Custom follow rest for long tapers

[Joe Gwinn]

Hi Joe Gwinn:
Yeah, that would work so long as the total travel of each roller remains small enough to operate within the limits of the dampers.

Hi. Over 25" of length, the diameter goes linearly from 1.25" to 1.00". so the radial motion is 0.125".

This ought to be doable by choosing a suitable vibration damper. I do se suitable options. Note that one must use the Soft durometer choices for this.
.

The nice thing about using hydraulics for this is that the force is automatically equalized between rollers (so long as they're all connected in parallel) and remains almost linear over the whole travel of the rollers, even when the stroke is quite large.
The downside, of course, is the complexity and the mess if something leaks.

Yes. The complexity and cost is also higher, but it is the better approach, especially if one will make many pieces.

 

[MicroMatcher]

Here I'm at work and this is the issue

I've switched to positive rake sharpest tool I got 55 degree, I'm making a 0.01 thou cut and experimented with feed rates between 5.4 to 12 IPM at 600rpm

 

[4GSR]

Got to get away from negative rake tooling for this type of work.

 

[michiganbuck]

Got to get away from negative rake tooling for this type of work.

Two kinds of positive, the side cutting edge angle and the back rake angle..borh reduce cutting pressure..witch cause chatter, poor finish, deflection, poor tool life, and difficulty holding size..

And the tool swing angle should not be into the part.
And fingernail sharp for flie mild steel.

 

[implmex]

Hi specnaz:
Were you aware that once you have chatter on the surface of a part, it is the Devil's very own to try to turn it away again?
You need some kind of travelling steady or you'll be fighting this bitch for a hundred years and never get it nice.
Break the setup, build the gadget and then try again...you'll be amazed.
Even if you just press a teflon pad against it with your hand you'll do a lot better than what I see there.
But you gotta eliminate the chatter marks completely before the finish cut or you'll fuck up the job.

Cheers
Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[specnaz]

Two kinds of positive, the side cutting edge angle and the back rake angle..borh reduce cutting pressure..witch cause chatter, poor finish, deflection, poor tool life, and difficulty holding size..

And the tool swing angle should not be into the part.
And fingernail sharp for flie mild steel.

Can you explain better what you mean?
This is stainless steel gun barrel trying to make a taper

 

[specnaz]

Got to get away from negative rake tooling for this type of work.

You can see in the photo I'm using positive rake 55 degree insert

 

[4GSR]

I know we are not supposed to post Chinese stuff here.
This is the insert I got turned on using for stuff like this by the guy in the YT video I posted this past weekend.

10Pcs DCGT11T304-AK H01 Metal Carbide Blade Inserts CNC Lathe Cutter Tool CS | eBay

Sharp blade, features impact resistance, fast cutting and processing. 10 x Inserts. No tool bar, high brightness machining surface. Color: silver. We will solver the problem for you with a satisfactory solution.

www.ebay.com

Yeah, they are made specifically for aluminum but that doesn't mean they can't be used on 400 series stainless. You may only get one edge per part but so what? If it gets the job done that all that counts.

 

[4GSR]

You can see in the photo I'm using positive rake 55 degree insert

That's a positive-negative insert, not good enough. Heavily honed edge. Still too large nose radius.

 

[specnaz]

Hi MicroMach:
Were you aware that once you have chatter on the surface of a part, it is the Devil's very own to try to turn it away again?
You need some kind of travelling steady or you'll be fighting this bitch for a hundred years and never get it nice.
Break the setup, build the gadget and then try again...you'll be amazed.
Even if you just press a teflon pad against it with your hand you'll do a lot better than what I see there.
But you gotta eliminate the chatter marks completely before the finish cut or you'll fuck up the job.

Cheers
Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Yeah I figured that I will have to modify old follower rest and come up with spring system for it in order to make taper. The side I was doing test cuts needs to be cut to 0.95" and it's currently at 1.25" so i'm not too worried about it yet. I tried putting wood and scuff pad with my hand on it, it's still chattering