How Do I Crown This Wheel?

W

Wiebster

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Hi, I'm pretty inexperienced at machining and don't know what my next step is to crown this wheel. The wheel is 5" diameter and 3 1/2" wide. 1/4" of it is held in the chuck. I want the finished wheel to be 2 1/4" wide, crowned, and a LH 1/2-13 threaded hole right where the live center is located. On the chuck side of the wheel I would like to dish or recess the wheel to make it lighter. Can anyone tell me what order my next steps are to be to keep the the wheel concentric and the taper or crown centered? Thanks for your advice and sharing your knowledge.IMG_3850.JPG
 
This is not the "correct" way but it worked for me. I cut a rough crown in 4 passes. On the ends I set the compound at 1.5 deg and cut a taper each way. Then I set the compound at .75 deg and cut the next pass towards the middle. After that I ran the lathe and took off the high spots with an angle grinder (hand held) to make a gentle curve. This worked well for my belt grinder. Dishing the wheel is not imperative for most applications but if you need to I would do half from each side. The threaded hole can probably be done last.
R
 
Thanks for your reply. I have made a jig to crown an idler wheel but I too plan on using the compound to crown this one much like you stated. I just don't know where to hold this piece to do that. The wheel is not its final width and I don't know what order to take to get it to its desired shape. Do I taper it before I part it to its final size? If so the left side would have to be plunged into the full diameter of the wheel. If I part it to the final width how do I hold it and taper both sides with the chuck in the way?
 
Cut your recess, and thread your center hole. Then make an arbor to fit the threaded hole and turn between centers. Plan for the excess width to be parted off of the recessed side so you don't have as much metal to part. Do the crowning last.
That's how I would do it, so everything is concentric to the centerline.

You may even wait till last to thread your hole if you are threading with a tap.

As long as The cuts are kept minimal The wheel can be superglue to a snug fitting arbor. The glue bond can be broken with The application of some heat.

The crowning with the compound as stated above is how I would do it also.

Sent from somwhere in east Texas by Jake!
 
Jake makes some good points. The wheel would definitely be concentric to the shaft that way. I wanted to avoid making an arbor. Keep in mind the wheel can be gripped in the chuck even after cutting the crown since it is so shallow. So you could flip the workpiece to cut the crown on the other end.
And sometimes I skin my cats from the tail first.
R
 
Those are great ideas. I am using a LH tap for the threads. What size would you suggest for the arbor? The drill size for 1/2-13? Or something smaller? Parting after recessing is something I did not think of and is a great idea. How do I protect my new crown from the jaws while I tap the hole? Thanks for your suggestions!
 
rwm, you have already figured out what I'm making...a drive wheel for a belt grinder. Do you think it is not necessary to lighten the wheel with a recess? Any pros or cons to either way?
 
The added rotational mass may help an underpowered motor

Sent from somwhere in east Texas by Jake!
 
Wiebster said:
How do I protect my new crown from the jaws while I tap the hole?
Click to expand...
After you have recessed your wheel you will have a boss in the centre that you may be able to reach with your jaws flipped around. Otherwise you can grip the inside lip of the outer wheel by opening your jaws to grip. Expanding the chuck jaws as opposed to clamping them closed on the workpiece

Cheers Phil
 
I made a smaller sized tension roller the other day, i cut the angles using the compound set around 1 or 2 degrees and filed and sanded to final shape, i did flip it to finnish the outside , i stood it on a sacrificial piece of aluminium on a face plate and used some all thread as a draw bar through the spindle to hold it down. Indicating it was a bit of a pain as i had to use a rubber mallet method to get it into position, once their it worked fine.

Useing a recess sounds easyer :)

Stuart
 
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