Skimming and AXA tool holder: which tool to use?

bigwave · Apr 8, 2020

Skimming an AXA tool holder: which tool to use?

Hi folks,

I need to remove a slight amount of material from some AXA tool holders so that they can sit 1-2mm lower than they do now. I have a pretty small mill setup (2MT and about 1/3HP).

This is because all the insert-bars are 1/2" and on my recently acquired lathe, It turns out i can't quite get the insert tips dead center on the spindle axis -- they're about 1mm proud. It never occurred to me to outfit with 3/8" tooling. dooh!

My thought is to skim the tool holders to let them sit just enough to get to dead center with a little wiggle room (1-2mm/.04"). They're cheap import holders so I'm not concerned about altering them.

My question -- should I use a small shell mill, carbide bit or a fly cutter? -- the holder is 1"x3". Hardness seems to be about HRC-55 and I think I can get away with using carbide(?) -- and no, i don't have a surface grinder :-(

Thanks,
Dave
[newbie]

4GSR · Apr 8, 2020

"C" All of the above!!!

No, carbide endmill or carbide fly cutter is probably the only thing that is going to get thru the case hardness of the tool holders.

rklopp · Apr 8, 2020

I assume you mean the holders are bottoming out on the top of your compound rest. If that is not the case, tell us more. You can either skim the bottom of the holder or lower the bottom of the slot that holds the tool. Assuming I have the right understanding of your situation, if skimming the bottom, you can probably get away with light cuts using, for example, a 1/2" endmill with at least four flutes and a corner radius. Try spinning at 1000 RPM and feeding at a rate to get .0015-.002" per tooth chip load and start with 0.01" depth of cut and see how it goes. Don't be scared if you see sparks and chips glowing orange. If lowering the bottom of the slot, you'd want to ditch the corner radius so that you end up with a sharp corner. You can even do the slot milling in your lathe if you can hold the endmill rigidly enough in a collet or 4-jaw. I would take light climb cuts starting at 0.005" full width in this scenario. I hope your mill is up to it. This kind of milling demands all of the rigidity your machine and setup can deliver. Don't dwell in the cut. I would either cut dry or flood the surface with sulfurized oil before starting the cut, and not add any more oil. By not adding oil, you avoid thermally shocking the cutter and potentially cracking it. I have machined slots deeper without much difficulty, but my machines have more than 1/3 HP and #2 MT spindles.

Be safe and healthy and good luck!

eKretz · Apr 8, 2020

Be easier and quicker to remove it from the bottom of the indexable toolholders I'd think. Then buy ⅜" for any future tooling.

PeteM · Apr 8, 2020

Couple ways to do it, as rklopp says.

One is to enlarge the slot, dropping it down a bit. At one point I measured the hardness of both import and genuine Aloris toolholders. The latter were several Rc points higher. The imports I've used machine quite nicely, even with sharp HSS rather than carbide tools. Just have to get below the case - so don't just skim this thousandths at a time. Take what would be a normal cut for your machine in somewhat hard steel.

I'll cold black the deeper slot and the whole thing looks near new. That's my preferred method.

Absent being able to test hardness, check with a file. Most of the imports shouldn't be too hard. And they're cheap enough to have dozens around - and hard enough to last forever in a home shop.

Other way, as eKretz suggests, is to cut the bottom a bit - especially if the swing of your lathe doesn't allow dropping the holder. This makes sense if you have a very small lathe and need the clearance. I've put AXA holders on an 8" swing lathe I use for second ops this way.

I've also cut genuine Aloris with a carbide end mill. Not sure your mill would handle a carbide face mill. Worst case, you could just grind or disc sand the bottoms. Tedious, but all you need is clearance.

eKretz · Apr 9, 2020

I meant to knock that 1mm or so off the bottom of the actual indexable turning tools. Much less material removal and probably softer - they are normally low to mid-40's Rc. If he wants to continue to use ½" tooling then he will be stuck cutting the QC toolpost holders.

