Thinking about getting an Aloris CXA-5 3MT Toolholder...

[gt40]

Has anyone used one of these. drilling with the tailstock is tedious with large holes. I am thinking one of these tool holders with an mt3 drill bit would allow me to use power feed on the lathe.

Here is a pic:

Concerns:

Is this practical?
How hard to center are these?
Is using the power feed to drill risky?

 

[precisionworks]

Never tried one, so they may be great or they may be awful :nana:

My spade drill cuts with little effort in either aluminum or mild steel, and it makes a 2" hole. For your MT3 ram, spades are available up to 1.75", and sometimes very cheap on eBay ($25 for mine).

 

[kromeke]

I've had problems with the off set nature of the holder. Feeding with the carriage puts a torque on the toolpost and can cause it to shift.

As a result, the toolholder does not get used much. Not saying that it doesn't work, but one that would attach to the left hand dovetail would potentially eliminate this torque, but I haven't seen an off the shelf holder that mounts on the left dovetail (of the tool post).

 

[gt40]

I've had problems with the off set nature of the holder. Feeding with the carriage puts a torque on the toolpost and can cause it to shift.

As a result, the toolholder does not get used much. Not saying that it doesn't work, but one that would attach to the left hand dovetail would potentially eliminate this torque, but I haven't seen an off the shelf holder that mounts on the left dovetail (of the tool post).

Thanks for the info.

 

[darkzero]

Good post, I'm curious too.

Seems like a MT TP holder would be annoying to quickly setup center? And exactly what would happen if you were to start drilling slightly off center? Would you might get away with it or just destroy the workpiece?

I haven't had any issues drilling with the tailstock yet, I just wish I had one more lower gear like in the 30-40 RPM range for the larger holes.

gt40, in regards to your other thread with the Morse Taper drills. Do you have the vertical or horizontal slot in you tailstock ram for the MT tang?

In shop class when drilling 1" holes & larger, the tang prevents the MT drills from spining at high torque low RPM. I don't have the slot on my lathe & I'm wondering how to seat a MT drill in the tailstock tightly.

Barry recommends using a hammer to seat the taper & is what I do with the drill chuck. I don't own any MT drills but I don't see using a hammer to seat one to be an option. In shop class I just grabbed onto the MT drill with a rag & slammed it into the tailstock. It seated ok but when I was drilling CRS at 30 RPM the taper eventually broke loose but the tang & feed kept it going. What is the proper way to seat one without the use of a tang or is it not recommended?

 

[precisionworks]

using a hammer to seat the taper

Hard to beat the BFH, especially if it's four pounds of solid copper

If you're concerned about hammering on the point of the drill (which is pretty tough in the larger sizes) make a "drill cap" out of any piece of solid steel round stock & strike the cap to drive the drill tang into the taper.

Another method is to hand seat the tang into the taper & bring the tailstock up close to the chuck - put a piece of thick aluminum between the drill point & the chuck, lock the tailstock down & crank the ram feed until it will turn no more. Not quite as positive as the BFH method but probably easier on tooling.

 

[gt40]

Good post, I'm curious too.

Seems like a MT TP holder would be annoying to quickly setup center? And exactly what would happen if you were to start drilling slightly off center? Would you might get away with it or just destroy the workpiece?

I haven't had any issues drilling with the tailstock yet, I just wish I had one more lower gear like in the 30-40 RPM range for the larger holes.

gt40, in regards to your other thread with the Morse Taper drills. Do you have the vertical or horizontal slot in you tailstock ram for the MT tang?

In shop class when drilling 1" holes & larger, the tang prevents the MT drills from spining at high torque low RPM. I don't have the slot on my lathe & I'm wondering how to seat a MT drill in the tailstock tightly.

Barry recommends using a hammer to seat the taper & is what I do with the drill chuck. I don't own any MT drills but I don't see using a hammer to seat one to be an option. In shop class I just grabbed onto the MT drill with a rag & slammed it into the tailstock. It seated ok but when I was drilling CRS at 30 RPM the taper eventually broke loose but the tang & feed kept it going. What is the proper way to seat one without the use of a tang or is it not recommended?

I just use a dead blow hammer to seat the taper. I do this after having a 1 1/2" mt3 drill start to spin in the taper. Now it doesn't.

