[gus]

As I calculate the bridgeport ratio it is 10:1, 2:1 pulleys driving a .2 pitch ballscrew, or maybe 5 mm, but same difference. I think Wells did it with right angle gearing. This ends up being a pretty pulley

[mactec54]

As I calculate the bridgeport ratio it is 10:1, 2:1 pulleys driving a .2 pitch ballscrew, or maybe 5 mm, but same difference. I think Wells did it with right angle gearing. This ends up being a pretty pulley

Yes with 2:1 the Bridgeport Boss 6 and above would be theoretically only be 7:1 with the Ballscrew addvantage, but that is driving a Ballscrew, that's a whole lot different than driving a Rack & Pinion like what they are doing here, the Boss 5 and before have a 1:1 ratio so would be 6:1 with the Ballscrew addvantage

[rcpilot82]

Mac,

I thought I had replied last night but I see this morning that it did not post.

When I talked to flash cut they said they used a 18 and 36 tooth gear on there setup. that's where I got the 2:1 ratio

I tried your settings above and they made no noticeable difference. DMM got back to me and after I provided them the same information we came up with for the z axis they came back and said there should be 2000 lbs of force acting on the Z.

I was looking at the old DC gear motor that was on the z axis and had the bright idea to tear down the motor and cut the motor shaft off essentially separating the motor from the gearbox. I am now in the process of re-building and adapting the now separated gearbox to try it. I know it will be overkill but I have calculated the gearbox to have a 40:1 reduction. coupling that with the 4:1 reduction of the pulleys should give me a 160:1 ratio acting on the pinion for the z axis. then factor in the 1:3.25 ratio of the Z.I think this will be ok since the servo has a max rpm of up to 5000 rpm which should yield a 101.56 in/min rate. At 500 rpm I still would have a 10.15 in/min rate. If my math and understanding is correct. No idea on torque though.

I should be able to determine if I can make these parts play nice together over the next few days.

My neighbor has a 90deg. reducer he is going to let me take a look at as well.

[mactec54]

rcpilot82

No it would not make a lot of difference changing the Drive parameters, but is were they need to be set for step/dir

You are not calculating your ratios correct, a 40:1 plus 4:1 is going to make it 44:1 not 160:1, then 44:1 minus the 3-1/4 for the rack & pinion will be 40.75:1 this is way more than you need, but you are working with what you have, a suggestion, would be not to use any timing pulleys belts, and you could mount the 750W motor direct to the input gear box shaft

So if you went with a direct drive to the gear box you would have a ratio of 36.75 : 1

What timing pulleys do you have that gives you 4:1 your 18 & 40 tooth timing pulleys, only give you 2.2:1

You would've needed an 18 & a 58 tooth timing pulley approximately, to give you a 1:1 ratio motor to quill

[rcpilot82]

Due to the configuration of the gearbox and how everything mounts, it is much easier to use the pulleys. I have the 18 tooth installed on the large 1.3 kw servo right now but its bore is too large for the smaller .75 kw motor.

Here is the proposed layout;

750 watt servo with 10 tooth pulley
input shaft of gearbox will have a 40 tooth pulley
gearbox is 40:1 reduction
Output shaft of gearbox coupled to pinion of Z axis
Z axis is 1:3.125

[mactec54]

Due to the configuration of the gearbox and how everything mounts, it is much easier to use the pulleys. I have the 18 tooth installed on the large 1.3 kw servo right now but its bore is too large for the smaller .75 kw motor.

