My reasoning was that x travel didn't really affect parting. But, next time I have trouble I'll try that. Who knows!
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AXA Tool Holder for Tapered Cut Off Blades
- Thread starter YYCHM
- Start date
My reasoning was that x travel didn't really affect parting. But, next time I have trouble I'll try that. Who knows!
DPittman
Ultra Member
Yup that should be a first step in trying to eliminate part off troubles.
Because this tool that Bill @Dusty sent me makes parting off so easy. I just parted off 5 times in a row zip zip zip done. No drama, No grief. Now to figure out why my T blade doesn't behave the same way.
For sure. I'd lock my compound as well if I could.
Your lathe may even be a bit stouter than my 14x40 (D1-4). Same generic tool post. Assuming decent parting tools clamp rigidity & correct alignment, you should be able to +/- replicate @dfloen parting right side up. That's pretty much what my parting looks like, although I always use cutting oil.
IMO you should always lock the free way on a lathe or a mill. It only takes a second, adds rigidity, prevents drift, arguably reduces wear. Your leadscrew might be more worn near your typical parting range, but if in doubt set up an indicator on the bed, push & pull on the carriage. Apply the lock & repeat. If your cutting tool is wanting to steer in a certain way & you allow it to happen, it's only going to get tighter as it cuts inward & potentially deflect other surfaces. There is just no advantage to leaving it unlocked I can think of. My lathe carriage lock was a POS. Possibly you have something similar. Mostly it was vague & iffy to set but it also didn't grip well. Pics show my version. Much more positive. I can finger tighten to the same pressure that required a wrench half turn before.
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Did you put a square up to it yet?
You can rest assured that I exhaustively evaluated those options a long time ago. And ya, I agree that it should have no problems. Yet for some crazy reasono, once in a while it does.
I'll try that next time it happens.
OK, I understand. Thank you.
Please keep me posted with whatever you learn about T-Blades.
Hmmm. To be honest, I'm not really sure how mine really works. It's an Allen head Machine Screw recessed into the top of my saddle. For all I know it bears on the ways..... Nah, can't be........! They would NEVER DO THAT...... Or would they?
I'll have to see if I can figure out how it works.
Nonetheless, I doubt I have a problem with the carriage moving. I have zero sense that the blade is bending or does anything other than follow the groove perfectly. But I guess you never know. I'll certainly try locking the carriage the next time I have a problem. Or more specifically, I'll give that a try on another spot with whatever part I had a problem with.
Put a square up to what?
Just set your assembly up on a flat datum, shine a light from behind & look for gap vs. square. You can check the toolholder face & the tool itself. It's not rigorous but might show you something especially if one cuts but not another. The tapered section blade surface of course can't be checked this way, but the T-section blade or rectangular insert holders can.
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I agree actually. It is hard to displace that big hunk of iron unless the leadscrew is quite worn. Even so the reaction force should be going cross bed, not acting to displace it. I'm just mentioning locking is a good habit, maybe something you would pick up like facing a large diameter. But what I really meant to say was locking the compound which hopefully you have. Some people orient the compound at an angle to help mitigate. For the most part mine sits at 45-deg but it does have a (rudimentary gib strip friction) lock. It probably helps to retract the compound so the dovetails have maximum engagement vs extended forward. I'm guessing you checked all these things so it is a bit mysterious.
I know some people like to bevel the edge of parting tool so it supposedly shears off at a point leaving the part cosmetically nicer. I dont think a little angle matters but the downside of larger angle IMO is it can drive the cutter in the direction of the point & things get jammy with extended blade. I prefer neutral (square) so the chip is uniform.
For the most part, I prefer a square neutral tip too. But I have also tried beveled, pointed, and forked (concave) tips too. For a while there I even tried alternating tips - regular PIA. Interestingly, concave on both the front surface and the chip breaker usually gave me slightly better performance. I'm not sure why.
Broke out the T Blade today and did some playing around.....
After checking that the blade was sitting upright and everything was setup properly and locked down I encountered a new phenomenon. It would cut a curled chip but after it reached 5-10mm in length the chip would weld itself to the point? Backing the blade out to keep the chips clear helped but eventually the blade would stop cutting without manual intervention.
Bad picture but that's a curled chip stuck to the point.
Cutting fluid didn't help. I'm at a loss on this one?
The tool isn't shaped that way, the tool is flat on top, that's how the chip builds up on the point. Sometimes requiring plyers to break it off.
Heat means rubbing/friction (welding in your case LOL). Anyways, not cutting or at least very inefficiently.
- You are 100% positive the dressed edge is on spindle center?
- If you trapped a thin rule in between cutter & part it would be perfectly vertical (orange).
- Blade is advancing perpendicular to work with the prior suggestions?
- A freshly ground edge should feel sharp to the touch even though the angle is different.
What material? Any oil? Does it do this on any material or is it a mystery bar? Did the Dusty tool part this same stock fine?
- You are 100% positive the dressed edge is on spindle center?
- If you trapped a thin rule in between cutter & part it would be perfectly vertical (orange).
- Blade is advancing perpendicular to work with the prior suggestions?
- A freshly ground edge should feel sharp to the touch even though the angle is different.
What material? Any oil? Does it do this on any material or is it a mystery bar? Did the Dusty tool part this same stock fine?
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Yup, a thin ruler was how I set the tool height. Blade is square and sharp. Same stock as what @Dusty 's blade motored through. Dunno.....
Hey Craig, never had this sort of issue ever and two possibilities come to mind. Keep in mind the blade holder automatically provides you with a 7 degree rake. Your blade tip appears like it's getting too hot or are my eyes deceiving me looking at your photo.
1. Is the front face angle of the blade ground spot on 7 degrees?
2. The front face 7 degree angle should also be on a slight angle going from right to left that way the material you're parting off has a clean finish?
3. Speed may have something to do with the chip welding its self to the blade? Sort of guessing on that.
Keep working at it likely a simple fix although the magic is in finding out the what? Wish I was there to help out.