Thread: VFD and 3 phase conversion of my 45 size gear head mill

Sorry for the confusion guys..

that is about what I use on the mill for size:
OMRON E2E-CR8C1 Proximity Sensor Switch 4mm | eBay
only that this particular model has a too small sensing distance of 0.8mm. You would have to look up the data sheet to find a model number with greater sensing distance. And it may take some searching and waiting to find it NOS at a reasonable price, say under $20.

Stuart, if you already have a capacitive sensor no worry, give it a try. The reason I used inductive was price, a few years ago capacitive sensors did cost new around $150 and inductive ones about $50. But now I see you can buy Chinese ones on eBay for $15 or so. In theory capacitive sensors should be superior to inductive ones - only maybe not if liquids are involved. But you do not want to use it inside a wet gearbox, so it should be fine.

Sorry for the confusion guys..

that is about what I use on the mill for size:
OMRON E2E-CR8C1 Proximity Sensor Switch 4mm | eBay
only that this particular model has a too small sensing distance of 0.8mm. You would have to look up the data sheet to find a model number with greater sensing distance. And it may take some searching and waiting to find it NOS at a reasonable price, say under $20.

Stuart, if you already have a capacitive sensor no worry, give it a try. The reason I used inductive was price, a few years ago capacitive sensors did cost new around $150 and inductive ones about $50. But now I see you can buy Chinese ones on eBay for $15 or so. In theory capacitive sensors should be superior to inductive ones - only maybe not if liquids are involved. But you do not want to use it inside a wet gearbox, so it should be fine.

Hi Chris,

I have nearly talked myself out of mounting inside the gearbox. I'm sure an inductive or Hall effect sensor would work OK in there but it's the "electrical plumbing side" that I'm going cold on. I had thought of doing what you suggested and turn up a flanged sleeve that would screw to the outside of the head in line with where a gear is inside and then tapping a thread inside the sleeve to house the sensor. This would mean making a big hole (20mm or so) in the side of my mill head. That's not going to happen!

On the other hand, my spindle protrudes about 30mm below where the quill finishes underneath. I may make a notched collar that can be clamped there. This would mean Zero mods to the quill or spindle, a sensor that is accessible, not immersed in oil and easily removed.

Also means I can start putting my mill head, gears and new bearings together! YAY!

Thanks for your help. You have redeemed yourself!

Hi Chris,
Thanks for all that, I'll have more of a play if the tacho ever turns up! ......... tomorrow maybe.
I'll likely order a couple of Inductive ones to play with also as they might be easier to mount and 100Hz is a little low if I pick up on both dogs. We'll find out soon I hope.

Stuart

Bought one of these earlier today.eBay Australia: Buy new & used fashion, electronics & home d

Also has a freq, response of 500Hz so should be fine.

Simon

I see yours and raise you 1 each of these.
Rectangle 5mm Inductive Proximity Sensor Switch Detector DC 6-36V 300mA NPN NO | eBay

DC 10-30V 4mm Inductive Green Proximity Sensor Switch 3-wire PNP NC SN04-P2 | eBay

Great another project. just what I need lol

Stuart

Originally Posted by Stustoys

I see yours and raise you 1 each of these.
Rectangle 5mm Inductive Proximity Sensor Switch Detector DC 6-36V 300mA NPN NO | eBay

DC 10-30V 4mm Inductive Green Proximity Sensor Switch 3-wire PNP NC SN04-P2 | eBay

Great another project. just what I need lol

Stuart

The second one is the style i bought for my stop switch. Still waiting on it to turn up......not that it matters with no DC motor

Originally Posted by Ueee

The second one is the style i bought for my stop switch. Still waiting on it to turn up......not that it matters with no DC motor

Perhaps a motor will turn up before the sensor does

OK. How you guys going with your tacho?

Well i finally got some time to work on the VFD project. I finished the adapter plate which comprised of a 4 hole pattern to match the existing bolt holes on the mill and 4 larger bolt hole pattern to match the 100L size motor I have. Half this adapter plate was made prior to owning my rotary table, talk about easier to drill 4 holes accurately spaced! Love my rotary table!

Anyway, since I had the mill head off, I also took liberty in replacing all the chinese bearings with nice NTN and FAG ones. I also made a decision to replace the ZZ metal cage bearings with 2RS (rubber seal) bearings. They have a little more frictional resistance because of the seals. Some of you may be interested to know that after putting it all back together and firing up the motor, that all the backlash noise, clunkety clunkety backlash noise has gone! All I hear now is the wirrrr of the gears not unlike my lathe. At higher speeds the gear noise is nearly all overcome by the noise coming from the fan of the motor, even with the spindle and quill in. Very happy with the result. The extra HP has not gone a stray, even at 5Hz with the spindle doing about 75RPM (gear setting H2), there is no way I can stop it with my hand. I was thinking that I would have to select between L2 and H2 to achieve the entire usable RPM from 50 - 1600rpm but it look like I may achieve this with just H2. I guess machining will be the true test!

