Cutting wheels on a Lathe

[K-Racing]

I've cut a few wheels on a lathe and I haven't quite got the process down yet that Im not getting a good surface. I have a couple questions for anyone that might know. /images/boards/smilies/wink.gif

Does the speed of the chuck have an effect on the cutting process?

What shape of bit does the best cut?

Thanks Guys...

 

[cozybldr]

I am assuming you are going right to left towards the headstock. You need a left handed cutting tool.
Follow that up with a finishing tool. Of course, you could just do the finishing tool considering how soft the plastic is. The generous radius will give a better finish.

Look here for the profiles:
http://mechanicalmfg.blogspot.com/2012/08/lathe.html

Speed wise, about 1000 rpms will give you a cutting speed of 250 SFM.

Rick

 

[Quicktimederby]

The thing with cutting wheel from my massive experience is practice makes better, not perfect. I'm new to the lathe world and have destroyed several sets of wheels!! It seems like the more I do the better they get, but still no where near the speed and quality I can get from DD4H. I practice with my wheels and race with his. For me slower cutting speed works better if I try and cut to fast it melts and chunks the plastic.

I've cut a few wheels on a lathe and I haven't quite got the process down yet

 

[K-Racing]

I don't know my Rpms on the lathe, its an old industrial metal lathe. it is on the slowest speed though. as for my bit, I just made a point out of stainless steel like the one in the picture above on the right. I take the bit in till I make contact then I do one pass. on the next pass I take .002 on each pass after that.

my issue is the surface after a cut, its very ruff. I've seen videos on YouTube cutting wheels and the wheels looks smooth. that's why I wonder about speed and bit shape. my bit is a very sharp point as well. I know my drawing isn't exact but my bit is held by a right hand holder.

 

[Dixie Derby Dude]

I have a Micro Mark lathe and I set the speed @500 rpm and use a right cut tool slowly fed towards the chuck.
Then I put the wheel/mandrel in a cordless drill and polish it with an 8" plastic buffing wheel for about 10 seconds or so.
Wheels come out super smooth and shiny.

 

[cozybldr]

Your right, it should be a right hand cutting tool. I was thinking of direction of travel. Mea culpa. According to Machinerys Handbook, polystyrene likes 95-250 SFM. That means 343-1000 rpms is an acceptable range. I turn my lathe right at 1000 rpms and feed slow across. I learned not to use my carbide inserts for this work. My custom grind with a more generous radius worked far better.

 

[Guest]

I don't know my Rpms on the lathe, its an old industrial metal lathe. it is on the slowest speed though. as for my bit, I just made a point out of stainless steel like the one in the picture above on the right. I take the bit in till I make contact then I do one pass. on the next pass I take .002 on each pass after that. my issue is the surface after a cut, its very ruff. I've seen videos on YouTube cutting wheels and the wheels looks smooth. that's why I wonder about speed and bit shape. my bit is a very sharp point as well. I know my drawing isn't exact but my bit is held by a right hand holder.

You never, ever, want to use any kind of soft steel as a tool bit. I like High Speed Steel vs Carbide for cutting BSA wheels. I like to start sharp, if I get a good finish great, if not, I will take a small sharpening stone and gently put a small radius on the tool bit where the sharp point was. I found using CRC-336 as a lubricant helps aid in the cutting process. If I remember correctly I believe I turn at around 500 RPM's.

 

[K-Racing]

Well I got the Lathe up to 500 RPMs. And I changed the bit shape and with these two adjustments what a HUGE difference. I'm getting a great smooth finish. So here's my process, and please let me know if I should change it.

I take the bit to the wheel till contact, then I let the machine do a pass. I bring the bit back and turn in .002 then let the machine do a pass. I do this a total of two to three times. After my last pass I'll do one more but by hand really slow, I seem to get a better and smoother finish this way. With this process Im getting a good finish.

I'm just starting to do this type of work so, I'm not worried about run out or over all diameter. Plus these wheels that I do want to cut are for my kids scout cars. I'm not fooling myself to think I can make a fast wheel, I just want a wheel that is better then out of the box for my kids. I'd like to broaden my ability with wheels with some day figuring out how you guys make your own wheels like 5Kidsracing.

One thing Im curious about it how do you mount your wheel when you want to take material out from the inside? Curious if I hold it like a do now and make a bit that will fit in there. /images/boards/smilies/wink.gif

Thanks for all the help guys,
K

Here's my new lastest setup. The bit is at a small angle when it contacts the wheel, it's not flush with the wheel surface. This is giving me a great finish.

 

[Dixie Derby Dude]

When I open the chuck jaws on mine,you can just slide the wheel all the way back against the headstock part of the chuck,and the wheel will turn perfectly true.....I just need to get a small enough boring bar bit to get in there.
Micro-Mark has one that would probably work.

http://www.micromark.com/8-piece-HSS-Micro-Tool-Bit-Set,8199.html

 

[K-Racing]

The one I use the headstock is open in the middle, I believe 2" to 4" so that part wouldn't work for me. I could clamp the wheel with the chuck but I just don't have anything like you to rest it up against is all.

 

[Dixie Derby Dude]

If you're using one of those PWD mandrels,you might try reversing the wheel and put a "fender washer" between the wheel and the mandrel.....you must have a pretty big lathe if you have more than a 2" headstock bore.

 

[K-Racing]

Yeap, I think its like 36" across, fully extended out. It's an older JET Lathe, Looks something like the one in the picture. Not exactly but pretty close. Buddy found it in a barn, a guy wanted to get rid of it for scrape. We cleaned it and wired it up. not to shabby. /images/boards/smilies/wink.gif