Here is the proposed layout;

750 watt servo with 10 tooth pulley
input shaft of gearbox will have a 40 tooth pulley
gearbox is 40:1 reduction
Output shaft of gearbox coupled to pinion of Z axis
Z axis is 1:3.125

Are ok so you have a 10 tooth & a 40 tooth timing pulley that gives you the 4:1, that should've been enough, but marginal to run your Zaxes

Now I just talked to a Bridgeport parts seller, he measured the Pinion and if your pinion is the same, then it would not be 1 : 3.250 as we though, it is 1 : 3.534 , giving you a slightly higher gear to turn, so you will have 160:1 minus the 3.534=156.456 : 1 overall ratio with using your 10 & 40 Tooth Timing pulleys, not using the 4 :1 pulley set and direct mount, which would be best, you would have a ratio of 36.466 : 1, still way more than you need, but won't be a problem if you set it up correct

[mactec54]

rcpilot82

A question what were your steps/per set at in Mach3 for the Z axes, this may have been were some of the problem was

[rcpilot82]

I can not remember what the steps were, they are all messed up now.

Why is the 500 best for the electronic gearing? I believe my XY are set at 2048 right now. Should I change them? those axis are all dialed in.

Hopefully I will be able to get the details figured out on hooking the parts up without too much of an issue.

[mactec54]

I can not remember what the steps were, they are all messed up now.

Why is the 500 best for the electronic gearing? I believe my XY are set at 2048 right now. Should I change them? those axis are all dialed in.

Hopefully I will be able to get the details figured out on hooking the parts up without too much of an issue.

The Step/per are very important, as to how the motor is going to run, 500 has always be the recommended even from DMM, for step/dir use, this gives you a smooth running motor, also is easy to work out the step/per
when set at 500 you will need 2000 steps per rev

[vmax549]

You guys may want to check your math . IF you are driving a 40:1 gear box with a 4:1 reduction on the input the output at teh gearbox will be 160:1 . The Z will be dog slow at that ratio. IF this were a stepper you would need to look at teh Quill moving 1" per rev of the stepper. For a servo you can do a lot less to get better resolution on teh quill and still have faster Z.

Just a thought , (;-) TP

[mactec54]

You guys may want to check your math . IF you are driving a 40:1 gear box with a 4:1 reduction on the input the output at teh gearbox will be 160:1 . The Z will be dog slow at that ratio. IF this were a stepper you would need to look at teh Quill moving 1" per rev of the stepper. For a servo you can do a lot less to get better resolution on teh quill and still have faster Z.

Just a thought , (;-) TP

Yes you are correct I was hoping he could do it direct and then you would only have 36.466 : 1 which would not be not so bad, he has up to 5000RPM for his motor if he needed it

[rcpilot82]

Even using the pulley system I should have up to 110 ipm max out of the Z. That will be more than I ever use on this mill.

I am just hoping it has enough A$$ to do something.

[vmax549]

The real problem you face is IF you bottom out the quill against the table or part that ratio will produce enough force to rip out the Quill gears. ALSO is your gearbox rated for that input RPM?

Your original setup was functional you just selected the wrong servo to drive teh quill. Your Servo is a high speed low torque configuration where as you needed a low speed High torque unit.


(;-) TP

[mactec54]

vmax549

I use the same motors, on these Bridgeports, and they have more than enough Torque, the difference I use ballscrews, for the quill movement, plus I use them at 1 : 1 ratio

I think it would of worked with his original 4 :1 setup, if everything had been set correct, steps/per and drive parameters, it may have been marginal, but should of worked

[rcpilot82]

The max rpm at the gearbox input should be 1250rpm. The DC motor that the gearbox came from was 2500 rpm so it should be fine.

I did not size any of the motors, DMM did all the sizing based on the original DC motors. I know very little about servos.

I was told that I should have been able to run at 1:1 with the servo setup they provided. when that did not work, I went to the 4:1 pulley setup. when that did not work DMM sent me the larger motor and I went to the 18tooth/40 tooth setup. when that did not work, well That's where I am now.

Here is the tag off the DC gearmotor I replaced.

[mactec54]

The max rpm at the gearbox input should be 1250rpm. The DC motor that the gearbox came from was 2500 rpm so it should be fine.

I did not size any of the motors, DMM did all the sizing based on the original DC motors. I know very little about servos.

