Beating dead centers to death...

[Marc Phillips]

Lemme say right off I sure appreciate all the information sharing y'all do... it really helps more than I can say!

OK... before I take the plunge and throw my mandrels away, I want to try and summarize all of this to make sure my widdle bwain has absorbed all of this correctly....

You use the bushings inserted into the blank and then mount the whole thing in between the centers... and turn each blank (upper and lower barrels) individually.

You then remove the blank, remove the bushings and remount the blank between centers to finish.

<h3>Advantages</h3>
Eliminates mandrel wobble
1. Using a CA finish, no more stuck bushings and chipping when removing stuck bushings
2. Shorter distance between centers = more stability, less wobble
3. Sanding without bushings eliminates bushing dust contaminating lighter colored woods and also bushing shrinkage []

<h3>Questions</h3>
1. Can homemade bushings be used? ... Corian, or whatever?
2. Any problems with rounding over the ends when sanding without a bushing supporting the end of the blank?
3. Does the blank self center easily or do you have fuss with it to get it spinning smoothly?
4. For those that buff their blanks (like me) do you mount the blanks on a mandrel to hold them for buffing?

Is the drawing I did accurate.... sorta?

Thanks again for your patience... and sorry for yet another dead center post... I have read the posts about using a dead center, and I would sure love to get rid of the out-of-round pen problem...

 

[Rifleman1776]

Questions 1,2,3: yes
#4: depends on individual
Do a search for 'no mandrel'. There have been threads on this subject previously.
Actually, just try it and your questions will be answered. I believe you will learn more at the lathe than the computer.

 

[Marc Phillips]

Originally posted by Rifleman1776

Actually, just try it and your questions will be answered. I believe you will learn more at the lathe than the computer.

Probably true, if I had unlimited funds... which I don't. I was hoping to ask questions here before I spend any money since my computer is already paid for.

 

[Monty]

Originally posted by Marc Phillips
Probably true, if I had unlimited funds... which I don't. I was hoping to ask questions here before I spend any money since my computer is already paid for.

If it's ruining blanks your worried about, go get a piece of firewood or a 2X4 and make some throwaway blanks for practice.[}][}]

 

[fiferb]

I can't answer 1-3 yet as I haven't tried this method.

#4, I buff holding the blank in my hand and off the mandrel. It took a little practice to keep the buffer from throwing my blank on the floor but I haven't had one do that in awhile.

I hold the blank at about a 45 degree angle and ease it into the buffing wheel below the center line. I rotate the blank while going back and forth. I then flip the blank and do it again. Repeat on the next wheel. Hope this helps.

 

[Firefyter-emt]

Yes, you are right on the money with everything. Give it a try with your stock bushings and if you like it, but some good bushings from Johnnycnc. With a tru-centered 60 degree hole on each end and the bushings sized based on that 60 degree center axis they will provide even better results. Once you start using good bushings, the more you see how poor the fit of the China made ones were. For example, my Jr.Statesman bushings will fall off the blank if I don't hold it. My buhsings can be turned upside down and not fall out.

Try it with your standard bushings and a cheap dead center. The worst-case you are out less than one really good pen blank.

As for rounding over when sanding, I start with 220 and with the 320 I lightly round the edge on purpose. The CA will "fill" over the edges and require you to flatten them. (This is why I started to make those sander mills in part) You can use your pen mill cutter, but it has a higher chance to chip the edge.

Look around, dead centers can be bought very cheap when compared to some pen kits, blanks, ect..

 

[Marc Phillips]

Originally posted by fiferb

#4, I buff holding the blank in my hand and off the mandrel. It took a little practice to keep the buffer from throwing my blank on the floor but I haven't had one do that in awhile.

I hold the blank at about a 45 degree angle and ease it into the buffing wheel below the center line. I rotate the blank while going back and forth. I then flip the blank and do it again. Repeat on the next wheel. Hope this helps.

Thanks... I would rather do it as you describe and not add a step such as remounting the blanks on a mandrel...

I appreciate the info!

 

[Marc Phillips]

Originally posted by Firefyter-emt

Yes, you are right on the money with everything. Give it a try with your stock bushings and if you like it, but some good bushings from Johnnycnc. With a tru-centered 60 degree hole on each end and the bushings sized based on that 60 degree center axis they will provide even better results. Once you start using good bushings, the more you see how poor the fit of the China made ones were. For example, my Jr.Statesman bushings will fall off the blank if I don't hold it. My buhsings can be turned upside down and not fall out.

