Turning a taper, which is the prefered method?

[Suzuki4evr]

If I wanted to taper a shaft that is approximately 26" or so long. I'm thinking gun barrel blank here. Would it be best to use my steady rest and move it the the desired offset. Or, would it be best to use my taper attachment which guides my cross slide as required?

Friend if you have a taper attachement why NOT use it. I wish I had one. I don't know how long it takes to set up,but if you can't use the compound for too long distance reasons, then the taper attachment is the way to go. Not so sure about your steady rest idea.

 

[jbobb1]

I'm working on making a taper offset tool. Got the plans off the internet.

 

[Tozguy]

Friend if you have a taper attachement why NOT use it. I wish I had one. I don't know how long it takes to set up,but if you can't use the compound for too long distance reasons, then the taper attachment is the way to go. Not so sure about your steady rest idea.

To me the crux of the matter of profiling a long rifle barrel is to prevent deflection. Regardless of which of the above approaches is used to set the taper, there must be a mechanism to prevent deflection of the barrel during the cut.

 

[Titanium Knurler]

Can’t contribute much to the conversation on deflection but I thought I would show you a nice Royal tailstock offset device I picked up used on eBay. It is exceptionally well made and incorporates some of the desirable features mention in this thread: a ball-end center and spirit level as well as a chart for setting the offset for various barrel lengths:

Unfortunately they are no longer manufactured but there are lesser versions available from China:

TK

 

[Janderso]

I had no idea there were so many tailstock tools to assist with taper turning.

 

[Tozguy]

TK that Royal is in a class of its own.
Wondering what the two dark rings on the cone mean. Would that be a carbide ball tip on the centre?

 

[Titanium Knurler]

Tozguy, yes, the Royal is a tool that is a pleasure to hold in your hand(probably not the best voice of words). The rings were on the tool when I got it and are fortunately just superficial wear marks. I am not sure if the ball tip is carbide but the center is “live”.

Just to, maybe, add a little something to your discussion regarding displacement, I did some tests a while ago to get an idea of what kinds of radial forces cause what kind of displacement of a workpiece. To do this I took a 1-1/2”, 12” MT5 standard rod that was placed directly in the spindle, a 1-1/2” Thomson rod mounted in a 4JC and a 1” Thomson rod in a 5C spindle chuck and pushed on them with a force generator at 0”, 6” and 12” from spindle and measured the displacement. Here is the set-up for the 4JC and the results for all three rods:





So, just looking at the 4JC at 0” from the spindle, there was no displacement until a 100# force was used; this caused a displacement of only .0002”. At six inches from the spindle a 15.5# force caused a displacement of .001” and at twelve inches from the spindle only 4.4# caused a displacement of .001”. How does this relate to real life? Not sure, but I did do some “live” experiments where I cut a rod unsupported by the Tailstock and measured the displacement while cutting. For example, with the one inch Thomson rod in the collet chuck at twelve inches there was .005” displacement which translates to about 13# of radial force under the cutting conditions I was using. If 13# of radial force is a reasonable ball park figure for a light cut you can go back to the chart and look at 13# for each rod and distance and get an idea of the displacement you will see. Bottom line: Tozguy, I think you are correct that support is key to getting a good cut, secondly, I obviously had too much time on my hands the day I put this stuff together.

TK

 

[Flyinfool]

Those 2 dark rings look like wear lines. Oopie!

I may have to make me one of those contraptions. It is such a PITA to get the tail stock back in the middle after off setting it.

I have only ever turned one barrel for my 6.5x55 Mauser. I did the taper with HSS cutters and just using tail stock offset. Yes I can measure that there was some deflection in the middle, the calculated center dimension is about .013 oversize, but the eye can not see it so it is good.
Since I planned to shorten the barrel by 4 inches I did not have to protect the muzzle during the tapper process. I used a center drill to make a good cone in the muzzle and then used a carbide dead center in the tail stock with a good load of wheel bearing grease. I just used very slow and shallow cuts to avoid climbing. At the end I did 5 or 6 spring passes to straighten it out as much as possible.