bigwave · Apr 9, 2020

rklopp said:
I assume you mean the holders are bottoming out on the top of your compound rest. If that is not the case, tell us more. You can either skim the bottom of the holder or lower the bottom of the slot that holds the tool. Assuming I have the right understanding of your situation, if skimming the bottom, you can probably get away with light cuts using, for example, a 1/2" endmill with at least four flutes and a corner radius. Try spinning at 1000 RPM and feeding at a rate to get .0015-.002" per tooth chip load and start with 0.01" depth of cut and see how it goes. Don't be scared if you see sparks and chips glowing orange. If lowering the bottom of the slot, you'd want to ditch the corner radius so that you end up with a sharp corner. You can even do the slot milling in your lathe if you can hold the endmill rigidly enough in a collet or 4-jaw. I would take light climb cuts starting at 0.005" full width in this scenario. I hope your mill is up to it. This kind of milling demands all of the rigidity your machine and setup can deliver. Don't dwell in the cut. I would either cut dry or flood the surface with sulfurized oil before starting the cut, and not add any more oil. By not adding oil, you avoid thermally shocking the cutter and potentially cracking it. I have machined slots deeper without much difficulty, but my machines have more than 1/3 HP and #2 MT spindles.

Be safe and healthy and good luck!

Cool thanks for the advice. you are correct - the holders are bottoming out on the cross slide. I was thinking the lathe spindle might be an option [big motor, beefy spindle] but I hadn't thought about slot milling. that's brilliant! since the tool holder is micro-adjustable. I've got a 5C collet chuck to hold the tool.

-Dave

bigwave · Apr 9, 2020

I tested approximate with hardness files. Lathe swing is 11" so I can try either method. Yes, I was thinking a face mill might not work and part of the reason for me posing the question was to get some feedback prior to buying some $$ tooling that turns out to be useless. What I'm curious about is that for insert tooling on the face mills, the tool's fpm is much higher than HSS so it would seem like a wider tool with a slower feed (and hence shallower DOC) might work?

-Dave

bigwave · Apr 9, 2020

eKretz said:
I meant to knock that 1mm or so off the bottom of the actual indexable turning tools. Much less material removal and probably softer - they are normally low to mid-40's Rc. If he wants to continue to use ½" tooling then he will be stuck cutting the QC toolpost holders.

Right. got that - Actually I had not thought of checking the hardness of the tool bars (index holders) - good call. My initial thought was that i've got a handful of those tool bars and mod'ing the holder was less work but yeah, any new tooling will be 3/8. It's not much to remove so i'll still be able to use the 3/8" tools. Either method, I'll get some good practice and/or frustration in while scaling the learning curve :-)

..this forum is awesome! thanks for the tips guys!

-D

thermite · Apr 9, 2020

bigwave said:
Right. got that - Actually I had not thought of checking the hardness of the tool bars (index holders) - good call. My initial thought was that i've got a handful of those tool bars and mod'ing the holder was less work but yeah, any new tooling will be 3/8. It's not much to remove so i'll still be able to use the 3/8" tools. Either method, I'll get some good practice and/or frustration in while scaling the learning curve :-)

True enough, but. So-far. you have unmodified holders some other Pilgrim could use as-is. Without mill or grinder, before I'd mess with trying the mods on the lathe, I'd be inclined to peddle what you have, unaltered, and put the proceeds toward ones that aready fit. Mind, if "handful of.." was a really large number...

..this forum is awesome! thanks for the tips guys!

It's "PM". It is SUPPOSED to be "awesome". Just Deal With That..

matt_isserstedt · Apr 9, 2020

For 1mm ~.040" I'd knock thru the case with an angle grinder (on the bottom flat surface). For all you care it could be the cutoff wheel on a dremel tool used on its OD as sort of a handheld surface grinder. Then bevel all of the sharp corners on a belt-sander. Now off to your milling machine

Now you've eaten all the case hardening with cheap abrasives. The pre-bevel is designed to help the entry and exit for your edge tool.

Should be easy to clean it back up after that. Nobody ever sees the roughing cuts

Limy Sami · Apr 9, 2020

Put the holders in the 4 jaw and use the oblique corners of C shape turning inserts - which are tougher and dirt cheap as ''everybody'' has no end with those corners fresh.

When it's that hard high speed and small DOC (0.005'') works for me.

Dumpster_diving · Apr 9, 2020

Sometimes you can get a little extra clearance by hanging the holder off to the side of the compound. Tee slot all the way to the left (but still in the slot).

bigwave · Apr 9, 2020

Dumpster_diving said:
Sometimes you can get a little extra clearance by hanging the holder off to the side of the compound. Tee slot all the way to the left (but still in the slot).

I checked. My lathe (Emco) has a fixed post, not a T-slot. Even if i straighten out the compound, holder does not sit over the edge of the compound.

