1/2" shank dovetail cutter in Taig ER16 headstock?

[KTP]

I am building a cnc mill and using a Taig spindle (coupled to a 300 watt brushless motor). The spindle is ER16 rated at 10,000 rpm. The largest collet is 3/8".

I have several 45 and 60 degree brand new Weldon dovetail cutters that would be nice to use in the mill for making various adapters, but they have a 1/2" shank.

I am pretty sure they are hardened, so turning them down to fit the 3/8" ER16 collet is less than desirable. Is there some sort of 1/2" endmill holder accessory that mounts on the nose threads of the ER16 spindle? I did not see such a thing on the Taig website.

Would you even attempt running this type of dovetail cutter with the Taig spindle? The mill itself has 300 watt brushless motors, ground ballscrews, and THK linear bearing box ways. About 60,000 pounds/inch rigidity.

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[awerby]

You can probably make a 1/2" endmill holder for the Taig spindle, but this is not going to work too well on anything but foam unless you also change the belt drive. On the Taig, the 1/8" wide belts work fine, and save the motor by spinning if the tool bogs down in the work, but this will work against you in this high-torque application.

[KTP]

Hi thanks. I am using timing belt and gear pulleys to couple the motor to the spindle, not the Taig pulleys and belt. The motor is actually closer to 400 watts (1.5N-m running torque) and spins at about 10,000 RPM max so I am gearing it one to one to the spindle. It has a 2000 line encoder and I am running it with a sinusoidal drive and will be able to send an error signal to the software if the motor bogs down.

I like the Taig accessories and didn't want to reinvent a nicely made $10 part that I didn't see on their website for some reason.

[Superman]

ER16 collets can be purchased that go to suit 10mm shank cutters

Cutter shanks on HSS cutters can be turned down to suit your collet size, older cutters were quite soft, so if you can make a mark on it with a file, it can be modified

IMO, if you create an adaptor to go onto your holder, you are :-
- building in runout error
- cutting area is further out from spindle, creates more vibration
- losing holding strength, tool will flex , as cutting pressure is not being directed perpendicular to edge being cut (ie straight cutter) or directed back up the spindle (ie drilling )

[Ican]

I wouldn't want to use an adapter and that large of cutter with that much extension. Runout would eat your lunch and you could most likely do better work with a file. All machines have their limits... I would think this surpasses the limits for any small machine.

[KTP]

I wouldn't want to use an adapter and that large of cutter with that much extension. Runout would eat your lunch and you could most likely do better work with a file. All machines have their limits... I would think this surpasses the limits for any small machine.

Yes, I am tending to agree, it is just that I have about 6 of these cutters unused and they were probably $$$ each new. Hate to toss them. Might try to turn down the shaft to 3/8" if it is just surface hardened or not hardened. I only want to cut dovetails in aluminum.

[Ican]

Yes, I am tending to agree, it is just that I have about 6 of these cutters unused and they were probably $$$ each new. Hate to toss them. Might try to turn down the shaft to 3/8" if it is just surface hardened or not hardened. I only want to cut dovetails in aluminum.

I understand... I think most of us have been in that exact spot more than once. Most of the time you can turn those down... or have someone grind them down for you. Shucks, sell the things and buy some you can use. The best of luck to you.

[awerby]

I don't think that's going to work too well in aluminum, even if you did get the cutters to fit in your spindle. You'd need to slow that thing way down, but I doubt that motor will work at those low speeds with any torque at all, given that you're running it 1:1. If you really want to do this, then set up a pulley cluster to trade speed for low-range torque.

[Eldon_Joh]

If you can find a helical dovetail cutter you might have some measure of success.


I have a taig spindle mounted to a Z axis traveling on a weldment of 20-100 times the rigidity of the stock TAIG milling machine (depending on what axis you measure the rigidity in).. and a 3/8th shank 3/4th diameter 60 degree cutter... I can do that in cast iron. maybe aluminum, but not steel.

with a helical cutter it would be butter.


I can stick a 1/4th inch diameter carbide endmill in the spindle and machine features 2 inches away from the spindle with less chatter and cutting edge destruction than a dovetail cutter... (regardless of rpm).


so if i wanted to make a dovetail.. just tilt the workpiece the 30 or 45 degrees and cut it with a helical endmill....


it is not a simple matter of rpm. a straight fluted dovetail cutter is dealing with 100 times more cutting forces than a helical fluted endmill, simply because the machine does not have the stiffeness needed to push the radius of the cutting edge under the metal. it does for a helical end mill, but not a straight fluted end mill (aka dovetail cutter)

you can try to plunge the dovetail cutter into the work at the angle of the dovetail cutter.. but it will wear the edge of the tool like nothing else and you will still have to resharpen it a dozen times.

[KTP]

Ok, good points. I am used to my Shizuoka B-3V bedmill which is where I have used these cutters. I guess considering just the spindle motor on it weighs more than 4 complete Taigs I am a bit spoiled on vibration and chatter. I am selling the house and can't take the Shizuoka in the RV!

I will just put the cutters in the giant yardsale of tooling we will have soon.

[rockcliff]

The dovetail cutter is Probably one of my least favorite cutters, even on a full sized mill,,,,,,,,,,,

If you can make a collet to hold it in the lathe, turning the shank end to 3/8" is possible, , use a good grade of carbide and high spindle speed,

[CS900]

You can also buy dovetail cutters with a 3/8 shank. I have several of them for my Taig mill.

Also A2Z CNC sells set screw holders for 1/2" shanks that screw right onto the spindle threads. They are even on sale right now!

[icepick method]

You can also buy dovetail cutters with a 3/8 shank. I have several of them for my Taig mill.

Also A2Z CNC sells set screw holders for 1/2" shanks that screw right onto the spindle threads. They are even on sale right now!

Damn, sold out? Says not available now.

[CS900]

Call them up. Looks like they are clearing the old ones out for their new X-series holders so I would thing you could at least get one of the new styles in 1/2.

If not, let me know I may have a spare kicking around somewhere.

[icepick method]

I've read about the runout issues with the old ones, think they're worth picking up for $12?

[CS900]

Maybe. They also have (cheap) blanks that you could machine yourself.

Just pre-drill to a slightly smaller size, install in your spindle, mount a small boring bar in your vice and make a makeshift lathe with your spindle. It's the best way to ensure minimal runout. I've done it a few time with great results.