball bearings.


Bill

[SteveHGraham]

Wondering if the famous Chinese precision protractor would help.

https://www.banggood.com/0-320-Degree-P ... 09115.html

Frank Ford has an interesting page on setting the compound with a sine bar, but you would have to know the angle.

http://www.frets.com/HomeShopTech/Tooli ... xture.html

Here's a nutty idea: how about putting a Sharpie in the tool holder? You could move it back and forth on the original part and bump the compound until it gave you a nice clean line from end to end. That would get you close. Then you could fine-tune the angle with Prussian blue to compensate for the kind of errors Harold mentions.

[curtis cutter]

Does this need a keyway as well?

[earlgo]

Wondering if the famous Chinese precision protractor would help.

Oh man, where was this when I needed it?

I have been successful measuring tapers with a simple tool, but one that has to be custom made for your application. It is basically 2 sharp edged discs, one mounted on a handle and one mounted on a sliding rod. The sharp edge needs to be on the 'outside' of the discs. One uses it by sliding the disk on the handle into the bore until it is snug, and then sliding the other disk until it also hits the bore. Clamp the thumb screw and then measure the separation of the discs with a micrometer. From there, knowing the OD of the discs and the separation, trig out the angle. Here is a pic of the small one I made for an internal grinder collet.

Taper gage

Make sure there is enough clearance behind the disc on the handle so that a true linear measurement is possible.
--earlgo