Now to rewire the entire thing! This will be fun. If I want to run everything from a single control box (tacho, speed control, jog, head up/down, light, coolant, tapping function and one shot lube) then I'll need about 18 wires into it. I'm thinking of using a DB25 connector since it will all be switching and signal currents and nothing heavy.

Next part will be to make the induction sensor pickup which will be at the bottom of the quill. I'm still waiting for the sensor to arrive. I think I will be waiting months since it usually happens that way when I'm waiting on it!

Cheers,

Simon2012-11-20_19-19-22_851.jpg2012-11-20_19-19-58_630.jpg2012-11-20_19-20-14_575.jpg

Well done Simon. Looks like you have a fair amount of wiring in your future.
I'm also waiting on my tacho etc. Still I have plenty else to keep me busy lol

Stuart

Thanks Stuart,

Yes a bit of wiring. I was hoping to leave all the original wiring in place (Making permanent changes or mods scares me a bit. At least if all stuffs up I have a fall back to original spec!) but this will be at best messy and at worst completely ridiculous as most of the original wiring will be obsolete including two of the latching relays. Adding my wiring on top would make it a nightmare so I think I am going to rip out everything that is no longer needed (after taking many pictures on my phone... just in case) I just think I need to bite the bullet and be honest with myself, once I get this going I'm never going to give up variable speed or go back to original!

Stuart (and/or anyone else) can I run an idea by you?

As part of the refurb, I need 12V DC for the tacho and also for the 10W LED downlight I plan on installing up underneath the head for a work light. I'm thinking of using one of these as a power supply DC 12V 2A 24W Switch Switching Mode Power Supply Driver For LED Strip Light Lamp | eBay

What are your thoughts on this? I'm a little wary as I know that some downlight power supplies produce 12AC and not DC and do not power up unless they have a certain load placed on them. If the worklight is off, will the tacho still run?

It does say 0 - 2A and 12DC. If it would work then it's a cheap, small and easy way to get the required 12V. It can be housed in the relay box of the mill and be hard wired in obviously so no need for ANOTHER power point which would be the case if I used a plug pack.

Simon

Yeah I tend to keep all the parts I pull off even though there is almost 0 chance I will need them.

How are you going to handle the latching?
How does the tapping function work?
Is everything inside that one control box?

I'm guessing like you that the power supply would be ok
Most pc power supplies need a load on the 5V line to power up. A 300ohm* resistor does the job, so I assume if you have a problem with that supply a resistor would fix that also.

Stuart

*from memory

Hi Stuart,

The latching for the main motor is no longer needed as it will be done through the VFD using the standard 3 wire system. The motor that moves the head up/down has no latching as it's only controlled with momentary activation via two regular contactors. These will stay.

The tapping function, I've never used it and was going to discard it to keep thing simple (electrically) but have since thought I may try and keep it. OK this is how it works. There are two limit micro switches inside the head, one higher than the other. The lower one triggers the motor to go from FOR to REV and the one at the stop is essentially a STOP button. The depth gauge on the front face plate is adjustable on a threaded rod, this is what touches the micro switches, so you work out what depth you want to thread to, disengage the quill fine feed, use the handle to lower the quill/tap to the job. You then select the slowest speed and feed the tap into the hole. The thread self feeds the quill into the job and when it reaches the pre-set point, the micro switch (inside the head) is triggered with the adjustable quill depth gauge which triggers the REV function. When the tap withdrawals from the job, the quill spring returns it to the top, triggering the upper micro switch to turn the motor of.

There is a switch on the panel to either switch on or off this function. The two micro switches would need to be incorporated into the VFD 3 wire control circuitry. To simplify, I could do away with the power off switch.

The mill has two control boxes, one at the rear containing the the relays and the one at the front, a crappy folded metal job with the control switches, this will be replaced with either an ABS or diecast box with tacho and other switches. The rear relay box will be neatened up and hopefully a 12V power supply will fit in there.

Simon

Hi Simon,
When using the three wire system, dont the fwd and rev signals need to latch?(yeah I know the manual shows momentary but I thought you'd told me they needed to be switches? I havent used three wire myself, I'll have a play this afternoon.)

Should be easy enough to keep the tapping function.(Does your quill have powerfedd? you could use the tapping functoin with a boring head, though you would want it to stop instead of rev, but that should be doable)

Stuart