TBC question...

[MatthewZS]

I've just begun looking at buying some of the stuff for turning between centers and an idea hit me. An Idea that is going to take more (I suspect) than I have here to implement... namely a metal lathe. Rather than keep it to myself I figure I'll throw it out here for someone WITH the proper setup to try it ..... if it hasn't been done already that is. All I ask is that if you try it and it works and makes you a brazillionare, I like the cheeseburger happy meals

I see people with the live and dead center setup for TBC but they still use those modified bushings for most of the process. I suspect that is because the very corner/edge of the brass tube against the metal of the center just wouldn't have enough "grip" to not slip when you tried turning the piece. Why not build a set of centers that instead of a smooth cone had a stair step to it to accommodate a number of tube sizes like an aztec pyramid? See attached image.... and yes, It was a quick slap together image just to convey the idea, it's way off square.

I know there are MANY tube sizes, but you could build one center set with 5 or 6 of the most common sizes, then another set with the others or some such. This would provide just that little bit of flat straight on surface to really grip the end of the blank and turn it, it would remove bushings from the picture all togther, and should be EASY to produce for someone with a metal lathe.

 

[Snorton20]

You should have kept this to yourself and you could have made some money. I would have never thought of that. Great Idea and I think it would work great.

 

[MatthewZS]

Eh, I'm not too worried about it I will revise my previous tho and say a happy meal and a set of centers would be cool

 

[workinforwood]

It's an ok idea, but it isn't the greatest. It is the type of idea that could only work for people that spin with calipers. The idea of bushings is not only to hold steady the inside diameter of the tubes, but to also guide the person where to stop spinning to obtain the proper outside diameter. You device would not do that, because the next step one your center is for the next tube size. You can't possibly have enough steps on a center and still maintain some length to each step to cover both the ID's and OD's of all the different sizes of pens. Beyond that problem, I can also forsee other issues, but the other issues are all human error issues, like people gluing the centers to their pens, or hitting the centers with chisels or tool rests and damaging them.

 

[MatthewZS]

Oh, that reminds me.... to hijack my own thread. Pam cooking spray works great for making sure I don't glue blanks to my mandrels

Yeah, I knew not everyone worked with calipers...and some of the issues you list are issues faced already with current tools and equipment.

It's like like everything else, this idea isn't the ONLY idea.... it's just one more idea. I though, that it would be a GODSEND the way I turn, and I furthermore thought "maybe someone else will think so too"...

 

[RDH79]

Hi Matt This would probably work for maybe certian kits Like the Jr Gent that the 2 tube sizes are 2mm's differant. Thee would be 4 steps in each bushing. Having a set that would ft different pens would be really confusing Too me anyways.But Cost would be my concern. I am not a machinist but the labor and material would be high. I hit my bushings too many times. To spend more than I do now.
But good idea anyways. Thats how things get invented .

 

[toddlajoie]

I do TBC all the time without bushings, the 60 deg centers have enough grip to keep things spinning, but you do need to be careful not to tighten too much or you will crack the blank, and you do need to clean out the inside of the tube when you're done, as the first 1/8 inch or so of the tube gets a bit flared and rubbed. The bushings do make things go MUCH faster for me, as it gives me a ballpark for sizing, but I only rough size with the bushings, then remove them and do final sizing with calipers and bare centers.

My main concern with your idea (it is a fantastic idea, and would probably work if you kept it to a few sizes per unit) but if you look at the GOOD bushings (i.e. like JohnnyCNC's that I have) they stick in the tubes MUCH farther than the stock bushings (probably around 3/4 inc versus less than 1/4 for the stock ones) which is going to make the steps quite long and extend the length of your center. It is a great idea, and if you mix it together with sizing rings similar to JohnnyCNCs tripple play set (a slimline size bushing set with heavy "washers" that go on the bushing for some of the other 7mm sizes) you could have a great idea.

 

[MatthewZS]

The pictures I see seems like the bushings are always there so I just figured it was necessary. Thanks for that info.