My X2 mill is losing power

[Lykle]

I think my X2 (Real Bull) milling machine is losing power.

It seems even the simplest jobs it just stops. Drilling 10 mm in stainless steel. It stops, even with a fresh drill and clean stainless steel. And even with a pilot hole of 4 mm. It is getting silly.

I modified the mill with a belt drive, but kept the original motor. It is a variable speed motor that came standard with the mill. I think it is the power board that is giving me the trouble.

Now, how do I check if it is the board? What else could it be? I have no idea and am stumped. Of course I had a look at the board, but all looked normal, no blackened parts or wires looking suspect.

Any suggestions what to measure or check? Thank in advance.

Lykle

[lordedmond]

Turn off the power

and check the motor brushes if they are worn replace them ( less than 5 mm in length )


Stuart

[Chuck in E. TN]

I second checking the brushes.
I had a similar problem with my mini lathe, and one of the brush caps was broken. Bought a replacement set plus a spare.
Chuck

[Lykle]

Thanks for the advice.
I went and had a look, no luck with the brushes, nice and long.

And as fro the power, I switch everything off every night. I have a main switch that switches off the power to all my machines, next to the door. it is now automatic to hit it when I leave. Simple.

Lykle

[John Rudd]

Lykle,
Can you upload a foto of the control board?

or tell us if its KBIC/KBLC board or something else...?

Narrows down what the problem may be...

[doug mclaren]

When my X1 mill started doing that sort of thing it turned out to be the speed control pot. Very simple to replace.

[velocette]

Hi
Are you losing power or is it that the job in hand is stalling the motor. Stainless steel is a very tough metal to work with.

Cutting oil is essential for good results.

If the belt drive is less than 5.45 to 1 then there is reduction in the torque available at the spindle

1100 rpm is the original low speed on an X2 Mill with the motor on FULL speed of  6000 RPM 

 Therefore if the spindle speed is is greater in low speed then the drop in available torque is proportionately less.

Please check the ratios on the belt drive you have fitted.

This is the specs for a Steele's belt drive kit lifted from their sales pitch.

""Change speeds without any tools. Simply remove the guard, loosen the lever locks and move the belt from one pair of pulleys to the other. Low speed range is 0-1700 RPM. High speed range is 0-4300 RPM.""

This equates to at least 30% reduction in torque at the spindle.

Hope this is some help  I Added a Photo of my Mk 1 belt drive

Eric

[Lykle]

I thought the power issue was resolved. I twiddled the pot meters a bit and it seemed to be better.
But then yesterday I was drilling a 10 mm hole and again it stalled. Even though I had pre-drilled with 5 mm.
And it was a relatively new drill too.

Anyway, I have attached a photo of my control board. I wonder what the end result will be.

Thanks for any help you guys can give me.

Lykle

[John Rudd]

That's a KB board...

What experience do you have  of electronics?

I can send you the schematic to work through...

The majority of faults are  caused by dried up capacitors/zener diodes/dodgy potentiometers..

Component replacement isnt particularly easy because the parts are smd or pth...

I'd start by checking the 12v rail and the 22v rail, but you need a schematic...pm me your email addy and I'll email you a copy

[Lykle]

After receiving the schematic from John (Thanks John) I realise this is going to be a bit more of a challenge that I initially thought.

For instance, John told me to check the 12 and 22V rails. I can only find the 12V one on the schematic.

Does anybody know what the IR and CL pot meters are for? MIN, MAX and Accel I can figure out. But the other two, no not yet.

Lykle

[hopefuldave]

Hi Lykle,
CL is the current limit adjustment, if set too low it could reduce the motor torque, set too high it could cook the motor... If you fiddle with it, put an ammeter in one of the motor leads, reckon about 4.5 Amps per HP on 220/240v, 9 Amps on 110/120. EDIT - AT FULL LOAD - 1 hp load is about a cubic inch per minute of hot-rolled steel with HSS cutters and flood coolant, figure a 1/2" endmill, 180 rpm, 1/16" depth of cut at 32"/min feed, cutting a slot...


The 'horsepower resistor' (tan block on the daughter-board) should be marked with two values, the higher is for 220/240 volt supplies (180 to the motor), t'other for 110-120 (90 to the motor) - check the marked value!

IR is the IR compensation adjustment, which allows for the *resistive* losses in the armature at low rpm where that increases relative to the motor's back-emf (the 'generator' voltage from the coil cutting the magnetic field, proportional to rpm) to maintain torque at low rpm... There's a sweet spot, too far one way and the motor stalls under load at low rpm (Aha!), too far the other and the motor starts cogging (moving in jerks at low rpm rather than smoothly) 

If you feel confident and competent to have a twiddle, bear in mind that the KB boards aren't isolated from mains, so keep your fingers clear and your other hand in your pocket...

If the belt-drive doesn't give as much speed reduction / torque multiplication, you may be limited by the change in gear ratio, as others have pointed out...

Just my ha'pennorth,
Dave H. (the other one)

[John Rudd]

For instance, John told me to check the 12 and 22V rails. I can only find the 12V one on the schematic.


Lykle

Lykle,

The 22v volt rail is straight off the big 15k resistor R17a...and is stabilised by ZD2 which is on the left side of the board looking down with the pots along the front...

If either of these rails are low, then the zener diodes are first suspects...followed by C19 and C1

(I've actually had one of these boards fail where the LM324 has been responsible for low voltages)

[ibuildstuff4u]

Take the board out and replace it with a KBIC 120.  You can get them off E-bay for around $50.00 and they offer a lot more torque than the stock board and will also give you more RPM.  I replaced my board with the KB 120 a few years ago and love it.  It's a very good board and pretty easy to wire up.  I would never go back to the stock board after using the KBIC 120.

Dale P.

[andyf]

Lykle, you're in Cyprus, so on 230VAC mains, and your motor will be 180VDC or thereabouts.  You would need a KBIC 240 board if your motor is under 1HP (750W) or a KBIC 240D if between 1 and 2HP. "Horsepower resistor" to suit the motor, as shown on page 8 of this manual:
http://www.kbelectronics.com/manuals/kbic_manual.pdf .

KBIC 120s are for 115VAC mains and 90VDC motors.

Andy

[John Rudd]

Guys, think you may be missing the point...?

He already has a KBIC board but its broken and he wants to repair it......

I've sent him the schematics to aid recovery but being in Cyprus doesnt help a great deal for spares or even getting a new board. 


(Although I have spare boards and have offered him that option.      )

[ibuildstuff4u]

John,  Your right, repairing the board is the most rewarding and cheapest option, but if all else fails, I would go with the KBIC 240 board instead of looking for the same one to replace it with as the KBIC 240 seems to offer more torque and RPM.  It will also remove the annoying safety that makes you turn the speed control to 0 every time you restart your mill.

My speed control went out in my CNC lathe last month and the guys here help me fix it.  It was very rewarding to be able to fix it my self and it also saved me some cash as the parts were pretty cheap.

Good luck!
Dale P.