Facing an inside shoulder .?s

[Naiveambition]

Been messing with some drag wheels for my fishing poles and needed to take .050 of an inside( bored) hole.

So now the problem When facing I would start at center and work to the edge, but there would always be a beveled edge in the corner. And for the life of me i, couldn't get a bite. squealed the whole time in the corners. Change tools, change height, grind new tools,. Nothing...:mad.

Up to the corner it would cut okish besides the terrible corners. I don't believe there hardened since I could get curls here and there.
Does the boring bar need to be above center a little since the work is coming in at a different angle than outside diameter cuts.
I finally got them acceptable, although the cuts needed were way beyond normal force wise.

What the. Heck am I missing here??

 

[tomrux]

I'll take a punt and bet you don't have enough clearance on the front. because of the arc the inside takes you need more than normal clearance below the cutting edge.

Tom R

 

[tms6401]

In that situation, I tilt the head of the boring bar down a tad, and I grind the boring head bottom so it has enough clearance so it doesn't rub. Very fine cuts and the results are usually good. Also, use the thickest boring head you can for the rigidity, and have it sticking out of the tool holder as little as possible.

Tom

 

[ShopShoe]

I have to agree with tomrux and tms6401. I have experienced the same symptoms in a similar situation and It turned out to be something making contact other than the cutting edge. Lots of time lost and problem finally solved with grinding the toolbit or boring bar. It has often taken several tries to get things exactly right to keep cutting. I have used combination of mirrors, magnifiers, and high-intensity lights to observe the cutting edge in situ to try to determine "where's the rub?"

--ShopShoe

 

[cheepo45]

If you coat the tip of the cutting tool with layout dye (dykem), you can see where it's rubbing and grind off the offending area.
cheepo45

 

[mcostello]

Sharpie works also.

 

[Naiveambition]

Well I'm glad my thinking wasn't to far off. I was using dykem and of course my sharpie goin down. Was marking the work and not the tool.
Well I went on a grinding spree and made up 4 double tipped tools. And broke out a little puny grinder I had when starting out, that for some reason makes the tools cut great every time , whereas on a different grinder the results are always poorish.
When facing the gears, I used a boring bar that uses carbide inserts and front clearance may be the issue since it happens most times I try inside corners.

 

[mcostello]

Could it be that the little grinder has a smaller wheel and puts more clearance on the tool?

 

[Naiveambition]

Yes it does have a smaller wheel. So you are prob correct. I used what I thought was good clearance in front. Although these were freehand grinds and not against the wheel table.. Or whatever it's called. The tool would blunt rather quickly if I fed it in the corner. The rest of the cut was ok .

Most of the cut was done and I went back to clean up the corners and could not get a cut for nothing. I would spit little pieces at a raised height above centerline. But at center it was useless. Most of the chips were pieces rather than long strings on the long cut. I'm guessing it could be an metal alloy of sorts and I'm guessing stainless, and the finish is beautiful when done. I wouldn't mind having some for my model building. With that said, it is the drag gear for a ocean fishing reel. There are discs that goes inside and offer the drag, so I would think it needs to be a hard metal but not hardened.