[digits]

wow that's big, is it just clamped to your spindle flange or id you add a keyway?
definitely heavy duty looking and better than the plastic gears by far.
Hoss

It's just clamped onto the top 8mm or so of the OD of the spindle at the moment. I suppose if I removed the spindle, I could drill a hole for a radial grub screw - I can't really mill in a key way, let alone one 14mm wide to fit the taper-bush!

[photomankc]

So you just need a bushing then for that spindle pulley right?

[digits]

So you just need a bushing then for that spindle pulley right?

The reason I went for taper-lock rather than boring out a normal HTD pulley to size was that I don't have much luck (read that skill/ability) producing press-fit parts on my mini-lathe. I therefore don't have much faith in me producing a bushing to fit the spindle either...

[LongRat]

Any more progress on this?
Mine is apart this weekend, planning a 2-speed belt drive myself. I am going to use A-section v belts though, and nothing like the heavy duty stuff you are running! One thing that doesn't seem right though, the motor speed. I'm getting a ratio between the motor pinion and the gear it drives of 19:39. Then about a 1.5:1 ratio from there to the spindle when in high gear. That is a total ratio of about 3:1 from the motor to the spindle. You would need something close to 5000 RPM at the motor to achieve the stock 2250-2500 RPM spindle speed max, not the 2740 you have measured. Are you sure you measured that right? I don't have a tacho so I can't confirm the speed of my motor. If the motor is 5000 RPM, I going to shoot for ratios of 1:1 and probably 3:1 on my pulleys. One more thing to note, my motor has a direction of rotation arrow on it which is opposite to the direction the motor actually spins when running in the forward direction. This is very confusing and suggests to me that the motor may actually be timed totally wrong for forwards operation in this machine.

[digits]

Any more progress on this?
Mine is apart this weekend, planning a 2-speed belt drive myself. I am going to use A-section v belts though, and nothing like the heavy duty stuff you are running! One thing that doesn't seem right though, the motor speed. I'm getting a ratio between the motor pinion and the gear it drives of 19:39. Then about a 1.5:1 ratio from there to the spindle when in high gear. That is a total ratio of about 3:1 from the motor to the spindle. You would need something close to 5000 RPM at the motor to achieve the stock 2250-2500 RPM spindle speed max, not the 2740 you have measured. Are you sure you measured that right? I don't have a tacho so I can't confirm the speed of my motor. If the motor is 5000 RPM, I going to shoot for ratios of 1:1 and probably 3:1 on my pulleys. One more thing to note, my motor has a direction of rotation arrow on it which is opposite to the direction the motor actually spins when running in the forward direction. This is very confusing and suggests to me that the motor may actually be timed totally wrong for forwards operation in this machine.

No, I'm not at all sure about the motor speed - my tacho had not been used in about 2 years, and so had suffered a battery leak and some contact corrosion. I cleaned it up a bit but the only AA's I had to had were 1.2v NiMh rechargables - I don't think it liked the lower voltage, especially with slightly corroded contacts. I've got some new batteries, I can give it another go today or tomorrow...

Did you work out the gear ratios by counting teeth, or from your parts manual? I am pretty sure the numbers in my exploded diagram are all from a BF20

As for the motor direction - you are most probably correct - it always did seem rather noisy to me when out of the mill -and it reminded me of the noise I heard when running brushed DC motors the 'wrong' way...

I guess it's some sort of click from the bushes against the commutator segments...

[LongRat]

Motor pinion to secondary gear are exposed, so I counted teeth (19:39). For the secondary stage (in the hi-lo selector gearbox), I just turned the spindle one rotation and observed the number of rotations the aforementioned secondary gear performed. I have never opened up the gearbox to count the teeth and I don't intend to open it up to do the belt drive, I will just slap that on top of the existing set up.

Sorry I have a correction to make. The spindle rotates about 1.4 revs for every turn of the secondary gear (not the other way round). So the HI selection in the gearbox actually gears UP slightly. This makes the required motor speed for 2250RPM at the spindle slower than 5000RPM. It is actually

2250*(39/19)/1.4 = 3307 RPM at the motor.

[digits]

Motor pinion to secondary gear are exposed, so I counted teeth (19:39). For the secondary stage (in the hi-lo selector gearbox), I just turned the spindle one rotation and observed the number of rotations the aforementioned secondary gear performed. I have never opened up the gearbox to count the teeth and I don't intend to open it up to do the belt drive, I will just slap that on top of the existing set up.

Sorry I have a correction to make. The spindle rotates about 1.4 revs for every turn of the secondary gear (not the other way round). So the HI selection in the gearbox actually gears UP slightly. This makes the required motor speed for 2250RPM at the spindle slower than 5000RPM. It is actually

2250*(39/19)/1.4 = 3307 RPM at the motor.

