Haynie
Member
Curiosity here
Do I need 60 degree bushings to turn between centers?
Do I need 60 degree bushings to turn between centers?
60 degree bushings
- Thread starter Haynie
- Start date
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glycerine
Member
No.
Andrew_K99
Member
For TBC you have a few options
- No bushings, use calipers instead.
- Use standard bushings (I've had mixed results with this)
- Use 60° TBC bushings.
AK
- No bushings, use calipers instead.
- Use standard bushings (I've had mixed results with this)
- Use 60° TBC bushings.
AK
Haynie
Member
I tried not using bushings and was not able to cut anything. The blank would hit the skew or gouge and just stop while the head stock turned away. If I tightened it anymore I flared the brass.
dbledsoe
Member
If you try to use the standard bushings you buy with the components you will have concentricity issues, because they are not concentric (or round, for that matter) to begin with. If you want to use bushings, buy the precision ones from one of the IAP members, or make your own (that did not work for me).
The only problem I have working without bushings is the live center and the dead center tend to flare the end of the bushing, and that puts pressure on the end of the blank. I think it makes it more likely to chip out on the ends.
The only problem I have working without bushings is the live center and the dead center tend to flare the end of the bushing, and that puts pressure on the end of the blank. I think it makes it more likely to chip out on the ends.
BassBlaster
Member
Haynie, I turn between centers without bushings. I use a mandrel and bushings to get close and then go to between centers to finish up using calipers to match the componants. If you get it close enough with the bushing, then you are only taking very light cuts between centers. The only time I have issues with the blank spinning is while polishing wet.
Haynie
Member
I shall give it a try. Thanks.
leehljp
Member Liaison
There is a lot of misconception about " 60° ".
AS an absolute, you do NOT have to have 60° bushings to turn TBC. JohnnyCNC makes and sells the finest bushings you can get. His bushings are chamfered to 60°, so with his, they will match the 60° live center and dead center. But even if you are using 60° live and dead centers, it is not necessary to have to have a 60° bushing. More on this in the 3rd paragraph.
You can use standard bushings that are used on mandrels - I, and others, used these long before John started selling his 60° bushings. These mandrel bushings as a whole are not as good as John's but some work reasonably well.
Unless you are using John's special bushings or using someone elses or your own that have been chamfered to 60°, you don't even need 60° live center or dead center. Here is a link to a dead center that I made back in '07 that I used with non-60° bushings that were made for mandrels. http://www.penturners.org/photos/images/940/1_Dead_drive_2.jpg
It is obvious to the naked eye that it is not 60°. I used this dead center for a couple of years before getting one from Grizzly and one from somewhere else. (Little Machine Shop? maybe.)
Mandrels have a dimple on the live center end that does require 60° live centers. Some people falsely transfer this idea to the TBC requirements. It is not necessary - unless you buy or make your own chamfered bushings that are 60°. But your quesiton was about 60° bushings, so the answer is no.
But the 60° bushings are mfg to a much higher tolerance than the commercial ones.
AS an absolute, you do NOT have to have 60° bushings to turn TBC. JohnnyCNC makes and sells the finest bushings you can get. His bushings are chamfered to 60°, so with his, they will match the 60° live center and dead center. But even if you are using 60° live and dead centers, it is not necessary to have to have a 60° bushing. More on this in the 3rd paragraph.
You can use standard bushings that are used on mandrels - I, and others, used these long before John started selling his 60° bushings. These mandrel bushings as a whole are not as good as John's but some work reasonably well.
Unless you are using John's special bushings or using someone elses or your own that have been chamfered to 60°, you don't even need 60° live center or dead center. Here is a link to a dead center that I made back in '07 that I used with non-60° bushings that were made for mandrels. http://www.penturners.org/photos/images/940/1_Dead_drive_2.jpg
It is obvious to the naked eye that it is not 60°. I used this dead center for a couple of years before getting one from Grizzly and one from somewhere else. (Little Machine Shop? maybe.)
Mandrels have a dimple on the live center end that does require 60° live centers. Some people falsely transfer this idea to the TBC requirements. It is not necessary - unless you buy or make your own chamfered bushings that are 60°. But your quesiton was about 60° bushings, so the answer is no.
But the 60° bushings are mfg to a much higher tolerance than the commercial ones.
Last edited:
1080Wayne
Member
A bit of flaring should not be a problem if it happens when the blank is nearly full size . The barrel ends will just be a bit thinner . However , if you flare it when essentially down to size , there is a risk of cracking a brittle material .
Haynie
Member
Thanks folks.