Search found 91 matches

by rexcsmith
Mon Feb 13, 2017 1:47 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

OK, now I get that the only thing that will cause a taper is the work piece flexing or moving away from the cutter, assuming the cutter is moving parallel to the spindle axis, which it is. That's progress on this end. hmm Actually, when I put the precision bar in the 3 jaw Bison, I get less than .00...
by rexcsmith
Mon Feb 13, 2017 12:06 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

Are you saying that lack of parallelism between the workpiece and the spindle doesn't cause taper? I know that one cause of taper can be deflection of the workpiece while cutting. I've pretty much ruled out deflection for a couple of reasons. The main reason is that I can put the workpiece in my 3 j...
by rexcsmith
Mon Feb 13, 2017 8:52 am
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

It cuts a taper every time, and to the same degree, and from my measurements, I'm pretty convinced the chuck/collet is not holding the workpiece parallel to the spindle. But, I'm not going to cut the collet chuck mount based on my own limited understanding. I know a machinist who deals with such thi...
by rexcsmith
Mon Feb 13, 2017 8:39 am
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

I'm actually not turning anything, just making measurements. Back when I did the turning, I observed the problem on around 10 different work-pieces; always made sure they were tight. I tried pushing on the workpiece with my hand during measurement; less than 1 thou measured on the dial.
by rexcsmith
Sun Feb 12, 2017 11:43 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

I think I'm onto what's going on, thanks to suggestions from this board. I got a piece of precision stock and made runout measurements. Long story short, the runout is due to the chuck/collet and not the workpiece. I then took the collet out of the chuck. Measured inside the nose end of the chuck (r...
by rexcsmith
Wed Feb 08, 2017 1:07 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

BTW, same results with carbide inserted cutter.
by rexcsmith
Wed Feb 08, 2017 1:02 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

Harold; I'll follow your procedure as soon as I get the precision bar. Thanks Glenn, I'm cutting hard steel; rockwell 30. However, I get the same with mild steel and drill rod. Using a HSS cutter I ground myself. Works great when using a chuck. Cuts a very nice finish with either a chuck or a collet...
by rexcsmith
Tue Feb 07, 2017 11:24 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

My apologies, I let an extra zero slip in there. I mean 2 thou and 4 thou. Not getting repeatable readings tonight so I'm going to call it a night. I ordered some precision bar and I'm going to start afresh with that and see if I can get a solid set of results. The only thing I've been able to repea...
by rexcsmith
Tue Feb 07, 2017 8:34 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

I don't have a precision bar yet, although I have a hard steel bar, a mild steel bar, and a drill rod bar. They all behave the same. It is runout because when you rotate the uncut bar, the dial indicator moves between 0 and .0002" When you measure the diameter after a cut, the end of the bar is .000...
by rexcsmith
Tue Feb 07, 2017 3:57 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

Re: 5C taper problem again

I'll start by saying I'm not an experienced machinist; merely a hobbyist that's about a year into it. I'm using 3/4" drill rod, although I don't know if I can count on that to be precision. If not, where can I get some precision 3/4" rod? I have indicated it with and without the live center. Same re...
by rexcsmith
Tue Feb 07, 2017 2:11 pm
Forum: Lathes
Topic: 5C taper problem again
Replies: 44
Views: 11597

5C taper problem again

I posted on this a few months ago. I've tried all the suggestions and have not solved the problem. An update. I have a Monarch 10EE with the drawbar/nose-cone 5C collet system. I'm using a 3/4" Lyndex collet. When I reduce the diameter of a 3/4" rod, it tapers down toward the collet. Over 3", the ta...
by rexcsmith
Sun Oct 16, 2016 5:40 pm
Forum: General Discussion
Topic: Filleting on a Lathe
Replies: 15
Views: 3858

Re: Filleting on a Lathe

Never mind, I just realized what you meant by rake.