4 thousand of an inch run out too much?

[andy photenas]

Hello everyone I'm having trouble getting my smaller one and a half horsepower jet shaper with the three quarter inch spindle mounted to make a good Cope cut I'm finding there is more than 90 degrees on the bottom side of the cope cut when I put a square in it.
I'm trying to trace where this issue is coming from and I've been finding 4 thousands of an inch run out on the spindle at about halfway up is that too much run out and going to cause a bad joint fit?

[Rod Sheridan]

That's a lot, I would expect less than 0.001".

Is it runout or no square to the table?

Not square to the table will cause poor fit as well...................Regards, Rod.

[Steve Jenkins]

With a 3/4 spindle it’s important to have the cutter as low on the spindle as possibly to reduce flex

[Jeff Duncan]

No offense to Rod, but I'd be really impressed if you could get any Jet machine, or any machine in that class to run less than .001 runout. My Martin shaper is about +/-.001. The Deltas and Powermatics I had previously were not that tight:( Not trying to sound like a machine snob, its just the nature of the beast..... less expensive machines generally aren't as precise as more expensive machines.

Having said that I don't think the .004 is as much the problem as the spindle may not be perpendicular to the table. If the cutters are not pretty close to perfectly parallel to the table then they are cutting at an angle, and that is one cause of poor fitting joints. Also why your cut is not square. I would check your spindle carefully and see if you can reduce the amount of runout and ensure it's as perpendicular to the table as you can get it.

good luck,
JeffD

[Jared Sankovich]

No offense to Rod, but I'd be really impressed if you could get any Jet machine, or any machine in that class to run less than .001 runout. My Martin shaper is about +/-.001. The Deltas and Powermatics I had previously were not that tight:( Not trying to sound like a machine snob, its just the nature of the beast..... less expensive machines generally aren't as precise as more expensive machines.

Having said that I don't think the .004 is as much the problem as the spindle may not be perpendicular to the table. If the cutters are not pretty close to perfectly parallel to the table then they are cutting at an angle, and that is one cause of poor fitting joints. Also why your cut is not square. I would check your spindle carefully and see if you can reduce the amount of runout and ensure it's as perpendicular to the table as you can get it.

good luck,
JeffD

For reference, my delta hd has about. 002", my grizzly 5hp has about. 001" and my bridgewood measures at .0002"

[Warren Lake]

SCM T 130, less than .0005 at the top then have another one that had a hard life .007 at the top. with old style cutters you can set up with a rub test and get things closer than what the spindle will do, cutters move in the head so you adjust them more true.


395306

[David Kumm]

It should also be specified if the measurement is when under power or not. I suspect not as measuring with a dial when the spindle is running is hard. Cheaper machines run smaller cheaper bearings, sometimes with C3 or greater clearance to keep them from wearing prematurely. That means the spindle will show some variation when turned by hand but tighten up as the bearings heat up. Another measure is to push the spindle and see how much you can move the dial. That gives you some idea how the spindle may flex when the cut is deep which may be a bigger deal than runout with no force applied. I've also had spindles that were not straight by a few thou. Removing and resetting a spindle can also change the runout. A touch of rust in the quill will cause it too. Lots of things to check. 004 is too much even when at the top of a long spindle but when cutters are loaded at the bottom, the runout is greatly reduced. Dave

[Rod Sheridan]

No offense to Rod, but I'd be really impressed if you could get any Jet machine, or any machine in that class to run less than .001 runout. My Martin shaper is about +/-.001. The Deltas and Powermatics I had previously were not that tight:( Not trying to sound like a machine snob, its just the nature of the beast..... less expensive machines generally aren't as precise as more expensive machines.

Having said that I don't think the .004 is as much the problem as the spindle may not be perpendicular to the table. If the cutters are not pretty close to perfectly parallel to the table then they are cutting at an angle, and that is one cause of poor fitting joints. Also why your cut is not square. I would check your spindle carefully and see if you can reduce the amount of runout and ensure it's as perpendicular to the table as you can get it.

good luck,
JeffD

No offence taken Jeff, I think we're in agreement that it's too much. That said, you're correct that I've never measured a Jet shaper.................Regards, Rod.