Turning between centers

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Guthriecb

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Jul 19, 2019
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I like finishing my blanks between centers but I turn them on a mandrel. Can I TBC with regular bushings or is it absolutely necessary to get TBC bushings (or bushing adapters)? It seems that with my 60 degree live and dead centers that I should be able to use regular bushings without buying the adapters or investing in new bushings. Has anyone tried this? How did it work out for you? Thanks guys.


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KLJ

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I do it all the time and the only issue has been a mark or line worn on my dead center. You can only use the type bushings that stick into the tube not the 7mm type for a slim line. I have read on here where some don't use bushings at all, turn just the blank and use calipers to get final dimension but I have not done that yet. As far as the pens go they have turned out fine. I figure the right tool for the right job would have some advantages but I am using what i have on hand for now, and like it much better than the mandrel. Hope this helps and I will be watching this to learn from the others with more knowledge and experience, glad you asked this question.
 

FGarbrecht

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Aug 22, 2019
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As KLJ says, you can use any bushings or none at all. I use them if I have the right ones and am feeling lazy, but usually don't use them. I've been burned too many times relying on bushings to be the correct size so I always use my calipers to determine final size whether I TBC or TBB. Sometimes I'll put them on just for the rough turning to get close to the right size quickly and then take them off for final work on the blank.
 

Monty

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Like FGarbrecht, I too will use bushings to quickly get to approximate size, plus they help hold the blank when roughing the blank with out putting undue stress on the ends of the blank. To help the bushings get a better "grip" on the centers, I placed the bushings in my collet chuck and used a center bit to make the hole in the bushing 60* match the drive and live centers.
 

Guthriecb

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Thanks for the info guys. I use bushings as a guide also and still use calipers once I start getting close. I appreciate the help!


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Guthriecb

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I have HDPE bushings that are tapered to substitute for metal bushings. Taper fits into any tube. Photo attached.View attachment 231299
Thanks for the feedback. I also have hose bushings for finishing but I prefer to TBC while finishing and don’t bother with a mandrel and bushings at all anymore. I was just curious about roughing between centers also. Thanks!


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Dehn0045

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Mar 19, 2017
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I turn round prior to drilling (I drill on the lathe), this allows me to TBC the whole way without bushings. Knocking the corners can be a little difficult without bushings, if you bear down too hard you can flare the brass. I only tighten down just enough to keep it on the drive without spinning.
 

Woodchipper

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Cleveland, TN
I feel that the HDPE will allow the tube to bite into the plastic and not flare the tube. Calipers are a must for accurate turning. AMHIK.
 

leehljp

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Tunica, MS,
Good advice from all above. From the very beginning TBC was started with using the regular bushings. The specialized TBC bushings came about because some of the commercial store bushings were having quality control issues, and the original TBC bushing maker here was John Goodin who went under the name of Johnnycnc. He started making them so that the fit into the tubes were perfect with no slop. Others are making the bushing now to the same high quality tolerance levels that John did. The commercial ones seem to be a tad better today than they had gotten to be in the 2007-2008, but still not as good as the custom made ones. I had one set of commercial bushings in which the mandrel hole was visibly off center. But if your commercial bushings are OK, they will work.
 

Jolly Red

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Carterville, IL
I always check my bushings with calipers before use to determine if they are the correct size. I do this every time I use them, even if I have checked them before. Most of the time I find the diameter to be within a couple of thousandths of the correct size. The big problem with the bushings is if they are concentric and a good fit on the mandrel. Using the cone center and dead center will help ensure the concentricity and eliminate the worry about the fit of the mandrel.

Tom
 

ramaroodle

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Feb 15, 2018
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Seattle
Just out of curiosity, couldn't you just use a countersink or center bit in the end of the bushing to add a little taper to get a more secure fit. Doesn't even have to be 60 degrees I wouldn't think.

EDIT!! I guess I should have read the whole thread.
Like FGarbrecht, I too will use bushings to quickly get to approximate size, plus they help hold the blank when roughing the blank with out putting undue stress on the ends of the blank. To help the bushings get a better "grip" on the centers, I placed the bushings in my collet chuck and used a center bit to make the hole in the bushing 60* match the drive and live centers.
 
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