Try it with your standard bushings and a cheap dead center. The worst-case you are out less than one really good pen blank.

As for rounding over when sanding, I start with 220 and with the 320 I lightly round the edge on purpose. The CA will "fill" over the edges and require you to flatten them. (This is why I started to make those sander mills in part) You can use your pen mill cutter, but it has a higher chance to chip the edge.

Look around, dead centers can be bought very cheap when compared to some pen kits, blanks, etc..

Thanks... I will shop around for both a dead center and a 60 degree live center... I still have just the stock live center that the Jet came with... then hopefully I can get the custom bushings....

 

[Rmartin]

I think you described the process very well. I really like the idea of making corian bushings. I'm just too busy or lazy to make some. My turning time is limited and I prefer to turn pens more I guess. The thing is, I've just started using a CA/BLO finish, but I haven't had a problem with my blanks sticking to the bushing, so I do the whole thing start to finish without removing the bushings. I will sometimes however, do my finishing with both blanks on a mandrel after I have turned them between centers.

 

[Firefyter-emt]

BTW, Marc... for now, you could still use a non-60 degree center with stock bushings. The hole in the bushing is not tapered so the live center will grab at what ever point it hits at.

 

[Marc Phillips]

Originally posted by Firefyter-emt

BTW, Marc... for now, you could still use a non-60 degree center with stock bushings. The hole in the bushing is not tapered so the live center will grab at what ever point it hits at.

Thanks... I went ahead and ordered a dead and live center today....

Looking forward to trying this now...

 

[johnnycnc]

Marc,I like your drawing!

 

[kirkfranks]

I would like to add another question to this discussion.
I believe that some (maybe all, but I doubt that) of my mandrel wobble is caused by the lathe not being perfectly point to point as built. The live center does not exactly line up with the drive center.
If I go to turning between centers does that method help any with this problem?
I would think that the blank (with bushings) would sort of self center themselves between the centers. They may do it better with the stock bushings than with 60degree bushings. Anyone have any opinion on this (like that is a high probability)?

 

[Firefyter-emt]

Kirk, this very well could be the case. Some lathes have the ability to adjust the tailstock side to side to set up the lathe. Or maybe you can unbolt and adjust the headstock to fit.

You may be stuck with an un-adjustable lathe that is poorly built. The other problems could include the taper not being concentric to the mandrel or the mandrel being bent.

Here is the adjustment on my tailstock. The small pan headded slot screw is adjusted in and out on both sides to adjust the center line. Any height changes would either need to be shimmed or have the ways scraped. (beyond the normal woodworker)

(old photo, the handle has been polished and powdercoated clear)

 

[kirkfranks]

Lee,

The alignment is all the lathe. Turncrafter plus (the small one from PSI)
I do have some side to side <s>adjustment</s> slop in the tailstock so I can and do loosen the hold down and adjust for best fit. I think I am ready to try loosening the headstock block and shim up (the tail stock is higher) to see if I can get things more even vertically.

I Was really looking to see if you had any opinion if turning between centers would make these adjustments un-necessary. (as would a better lathe with #2 tapers...)

Thanks

 

[Firefyter-emt]

No, you need a centerline before anything. It all transfers from there. If your tailstock is too low, and your headstock bolts on, by all means, shim it up! You may be able you use paper or tinfoil to do this, brass shim stock is the best, but you have to weigh the cost / gain ratio.

Side to side due to slop is harder to fix and I would have to see the design to see what would be the best way to try to solve the slop.

However, bringing the height in line will make them better, and with a combo of between center and rotating your blank in the final sanding stages may get the pens pretty dang close.

 

[Mather323]

I am buying my dead center this weedend, thanks for the thread!

 

[Marc Phillips]

Originally posted by johnnycnc

Marc,I like your drawing!

Thanks.... it's all yours if it will be useful!

 

[CHICAGOHAND]

Lee you should be embarassed to show that tail stock in that condition.
Have you no shame?

 

[Firefyter-emt]

I know... I hated how it looked with the handle painted so I took the time to sand the casting lines off and fully polish and buff it like chrome. I then clear powder-coated it so it did not tarnish. [}]

Marc, if it's ok.. I would love to borrow that photo from time to time when it's needed.