I was told that I should have been able to run at 1:1 with the servo setup they provided. when that did not work, I went to the 4:1 pulley setup. when that did not work DMM sent me the larger motor and I went to the 18tooth/40 tooth setup. when that did not work, well That's where I am now.

Here is the tag off the DC gearmotor I replaced.

That is what they worked it out from having that same ratio as the original motor was using the gearbox, with using that gear box you could've used a 400W motor,and run it direct 1 : 1, 4 : 1 would of been very marginal,( light loading/cutting ) if you had done a 6 :1 or 7 : 1 you would of be running, ideal would be 10 : 1

Make a coupling and direct drive the Gear box, with the 750w motor, then you can sell your timing pulleys etc

[vmax549]

Thinking about this again I am with Mactec on this one. I think there is something serious WRONG in your servo drive parameters setup . While this would not be optimum it SHOULD work just fine. That fact that you are erroring out on HIGH TEMP tells me teh servo drive parameters are wrong. IF they were right your could load it to teh max torque all day long and it not overheat.

IF your PID values are not right it will not pull a baby off the potty box.

I have a Series1 CNC here with a 1kw Quill drive that can be used as a punch press it is that strong.

NOW that said there IS a bug in Mach3 when using certain canned cycles that will Trip Z off . The z will do uncontrolled overspeed moves DOWN and the drive will trip out on overload. But that is a random bug.

[rcpilot82]

I asked DMM about this and they said there is not an error for over torque. They said that pretty much if it over torques it overheats and throws that error.

I have tried well over a dozen different settings on the drive based on DMMs suggestions. I also tried Mactecs' settings all to no avail. I have verified that the motor parameters are correct through DMM and they have verified the firmware on the drive.

The gearbox is ready to go back together and the input shaft that needed turned down will be done today. With any luck I should be able to test it out tomorrow and see where it stands.

VMAX, Could you tell me about the bug in Mach with canned cycles?

[mactec54]

I asked DMM about this and they said there is not an error for over torque. They said that pretty much if it over torques it overheats and throws that error.

I have tried well over a dozen different settings on the drive based on DMMs suggestions. I also tried Mactecs' settings all to no avail. I have verified that the motor parameters are correct through DMM and they have verified the firmware on the drive.

The drive setting may have even been correct at some stage,they have adaptive control, so you only need the setting to be close, and the Drive will set to suit the load, but having the electronic gearing set at 4096 Default,was not going to help, 500 and you would of had some steps/per to play with,If the steps/per ,Velocity & acceleration were off, it's was not going to go anywhere

From Dmm PDF manual as you can see the 4096 is best used if you are using Analog, Position Control, You are using Step/Dir, so 500 is the best setting for your electronic gear setting, this may be able to be changed with using the Gear Box, but still most likely will be best set at 500

Gear number (Gear_Num) is set from 500 to 16,384, default value is 4,096. Gear number provides an
electrical gear ratio: 4096 / Gear_Num, from 0.25 ~ 8.192. For example, if Gear number = 4,096, then
16,384 input counts from pulse will turn motor exactly one revolution. If Gear number = 500, 2,000 pulses
will turn motor one revolution. Gear number parameter is only applicable to position servo mode.

So what kind of steps per did you have set with the 4096 setting

[vmax549]

The odd thing is we KNOW that the original design worked fine with a Flashcut setup. The larger motor you used would have PLENTY of torque to do teh job just as welll as a Flashcut setup.

THAT IS IF teh motor was actually putting out teh torque it is suppose to put out . I would bet for some reason it was NOT. (;-) Either a DRIVE problem or a PID value problem . Like I said earlier IF teh PID values are wrong for that setup it will NOT have any power to speak of.. ALSO when you changed motros did you change drives to match the larger motor ??? It would NOT have used teh same PID values.

What you need to be concerned with is you are feeding a very low rated gearbox more that 1 hp now

(;-) TP