Spindle motor swap, or servo swap?

[Chuck Reamer]

Good day all, we received a new Tormach about 4 or 5 weeks ago. The machine is being used for injection mold work, mostly cutting 4140 and p-20 (prehard 29-36RC).

Machine limitations are becoming very apparent, torque is a problem. Low range doesn't have enough of it and high range has very little. Roughing pockets with cobalt roughers is problematic, using carbide to rough is nearly impossible.

I understand that it is a light duty machine, but it could be modified to be more powerful. A high torque motor would make a difference. There would be a lot more torque in low range, high range would also be a big improvement.

One other issue is the feed rates; do you think a servo conversion would be a big problem? Tormach offers consulting on this but they don't do it for cheap. Has any one of you switched to servo motors? If the feed rates could increase to at least 100 IPM, it would be a great improvement.

What other problems would the servos, or higher feed rates cause with the bearings?

Any input would be appreciated. These are just preliminary ideas and may not be worthwhile to pursue. If it can improve the machine then why not?

[Pres]

You gotta use smaller cutters (carbide is ok), go slower, and make more passes with less stepover.

Also, use a light mist cutting fluid with lots of air. (i.e. not flood)

It's not how fast you can remove material but how accurate.
A lot of patience will be your best solution.

HTH, Pres
Or, for around $100k a new HAAS can help you out.

[Chuck Reamer]

I am using smaller cutters and going slow, it is cutting surprisingly accurate.

I am still working on the patience thing, it just hurts to know that it could be done in one hour and takes 4 or 5.

Originally Posted by Pres Or, for around $100k a new HAAS can help you out.

That is the next step were working on, the Tormach will then be for plastic or little jobs.

[philbur]

I think removal rate is not directly about torque it's about usable horsepower at the cutter. Keeping the rpm high (at least so the motor is running at its rated rpm) by selecting an appropriate size cutter will help keep the HP up and hence the potential removal rate.

Just curious, why are you keen for 100 ipm for mold making. I would have assumed you spend 95% of the running time cutting material at low ipm.

Regards
Phil

Originally Posted by Chuck Reamer Good day all, we received a new Tormach about 4 or 5 weeks ago. The machine is being used for injection mold work, mostly cutting 4140 and p-20 (prehard 29-36RC). Machine limitations are becoming very apparent, torque is a problem. Low range doesn't have enough of it and high range has very little. Roughing pockets with cobalt roughers is problematic, using carbide to rough is nearly impossible. I understand that it is a light duty machine, but it could be modified to be more powerful. A high torque motor would make a difference. There would be a lot more torque in low range, high range would also be a big improvement. One other issue is the feed rates; do you think a servo conversion would be a big problem? Tormach offers consulting on this but they don't do it for cheap. Has any one of you switched to servo motors? If the feed rates could increase to at least 100 IPM, it would be a great improvement. What other problems would the servos, or higher feed rates cause with the bearings? Any input would be appreciated. These are just preliminary ideas and may not be worthwhile to pursue. If it can improve the machine then why not?

[Chuck Reamer]

Originally Posted by philbur Just curious, why are you keen for 100 ipm for mold making. I would have assumed you spend 95% of the running time cutting material at low ipm. Regards Phil

Im actually looking for 500+ IPM, for 3-D surface finishing of cavities. (not from the Tormach though, I am not that crazy) From the Tormach I would like to try and get 100IPM.


As far as appropriate cutter size, I find it to be a pain using only a 3/8" to pocket out a fairly large cavity.

[Andre' B]

Originally Posted by Chuck Reamer Im actually looking for 500+ IPM, for 3-D surface finishing of cavities.

Maybe want to be looking a machines with names like Yasda and Roders then.

As far as appropriate cutter size, I find it to be a pain using only a 3/8" to pocket out a fairly large cavity.

Bigger cutters need more HP, without enough power metal removal rate drops as the cutter gets larger.
More HP requires a larger machine or you will beat the slides and screws to death.

[Chuck Reamer]

Originally Posted by Andre' B Maybe want to be looking a machines with names like Yasda and Roders then. Bigger cutters need more HP, without enough power metal removal rate drops as the cutter gets larger. More HP requires a larger machine or you will beat the slides and screws to death.

I realize that its impossible to get to that feed, but 100IPM should be more than possible.

Big cutters need more HP, I understand that but a 1/2" endmill is not that huge.



Wow with all the responses so far, this is almost starting to seem like a bad idea......................almost.

[Willyb]

[QUOTE=Chuck Reamer;344741]Im actually looking for 500+ IPM, for 3-D surface finishing of cavities.QUOTE]

You have purchased the wrong machine if you want 500IPM. Don't get me wrong, the Tormach is a great machine for what is was designed for. It was never designed for 500IPM. You will need to spend allot more money to get those speeds.

Willy

[Chuck Reamer]

Originally Posted by Willyb You have purchased the wrong machine if you want 500IPM. Don't get me wrong, the Tormach is a great machine for what is was designed for. It was never designed for 500IPM. You will need to spend allot more money to get those speeds. Willy

I don't want or expect 500IPM from the Tormach, I was just responding to philbur. He was wondering why I would want 100IPM for mold work.

I agree the Tormach is a great little machine, and is even more than expected. With a little extra modification it would be a lot better, I am just wondering if any one has done the same.

[Willyb]

Hi Chuck

I would think that 100IPM would be easy for the Tormach. One of the main reasons for keeping it at 65IPM is it's open structure?

Willy

[philbur]

Hi Chuck Reamer,

I'm interested in the process for surface finishing. Could you please expand on this.

Regards
Phil

Originally Posted by Chuck Reamer Im actually looking for 500+ IPM, for 3-D surface finishing of cavities. (not from the Tormach though, I am not that crazy) From the Tormach I would like to try and get 100IPM. As far as appropriate cutter size, I find it to be a pain using only a 3/8" to pocket out a fairly large cavity.

[Andre' B]

Originally Posted by Chuck Reamer I realize that its impossible to get to that feed, but 100IPM should be more than possible. Big cutters need more HP, I understand that but a 1/2" end mill is not that huge.

No a 1/2" end mill is not that big and can be an advantage in softer stuff.

They tend to have the same number of cutting edges but can only be run at 75% of the RPM of a 3/8 for any given SFM.
In harder materials you often can not increase step over and feed enough to compensate for that without reducing tool life below that of the 3/8 tool. Because the larger radius of the tool means that for any given step over the cutting edge is in the cut longer and getting hotter and so it swings thru a larger temperature range every revolution.
And 1/2 end mills are 130 to 160 percent more money.

Wow with all the responses so far, this is almost starting to seem like a bad idea......................almost.

Not so much a bad idea as it is not a simple as it may seem.
I have seen a lot of hobby level machines that could feed at 100 IPM but very few that could accurately follow a complex tool path at that speed.


Personally I would go to servos just to get away from the singing stepper motors, I am not talking a servo motor with a step/dir driver either.


Philbur
Here is a good over view of this type of machining.
http://www.haascnc.com/solutions_3D.asp