 

[wquiles]

I just use a dead blow hammer to seat the taper. I do this after having a 1 1/2" mt3 drill start to spin in the taper. Now it doesn't.

+1

Same here - dead blow hammer with its soft, rubber face works perfect for me.

 

[olephart]

exactly what would happen if you were to start drilling slightly off center?

You would just have a slightly off center hole. Using an undersized bit, you could true it up with a boring bar.

Intentionally off centering a hole by adjusting a 4 jaw was common before cnc stuff came along. Sometimes it was considerably away from center and additional weight had to be added to balance the rotation. You could use this technique to tri-bore a mag tube for 18650's.

 

[65535]

You would just have a slightly off center hole. Using an undersized bit, you could true it up with a boring bar.

Intentionally off centering a hole by adjusting a 4 jaw was common before cnc stuff came along. Sometimes it was considerably away from center and additional weight had to be added to balance the rotation. You could use this technique to tri-bore a mag tube for 18650's.

I think he means if the drill was off rotational center not the part. If the drill is not on the same axis as the workpiece.

If that were the case:

First when starting the op. the drill would vibrate like crazy as it walked in circles around the axis, bending. Now if it did catch and start cutting the workpiece, you'd get lots of vibration which could break the bit, cause damage to the headstock bearings (if it happens multiple times) and the worst, throw your part, which needless to say is about the worst thing that can happen in machining.

 

[olephart]

You're right, of course. I had his question bass ackwards.

 

[darkzero]

Hard to beat the BFH, especially if it's four pounds of solid copper

If you're concerned about hammering on the point of the drill (which is pretty tough in the larger sizes) make a "drill cap" out of any piece of solid steel round stock & strike the cap to drive the drill tang into the taper.

Another method is to hand seat the tang into the taper & bring the tailstock up close to the chuck - put a piece of thick aluminum between the drill point & the chuck, lock the tailstock down & crank the ram feed until it will turn no more. Not quite as positive as the BFH method but probably easier on tooling.

Thanks Barry for those ideas. Also never would have thought to assume the drill bit's chisel & cutting edges would withstand a blow of a BFH. Then again a copper or lead mallet is pretty soft. I only use a rubber or soft face hammer, I think my brass hammer would do damage.

I think he means if the drill was off rotational center not the part. If the drill is not on the same axis as the workpiece.

If that were the case:

First when starting the op. the drill would vibrate like crazy as it walked in circles around the axis, bending. Now if it did catch and start cutting the workpiece, you'd get lots of vibration which could break the bit, cause damage to the headstock bearings (if it happens multiple times) and the worst, throw your part, which needless to say is about the worst thing that can happen in machining.

Yup, thank you for that perspective. I guess an endmill might be more forgiving in a tool holder as long as it's still sharp & not fed to fast. I'll just stick with the tailstock.

 

[precisionworks]

The best way to tell if a MT shank is well seated is by the amount of force needed to free the shank. A lead hammer or copper hammer seats the taper really well, and a great deal of torque on the tailstock feed wheel is needed to release the taper. A soft faced hammer (wood, plastic, rawhide, etc.) gives a less secure fit, which is indicated by the small amount of torque needed to free the taper.

In most production shops or job shops, each lathe has a Tommy bar, roughly 18" long, that fits through the spokes of the ram feed wheel. Almost any twist drill will feed well when pushed with that much torque. Tommy bars work well on larger tailstocks, usually 4MT, 5MT or 6MT. Be careful if you try one on a smaller tailstock ram.

 

[bstrickler]

First when starting the op. the drill would vibrate like crazy as it walked in circles around the axis, bending. Now if it did catch and start cutting the workpiece, you'd get lots of vibration which could break the bit, cause damage to the headstock bearings (if it happens multiple times) and the worst, throw your part, which needless to say is about the worst thing that can happen in machining.

Not just the worst, but also one of the most painful!!! Especially when you have a 1/4 pound chunk of aluminum hurtling at your forehead before you notice (I made the mistake of feeding too fast, too far out, with the chuck only holding about 1/2")!!! Ripped it right out of the jaws, and threw it at my face (luckily, I was standing off to the right, so it whizzed past my ear). Scared the hell out of me. If I had been standing 6-8" to the left, it would've smacked me right in the face.

Lesson learned.

~Brian