-Dave

bigwave · Apr 9, 2020

thermite said:
True enough, but. So-far. you have unmodified holders some other Pilgrim could use as-is. Without mill or grinder, before I'd mess with trying the mods on the lathe, I'd be inclined to peddle what you have, unaltered, and put the proceeds toward ones that aready fit. Mind, if "handful of.." was a really large number...

It's "PM". It is SUPPOSED to be "awesome". Just Deal With That..

Yeah, it's true, i could do that - I figure it's worth trying to use what I've got and I do like idea of using the stiffer insert holders. If it doesn't work out, I'm not out that much...

-D

thermite · Apr 9, 2020

bigwave said:
Yeah, it's true, i could do that - I figure it's worth trying to use what I've got and I do like idea of using the stiffer insert holders. If it doesn't work out, I'm not out that much...

-D

Larger is not only stiffer. it transfers more heat way form the cutting-edge, faster.

"HSS guy" here. Some of my blanks don't even go into a 4-Way. They sit between hold-dowwn bolts on a THIN shim. Cutting zone is no larger. Mass back of it carrying away heat very much IS! Stiff as a prom-night teen-age dick with no conscience, too!

Superbowl · Apr 9, 2020

Can"t you just mill down the bottom of the insert bars? Then you don't have to make permanent changes to the tool holders.

bigwave · Apr 13, 2020

Superbowl said:
Can"t you just mill down the bottom of the insert bars? Then you don't have to make permanent changes to the tool holders.

Yah, discussed that earlier. Chose to mod the holders.

-D

bigwave · Apr 13, 2020

bigwave said:
Hi folks,

I need to remove a slight amount of material from some AXA tool holders so that they can sit 1-2mm lower than they do now. I have a pretty small mill setup (2MT and about 1/3HP).

This is because all the insert-bars are 1/2" and on my recently acquired lathe, It turns out i can't quite get the insert tips dead center on the spindle axis -- they're about 1mm proud. It never occurred to me to outfit with 3/8" tooling. dooh!

My thought is to skim the tool holders to let them sit just enough to get to dead center with a little wiggle room (1-2mm/.04"). They're cheap import holders so I'm not concerned about altering them.

My question -- should I use a small shell mill, carbide bit or a fly cutter? -- the holder is 1"x3". Hardness seems to be about HRC-55 and I think I can get away with using carbide(?) -- and no, i don't have a surface grinder :-(

Thanks,
Dave
[newbie]

And the winner is....

Carbide end mill in in the lathe's collet chuck.

Being impatient to get the job done, I had a "smoke 'em if you got 'em" type situation -- I thought my little fly cutter might work but realized its shank is actually tapered and I don't have a collet to hold it in the mill (it's from a little Sherline with a small taper holder).

I also thought i had some larger carbide end-mills but alas, they're all HSS. Luckily, i had a 1/4" 4 flute carbide cutter and a small cylindrical grinder. After starting with the grinder, I was able to easily cut the floor of the tool holder slot. as it turns out, I didn't need the grinder at all [to cut the case hardening] and for subsequent holders (4 in all), I just used the end mill which performed great. The adjustment screw on the tool holder gave ~1mm per turn so I put about 1/3 turn on each cut. (which should be about 10-12 thou). I ran the spindle at 2200 RPM with the cross-feed was as slow as I could get it using the gearbox.

Biggest problem I had was the tool post rotating out of square when I would tighten it - I goofed up the slot chamfers as a result but not a problem.

Thanks all for the advice!

-Dave

bigwave · Apr 13, 2020

rklopp said:
... Try spinning at 1000 RPM and feeding at a rate to get .0015-.002" per tooth chip load and start with 0.01" depth of cut and see how it goes. Don't be scared if you see sparks and chips glowing orange.

Be safe and healthy and good luck!

That suggestion worked fine. I used a smaller 1/4" carbide end mill but ran the spindle up to 2200-- as fast as it goes. Climb-cut Per chip load on the heaviest cut was .0027" with the chip coming off pretty hot (annealing) this was no problem for the spindle motor :-). DOC was about .010" across the full width.

-Dave

Skimming and AXA tool holder: which tool to use?

Aluminum

Diamond

Diamond

Diamond; Mod Squad

Diamond

Diamond; Mod Squad

Aluminum

Aluminum

Aluminum

Diamond

Diamond

Diamond

Cast Iron

Aluminum

Aluminum

Diamond

Hot Rolled

Aluminum

Aluminum

Aluminum

Similar threads