Well I made the motor to be 2740rpm with my tacho and duff batteries for a spindle speed of 1970 in high gear- with your formula, that would imply a motor speed of 2888 rpm from 1970 at the spindle, well within the margin of error IMO...

Guess I need to up my max-speed pot a bit to get 3300 rpm on the motor...

[LongRat]

I'm interested to see if you've finished the belt drive on your machine yet. With the ~3000 RPM you need at the motor, running a delta-wound AC motor at 50Hz will get you 2800 RPM which is fine, that is what I used on my conversion.
Now my concern turns to the taper roller bearings. Mine get insanely hot. When you had your spindle apart, did you measure the size of these bearings?

[digits]

I'm interested to see if you've finished the belt drive on your machine yet. With the ~3000 RPM you need at the motor, running a delta-wound AC motor at 50Hz will get you 2800 RPM which is fine, that is what I used on my conversion.
Now my concern turns to the taper roller bearings. Mine get insanely hot. When you had your spindle apart, did you measure the size of these bearings?

Hi LongRat - sorry I've not even set eyes on my mill in weeks

Here are the pics I took during disassembly:


6207 on the base of that gear, I think.



And I think that's a 6211 on the top:


I've no idea what bearings are in the quill though as I didn't take it apart...

I hope that helps a little.

[LongRat]

Thanks.
You may have seen my temperature chart in the other thread. Based on that and these bearing sizes, I'm pretty confident I am safe for running extended periods at 4000RPM.

[pa3eka]

Hello all
From an other BF30 user from de Netherlands
The complete head of the mill gets hot , about 50 degrees celcius after a 1/2 hour
Even the Dig. readout stops counting because the sensor get,s to hot
The upper bearing hole is to small
Replacing the bearing did not help to solve the problem
grtz
Bert

[digits]

I don't suppose you know whether it's the bearings on the gear, or in the quill that are actually overheating?

I've just cut my first test part in 3D, and I could really do with some more rpm and a whole lot less spindle/motor noise - it's practically impossible to hear the cut!

[LongRat]

It's the taper roller bearings in the bottom end of the spindle.
I've settled on a speed of 3500 RPM and I will never go back. I can run for hours, yes the head gets hot but it is safe.

[digits]

Do you think that if you could fit better bearings if you were willing to lose the quill? Now that my mill is CNC'ed it just seems like another source of slop...

[LongRat]

You could fit better bearings and still keep the quill. I use it all the time so won't be giving it up. Remember my spindle won't get anywhere near the surface of the table without the quill extended. If you got rid of the quill it would imply that the bearings you would install would be larger, which generally would have a lower speed rating.

[digits]

Well, it's far from finished, but it's getting there at last - I've temporarily mounted my 1.6kW Servo on the mill for a trial run. I've had to remove my power-drawbar for now, but I think they'll both just about fit on there



The wiring still needs a fair bit of work - I really need some strain reliefs and some heat-shrink, but it works well enough for a test run:



Unlike most VFD's I've seen, the control panel on this is rather risky to use - literally mm away from the mains input and the high-voltage motor outputs!

I have rather gingerly run the thing in speed control mode via the front panel - it seems much quieter than the stock motor + gearbox, but it's not exactly silent at the motor full speed of 3,000 rpm. I will take some sound level readings when I run it again.

[nolage]

No more massive pulley?

[digits]

No more massive pulley?

No, that was never going to fly! With these pulleys, I have a 1.1:1 ratio between the spindle and the motor - so a max speed of 3,300rpm at the motors nominal speed. That seems to be what the bearings can take without getting too hot according to others that have tried it.

[nolage]

What a shame, it gave me quite a laugh.
Good luck!

[digits]

LOL, thanks!

I've still not cut any metal with this, but I did a bit more wiring at the weekend, and I have an E-stop finally!

This motor is blooming awesome! I hit E-stop at 1,000 rpm and the spindle just stops instantly - the drive is clearly doing active braking. More impressively though, clear the E-stop and it goes back to 1,000 rpm with no appreciable spin-up.

It can't quite manage that trick from 3000-0-3000, the spin-down is under a second, but it just alarms out to tell me it can't manage the instant restart, but I do wonder what it could manage if I really could supply it with 30A!

I still need to figure out how to get EMC2 to output step/direction to control the motor speed, but I think this thing has some real potential for CNC tapping

It's pretty quiet too, as I've removed all the plastic gears. I measured 60dB at 1,100 at the spindle, and 74dB with 3,300 rpm at the spindle (max speed). The lower spindle bearing was warm after a few mins at max speed, but not too hot to touch.